| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * kernel/sched/core.c |
| 4 | * |
| 5 | * Core kernel scheduler code and related syscalls |
| 6 | * |
| 7 | * Copyright (C) 1991-2002 Linus Torvalds |
| 8 | */ |
| 9 | #include "sched.h" |
| 10 | |
| 11 | #include <linux/nospec.h> |
| 12 | |
| 13 | #include <linux/kcov.h> |
| 14 | |
| 15 | #include <asm/switch_to.h> |
| 16 | #include <asm/tlb.h> |
| 17 | |
| 18 | #include "../workqueue_internal.h" |
| 19 | #include "../smpboot.h" |
| 20 | |
| 21 | #include "pelt.h" |
| 22 | |
| 23 | #define CREATE_TRACE_POINTS |
| 24 | #include <trace/events/sched.h> |
| 25 | |
| 26 | /* |
| 27 | * Export tracepoints that act as a bare tracehook (ie: have no trace event |
| 28 | * associated with them) to allow external modules to probe them. |
| 29 | */ |
| 30 | EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_cfs_tp); |
| 31 | EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp); |
| 32 | EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp); |
| 33 | EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp); |
| 34 | EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp); |
| 35 | EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp); |
| 36 | |
| 37 | DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); |
| 38 | |
| 39 | #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_JUMP_LABEL) |
| 40 | /* |
| 41 | * Debugging: various feature bits |
| 42 | * |
| 43 | * If SCHED_DEBUG is disabled, each compilation unit has its own copy of |
| 44 | * sysctl_sched_features, defined in sched.h, to allow constants propagation |
| 45 | * at compile time and compiler optimization based on features default. |
| 46 | */ |
| 47 | #define SCHED_FEAT(name, enabled) \ |
| 48 | (1UL << __SCHED_FEAT_##name) * enabled | |
| 49 | const_debug unsigned int sysctl_sched_features = |
| 50 | #include "features.h" |
| 51 | 0; |
| 52 | #undef SCHED_FEAT |
| 53 | #endif |
| 54 | |
| 55 | /* |
| 56 | * Number of tasks to iterate in a single balance run. |
| 57 | * Limited because this is done with IRQs disabled. |
| 58 | */ |
| 59 | const_debug unsigned int sysctl_sched_nr_migrate = 32; |
| 60 | |
| 61 | /* |
| 62 | * period over which we measure -rt task CPU usage in us. |
| 63 | * default: 1s |
| 64 | */ |
| 65 | unsigned int sysctl_sched_rt_period = 1000000; |
| 66 | |
| 67 | __read_mostly int scheduler_running; |
| 68 | |
| 69 | /* |
| 70 | * part of the period that we allow rt tasks to run in us. |
| 71 | * default: 0.95s |
| 72 | */ |
| 73 | int sysctl_sched_rt_runtime = 950000; |
| 74 | |
| 75 | /* |
| 76 | * __task_rq_lock - lock the rq @p resides on. |
| 77 | */ |
| 78 | struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) |
| 79 | __acquires(rq->lock) |
| 80 | { |
| 81 | struct rq *rq; |
| 82 | |
| 83 | lockdep_assert_held(&p->pi_lock); |
| 84 | |
| 85 | for (;;) { |
| 86 | rq = task_rq(p); |
| 87 | raw_spin_lock(&rq->lock); |
| 88 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { |
| 89 | rq_pin_lock(rq, rf); |
| 90 | return rq; |
| 91 | } |
| 92 | raw_spin_unlock(&rq->lock); |
| 93 | |
| 94 | while (unlikely(task_on_rq_migrating(p))) |
| 95 | cpu_relax(); |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. |
| 101 | */ |
| 102 | struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) |
| 103 | __acquires(p->pi_lock) |
| 104 | __acquires(rq->lock) |
| 105 | { |
| 106 | struct rq *rq; |
| 107 | |
| 108 | for (;;) { |
| 109 | raw_spin_lock_irqsave(&p->pi_lock, rf->flags); |
| 110 | rq = task_rq(p); |
| 111 | raw_spin_lock(&rq->lock); |
| 112 | /* |
| 113 | * move_queued_task() task_rq_lock() |
| 114 | * |
| 115 | * ACQUIRE (rq->lock) |
| 116 | * [S] ->on_rq = MIGRATING [L] rq = task_rq() |
| 117 | * WMB (__set_task_cpu()) ACQUIRE (rq->lock); |
| 118 | * [S] ->cpu = new_cpu [L] task_rq() |
| 119 | * [L] ->on_rq |
| 120 | * RELEASE (rq->lock) |
| 121 | * |
| 122 | * If we observe the old CPU in task_rq_lock(), the acquire of |
| 123 | * the old rq->lock will fully serialize against the stores. |
| 124 | * |
| 125 | * If we observe the new CPU in task_rq_lock(), the address |
| 126 | * dependency headed by '[L] rq = task_rq()' and the acquire |
| 127 | * will pair with the WMB to ensure we then also see migrating. |
| 128 | */ |
| 129 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { |
| 130 | rq_pin_lock(rq, rf); |
| 131 | return rq; |
| 132 | } |
| 133 | raw_spin_unlock(&rq->lock); |
| 134 | raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); |
| 135 | |
| 136 | while (unlikely(task_on_rq_migrating(p))) |
| 137 | cpu_relax(); |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | /* |
| 142 | * RQ-clock updating methods: |
| 143 | */ |
| 144 | |
| 145 | static void update_rq_clock_task(struct rq *rq, s64 delta) |
| 146 | { |
| 147 | /* |
| 148 | * In theory, the compile should just see 0 here, and optimize out the call |
| 149 | * to sched_rt_avg_update. But I don't trust it... |
| 150 | */ |
| 151 | s64 __maybe_unused steal = 0, irq_delta = 0; |
| 152 | |
| 153 | #ifdef CONFIG_IRQ_TIME_ACCOUNTING |
| 154 | irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; |
| 155 | |
| 156 | /* |
| 157 | * Since irq_time is only updated on {soft,}irq_exit, we might run into |
| 158 | * this case when a previous update_rq_clock() happened inside a |
| 159 | * {soft,}irq region. |
| 160 | * |
| 161 | * When this happens, we stop ->clock_task and only update the |
| 162 | * prev_irq_time stamp to account for the part that fit, so that a next |
| 163 | * update will consume the rest. This ensures ->clock_task is |
| 164 | * monotonic. |
| 165 | * |
| 166 | * It does however cause some slight miss-attribution of {soft,}irq |
| 167 | * time, a more accurate solution would be to update the irq_time using |
| 168 | * the current rq->clock timestamp, except that would require using |
| 169 | * atomic ops. |
| 170 | */ |
| 171 | if (irq_delta > delta) |
| 172 | irq_delta = delta; |
| 173 | |
| 174 | rq->prev_irq_time += irq_delta; |
| 175 | delta -= irq_delta; |
| 176 | #endif |
| 177 | #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING |
| 178 | if (static_key_false((¶virt_steal_rq_enabled))) { |
| 179 | steal = paravirt_steal_clock(cpu_of(rq)); |
| 180 | steal -= rq->prev_steal_time_rq; |
| 181 | |
| 182 | if (unlikely(steal > delta)) |
| 183 | steal = delta; |
| 184 | |
| 185 | rq->prev_steal_time_rq += steal; |
| 186 | delta -= steal; |
| 187 | } |
| 188 | #endif |
| 189 | |
| 190 | rq->clock_task += delta; |
| 191 | |
| 192 | #ifdef CONFIG_HAVE_SCHED_AVG_IRQ |
| 193 | if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) |
| 194 | update_irq_load_avg(rq, irq_delta + steal); |
| 195 | #endif |
| 196 | update_rq_clock_pelt(rq, delta); |
| 197 | } |
| 198 | |
| 199 | void update_rq_clock(struct rq *rq) |
| 200 | { |
| 201 | s64 delta; |
| 202 | |
| 203 | lockdep_assert_held(&rq->lock); |
| 204 | |
| 205 | if (rq->clock_update_flags & RQCF_ACT_SKIP) |
| 206 | return; |
| 207 | |
| 208 | #ifdef CONFIG_SCHED_DEBUG |
| 209 | if (sched_feat(WARN_DOUBLE_CLOCK)) |
| 210 | SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); |
| 211 | rq->clock_update_flags |= RQCF_UPDATED; |
| 212 | #endif |
| 213 | |
| 214 | delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; |
| 215 | if (delta < 0) |
| 216 | return; |
| 217 | rq->clock += delta; |
| 218 | update_rq_clock_task(rq, delta); |
| 219 | } |
| 220 | |
| 221 | |
| 222 | #ifdef CONFIG_SCHED_HRTICK |
| 223 | /* |
| 224 | * Use HR-timers to deliver accurate preemption points. |
| 225 | */ |
| 226 | |
| 227 | static void hrtick_clear(struct rq *rq) |
| 228 | { |
| 229 | if (hrtimer_active(&rq->hrtick_timer)) |
| 230 | hrtimer_cancel(&rq->hrtick_timer); |
| 231 | } |
| 232 | |
| 233 | /* |
| 234 | * High-resolution timer tick. |
| 235 | * Runs from hardirq context with interrupts disabled. |
| 236 | */ |
| 237 | static enum hrtimer_restart hrtick(struct hrtimer *timer) |
| 238 | { |
| 239 | struct rq *rq = container_of(timer, struct rq, hrtick_timer); |
| 240 | struct rq_flags rf; |
| 241 | |
| 242 | WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); |
| 243 | |
| 244 | rq_lock(rq, &rf); |
| 245 | update_rq_clock(rq); |
| 246 | rq->curr->sched_class->task_tick(rq, rq->curr, 1); |
| 247 | rq_unlock(rq, &rf); |
| 248 | |
| 249 | return HRTIMER_NORESTART; |
| 250 | } |
| 251 | |
| 252 | #ifdef CONFIG_SMP |
| 253 | |
| 254 | static void __hrtick_restart(struct rq *rq) |
| 255 | { |
| 256 | struct hrtimer *timer = &rq->hrtick_timer; |
| 257 | |
| 258 | hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD); |
| 259 | } |
| 260 | |
| 261 | /* |
| 262 | * called from hardirq (IPI) context |
| 263 | */ |
| 264 | static void __hrtick_start(void *arg) |
| 265 | { |
| 266 | struct rq *rq = arg; |
| 267 | struct rq_flags rf; |
| 268 | |
| 269 | rq_lock(rq, &rf); |
| 270 | __hrtick_restart(rq); |
| 271 | rq->hrtick_csd_pending = 0; |
| 272 | rq_unlock(rq, &rf); |
| 273 | } |
| 274 | |
| 275 | /* |
| 276 | * Called to set the hrtick timer state. |
| 277 | * |
| 278 | * called with rq->lock held and irqs disabled |
| 279 | */ |
| 280 | void hrtick_start(struct rq *rq, u64 delay) |
| 281 | { |
| 282 | struct hrtimer *timer = &rq->hrtick_timer; |
| 283 | ktime_t time; |
| 284 | s64 delta; |
| 285 | |
| 286 | /* |
| 287 | * Don't schedule slices shorter than 10000ns, that just |
| 288 | * doesn't make sense and can cause timer DoS. |
| 289 | */ |
| 290 | delta = max_t(s64, delay, 10000LL); |
| 291 | time = ktime_add_ns(timer->base->get_time(), delta); |
| 292 | |
| 293 | hrtimer_set_expires(timer, time); |
| 294 | |
| 295 | if (rq == this_rq()) { |
| 296 | __hrtick_restart(rq); |
| 297 | } else if (!rq->hrtick_csd_pending) { |
| 298 | smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); |
| 299 | rq->hrtick_csd_pending = 1; |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | #else |
| 304 | /* |
| 305 | * Called to set the hrtick timer state. |
| 306 | * |
| 307 | * called with rq->lock held and irqs disabled |
| 308 | */ |
| 309 | void hrtick_start(struct rq *rq, u64 delay) |
| 310 | { |
| 311 | /* |
| 312 | * Don't schedule slices shorter than 10000ns, that just |
| 313 | * doesn't make sense. Rely on vruntime for fairness. |
| 314 | */ |
| 315 | delay = max_t(u64, delay, 10000LL); |
| 316 | hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), |
| 317 | HRTIMER_MODE_REL_PINNED_HARD); |
| 318 | } |
| 319 | #endif /* CONFIG_SMP */ |
| 320 | |
| 321 | static void hrtick_rq_init(struct rq *rq) |
| 322 | { |
| 323 | #ifdef CONFIG_SMP |
| 324 | rq->hrtick_csd_pending = 0; |
| 325 | |
| 326 | rq->hrtick_csd.flags = 0; |
| 327 | rq->hrtick_csd.func = __hrtick_start; |
| 328 | rq->hrtick_csd.info = rq; |
| 329 | #endif |
| 330 | |
| 331 | hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); |
| 332 | rq->hrtick_timer.function = hrtick; |
| 333 | } |
| 334 | #else /* CONFIG_SCHED_HRTICK */ |
| 335 | static inline void hrtick_clear(struct rq *rq) |
| 336 | { |
| 337 | } |
| 338 | |
| 339 | static inline void hrtick_rq_init(struct rq *rq) |
| 340 | { |
| 341 | } |
| 342 | #endif /* CONFIG_SCHED_HRTICK */ |
| 343 | |
| 344 | /* |
| 345 | * cmpxchg based fetch_or, macro so it works for different integer types |
| 346 | */ |
| 347 | #define fetch_or(ptr, mask) \ |
| 348 | ({ \ |
| 349 | typeof(ptr) _ptr = (ptr); \ |
| 350 | typeof(mask) _mask = (mask); \ |
| 351 | typeof(*_ptr) _old, _val = *_ptr; \ |
| 352 | \ |
| 353 | for (;;) { \ |
| 354 | _old = cmpxchg(_ptr, _val, _val | _mask); \ |
| 355 | if (_old == _val) \ |
| 356 | break; \ |
| 357 | _val = _old; \ |
| 358 | } \ |
| 359 | _old; \ |
| 360 | }) |
| 361 | |
| 362 | #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) |
| 363 | /* |
| 364 | * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, |
| 365 | * this avoids any races wrt polling state changes and thereby avoids |
| 366 | * spurious IPIs. |
| 367 | */ |
| 368 | static bool set_nr_and_not_polling(struct task_struct *p) |
| 369 | { |
| 370 | struct thread_info *ti = task_thread_info(p); |
| 371 | return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG); |
| 372 | } |
| 373 | |
| 374 | /* |
| 375 | * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. |
| 376 | * |
| 377 | * If this returns true, then the idle task promises to call |
| 378 | * sched_ttwu_pending() and reschedule soon. |
| 379 | */ |
| 380 | static bool set_nr_if_polling(struct task_struct *p) |
| 381 | { |
| 382 | struct thread_info *ti = task_thread_info(p); |
| 383 | typeof(ti->flags) old, val = READ_ONCE(ti->flags); |
| 384 | |
| 385 | for (;;) { |
| 386 | if (!(val & _TIF_POLLING_NRFLAG)) |
| 387 | return false; |
| 388 | if (val & _TIF_NEED_RESCHED) |
| 389 | return true; |
| 390 | old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); |
| 391 | if (old == val) |
| 392 | break; |
| 393 | val = old; |
| 394 | } |
| 395 | return true; |
| 396 | } |
| 397 | |
| 398 | #else |
| 399 | static bool set_nr_and_not_polling(struct task_struct *p) |
| 400 | { |
| 401 | set_tsk_need_resched(p); |
| 402 | return true; |
| 403 | } |
| 404 | |
| 405 | #ifdef CONFIG_SMP |
| 406 | static bool set_nr_if_polling(struct task_struct *p) |
| 407 | { |
| 408 | return false; |
| 409 | } |
| 410 | #endif |
| 411 | #endif |
| 412 | |
| 413 | static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task) |
| 414 | { |
| 415 | struct wake_q_node *node = &task->wake_q; |
| 416 | |
| 417 | /* |
| 418 | * Atomically grab the task, if ->wake_q is !nil already it means |
| 419 | * its already queued (either by us or someone else) and will get the |
| 420 | * wakeup due to that. |
| 421 | * |
| 422 | * In order to ensure that a pending wakeup will observe our pending |
| 423 | * state, even in the failed case, an explicit smp_mb() must be used. |
| 424 | */ |
| 425 | smp_mb__before_atomic(); |
| 426 | if (unlikely(cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL))) |
| 427 | return false; |
| 428 | |
| 429 | /* |
| 430 | * The head is context local, there can be no concurrency. |
| 431 | */ |
| 432 | *head->lastp = node; |
| 433 | head->lastp = &node->next; |
| 434 | return true; |
| 435 | } |
| 436 | |
| 437 | /** |
| 438 | * wake_q_add() - queue a wakeup for 'later' waking. |
| 439 | * @head: the wake_q_head to add @task to |
| 440 | * @task: the task to queue for 'later' wakeup |
| 441 | * |
| 442 | * Queue a task for later wakeup, most likely by the wake_up_q() call in the |
| 443 | * same context, _HOWEVER_ this is not guaranteed, the wakeup can come |
| 444 | * instantly. |
| 445 | * |
| 446 | * This function must be used as-if it were wake_up_process(); IOW the task |
| 447 | * must be ready to be woken at this location. |
| 448 | */ |
| 449 | void wake_q_add(struct wake_q_head *head, struct task_struct *task) |
| 450 | { |
| 451 | if (__wake_q_add(head, task)) |
| 452 | get_task_struct(task); |
| 453 | } |
| 454 | |
| 455 | /** |
| 456 | * wake_q_add_safe() - safely queue a wakeup for 'later' waking. |
| 457 | * @head: the wake_q_head to add @task to |
| 458 | * @task: the task to queue for 'later' wakeup |
| 459 | * |
| 460 | * Queue a task for later wakeup, most likely by the wake_up_q() call in the |
| 461 | * same context, _HOWEVER_ this is not guaranteed, the wakeup can come |
| 462 | * instantly. |
| 463 | * |
| 464 | * This function must be used as-if it were wake_up_process(); IOW the task |
| 465 | * must be ready to be woken at this location. |
| 466 | * |
| 467 | * This function is essentially a task-safe equivalent to wake_q_add(). Callers |
| 468 | * that already hold reference to @task can call the 'safe' version and trust |
| 469 | * wake_q to do the right thing depending whether or not the @task is already |
| 470 | * queued for wakeup. |
| 471 | */ |
| 472 | void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task) |
| 473 | { |
| 474 | if (!__wake_q_add(head, task)) |
| 475 | put_task_struct(task); |
| 476 | } |
| 477 | |
| 478 | void wake_up_q(struct wake_q_head *head) |
| 479 | { |
| 480 | struct wake_q_node *node = head->first; |
| 481 | |
| 482 | while (node != WAKE_Q_TAIL) { |
| 483 | struct task_struct *task; |
| 484 | |
| 485 | task = container_of(node, struct task_struct, wake_q); |
| 486 | BUG_ON(!task); |
| 487 | /* Task can safely be re-inserted now: */ |
| 488 | node = node->next; |
| 489 | task->wake_q.next = NULL; |
| 490 | |
| 491 | /* |
| 492 | * wake_up_process() executes a full barrier, which pairs with |
| 493 | * the queueing in wake_q_add() so as not to miss wakeups. |
| 494 | */ |
| 495 | wake_up_process(task); |
| 496 | put_task_struct(task); |
| 497 | } |
| 498 | } |
| 499 | |
| 500 | /* |
| 501 | * resched_curr - mark rq's current task 'to be rescheduled now'. |
| 502 | * |
| 503 | * On UP this means the setting of the need_resched flag, on SMP it |
| 504 | * might also involve a cross-CPU call to trigger the scheduler on |
| 505 | * the target CPU. |
| 506 | */ |
| 507 | void resched_curr(struct rq *rq) |
| 508 | { |
| 509 | struct task_struct *curr = rq->curr; |
| 510 | int cpu; |
| 511 | |
| 512 | lockdep_assert_held(&rq->lock); |
| 513 | |
| 514 | if (test_tsk_need_resched(curr)) |
| 515 | return; |
| 516 | |
| 517 | cpu = cpu_of(rq); |
| 518 | |
| 519 | if (cpu == smp_processor_id()) { |
| 520 | set_tsk_need_resched(curr); |
| 521 | set_preempt_need_resched(); |
| 522 | return; |
| 523 | } |
| 524 | |
| 525 | if (set_nr_and_not_polling(curr)) |
| 526 | smp_send_reschedule(cpu); |
| 527 | else |
| 528 | trace_sched_wake_idle_without_ipi(cpu); |
| 529 | } |
| 530 | |
| 531 | void resched_cpu(int cpu) |
| 532 | { |
| 533 | struct rq *rq = cpu_rq(cpu); |
| 534 | unsigned long flags; |
| 535 | |
| 536 | raw_spin_lock_irqsave(&rq->lock, flags); |
| 537 | if (cpu_online(cpu) || cpu == smp_processor_id()) |
| 538 | resched_curr(rq); |
| 539 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
| 540 | } |
| 541 | |
| 542 | #ifdef CONFIG_SMP |
| 543 | #ifdef CONFIG_NO_HZ_COMMON |
| 544 | /* |
| 545 | * In the semi idle case, use the nearest busy CPU for migrating timers |
| 546 | * from an idle CPU. This is good for power-savings. |
| 547 | * |
| 548 | * We don't do similar optimization for completely idle system, as |
| 549 | * selecting an idle CPU will add more delays to the timers than intended |
| 550 | * (as that CPU's timer base may not be uptodate wrt jiffies etc). |
| 551 | */ |
| 552 | int get_nohz_timer_target(void) |
| 553 | { |
| 554 | int i, cpu = smp_processor_id(); |
| 555 | struct sched_domain *sd; |
| 556 | |
| 557 | if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER)) |
| 558 | return cpu; |
| 559 | |
| 560 | rcu_read_lock(); |
| 561 | for_each_domain(cpu, sd) { |
| 562 | for_each_cpu(i, sched_domain_span(sd)) { |
| 563 | if (cpu == i) |
| 564 | continue; |
| 565 | |
| 566 | if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) { |
| 567 | cpu = i; |
| 568 | goto unlock; |
| 569 | } |
| 570 | } |
| 571 | } |
| 572 | |
| 573 | if (!housekeeping_cpu(cpu, HK_FLAG_TIMER)) |
| 574 | cpu = housekeeping_any_cpu(HK_FLAG_TIMER); |
| 575 | unlock: |
| 576 | rcu_read_unlock(); |
| 577 | return cpu; |
| 578 | } |
| 579 | |
| 580 | /* |
| 581 | * When add_timer_on() enqueues a timer into the timer wheel of an |
| 582 | * idle CPU then this timer might expire before the next timer event |
| 583 | * which is scheduled to wake up that CPU. In case of a completely |
| 584 | * idle system the next event might even be infinite time into the |
| 585 | * future. wake_up_idle_cpu() ensures that the CPU is woken up and |
| 586 | * leaves the inner idle loop so the newly added timer is taken into |
| 587 | * account when the CPU goes back to idle and evaluates the timer |
| 588 | * wheel for the next timer event. |
| 589 | */ |
| 590 | static void wake_up_idle_cpu(int cpu) |
| 591 | { |
| 592 | struct rq *rq = cpu_rq(cpu); |
| 593 | |
| 594 | if (cpu == smp_processor_id()) |
| 595 | return; |
| 596 | |
| 597 | if (set_nr_and_not_polling(rq->idle)) |
| 598 | smp_send_reschedule(cpu); |
| 599 | else |
| 600 | trace_sched_wake_idle_without_ipi(cpu); |
| 601 | } |
| 602 | |
| 603 | static bool wake_up_full_nohz_cpu(int cpu) |
| 604 | { |
| 605 | /* |
| 606 | * We just need the target to call irq_exit() and re-evaluate |
| 607 | * the next tick. The nohz full kick at least implies that. |
| 608 | * If needed we can still optimize that later with an |
| 609 | * empty IRQ. |
| 610 | */ |
| 611 | if (cpu_is_offline(cpu)) |
| 612 | return true; /* Don't try to wake offline CPUs. */ |
| 613 | if (tick_nohz_full_cpu(cpu)) { |
| 614 | if (cpu != smp_processor_id() || |
| 615 | tick_nohz_tick_stopped()) |
| 616 | tick_nohz_full_kick_cpu(cpu); |
| 617 | return true; |
| 618 | } |
| 619 | |
| 620 | return false; |
| 621 | } |
| 622 | |
| 623 | /* |
| 624 | * Wake up the specified CPU. If the CPU is going offline, it is the |
| 625 | * caller's responsibility to deal with the lost wakeup, for example, |
| 626 | * by hooking into the CPU_DEAD notifier like timers and hrtimers do. |
| 627 | */ |
| 628 | void wake_up_nohz_cpu(int cpu) |
| 629 | { |
| 630 | if (!wake_up_full_nohz_cpu(cpu)) |
| 631 | wake_up_idle_cpu(cpu); |
| 632 | } |
| 633 | |
| 634 | static inline bool got_nohz_idle_kick(void) |
| 635 | { |
| 636 | int cpu = smp_processor_id(); |
| 637 | |
| 638 | if (!(atomic_read(nohz_flags(cpu)) & NOHZ_KICK_MASK)) |
| 639 | return false; |
| 640 | |
| 641 | if (idle_cpu(cpu) && !need_resched()) |
| 642 | return true; |
| 643 | |
| 644 | /* |
| 645 | * We can't run Idle Load Balance on this CPU for this time so we |
| 646 | * cancel it and clear NOHZ_BALANCE_KICK |
| 647 | */ |
| 648 | atomic_andnot(NOHZ_KICK_MASK, nohz_flags(cpu)); |
| 649 | return false; |
| 650 | } |
| 651 | |
| 652 | #else /* CONFIG_NO_HZ_COMMON */ |
| 653 | |
| 654 | static inline bool got_nohz_idle_kick(void) |
| 655 | { |
| 656 | return false; |
| 657 | } |
| 658 | |
| 659 | #endif /* CONFIG_NO_HZ_COMMON */ |
| 660 | |
| 661 | #ifdef CONFIG_NO_HZ_FULL |
| 662 | bool sched_can_stop_tick(struct rq *rq) |
| 663 | { |
| 664 | int fifo_nr_running; |
| 665 | |
| 666 | /* Deadline tasks, even if single, need the tick */ |
| 667 | if (rq->dl.dl_nr_running) |
| 668 | return false; |
| 669 | |
| 670 | /* |
| 671 | * If there are more than one RR tasks, we need the tick to effect the |
| 672 | * actual RR behaviour. |
| 673 | */ |
| 674 | if (rq->rt.rr_nr_running) { |
| 675 | if (rq->rt.rr_nr_running == 1) |
| 676 | return true; |
| 677 | else |
| 678 | return false; |
| 679 | } |
| 680 | |
| 681 | /* |
| 682 | * If there's no RR tasks, but FIFO tasks, we can skip the tick, no |
| 683 | * forced preemption between FIFO tasks. |
| 684 | */ |
| 685 | fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running; |
| 686 | if (fifo_nr_running) |
| 687 | return true; |
| 688 | |
| 689 | /* |
| 690 | * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left; |
| 691 | * if there's more than one we need the tick for involuntary |
| 692 | * preemption. |
| 693 | */ |
| 694 | if (rq->nr_running > 1) |
| 695 | return false; |
| 696 | |
| 697 | return true; |
| 698 | } |
| 699 | #endif /* CONFIG_NO_HZ_FULL */ |
| 700 | #endif /* CONFIG_SMP */ |
| 701 | |
| 702 | #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ |
| 703 | (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) |
| 704 | /* |
| 705 | * Iterate task_group tree rooted at *from, calling @down when first entering a |
| 706 | * node and @up when leaving it for the final time. |
| 707 | * |
| 708 | * Caller must hold rcu_lock or sufficient equivalent. |
| 709 | */ |
| 710 | int walk_tg_tree_from(struct task_group *from, |
| 711 | tg_visitor down, tg_visitor up, void *data) |
| 712 | { |
| 713 | struct task_group *parent, *child; |
| 714 | int ret; |
| 715 | |
| 716 | parent = from; |
| 717 | |
| 718 | down: |
| 719 | ret = (*down)(parent, data); |
| 720 | if (ret) |
| 721 | goto out; |
| 722 | list_for_each_entry_rcu(child, &parent->children, siblings) { |
| 723 | parent = child; |
| 724 | goto down; |
| 725 | |
| 726 | up: |
| 727 | continue; |
| 728 | } |
| 729 | ret = (*up)(parent, data); |
| 730 | if (ret || parent == from) |
| 731 | goto out; |
| 732 | |
| 733 | child = parent; |
| 734 | parent = parent->parent; |
| 735 | if (parent) |
| 736 | goto up; |
| 737 | out: |
| 738 | return ret; |
| 739 | } |
| 740 | |
| 741 | int tg_nop(struct task_group *tg, void *data) |
| 742 | { |
| 743 | return 0; |
| 744 | } |
| 745 | #endif |
| 746 | |
| 747 | static void set_load_weight(struct task_struct *p, bool update_load) |
| 748 | { |
| 749 | int prio = p->static_prio - MAX_RT_PRIO; |
| 750 | struct load_weight *load = &p->se.load; |
| 751 | |
| 752 | /* |
| 753 | * SCHED_IDLE tasks get minimal weight: |
| 754 | */ |
| 755 | if (task_has_idle_policy(p)) { |
| 756 | load->weight = scale_load(WEIGHT_IDLEPRIO); |
| 757 | load->inv_weight = WMULT_IDLEPRIO; |
| 758 | p->se.runnable_weight = load->weight; |
| 759 | return; |
| 760 | } |
| 761 | |
| 762 | /* |
| 763 | * SCHED_OTHER tasks have to update their load when changing their |
| 764 | * weight |
| 765 | */ |
| 766 | if (update_load && p->sched_class == &fair_sched_class) { |
| 767 | reweight_task(p, prio); |
| 768 | } else { |
| 769 | load->weight = scale_load(sched_prio_to_weight[prio]); |
| 770 | load->inv_weight = sched_prio_to_wmult[prio]; |
| 771 | p->se.runnable_weight = load->weight; |
| 772 | } |
| 773 | } |
| 774 | |
| 775 | #ifdef CONFIG_UCLAMP_TASK |
| 776 | /* |
| 777 | * Serializes updates of utilization clamp values |
| 778 | * |
| 779 | * The (slow-path) user-space triggers utilization clamp value updates which |
| 780 | * can require updates on (fast-path) scheduler's data structures used to |
| 781 | * support enqueue/dequeue operations. |
| 782 | * While the per-CPU rq lock protects fast-path update operations, user-space |
| 783 | * requests are serialized using a mutex to reduce the risk of conflicting |
| 784 | * updates or API abuses. |
| 785 | */ |
| 786 | static DEFINE_MUTEX(uclamp_mutex); |
| 787 | |
| 788 | /* Max allowed minimum utilization */ |
| 789 | unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE; |
| 790 | |
| 791 | /* Max allowed maximum utilization */ |
| 792 | unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE; |
| 793 | |
| 794 | /* All clamps are required to be less or equal than these values */ |
| 795 | static struct uclamp_se uclamp_default[UCLAMP_CNT]; |
| 796 | |
| 797 | /* Integer rounded range for each bucket */ |
| 798 | #define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS) |
| 799 | |
| 800 | #define for_each_clamp_id(clamp_id) \ |
| 801 | for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++) |
| 802 | |
| 803 | static inline unsigned int uclamp_bucket_id(unsigned int clamp_value) |
| 804 | { |
| 805 | return clamp_value / UCLAMP_BUCKET_DELTA; |
| 806 | } |
| 807 | |
| 808 | static inline unsigned int uclamp_bucket_base_value(unsigned int clamp_value) |
| 809 | { |
| 810 | return UCLAMP_BUCKET_DELTA * uclamp_bucket_id(clamp_value); |
| 811 | } |
| 812 | |
| 813 | static inline enum uclamp_id uclamp_none(enum uclamp_id clamp_id) |
| 814 | { |
| 815 | if (clamp_id == UCLAMP_MIN) |
| 816 | return 0; |
| 817 | return SCHED_CAPACITY_SCALE; |
| 818 | } |
| 819 | |
| 820 | static inline void uclamp_se_set(struct uclamp_se *uc_se, |
| 821 | unsigned int value, bool user_defined) |
| 822 | { |
| 823 | uc_se->value = value; |
| 824 | uc_se->bucket_id = uclamp_bucket_id(value); |
| 825 | uc_se->user_defined = user_defined; |
| 826 | } |
| 827 | |
| 828 | static inline unsigned int |
| 829 | uclamp_idle_value(struct rq *rq, enum uclamp_id clamp_id, |
| 830 | unsigned int clamp_value) |
| 831 | { |
| 832 | /* |
| 833 | * Avoid blocked utilization pushing up the frequency when we go |
| 834 | * idle (which drops the max-clamp) by retaining the last known |
| 835 | * max-clamp. |
| 836 | */ |
| 837 | if (clamp_id == UCLAMP_MAX) { |
| 838 | rq->uclamp_flags |= UCLAMP_FLAG_IDLE; |
| 839 | return clamp_value; |
| 840 | } |
| 841 | |
| 842 | return uclamp_none(UCLAMP_MIN); |
| 843 | } |
| 844 | |
| 845 | static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id, |
| 846 | unsigned int clamp_value) |
| 847 | { |
| 848 | /* Reset max-clamp retention only on idle exit */ |
| 849 | if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE)) |
| 850 | return; |
| 851 | |
| 852 | WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value); |
| 853 | } |
| 854 | |
| 855 | static inline |
| 856 | enum uclamp_id uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id, |
| 857 | unsigned int clamp_value) |
| 858 | { |
| 859 | struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket; |
| 860 | int bucket_id = UCLAMP_BUCKETS - 1; |
| 861 | |
| 862 | /* |
| 863 | * Since both min and max clamps are max aggregated, find the |
| 864 | * top most bucket with tasks in. |
| 865 | */ |
| 866 | for ( ; bucket_id >= 0; bucket_id--) { |
| 867 | if (!bucket[bucket_id].tasks) |
| 868 | continue; |
| 869 | return bucket[bucket_id].value; |
| 870 | } |
| 871 | |
| 872 | /* No tasks -- default clamp values */ |
| 873 | return uclamp_idle_value(rq, clamp_id, clamp_value); |
| 874 | } |
| 875 | |
| 876 | static inline struct uclamp_se |
| 877 | uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id) |
| 878 | { |
| 879 | struct uclamp_se uc_req = p->uclamp_req[clamp_id]; |
| 880 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 881 | struct uclamp_se uc_max; |
| 882 | |
| 883 | /* |
| 884 | * Tasks in autogroups or root task group will be |
| 885 | * restricted by system defaults. |
| 886 | */ |
| 887 | if (task_group_is_autogroup(task_group(p))) |
| 888 | return uc_req; |
| 889 | if (task_group(p) == &root_task_group) |
| 890 | return uc_req; |
| 891 | |
| 892 | uc_max = task_group(p)->uclamp[clamp_id]; |
| 893 | if (uc_req.value > uc_max.value || !uc_req.user_defined) |
| 894 | return uc_max; |
| 895 | #endif |
| 896 | |
| 897 | return uc_req; |
| 898 | } |
| 899 | |
| 900 | /* |
| 901 | * The effective clamp bucket index of a task depends on, by increasing |
| 902 | * priority: |
| 903 | * - the task specific clamp value, when explicitly requested from userspace |
| 904 | * - the task group effective clamp value, for tasks not either in the root |
| 905 | * group or in an autogroup |
| 906 | * - the system default clamp value, defined by the sysadmin |
| 907 | */ |
| 908 | static inline struct uclamp_se |
| 909 | uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id) |
| 910 | { |
| 911 | struct uclamp_se uc_req = uclamp_tg_restrict(p, clamp_id); |
| 912 | struct uclamp_se uc_max = uclamp_default[clamp_id]; |
| 913 | |
| 914 | /* System default restrictions always apply */ |
| 915 | if (unlikely(uc_req.value > uc_max.value)) |
| 916 | return uc_max; |
| 917 | |
| 918 | return uc_req; |
| 919 | } |
| 920 | |
| 921 | enum uclamp_id uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id) |
| 922 | { |
| 923 | struct uclamp_se uc_eff; |
| 924 | |
| 925 | /* Task currently refcounted: use back-annotated (effective) value */ |
| 926 | if (p->uclamp[clamp_id].active) |
| 927 | return p->uclamp[clamp_id].value; |
| 928 | |
| 929 | uc_eff = uclamp_eff_get(p, clamp_id); |
| 930 | |
| 931 | return uc_eff.value; |
| 932 | } |
| 933 | |
| 934 | /* |
| 935 | * When a task is enqueued on a rq, the clamp bucket currently defined by the |
| 936 | * task's uclamp::bucket_id is refcounted on that rq. This also immediately |
| 937 | * updates the rq's clamp value if required. |
| 938 | * |
| 939 | * Tasks can have a task-specific value requested from user-space, track |
| 940 | * within each bucket the maximum value for tasks refcounted in it. |
| 941 | * This "local max aggregation" allows to track the exact "requested" value |
| 942 | * for each bucket when all its RUNNABLE tasks require the same clamp. |
| 943 | */ |
| 944 | static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p, |
| 945 | enum uclamp_id clamp_id) |
| 946 | { |
| 947 | struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id]; |
| 948 | struct uclamp_se *uc_se = &p->uclamp[clamp_id]; |
| 949 | struct uclamp_bucket *bucket; |
| 950 | |
| 951 | lockdep_assert_held(&rq->lock); |
| 952 | |
| 953 | /* Update task effective clamp */ |
| 954 | p->uclamp[clamp_id] = uclamp_eff_get(p, clamp_id); |
| 955 | |
| 956 | bucket = &uc_rq->bucket[uc_se->bucket_id]; |
| 957 | bucket->tasks++; |
| 958 | uc_se->active = true; |
| 959 | |
| 960 | uclamp_idle_reset(rq, clamp_id, uc_se->value); |
| 961 | |
| 962 | /* |
| 963 | * Local max aggregation: rq buckets always track the max |
| 964 | * "requested" clamp value of its RUNNABLE tasks. |
| 965 | */ |
| 966 | if (bucket->tasks == 1 || uc_se->value > bucket->value) |
| 967 | bucket->value = uc_se->value; |
| 968 | |
| 969 | if (uc_se->value > READ_ONCE(uc_rq->value)) |
| 970 | WRITE_ONCE(uc_rq->value, uc_se->value); |
| 971 | } |
| 972 | |
| 973 | /* |
| 974 | * When a task is dequeued from a rq, the clamp bucket refcounted by the task |
| 975 | * is released. If this is the last task reference counting the rq's max |
| 976 | * active clamp value, then the rq's clamp value is updated. |
| 977 | * |
| 978 | * Both refcounted tasks and rq's cached clamp values are expected to be |
| 979 | * always valid. If it's detected they are not, as defensive programming, |
| 980 | * enforce the expected state and warn. |
| 981 | */ |
| 982 | static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, |
| 983 | enum uclamp_id clamp_id) |
| 984 | { |
| 985 | struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id]; |
| 986 | struct uclamp_se *uc_se = &p->uclamp[clamp_id]; |
| 987 | struct uclamp_bucket *bucket; |
| 988 | unsigned int bkt_clamp; |
| 989 | unsigned int rq_clamp; |
| 990 | |
| 991 | lockdep_assert_held(&rq->lock); |
| 992 | |
| 993 | bucket = &uc_rq->bucket[uc_se->bucket_id]; |
| 994 | SCHED_WARN_ON(!bucket->tasks); |
| 995 | if (likely(bucket->tasks)) |
| 996 | bucket->tasks--; |
| 997 | uc_se->active = false; |
| 998 | |
| 999 | /* |
| 1000 | * Keep "local max aggregation" simple and accept to (possibly) |
| 1001 | * overboost some RUNNABLE tasks in the same bucket. |
| 1002 | * The rq clamp bucket value is reset to its base value whenever |
| 1003 | * there are no more RUNNABLE tasks refcounting it. |
| 1004 | */ |
| 1005 | if (likely(bucket->tasks)) |
| 1006 | return; |
| 1007 | |
| 1008 | rq_clamp = READ_ONCE(uc_rq->value); |
| 1009 | /* |
| 1010 | * Defensive programming: this should never happen. If it happens, |
| 1011 | * e.g. due to future modification, warn and fixup the expected value. |
| 1012 | */ |
| 1013 | SCHED_WARN_ON(bucket->value > rq_clamp); |
| 1014 | if (bucket->value >= rq_clamp) { |
| 1015 | bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value); |
| 1016 | WRITE_ONCE(uc_rq->value, bkt_clamp); |
| 1017 | } |
| 1018 | } |
| 1019 | |
| 1020 | static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) |
| 1021 | { |
| 1022 | enum uclamp_id clamp_id; |
| 1023 | |
| 1024 | if (unlikely(!p->sched_class->uclamp_enabled)) |
| 1025 | return; |
| 1026 | |
| 1027 | for_each_clamp_id(clamp_id) |
| 1028 | uclamp_rq_inc_id(rq, p, clamp_id); |
| 1029 | |
| 1030 | /* Reset clamp idle holding when there is one RUNNABLE task */ |
| 1031 | if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) |
| 1032 | rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE; |
| 1033 | } |
| 1034 | |
| 1035 | static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) |
| 1036 | { |
| 1037 | enum uclamp_id clamp_id; |
| 1038 | |
| 1039 | if (unlikely(!p->sched_class->uclamp_enabled)) |
| 1040 | return; |
| 1041 | |
| 1042 | for_each_clamp_id(clamp_id) |
| 1043 | uclamp_rq_dec_id(rq, p, clamp_id); |
| 1044 | } |
| 1045 | |
| 1046 | static inline void |
| 1047 | uclamp_update_active(struct task_struct *p, enum uclamp_id clamp_id) |
| 1048 | { |
| 1049 | struct rq_flags rf; |
| 1050 | struct rq *rq; |
| 1051 | |
| 1052 | /* |
| 1053 | * Lock the task and the rq where the task is (or was) queued. |
| 1054 | * |
| 1055 | * We might lock the (previous) rq of a !RUNNABLE task, but that's the |
| 1056 | * price to pay to safely serialize util_{min,max} updates with |
| 1057 | * enqueues, dequeues and migration operations. |
| 1058 | * This is the same locking schema used by __set_cpus_allowed_ptr(). |
| 1059 | */ |
| 1060 | rq = task_rq_lock(p, &rf); |
| 1061 | |
| 1062 | /* |
| 1063 | * Setting the clamp bucket is serialized by task_rq_lock(). |
| 1064 | * If the task is not yet RUNNABLE and its task_struct is not |
| 1065 | * affecting a valid clamp bucket, the next time it's enqueued, |
| 1066 | * it will already see the updated clamp bucket value. |
| 1067 | */ |
| 1068 | if (!p->uclamp[clamp_id].active) { |
| 1069 | uclamp_rq_dec_id(rq, p, clamp_id); |
| 1070 | uclamp_rq_inc_id(rq, p, clamp_id); |
| 1071 | } |
| 1072 | |
| 1073 | task_rq_unlock(rq, p, &rf); |
| 1074 | } |
| 1075 | |
| 1076 | static inline void |
| 1077 | uclamp_update_active_tasks(struct cgroup_subsys_state *css, |
| 1078 | unsigned int clamps) |
| 1079 | { |
| 1080 | enum uclamp_id clamp_id; |
| 1081 | struct css_task_iter it; |
| 1082 | struct task_struct *p; |
| 1083 | |
| 1084 | css_task_iter_start(css, 0, &it); |
| 1085 | while ((p = css_task_iter_next(&it))) { |
| 1086 | for_each_clamp_id(clamp_id) { |
| 1087 | if ((0x1 << clamp_id) & clamps) |
| 1088 | uclamp_update_active(p, clamp_id); |
| 1089 | } |
| 1090 | } |
| 1091 | css_task_iter_end(&it); |
| 1092 | } |
| 1093 | |
| 1094 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 1095 | static void cpu_util_update_eff(struct cgroup_subsys_state *css); |
| 1096 | static void uclamp_update_root_tg(void) |
| 1097 | { |
| 1098 | struct task_group *tg = &root_task_group; |
| 1099 | |
| 1100 | uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN], |
| 1101 | sysctl_sched_uclamp_util_min, false); |
| 1102 | uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX], |
| 1103 | sysctl_sched_uclamp_util_max, false); |
| 1104 | |
| 1105 | rcu_read_lock(); |
| 1106 | cpu_util_update_eff(&root_task_group.css); |
| 1107 | rcu_read_unlock(); |
| 1108 | } |
| 1109 | #else |
| 1110 | static void uclamp_update_root_tg(void) { } |
| 1111 | #endif |
| 1112 | |
| 1113 | int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, |
| 1114 | void __user *buffer, size_t *lenp, |
| 1115 | loff_t *ppos) |
| 1116 | { |
| 1117 | bool update_root_tg = false; |
| 1118 | int old_min, old_max; |
| 1119 | int result; |
| 1120 | |
| 1121 | mutex_lock(&uclamp_mutex); |
| 1122 | old_min = sysctl_sched_uclamp_util_min; |
| 1123 | old_max = sysctl_sched_uclamp_util_max; |
| 1124 | |
| 1125 | result = proc_dointvec(table, write, buffer, lenp, ppos); |
| 1126 | if (result) |
| 1127 | goto undo; |
| 1128 | if (!write) |
| 1129 | goto done; |
| 1130 | |
| 1131 | if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max || |
| 1132 | sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE) { |
| 1133 | result = -EINVAL; |
| 1134 | goto undo; |
| 1135 | } |
| 1136 | |
| 1137 | if (old_min != sysctl_sched_uclamp_util_min) { |
| 1138 | uclamp_se_set(&uclamp_default[UCLAMP_MIN], |
| 1139 | sysctl_sched_uclamp_util_min, false); |
| 1140 | update_root_tg = true; |
| 1141 | } |
| 1142 | if (old_max != sysctl_sched_uclamp_util_max) { |
| 1143 | uclamp_se_set(&uclamp_default[UCLAMP_MAX], |
| 1144 | sysctl_sched_uclamp_util_max, false); |
| 1145 | update_root_tg = true; |
| 1146 | } |
| 1147 | |
| 1148 | if (update_root_tg) |
| 1149 | uclamp_update_root_tg(); |
| 1150 | |
| 1151 | /* |
| 1152 | * We update all RUNNABLE tasks only when task groups are in use. |
| 1153 | * Otherwise, keep it simple and do just a lazy update at each next |
| 1154 | * task enqueue time. |
| 1155 | */ |
| 1156 | |
| 1157 | goto done; |
| 1158 | |
| 1159 | undo: |
| 1160 | sysctl_sched_uclamp_util_min = old_min; |
| 1161 | sysctl_sched_uclamp_util_max = old_max; |
| 1162 | done: |
| 1163 | mutex_unlock(&uclamp_mutex); |
| 1164 | |
| 1165 | return result; |
| 1166 | } |
| 1167 | |
| 1168 | static int uclamp_validate(struct task_struct *p, |
| 1169 | const struct sched_attr *attr) |
| 1170 | { |
| 1171 | unsigned int lower_bound = p->uclamp_req[UCLAMP_MIN].value; |
| 1172 | unsigned int upper_bound = p->uclamp_req[UCLAMP_MAX].value; |
| 1173 | |
| 1174 | if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) |
| 1175 | lower_bound = attr->sched_util_min; |
| 1176 | if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) |
| 1177 | upper_bound = attr->sched_util_max; |
| 1178 | |
| 1179 | if (lower_bound > upper_bound) |
| 1180 | return -EINVAL; |
| 1181 | if (upper_bound > SCHED_CAPACITY_SCALE) |
| 1182 | return -EINVAL; |
| 1183 | |
| 1184 | return 0; |
| 1185 | } |
| 1186 | |
| 1187 | static void __setscheduler_uclamp(struct task_struct *p, |
| 1188 | const struct sched_attr *attr) |
| 1189 | { |
| 1190 | enum uclamp_id clamp_id; |
| 1191 | |
| 1192 | /* |
| 1193 | * On scheduling class change, reset to default clamps for tasks |
| 1194 | * without a task-specific value. |
| 1195 | */ |
| 1196 | for_each_clamp_id(clamp_id) { |
| 1197 | struct uclamp_se *uc_se = &p->uclamp_req[clamp_id]; |
| 1198 | unsigned int clamp_value = uclamp_none(clamp_id); |
| 1199 | |
| 1200 | /* Keep using defined clamps across class changes */ |
| 1201 | if (uc_se->user_defined) |
| 1202 | continue; |
| 1203 | |
| 1204 | /* By default, RT tasks always get 100% boost */ |
| 1205 | if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) |
| 1206 | clamp_value = uclamp_none(UCLAMP_MAX); |
| 1207 | |
| 1208 | uclamp_se_set(uc_se, clamp_value, false); |
| 1209 | } |
| 1210 | |
| 1211 | if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP))) |
| 1212 | return; |
| 1213 | |
| 1214 | if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) { |
| 1215 | uclamp_se_set(&p->uclamp_req[UCLAMP_MIN], |
| 1216 | attr->sched_util_min, true); |
| 1217 | } |
| 1218 | |
| 1219 | if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) { |
| 1220 | uclamp_se_set(&p->uclamp_req[UCLAMP_MAX], |
| 1221 | attr->sched_util_max, true); |
| 1222 | } |
| 1223 | } |
| 1224 | |
| 1225 | static void uclamp_fork(struct task_struct *p) |
| 1226 | { |
| 1227 | enum uclamp_id clamp_id; |
| 1228 | |
| 1229 | for_each_clamp_id(clamp_id) |
| 1230 | p->uclamp[clamp_id].active = false; |
| 1231 | |
| 1232 | if (likely(!p->sched_reset_on_fork)) |
| 1233 | return; |
| 1234 | |
| 1235 | for_each_clamp_id(clamp_id) { |
| 1236 | unsigned int clamp_value = uclamp_none(clamp_id); |
| 1237 | |
| 1238 | /* By default, RT tasks always get 100% boost */ |
| 1239 | if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) |
| 1240 | clamp_value = uclamp_none(UCLAMP_MAX); |
| 1241 | |
| 1242 | uclamp_se_set(&p->uclamp_req[clamp_id], clamp_value, false); |
| 1243 | } |
| 1244 | } |
| 1245 | |
| 1246 | static void __init init_uclamp(void) |
| 1247 | { |
| 1248 | struct uclamp_se uc_max = {}; |
| 1249 | enum uclamp_id clamp_id; |
| 1250 | int cpu; |
| 1251 | |
| 1252 | mutex_init(&uclamp_mutex); |
| 1253 | |
| 1254 | for_each_possible_cpu(cpu) { |
| 1255 | memset(&cpu_rq(cpu)->uclamp, 0, sizeof(struct uclamp_rq)); |
| 1256 | cpu_rq(cpu)->uclamp_flags = 0; |
| 1257 | } |
| 1258 | |
| 1259 | for_each_clamp_id(clamp_id) { |
| 1260 | uclamp_se_set(&init_task.uclamp_req[clamp_id], |
| 1261 | uclamp_none(clamp_id), false); |
| 1262 | } |
| 1263 | |
| 1264 | /* System defaults allow max clamp values for both indexes */ |
| 1265 | uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX), false); |
| 1266 | for_each_clamp_id(clamp_id) { |
| 1267 | uclamp_default[clamp_id] = uc_max; |
| 1268 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 1269 | root_task_group.uclamp_req[clamp_id] = uc_max; |
| 1270 | root_task_group.uclamp[clamp_id] = uc_max; |
| 1271 | #endif |
| 1272 | } |
| 1273 | } |
| 1274 | |
| 1275 | #else /* CONFIG_UCLAMP_TASK */ |
| 1276 | static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { } |
| 1277 | static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { } |
| 1278 | static inline int uclamp_validate(struct task_struct *p, |
| 1279 | const struct sched_attr *attr) |
| 1280 | { |
| 1281 | return -EOPNOTSUPP; |
| 1282 | } |
| 1283 | static void __setscheduler_uclamp(struct task_struct *p, |
| 1284 | const struct sched_attr *attr) { } |
| 1285 | static inline void uclamp_fork(struct task_struct *p) { } |
| 1286 | static inline void init_uclamp(void) { } |
| 1287 | #endif /* CONFIG_UCLAMP_TASK */ |
| 1288 | |
| 1289 | static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) |
| 1290 | { |
| 1291 | if (!(flags & ENQUEUE_NOCLOCK)) |
| 1292 | update_rq_clock(rq); |
| 1293 | |
| 1294 | if (!(flags & ENQUEUE_RESTORE)) { |
| 1295 | sched_info_queued(rq, p); |
| 1296 | psi_enqueue(p, flags & ENQUEUE_WAKEUP); |
| 1297 | } |
| 1298 | |
| 1299 | uclamp_rq_inc(rq, p); |
| 1300 | p->sched_class->enqueue_task(rq, p, flags); |
| 1301 | } |
| 1302 | |
| 1303 | static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) |
| 1304 | { |
| 1305 | if (!(flags & DEQUEUE_NOCLOCK)) |
| 1306 | update_rq_clock(rq); |
| 1307 | |
| 1308 | if (!(flags & DEQUEUE_SAVE)) { |
| 1309 | sched_info_dequeued(rq, p); |
| 1310 | psi_dequeue(p, flags & DEQUEUE_SLEEP); |
| 1311 | } |
| 1312 | |
| 1313 | uclamp_rq_dec(rq, p); |
| 1314 | p->sched_class->dequeue_task(rq, p, flags); |
| 1315 | } |
| 1316 | |
| 1317 | void activate_task(struct rq *rq, struct task_struct *p, int flags) |
| 1318 | { |
| 1319 | if (task_contributes_to_load(p)) |
| 1320 | rq->nr_uninterruptible--; |
| 1321 | |
| 1322 | enqueue_task(rq, p, flags); |
| 1323 | |
| 1324 | p->on_rq = TASK_ON_RQ_QUEUED; |
| 1325 | } |
| 1326 | |
| 1327 | void deactivate_task(struct rq *rq, struct task_struct *p, int flags) |
| 1328 | { |
| 1329 | p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING; |
| 1330 | |
| 1331 | if (task_contributes_to_load(p)) |
| 1332 | rq->nr_uninterruptible++; |
| 1333 | |
| 1334 | dequeue_task(rq, p, flags); |
| 1335 | } |
| 1336 | |
| 1337 | /* |
| 1338 | * __normal_prio - return the priority that is based on the static prio |
| 1339 | */ |
| 1340 | static inline int __normal_prio(struct task_struct *p) |
| 1341 | { |
| 1342 | return p->static_prio; |
| 1343 | } |
| 1344 | |
| 1345 | /* |
| 1346 | * Calculate the expected normal priority: i.e. priority |
| 1347 | * without taking RT-inheritance into account. Might be |
| 1348 | * boosted by interactivity modifiers. Changes upon fork, |
| 1349 | * setprio syscalls, and whenever the interactivity |
| 1350 | * estimator recalculates. |
| 1351 | */ |
| 1352 | static inline int normal_prio(struct task_struct *p) |
| 1353 | { |
| 1354 | int prio; |
| 1355 | |
| 1356 | if (task_has_dl_policy(p)) |
| 1357 | prio = MAX_DL_PRIO-1; |
| 1358 | else if (task_has_rt_policy(p)) |
| 1359 | prio = MAX_RT_PRIO-1 - p->rt_priority; |
| 1360 | else |
| 1361 | prio = __normal_prio(p); |
| 1362 | return prio; |
| 1363 | } |
| 1364 | |
| 1365 | /* |
| 1366 | * Calculate the current priority, i.e. the priority |
| 1367 | * taken into account by the scheduler. This value might |
| 1368 | * be boosted by RT tasks, or might be boosted by |
| 1369 | * interactivity modifiers. Will be RT if the task got |
| 1370 | * RT-boosted. If not then it returns p->normal_prio. |
| 1371 | */ |
| 1372 | static int effective_prio(struct task_struct *p) |
| 1373 | { |
| 1374 | p->normal_prio = normal_prio(p); |
| 1375 | /* |
| 1376 | * If we are RT tasks or we were boosted to RT priority, |
| 1377 | * keep the priority unchanged. Otherwise, update priority |
| 1378 | * to the normal priority: |
| 1379 | */ |
| 1380 | if (!rt_prio(p->prio)) |
| 1381 | return p->normal_prio; |
| 1382 | return p->prio; |
| 1383 | } |
| 1384 | |
| 1385 | /** |
| 1386 | * task_curr - is this task currently executing on a CPU? |
| 1387 | * @p: the task in question. |
| 1388 | * |
| 1389 | * Return: 1 if the task is currently executing. 0 otherwise. |
| 1390 | */ |
| 1391 | inline int task_curr(const struct task_struct *p) |
| 1392 | { |
| 1393 | return cpu_curr(task_cpu(p)) == p; |
| 1394 | } |
| 1395 | |
| 1396 | /* |
| 1397 | * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock, |
| 1398 | * use the balance_callback list if you want balancing. |
| 1399 | * |
| 1400 | * this means any call to check_class_changed() must be followed by a call to |
| 1401 | * balance_callback(). |
| 1402 | */ |
| 1403 | static inline void check_class_changed(struct rq *rq, struct task_struct *p, |
| 1404 | const struct sched_class *prev_class, |
| 1405 | int oldprio) |
| 1406 | { |
| 1407 | if (prev_class != p->sched_class) { |
| 1408 | if (prev_class->switched_from) |
| 1409 | prev_class->switched_from(rq, p); |
| 1410 | |
| 1411 | p->sched_class->switched_to(rq, p); |
| 1412 | } else if (oldprio != p->prio || dl_task(p)) |
| 1413 | p->sched_class->prio_changed(rq, p, oldprio); |
| 1414 | } |
| 1415 | |
| 1416 | void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) |
| 1417 | { |
| 1418 | const struct sched_class *class; |
| 1419 | |
| 1420 | if (p->sched_class == rq->curr->sched_class) { |
| 1421 | rq->curr->sched_class->check_preempt_curr(rq, p, flags); |
| 1422 | } else { |
| 1423 | for_each_class(class) { |
| 1424 | if (class == rq->curr->sched_class) |
| 1425 | break; |
| 1426 | if (class == p->sched_class) { |
| 1427 | resched_curr(rq); |
| 1428 | break; |
| 1429 | } |
| 1430 | } |
| 1431 | } |
| 1432 | |
| 1433 | /* |
| 1434 | * A queue event has occurred, and we're going to schedule. In |
| 1435 | * this case, we can save a useless back to back clock update. |
| 1436 | */ |
| 1437 | if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) |
| 1438 | rq_clock_skip_update(rq); |
| 1439 | } |
| 1440 | |
| 1441 | #ifdef CONFIG_SMP |
| 1442 | |
| 1443 | static inline bool is_per_cpu_kthread(struct task_struct *p) |
| 1444 | { |
| 1445 | if (!(p->flags & PF_KTHREAD)) |
| 1446 | return false; |
| 1447 | |
| 1448 | if (p->nr_cpus_allowed != 1) |
| 1449 | return false; |
| 1450 | |
| 1451 | return true; |
| 1452 | } |
| 1453 | |
| 1454 | /* |
| 1455 | * Per-CPU kthreads are allowed to run on !active && online CPUs, see |
| 1456 | * __set_cpus_allowed_ptr() and select_fallback_rq(). |
| 1457 | */ |
| 1458 | static inline bool is_cpu_allowed(struct task_struct *p, int cpu) |
| 1459 | { |
| 1460 | if (!cpumask_test_cpu(cpu, p->cpus_ptr)) |
| 1461 | return false; |
| 1462 | |
| 1463 | if (is_per_cpu_kthread(p)) |
| 1464 | return cpu_online(cpu); |
| 1465 | |
| 1466 | return cpu_active(cpu); |
| 1467 | } |
| 1468 | |
| 1469 | /* |
| 1470 | * This is how migration works: |
| 1471 | * |
| 1472 | * 1) we invoke migration_cpu_stop() on the target CPU using |
| 1473 | * stop_one_cpu(). |
| 1474 | * 2) stopper starts to run (implicitly forcing the migrated thread |
| 1475 | * off the CPU) |
| 1476 | * 3) it checks whether the migrated task is still in the wrong runqueue. |
| 1477 | * 4) if it's in the wrong runqueue then the migration thread removes |
| 1478 | * it and puts it into the right queue. |
| 1479 | * 5) stopper completes and stop_one_cpu() returns and the migration |
| 1480 | * is done. |
| 1481 | */ |
| 1482 | |
| 1483 | /* |
| 1484 | * move_queued_task - move a queued task to new rq. |
| 1485 | * |
| 1486 | * Returns (locked) new rq. Old rq's lock is released. |
| 1487 | */ |
| 1488 | static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, |
| 1489 | struct task_struct *p, int new_cpu) |
| 1490 | { |
| 1491 | lockdep_assert_held(&rq->lock); |
| 1492 | |
| 1493 | WRITE_ONCE(p->on_rq, TASK_ON_RQ_MIGRATING); |
| 1494 | dequeue_task(rq, p, DEQUEUE_NOCLOCK); |
| 1495 | set_task_cpu(p, new_cpu); |
| 1496 | rq_unlock(rq, rf); |
| 1497 | |
| 1498 | rq = cpu_rq(new_cpu); |
| 1499 | |
| 1500 | rq_lock(rq, rf); |
| 1501 | BUG_ON(task_cpu(p) != new_cpu); |
| 1502 | enqueue_task(rq, p, 0); |
| 1503 | p->on_rq = TASK_ON_RQ_QUEUED; |
| 1504 | check_preempt_curr(rq, p, 0); |
| 1505 | |
| 1506 | return rq; |
| 1507 | } |
| 1508 | |
| 1509 | struct migration_arg { |
| 1510 | struct task_struct *task; |
| 1511 | int dest_cpu; |
| 1512 | }; |
| 1513 | |
| 1514 | /* |
| 1515 | * Move (not current) task off this CPU, onto the destination CPU. We're doing |
| 1516 | * this because either it can't run here any more (set_cpus_allowed() |
| 1517 | * away from this CPU, or CPU going down), or because we're |
| 1518 | * attempting to rebalance this task on exec (sched_exec). |
| 1519 | * |
| 1520 | * So we race with normal scheduler movements, but that's OK, as long |
| 1521 | * as the task is no longer on this CPU. |
| 1522 | */ |
| 1523 | static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf, |
| 1524 | struct task_struct *p, int dest_cpu) |
| 1525 | { |
| 1526 | /* Affinity changed (again). */ |
| 1527 | if (!is_cpu_allowed(p, dest_cpu)) |
| 1528 | return rq; |
| 1529 | |
| 1530 | update_rq_clock(rq); |
| 1531 | rq = move_queued_task(rq, rf, p, dest_cpu); |
| 1532 | |
| 1533 | return rq; |
| 1534 | } |
| 1535 | |
| 1536 | /* |
| 1537 | * migration_cpu_stop - this will be executed by a highprio stopper thread |
| 1538 | * and performs thread migration by bumping thread off CPU then |
| 1539 | * 'pushing' onto another runqueue. |
| 1540 | */ |
| 1541 | static int migration_cpu_stop(void *data) |
| 1542 | { |
| 1543 | struct migration_arg *arg = data; |
| 1544 | struct task_struct *p = arg->task; |
| 1545 | struct rq *rq = this_rq(); |
| 1546 | struct rq_flags rf; |
| 1547 | |
| 1548 | /* |
| 1549 | * The original target CPU might have gone down and we might |
| 1550 | * be on another CPU but it doesn't matter. |
| 1551 | */ |
| 1552 | local_irq_disable(); |
| 1553 | /* |
| 1554 | * We need to explicitly wake pending tasks before running |
| 1555 | * __migrate_task() such that we will not miss enforcing cpus_ptr |
| 1556 | * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. |
| 1557 | */ |
| 1558 | sched_ttwu_pending(); |
| 1559 | |
| 1560 | raw_spin_lock(&p->pi_lock); |
| 1561 | rq_lock(rq, &rf); |
| 1562 | /* |
| 1563 | * If task_rq(p) != rq, it cannot be migrated here, because we're |
| 1564 | * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because |
| 1565 | * we're holding p->pi_lock. |
| 1566 | */ |
| 1567 | if (task_rq(p) == rq) { |
| 1568 | if (task_on_rq_queued(p)) |
| 1569 | rq = __migrate_task(rq, &rf, p, arg->dest_cpu); |
| 1570 | else |
| 1571 | p->wake_cpu = arg->dest_cpu; |
| 1572 | } |
| 1573 | rq_unlock(rq, &rf); |
| 1574 | raw_spin_unlock(&p->pi_lock); |
| 1575 | |
| 1576 | local_irq_enable(); |
| 1577 | return 0; |
| 1578 | } |
| 1579 | |
| 1580 | /* |
| 1581 | * sched_class::set_cpus_allowed must do the below, but is not required to |
| 1582 | * actually call this function. |
| 1583 | */ |
| 1584 | void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask) |
| 1585 | { |
| 1586 | cpumask_copy(&p->cpus_mask, new_mask); |
| 1587 | p->nr_cpus_allowed = cpumask_weight(new_mask); |
| 1588 | } |
| 1589 | |
| 1590 | void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) |
| 1591 | { |
| 1592 | struct rq *rq = task_rq(p); |
| 1593 | bool queued, running; |
| 1594 | |
| 1595 | lockdep_assert_held(&p->pi_lock); |
| 1596 | |
| 1597 | queued = task_on_rq_queued(p); |
| 1598 | running = task_current(rq, p); |
| 1599 | |
| 1600 | if (queued) { |
| 1601 | /* |
| 1602 | * Because __kthread_bind() calls this on blocked tasks without |
| 1603 | * holding rq->lock. |
| 1604 | */ |
| 1605 | lockdep_assert_held(&rq->lock); |
| 1606 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
| 1607 | } |
| 1608 | if (running) |
| 1609 | put_prev_task(rq, p); |
| 1610 | |
| 1611 | p->sched_class->set_cpus_allowed(p, new_mask); |
| 1612 | |
| 1613 | if (queued) |
| 1614 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
| 1615 | if (running) |
| 1616 | set_next_task(rq, p); |
| 1617 | } |
| 1618 | |
| 1619 | /* |
| 1620 | * Change a given task's CPU affinity. Migrate the thread to a |
| 1621 | * proper CPU and schedule it away if the CPU it's executing on |
| 1622 | * is removed from the allowed bitmask. |
| 1623 | * |
| 1624 | * NOTE: the caller must have a valid reference to the task, the |
| 1625 | * task must not exit() & deallocate itself prematurely. The |
| 1626 | * call is not atomic; no spinlocks may be held. |
| 1627 | */ |
| 1628 | static int __set_cpus_allowed_ptr(struct task_struct *p, |
| 1629 | const struct cpumask *new_mask, bool check) |
| 1630 | { |
| 1631 | const struct cpumask *cpu_valid_mask = cpu_active_mask; |
| 1632 | unsigned int dest_cpu; |
| 1633 | struct rq_flags rf; |
| 1634 | struct rq *rq; |
| 1635 | int ret = 0; |
| 1636 | |
| 1637 | rq = task_rq_lock(p, &rf); |
| 1638 | update_rq_clock(rq); |
| 1639 | |
| 1640 | if (p->flags & PF_KTHREAD) { |
| 1641 | /* |
| 1642 | * Kernel threads are allowed on online && !active CPUs |
| 1643 | */ |
| 1644 | cpu_valid_mask = cpu_online_mask; |
| 1645 | } |
| 1646 | |
| 1647 | /* |
| 1648 | * Must re-check here, to close a race against __kthread_bind(), |
| 1649 | * sched_setaffinity() is not guaranteed to observe the flag. |
| 1650 | */ |
| 1651 | if (check && (p->flags & PF_NO_SETAFFINITY)) { |
| 1652 | ret = -EINVAL; |
| 1653 | goto out; |
| 1654 | } |
| 1655 | |
| 1656 | if (cpumask_equal(p->cpus_ptr, new_mask)) |
| 1657 | goto out; |
| 1658 | |
| 1659 | dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask); |
| 1660 | if (dest_cpu >= nr_cpu_ids) { |
| 1661 | ret = -EINVAL; |
| 1662 | goto out; |
| 1663 | } |
| 1664 | |
| 1665 | do_set_cpus_allowed(p, new_mask); |
| 1666 | |
| 1667 | if (p->flags & PF_KTHREAD) { |
| 1668 | /* |
| 1669 | * For kernel threads that do indeed end up on online && |
| 1670 | * !active we want to ensure they are strict per-CPU threads. |
| 1671 | */ |
| 1672 | WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) && |
| 1673 | !cpumask_intersects(new_mask, cpu_active_mask) && |
| 1674 | p->nr_cpus_allowed != 1); |
| 1675 | } |
| 1676 | |
| 1677 | /* Can the task run on the task's current CPU? If so, we're done */ |
| 1678 | if (cpumask_test_cpu(task_cpu(p), new_mask)) |
| 1679 | goto out; |
| 1680 | |
| 1681 | if (task_running(rq, p) || p->state == TASK_WAKING) { |
| 1682 | struct migration_arg arg = { p, dest_cpu }; |
| 1683 | /* Need help from migration thread: drop lock and wait. */ |
| 1684 | task_rq_unlock(rq, p, &rf); |
| 1685 | stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); |
| 1686 | return 0; |
| 1687 | } else if (task_on_rq_queued(p)) { |
| 1688 | /* |
| 1689 | * OK, since we're going to drop the lock immediately |
| 1690 | * afterwards anyway. |
| 1691 | */ |
| 1692 | rq = move_queued_task(rq, &rf, p, dest_cpu); |
| 1693 | } |
| 1694 | out: |
| 1695 | task_rq_unlock(rq, p, &rf); |
| 1696 | |
| 1697 | return ret; |
| 1698 | } |
| 1699 | |
| 1700 | int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) |
| 1701 | { |
| 1702 | return __set_cpus_allowed_ptr(p, new_mask, false); |
| 1703 | } |
| 1704 | EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); |
| 1705 | |
| 1706 | void set_task_cpu(struct task_struct *p, unsigned int new_cpu) |
| 1707 | { |
| 1708 | #ifdef CONFIG_SCHED_DEBUG |
| 1709 | /* |
| 1710 | * We should never call set_task_cpu() on a blocked task, |
| 1711 | * ttwu() will sort out the placement. |
| 1712 | */ |
| 1713 | WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && |
| 1714 | !p->on_rq); |
| 1715 | |
| 1716 | /* |
| 1717 | * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING, |
| 1718 | * because schedstat_wait_{start,end} rebase migrating task's wait_start |
| 1719 | * time relying on p->on_rq. |
| 1720 | */ |
| 1721 | WARN_ON_ONCE(p->state == TASK_RUNNING && |
| 1722 | p->sched_class == &fair_sched_class && |
| 1723 | (p->on_rq && !task_on_rq_migrating(p))); |
| 1724 | |
| 1725 | #ifdef CONFIG_LOCKDEP |
| 1726 | /* |
| 1727 | * The caller should hold either p->pi_lock or rq->lock, when changing |
| 1728 | * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. |
| 1729 | * |
| 1730 | * sched_move_task() holds both and thus holding either pins the cgroup, |
| 1731 | * see task_group(). |
| 1732 | * |
| 1733 | * Furthermore, all task_rq users should acquire both locks, see |
| 1734 | * task_rq_lock(). |
| 1735 | */ |
| 1736 | WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || |
| 1737 | lockdep_is_held(&task_rq(p)->lock))); |
| 1738 | #endif |
| 1739 | /* |
| 1740 | * Clearly, migrating tasks to offline CPUs is a fairly daft thing. |
| 1741 | */ |
| 1742 | WARN_ON_ONCE(!cpu_online(new_cpu)); |
| 1743 | #endif |
| 1744 | |
| 1745 | trace_sched_migrate_task(p, new_cpu); |
| 1746 | |
| 1747 | if (task_cpu(p) != new_cpu) { |
| 1748 | if (p->sched_class->migrate_task_rq) |
| 1749 | p->sched_class->migrate_task_rq(p, new_cpu); |
| 1750 | p->se.nr_migrations++; |
| 1751 | rseq_migrate(p); |
| 1752 | perf_event_task_migrate(p); |
| 1753 | } |
| 1754 | |
| 1755 | __set_task_cpu(p, new_cpu); |
| 1756 | } |
| 1757 | |
| 1758 | #ifdef CONFIG_NUMA_BALANCING |
| 1759 | static void __migrate_swap_task(struct task_struct *p, int cpu) |
| 1760 | { |
| 1761 | if (task_on_rq_queued(p)) { |
| 1762 | struct rq *src_rq, *dst_rq; |
| 1763 | struct rq_flags srf, drf; |
| 1764 | |
| 1765 | src_rq = task_rq(p); |
| 1766 | dst_rq = cpu_rq(cpu); |
| 1767 | |
| 1768 | rq_pin_lock(src_rq, &srf); |
| 1769 | rq_pin_lock(dst_rq, &drf); |
| 1770 | |
| 1771 | deactivate_task(src_rq, p, 0); |
| 1772 | set_task_cpu(p, cpu); |
| 1773 | activate_task(dst_rq, p, 0); |
| 1774 | check_preempt_curr(dst_rq, p, 0); |
| 1775 | |
| 1776 | rq_unpin_lock(dst_rq, &drf); |
| 1777 | rq_unpin_lock(src_rq, &srf); |
| 1778 | |
| 1779 | } else { |
| 1780 | /* |
| 1781 | * Task isn't running anymore; make it appear like we migrated |
| 1782 | * it before it went to sleep. This means on wakeup we make the |
| 1783 | * previous CPU our target instead of where it really is. |
| 1784 | */ |
| 1785 | p->wake_cpu = cpu; |
| 1786 | } |
| 1787 | } |
| 1788 | |
| 1789 | struct migration_swap_arg { |
| 1790 | struct task_struct *src_task, *dst_task; |
| 1791 | int src_cpu, dst_cpu; |
| 1792 | }; |
| 1793 | |
| 1794 | static int migrate_swap_stop(void *data) |
| 1795 | { |
| 1796 | struct migration_swap_arg *arg = data; |
| 1797 | struct rq *src_rq, *dst_rq; |
| 1798 | int ret = -EAGAIN; |
| 1799 | |
| 1800 | if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu)) |
| 1801 | return -EAGAIN; |
| 1802 | |
| 1803 | src_rq = cpu_rq(arg->src_cpu); |
| 1804 | dst_rq = cpu_rq(arg->dst_cpu); |
| 1805 | |
| 1806 | double_raw_lock(&arg->src_task->pi_lock, |
| 1807 | &arg->dst_task->pi_lock); |
| 1808 | double_rq_lock(src_rq, dst_rq); |
| 1809 | |
| 1810 | if (task_cpu(arg->dst_task) != arg->dst_cpu) |
| 1811 | goto unlock; |
| 1812 | |
| 1813 | if (task_cpu(arg->src_task) != arg->src_cpu) |
| 1814 | goto unlock; |
| 1815 | |
| 1816 | if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr)) |
| 1817 | goto unlock; |
| 1818 | |
| 1819 | if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr)) |
| 1820 | goto unlock; |
| 1821 | |
| 1822 | __migrate_swap_task(arg->src_task, arg->dst_cpu); |
| 1823 | __migrate_swap_task(arg->dst_task, arg->src_cpu); |
| 1824 | |
| 1825 | ret = 0; |
| 1826 | |
| 1827 | unlock: |
| 1828 | double_rq_unlock(src_rq, dst_rq); |
| 1829 | raw_spin_unlock(&arg->dst_task->pi_lock); |
| 1830 | raw_spin_unlock(&arg->src_task->pi_lock); |
| 1831 | |
| 1832 | return ret; |
| 1833 | } |
| 1834 | |
| 1835 | /* |
| 1836 | * Cross migrate two tasks |
| 1837 | */ |
| 1838 | int migrate_swap(struct task_struct *cur, struct task_struct *p, |
| 1839 | int target_cpu, int curr_cpu) |
| 1840 | { |
| 1841 | struct migration_swap_arg arg; |
| 1842 | int ret = -EINVAL; |
| 1843 | |
| 1844 | arg = (struct migration_swap_arg){ |
| 1845 | .src_task = cur, |
| 1846 | .src_cpu = curr_cpu, |
| 1847 | .dst_task = p, |
| 1848 | .dst_cpu = target_cpu, |
| 1849 | }; |
| 1850 | |
| 1851 | if (arg.src_cpu == arg.dst_cpu) |
| 1852 | goto out; |
| 1853 | |
| 1854 | /* |
| 1855 | * These three tests are all lockless; this is OK since all of them |
| 1856 | * will be re-checked with proper locks held further down the line. |
| 1857 | */ |
| 1858 | if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) |
| 1859 | goto out; |
| 1860 | |
| 1861 | if (!cpumask_test_cpu(arg.dst_cpu, arg.src_task->cpus_ptr)) |
| 1862 | goto out; |
| 1863 | |
| 1864 | if (!cpumask_test_cpu(arg.src_cpu, arg.dst_task->cpus_ptr)) |
| 1865 | goto out; |
| 1866 | |
| 1867 | trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); |
| 1868 | ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); |
| 1869 | |
| 1870 | out: |
| 1871 | return ret; |
| 1872 | } |
| 1873 | #endif /* CONFIG_NUMA_BALANCING */ |
| 1874 | |
| 1875 | /* |
| 1876 | * wait_task_inactive - wait for a thread to unschedule. |
| 1877 | * |
| 1878 | * If @match_state is nonzero, it's the @p->state value just checked and |
| 1879 | * not expected to change. If it changes, i.e. @p might have woken up, |
| 1880 | * then return zero. When we succeed in waiting for @p to be off its CPU, |
| 1881 | * we return a positive number (its total switch count). If a second call |
| 1882 | * a short while later returns the same number, the caller can be sure that |
| 1883 | * @p has remained unscheduled the whole time. |
| 1884 | * |
| 1885 | * The caller must ensure that the task *will* unschedule sometime soon, |
| 1886 | * else this function might spin for a *long* time. This function can't |
| 1887 | * be called with interrupts off, or it may introduce deadlock with |
| 1888 | * smp_call_function() if an IPI is sent by the same process we are |
| 1889 | * waiting to become inactive. |
| 1890 | */ |
| 1891 | unsigned long wait_task_inactive(struct task_struct *p, long match_state) |
| 1892 | { |
| 1893 | int running, queued; |
| 1894 | struct rq_flags rf; |
| 1895 | unsigned long ncsw; |
| 1896 | struct rq *rq; |
| 1897 | |
| 1898 | for (;;) { |
| 1899 | /* |
| 1900 | * We do the initial early heuristics without holding |
| 1901 | * any task-queue locks at all. We'll only try to get |
| 1902 | * the runqueue lock when things look like they will |
| 1903 | * work out! |
| 1904 | */ |
| 1905 | rq = task_rq(p); |
| 1906 | |
| 1907 | /* |
| 1908 | * If the task is actively running on another CPU |
| 1909 | * still, just relax and busy-wait without holding |
| 1910 | * any locks. |
| 1911 | * |
| 1912 | * NOTE! Since we don't hold any locks, it's not |
| 1913 | * even sure that "rq" stays as the right runqueue! |
| 1914 | * But we don't care, since "task_running()" will |
| 1915 | * return false if the runqueue has changed and p |
| 1916 | * is actually now running somewhere else! |
| 1917 | */ |
| 1918 | while (task_running(rq, p)) { |
| 1919 | if (match_state && unlikely(p->state != match_state)) |
| 1920 | return 0; |
| 1921 | cpu_relax(); |
| 1922 | } |
| 1923 | |
| 1924 | /* |
| 1925 | * Ok, time to look more closely! We need the rq |
| 1926 | * lock now, to be *sure*. If we're wrong, we'll |
| 1927 | * just go back and repeat. |
| 1928 | */ |
| 1929 | rq = task_rq_lock(p, &rf); |
| 1930 | trace_sched_wait_task(p); |
| 1931 | running = task_running(rq, p); |
| 1932 | queued = task_on_rq_queued(p); |
| 1933 | ncsw = 0; |
| 1934 | if (!match_state || p->state == match_state) |
| 1935 | ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ |
| 1936 | task_rq_unlock(rq, p, &rf); |
| 1937 | |
| 1938 | /* |
| 1939 | * If it changed from the expected state, bail out now. |
| 1940 | */ |
| 1941 | if (unlikely(!ncsw)) |
| 1942 | break; |
| 1943 | |
| 1944 | /* |
| 1945 | * Was it really running after all now that we |
| 1946 | * checked with the proper locks actually held? |
| 1947 | * |
| 1948 | * Oops. Go back and try again.. |
| 1949 | */ |
| 1950 | if (unlikely(running)) { |
| 1951 | cpu_relax(); |
| 1952 | continue; |
| 1953 | } |
| 1954 | |
| 1955 | /* |
| 1956 | * It's not enough that it's not actively running, |
| 1957 | * it must be off the runqueue _entirely_, and not |
| 1958 | * preempted! |
| 1959 | * |
| 1960 | * So if it was still runnable (but just not actively |
| 1961 | * running right now), it's preempted, and we should |
| 1962 | * yield - it could be a while. |
| 1963 | */ |
| 1964 | if (unlikely(queued)) { |
| 1965 | ktime_t to = NSEC_PER_SEC / HZ; |
| 1966 | |
| 1967 | set_current_state(TASK_UNINTERRUPTIBLE); |
| 1968 | schedule_hrtimeout(&to, HRTIMER_MODE_REL); |
| 1969 | continue; |
| 1970 | } |
| 1971 | |
| 1972 | /* |
| 1973 | * Ahh, all good. It wasn't running, and it wasn't |
| 1974 | * runnable, which means that it will never become |
| 1975 | * running in the future either. We're all done! |
| 1976 | */ |
| 1977 | break; |
| 1978 | } |
| 1979 | |
| 1980 | return ncsw; |
| 1981 | } |
| 1982 | |
| 1983 | /*** |
| 1984 | * kick_process - kick a running thread to enter/exit the kernel |
| 1985 | * @p: the to-be-kicked thread |
| 1986 | * |
| 1987 | * Cause a process which is running on another CPU to enter |
| 1988 | * kernel-mode, without any delay. (to get signals handled.) |
| 1989 | * |
| 1990 | * NOTE: this function doesn't have to take the runqueue lock, |
| 1991 | * because all it wants to ensure is that the remote task enters |
| 1992 | * the kernel. If the IPI races and the task has been migrated |
| 1993 | * to another CPU then no harm is done and the purpose has been |
| 1994 | * achieved as well. |
| 1995 | */ |
| 1996 | void kick_process(struct task_struct *p) |
| 1997 | { |
| 1998 | int cpu; |
| 1999 | |
| 2000 | preempt_disable(); |
| 2001 | cpu = task_cpu(p); |
| 2002 | if ((cpu != smp_processor_id()) && task_curr(p)) |
| 2003 | smp_send_reschedule(cpu); |
| 2004 | preempt_enable(); |
| 2005 | } |
| 2006 | EXPORT_SYMBOL_GPL(kick_process); |
| 2007 | |
| 2008 | /* |
| 2009 | * ->cpus_ptr is protected by both rq->lock and p->pi_lock |
| 2010 | * |
| 2011 | * A few notes on cpu_active vs cpu_online: |
| 2012 | * |
| 2013 | * - cpu_active must be a subset of cpu_online |
| 2014 | * |
| 2015 | * - on CPU-up we allow per-CPU kthreads on the online && !active CPU, |
| 2016 | * see __set_cpus_allowed_ptr(). At this point the newly online |
| 2017 | * CPU isn't yet part of the sched domains, and balancing will not |
| 2018 | * see it. |
| 2019 | * |
| 2020 | * - on CPU-down we clear cpu_active() to mask the sched domains and |
| 2021 | * avoid the load balancer to place new tasks on the to be removed |
| 2022 | * CPU. Existing tasks will remain running there and will be taken |
| 2023 | * off. |
| 2024 | * |
| 2025 | * This means that fallback selection must not select !active CPUs. |
| 2026 | * And can assume that any active CPU must be online. Conversely |
| 2027 | * select_task_rq() below may allow selection of !active CPUs in order |
| 2028 | * to satisfy the above rules. |
| 2029 | */ |
| 2030 | static int select_fallback_rq(int cpu, struct task_struct *p) |
| 2031 | { |
| 2032 | int nid = cpu_to_node(cpu); |
| 2033 | const struct cpumask *nodemask = NULL; |
| 2034 | enum { cpuset, possible, fail } state = cpuset; |
| 2035 | int dest_cpu; |
| 2036 | |
| 2037 | /* |
| 2038 | * If the node that the CPU is on has been offlined, cpu_to_node() |
| 2039 | * will return -1. There is no CPU on the node, and we should |
| 2040 | * select the CPU on the other node. |
| 2041 | */ |
| 2042 | if (nid != -1) { |
| 2043 | nodemask = cpumask_of_node(nid); |
| 2044 | |
| 2045 | /* Look for allowed, online CPU in same node. */ |
| 2046 | for_each_cpu(dest_cpu, nodemask) { |
| 2047 | if (!cpu_active(dest_cpu)) |
| 2048 | continue; |
| 2049 | if (cpumask_test_cpu(dest_cpu, p->cpus_ptr)) |
| 2050 | return dest_cpu; |
| 2051 | } |
| 2052 | } |
| 2053 | |
| 2054 | for (;;) { |
| 2055 | /* Any allowed, online CPU? */ |
| 2056 | for_each_cpu(dest_cpu, p->cpus_ptr) { |
| 2057 | if (!is_cpu_allowed(p, dest_cpu)) |
| 2058 | continue; |
| 2059 | |
| 2060 | goto out; |
| 2061 | } |
| 2062 | |
| 2063 | /* No more Mr. Nice Guy. */ |
| 2064 | switch (state) { |
| 2065 | case cpuset: |
| 2066 | if (IS_ENABLED(CONFIG_CPUSETS)) { |
| 2067 | cpuset_cpus_allowed_fallback(p); |
| 2068 | state = possible; |
| 2069 | break; |
| 2070 | } |
| 2071 | /* Fall-through */ |
| 2072 | case possible: |
| 2073 | do_set_cpus_allowed(p, cpu_possible_mask); |
| 2074 | state = fail; |
| 2075 | break; |
| 2076 | |
| 2077 | case fail: |
| 2078 | BUG(); |
| 2079 | break; |
| 2080 | } |
| 2081 | } |
| 2082 | |
| 2083 | out: |
| 2084 | if (state != cpuset) { |
| 2085 | /* |
| 2086 | * Don't tell them about moving exiting tasks or |
| 2087 | * kernel threads (both mm NULL), since they never |
| 2088 | * leave kernel. |
| 2089 | */ |
| 2090 | if (p->mm && printk_ratelimit()) { |
| 2091 | printk_deferred("process %d (%s) no longer affine to cpu%d\n", |
| 2092 | task_pid_nr(p), p->comm, cpu); |
| 2093 | } |
| 2094 | } |
| 2095 | |
| 2096 | return dest_cpu; |
| 2097 | } |
| 2098 | |
| 2099 | /* |
| 2100 | * The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable. |
| 2101 | */ |
| 2102 | static inline |
| 2103 | int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) |
| 2104 | { |
| 2105 | lockdep_assert_held(&p->pi_lock); |
| 2106 | |
| 2107 | if (p->nr_cpus_allowed > 1) |
| 2108 | cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); |
| 2109 | else |
| 2110 | cpu = cpumask_any(p->cpus_ptr); |
| 2111 | |
| 2112 | /* |
| 2113 | * In order not to call set_task_cpu() on a blocking task we need |
| 2114 | * to rely on ttwu() to place the task on a valid ->cpus_ptr |
| 2115 | * CPU. |
| 2116 | * |
| 2117 | * Since this is common to all placement strategies, this lives here. |
| 2118 | * |
| 2119 | * [ this allows ->select_task() to simply return task_cpu(p) and |
| 2120 | * not worry about this generic constraint ] |
| 2121 | */ |
| 2122 | if (unlikely(!is_cpu_allowed(p, cpu))) |
| 2123 | cpu = select_fallback_rq(task_cpu(p), p); |
| 2124 | |
| 2125 | return cpu; |
| 2126 | } |
| 2127 | |
| 2128 | static void update_avg(u64 *avg, u64 sample) |
| 2129 | { |
| 2130 | s64 diff = sample - *avg; |
| 2131 | *avg += diff >> 3; |
| 2132 | } |
| 2133 | |
| 2134 | void sched_set_stop_task(int cpu, struct task_struct *stop) |
| 2135 | { |
| 2136 | struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; |
| 2137 | struct task_struct *old_stop = cpu_rq(cpu)->stop; |
| 2138 | |
| 2139 | if (stop) { |
| 2140 | /* |
| 2141 | * Make it appear like a SCHED_FIFO task, its something |
| 2142 | * userspace knows about and won't get confused about. |
| 2143 | * |
| 2144 | * Also, it will make PI more or less work without too |
| 2145 | * much confusion -- but then, stop work should not |
| 2146 | * rely on PI working anyway. |
| 2147 | */ |
| 2148 | sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); |
| 2149 | |
| 2150 | stop->sched_class = &stop_sched_class; |
| 2151 | } |
| 2152 | |
| 2153 | cpu_rq(cpu)->stop = stop; |
| 2154 | |
| 2155 | if (old_stop) { |
| 2156 | /* |
| 2157 | * Reset it back to a normal scheduling class so that |
| 2158 | * it can die in pieces. |
| 2159 | */ |
| 2160 | old_stop->sched_class = &rt_sched_class; |
| 2161 | } |
| 2162 | } |
| 2163 | |
| 2164 | #else |
| 2165 | |
| 2166 | static inline int __set_cpus_allowed_ptr(struct task_struct *p, |
| 2167 | const struct cpumask *new_mask, bool check) |
| 2168 | { |
| 2169 | return set_cpus_allowed_ptr(p, new_mask); |
| 2170 | } |
| 2171 | |
| 2172 | #endif /* CONFIG_SMP */ |
| 2173 | |
| 2174 | static void |
| 2175 | ttwu_stat(struct task_struct *p, int cpu, int wake_flags) |
| 2176 | { |
| 2177 | struct rq *rq; |
| 2178 | |
| 2179 | if (!schedstat_enabled()) |
| 2180 | return; |
| 2181 | |
| 2182 | rq = this_rq(); |
| 2183 | |
| 2184 | #ifdef CONFIG_SMP |
| 2185 | if (cpu == rq->cpu) { |
| 2186 | __schedstat_inc(rq->ttwu_local); |
| 2187 | __schedstat_inc(p->se.statistics.nr_wakeups_local); |
| 2188 | } else { |
| 2189 | struct sched_domain *sd; |
| 2190 | |
| 2191 | __schedstat_inc(p->se.statistics.nr_wakeups_remote); |
| 2192 | rcu_read_lock(); |
| 2193 | for_each_domain(rq->cpu, sd) { |
| 2194 | if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { |
| 2195 | __schedstat_inc(sd->ttwu_wake_remote); |
| 2196 | break; |
| 2197 | } |
| 2198 | } |
| 2199 | rcu_read_unlock(); |
| 2200 | } |
| 2201 | |
| 2202 | if (wake_flags & WF_MIGRATED) |
| 2203 | __schedstat_inc(p->se.statistics.nr_wakeups_migrate); |
| 2204 | #endif /* CONFIG_SMP */ |
| 2205 | |
| 2206 | __schedstat_inc(rq->ttwu_count); |
| 2207 | __schedstat_inc(p->se.statistics.nr_wakeups); |
| 2208 | |
| 2209 | if (wake_flags & WF_SYNC) |
| 2210 | __schedstat_inc(p->se.statistics.nr_wakeups_sync); |
| 2211 | } |
| 2212 | |
| 2213 | /* |
| 2214 | * Mark the task runnable and perform wakeup-preemption. |
| 2215 | */ |
| 2216 | static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags, |
| 2217 | struct rq_flags *rf) |
| 2218 | { |
| 2219 | check_preempt_curr(rq, p, wake_flags); |
| 2220 | p->state = TASK_RUNNING; |
| 2221 | trace_sched_wakeup(p); |
| 2222 | |
| 2223 | #ifdef CONFIG_SMP |
| 2224 | if (p->sched_class->task_woken) { |
| 2225 | /* |
| 2226 | * Our task @p is fully woken up and running; so its safe to |
| 2227 | * drop the rq->lock, hereafter rq is only used for statistics. |
| 2228 | */ |
| 2229 | rq_unpin_lock(rq, rf); |
| 2230 | p->sched_class->task_woken(rq, p); |
| 2231 | rq_repin_lock(rq, rf); |
| 2232 | } |
| 2233 | |
| 2234 | if (rq->idle_stamp) { |
| 2235 | u64 delta = rq_clock(rq) - rq->idle_stamp; |
| 2236 | u64 max = 2*rq->max_idle_balance_cost; |
| 2237 | |
| 2238 | update_avg(&rq->avg_idle, delta); |
| 2239 | |
| 2240 | if (rq->avg_idle > max) |
| 2241 | rq->avg_idle = max; |
| 2242 | |
| 2243 | rq->idle_stamp = 0; |
| 2244 | } |
| 2245 | #endif |
| 2246 | } |
| 2247 | |
| 2248 | static void |
| 2249 | ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, |
| 2250 | struct rq_flags *rf) |
| 2251 | { |
| 2252 | int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK; |
| 2253 | |
| 2254 | lockdep_assert_held(&rq->lock); |
| 2255 | |
| 2256 | #ifdef CONFIG_SMP |
| 2257 | if (p->sched_contributes_to_load) |
| 2258 | rq->nr_uninterruptible--; |
| 2259 | |
| 2260 | if (wake_flags & WF_MIGRATED) |
| 2261 | en_flags |= ENQUEUE_MIGRATED; |
| 2262 | #endif |
| 2263 | |
| 2264 | activate_task(rq, p, en_flags); |
| 2265 | ttwu_do_wakeup(rq, p, wake_flags, rf); |
| 2266 | } |
| 2267 | |
| 2268 | /* |
| 2269 | * Called in case the task @p isn't fully descheduled from its runqueue, |
| 2270 | * in this case we must do a remote wakeup. Its a 'light' wakeup though, |
| 2271 | * since all we need to do is flip p->state to TASK_RUNNING, since |
| 2272 | * the task is still ->on_rq. |
| 2273 | */ |
| 2274 | static int ttwu_remote(struct task_struct *p, int wake_flags) |
| 2275 | { |
| 2276 | struct rq_flags rf; |
| 2277 | struct rq *rq; |
| 2278 | int ret = 0; |
| 2279 | |
| 2280 | rq = __task_rq_lock(p, &rf); |
| 2281 | if (task_on_rq_queued(p)) { |
| 2282 | /* check_preempt_curr() may use rq clock */ |
| 2283 | update_rq_clock(rq); |
| 2284 | ttwu_do_wakeup(rq, p, wake_flags, &rf); |
| 2285 | ret = 1; |
| 2286 | } |
| 2287 | __task_rq_unlock(rq, &rf); |
| 2288 | |
| 2289 | return ret; |
| 2290 | } |
| 2291 | |
| 2292 | #ifdef CONFIG_SMP |
| 2293 | void sched_ttwu_pending(void) |
| 2294 | { |
| 2295 | struct rq *rq = this_rq(); |
| 2296 | struct llist_node *llist = llist_del_all(&rq->wake_list); |
| 2297 | struct task_struct *p, *t; |
| 2298 | struct rq_flags rf; |
| 2299 | |
| 2300 | if (!llist) |
| 2301 | return; |
| 2302 | |
| 2303 | rq_lock_irqsave(rq, &rf); |
| 2304 | update_rq_clock(rq); |
| 2305 | |
| 2306 | llist_for_each_entry_safe(p, t, llist, wake_entry) |
| 2307 | ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf); |
| 2308 | |
| 2309 | rq_unlock_irqrestore(rq, &rf); |
| 2310 | } |
| 2311 | |
| 2312 | void scheduler_ipi(void) |
| 2313 | { |
| 2314 | /* |
| 2315 | * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting |
| 2316 | * TIF_NEED_RESCHED remotely (for the first time) will also send |
| 2317 | * this IPI. |
| 2318 | */ |
| 2319 | preempt_fold_need_resched(); |
| 2320 | |
| 2321 | if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) |
| 2322 | return; |
| 2323 | |
| 2324 | /* |
| 2325 | * Not all reschedule IPI handlers call irq_enter/irq_exit, since |
| 2326 | * traditionally all their work was done from the interrupt return |
| 2327 | * path. Now that we actually do some work, we need to make sure |
| 2328 | * we do call them. |
| 2329 | * |
| 2330 | * Some archs already do call them, luckily irq_enter/exit nest |
| 2331 | * properly. |
| 2332 | * |
| 2333 | * Arguably we should visit all archs and update all handlers, |
| 2334 | * however a fair share of IPIs are still resched only so this would |
| 2335 | * somewhat pessimize the simple resched case. |
| 2336 | */ |
| 2337 | irq_enter(); |
| 2338 | sched_ttwu_pending(); |
| 2339 | |
| 2340 | /* |
| 2341 | * Check if someone kicked us for doing the nohz idle load balance. |
| 2342 | */ |
| 2343 | if (unlikely(got_nohz_idle_kick())) { |
| 2344 | this_rq()->idle_balance = 1; |
| 2345 | raise_softirq_irqoff(SCHED_SOFTIRQ); |
| 2346 | } |
| 2347 | irq_exit(); |
| 2348 | } |
| 2349 | |
| 2350 | static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags) |
| 2351 | { |
| 2352 | struct rq *rq = cpu_rq(cpu); |
| 2353 | |
| 2354 | p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); |
| 2355 | |
| 2356 | if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { |
| 2357 | if (!set_nr_if_polling(rq->idle)) |
| 2358 | smp_send_reschedule(cpu); |
| 2359 | else |
| 2360 | trace_sched_wake_idle_without_ipi(cpu); |
| 2361 | } |
| 2362 | } |
| 2363 | |
| 2364 | void wake_up_if_idle(int cpu) |
| 2365 | { |
| 2366 | struct rq *rq = cpu_rq(cpu); |
| 2367 | struct rq_flags rf; |
| 2368 | |
| 2369 | rcu_read_lock(); |
| 2370 | |
| 2371 | if (!is_idle_task(rcu_dereference(rq->curr))) |
| 2372 | goto out; |
| 2373 | |
| 2374 | if (set_nr_if_polling(rq->idle)) { |
| 2375 | trace_sched_wake_idle_without_ipi(cpu); |
| 2376 | } else { |
| 2377 | rq_lock_irqsave(rq, &rf); |
| 2378 | if (is_idle_task(rq->curr)) |
| 2379 | smp_send_reschedule(cpu); |
| 2380 | /* Else CPU is not idle, do nothing here: */ |
| 2381 | rq_unlock_irqrestore(rq, &rf); |
| 2382 | } |
| 2383 | |
| 2384 | out: |
| 2385 | rcu_read_unlock(); |
| 2386 | } |
| 2387 | |
| 2388 | bool cpus_share_cache(int this_cpu, int that_cpu) |
| 2389 | { |
| 2390 | return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); |
| 2391 | } |
| 2392 | #endif /* CONFIG_SMP */ |
| 2393 | |
| 2394 | static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) |
| 2395 | { |
| 2396 | struct rq *rq = cpu_rq(cpu); |
| 2397 | struct rq_flags rf; |
| 2398 | |
| 2399 | #if defined(CONFIG_SMP) |
| 2400 | if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { |
| 2401 | sched_clock_cpu(cpu); /* Sync clocks across CPUs */ |
| 2402 | ttwu_queue_remote(p, cpu, wake_flags); |
| 2403 | return; |
| 2404 | } |
| 2405 | #endif |
| 2406 | |
| 2407 | rq_lock(rq, &rf); |
| 2408 | update_rq_clock(rq); |
| 2409 | ttwu_do_activate(rq, p, wake_flags, &rf); |
| 2410 | rq_unlock(rq, &rf); |
| 2411 | } |
| 2412 | |
| 2413 | /* |
| 2414 | * Notes on Program-Order guarantees on SMP systems. |
| 2415 | * |
| 2416 | * MIGRATION |
| 2417 | * |
| 2418 | * The basic program-order guarantee on SMP systems is that when a task [t] |
| 2419 | * migrates, all its activity on its old CPU [c0] happens-before any subsequent |
| 2420 | * execution on its new CPU [c1]. |
| 2421 | * |
| 2422 | * For migration (of runnable tasks) this is provided by the following means: |
| 2423 | * |
| 2424 | * A) UNLOCK of the rq(c0)->lock scheduling out task t |
| 2425 | * B) migration for t is required to synchronize *both* rq(c0)->lock and |
| 2426 | * rq(c1)->lock (if not at the same time, then in that order). |
| 2427 | * C) LOCK of the rq(c1)->lock scheduling in task |
| 2428 | * |
| 2429 | * Release/acquire chaining guarantees that B happens after A and C after B. |
| 2430 | * Note: the CPU doing B need not be c0 or c1 |
| 2431 | * |
| 2432 | * Example: |
| 2433 | * |
| 2434 | * CPU0 CPU1 CPU2 |
| 2435 | * |
| 2436 | * LOCK rq(0)->lock |
| 2437 | * sched-out X |
| 2438 | * sched-in Y |
| 2439 | * UNLOCK rq(0)->lock |
| 2440 | * |
| 2441 | * LOCK rq(0)->lock // orders against CPU0 |
| 2442 | * dequeue X |
| 2443 | * UNLOCK rq(0)->lock |
| 2444 | * |
| 2445 | * LOCK rq(1)->lock |
| 2446 | * enqueue X |
| 2447 | * UNLOCK rq(1)->lock |
| 2448 | * |
| 2449 | * LOCK rq(1)->lock // orders against CPU2 |
| 2450 | * sched-out Z |
| 2451 | * sched-in X |
| 2452 | * UNLOCK rq(1)->lock |
| 2453 | * |
| 2454 | * |
| 2455 | * BLOCKING -- aka. SLEEP + WAKEUP |
| 2456 | * |
| 2457 | * For blocking we (obviously) need to provide the same guarantee as for |
| 2458 | * migration. However the means are completely different as there is no lock |
| 2459 | * chain to provide order. Instead we do: |
| 2460 | * |
| 2461 | * 1) smp_store_release(X->on_cpu, 0) |
| 2462 | * 2) smp_cond_load_acquire(!X->on_cpu) |
| 2463 | * |
| 2464 | * Example: |
| 2465 | * |
| 2466 | * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule) |
| 2467 | * |
| 2468 | * LOCK rq(0)->lock LOCK X->pi_lock |
| 2469 | * dequeue X |
| 2470 | * sched-out X |
| 2471 | * smp_store_release(X->on_cpu, 0); |
| 2472 | * |
| 2473 | * smp_cond_load_acquire(&X->on_cpu, !VAL); |
| 2474 | * X->state = WAKING |
| 2475 | * set_task_cpu(X,2) |
| 2476 | * |
| 2477 | * LOCK rq(2)->lock |
| 2478 | * enqueue X |
| 2479 | * X->state = RUNNING |
| 2480 | * UNLOCK rq(2)->lock |
| 2481 | * |
| 2482 | * LOCK rq(2)->lock // orders against CPU1 |
| 2483 | * sched-out Z |
| 2484 | * sched-in X |
| 2485 | * UNLOCK rq(2)->lock |
| 2486 | * |
| 2487 | * UNLOCK X->pi_lock |
| 2488 | * UNLOCK rq(0)->lock |
| 2489 | * |
| 2490 | * |
| 2491 | * However, for wakeups there is a second guarantee we must provide, namely we |
| 2492 | * must ensure that CONDITION=1 done by the caller can not be reordered with |
| 2493 | * accesses to the task state; see try_to_wake_up() and set_current_state(). |
| 2494 | */ |
| 2495 | |
| 2496 | /** |
| 2497 | * try_to_wake_up - wake up a thread |
| 2498 | * @p: the thread to be awakened |
| 2499 | * @state: the mask of task states that can be woken |
| 2500 | * @wake_flags: wake modifier flags (WF_*) |
| 2501 | * |
| 2502 | * If (@state & @p->state) @p->state = TASK_RUNNING. |
| 2503 | * |
| 2504 | * If the task was not queued/runnable, also place it back on a runqueue. |
| 2505 | * |
| 2506 | * Atomic against schedule() which would dequeue a task, also see |
| 2507 | * set_current_state(). |
| 2508 | * |
| 2509 | * This function executes a full memory barrier before accessing the task |
| 2510 | * state; see set_current_state(). |
| 2511 | * |
| 2512 | * Return: %true if @p->state changes (an actual wakeup was done), |
| 2513 | * %false otherwise. |
| 2514 | */ |
| 2515 | static int |
| 2516 | try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) |
| 2517 | { |
| 2518 | unsigned long flags; |
| 2519 | int cpu, success = 0; |
| 2520 | |
| 2521 | preempt_disable(); |
| 2522 | if (p == current) { |
| 2523 | /* |
| 2524 | * We're waking current, this means 'p->on_rq' and 'task_cpu(p) |
| 2525 | * == smp_processor_id()'. Together this means we can special |
| 2526 | * case the whole 'p->on_rq && ttwu_remote()' case below |
| 2527 | * without taking any locks. |
| 2528 | * |
| 2529 | * In particular: |
| 2530 | * - we rely on Program-Order guarantees for all the ordering, |
| 2531 | * - we're serialized against set_special_state() by virtue of |
| 2532 | * it disabling IRQs (this allows not taking ->pi_lock). |
| 2533 | */ |
| 2534 | if (!(p->state & state)) |
| 2535 | goto out; |
| 2536 | |
| 2537 | success = 1; |
| 2538 | cpu = task_cpu(p); |
| 2539 | trace_sched_waking(p); |
| 2540 | p->state = TASK_RUNNING; |
| 2541 | trace_sched_wakeup(p); |
| 2542 | goto out; |
| 2543 | } |
| 2544 | |
| 2545 | /* |
| 2546 | * If we are going to wake up a thread waiting for CONDITION we |
| 2547 | * need to ensure that CONDITION=1 done by the caller can not be |
| 2548 | * reordered with p->state check below. This pairs with mb() in |
| 2549 | * set_current_state() the waiting thread does. |
| 2550 | */ |
| 2551 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
| 2552 | smp_mb__after_spinlock(); |
| 2553 | if (!(p->state & state)) |
| 2554 | goto unlock; |
| 2555 | |
| 2556 | trace_sched_waking(p); |
| 2557 | |
| 2558 | /* We're going to change ->state: */ |
| 2559 | success = 1; |
| 2560 | cpu = task_cpu(p); |
| 2561 | |
| 2562 | /* |
| 2563 | * Ensure we load p->on_rq _after_ p->state, otherwise it would |
| 2564 | * be possible to, falsely, observe p->on_rq == 0 and get stuck |
| 2565 | * in smp_cond_load_acquire() below. |
| 2566 | * |
| 2567 | * sched_ttwu_pending() try_to_wake_up() |
| 2568 | * STORE p->on_rq = 1 LOAD p->state |
| 2569 | * UNLOCK rq->lock |
| 2570 | * |
| 2571 | * __schedule() (switch to task 'p') |
| 2572 | * LOCK rq->lock smp_rmb(); |
| 2573 | * smp_mb__after_spinlock(); |
| 2574 | * UNLOCK rq->lock |
| 2575 | * |
| 2576 | * [task p] |
| 2577 | * STORE p->state = UNINTERRUPTIBLE LOAD p->on_rq |
| 2578 | * |
| 2579 | * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in |
| 2580 | * __schedule(). See the comment for smp_mb__after_spinlock(). |
| 2581 | */ |
| 2582 | smp_rmb(); |
| 2583 | if (p->on_rq && ttwu_remote(p, wake_flags)) |
| 2584 | goto unlock; |
| 2585 | |
| 2586 | #ifdef CONFIG_SMP |
| 2587 | /* |
| 2588 | * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be |
| 2589 | * possible to, falsely, observe p->on_cpu == 0. |
| 2590 | * |
| 2591 | * One must be running (->on_cpu == 1) in order to remove oneself |
| 2592 | * from the runqueue. |
| 2593 | * |
| 2594 | * __schedule() (switch to task 'p') try_to_wake_up() |
| 2595 | * STORE p->on_cpu = 1 LOAD p->on_rq |
| 2596 | * UNLOCK rq->lock |
| 2597 | * |
| 2598 | * __schedule() (put 'p' to sleep) |
| 2599 | * LOCK rq->lock smp_rmb(); |
| 2600 | * smp_mb__after_spinlock(); |
| 2601 | * STORE p->on_rq = 0 LOAD p->on_cpu |
| 2602 | * |
| 2603 | * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in |
| 2604 | * __schedule(). See the comment for smp_mb__after_spinlock(). |
| 2605 | */ |
| 2606 | smp_rmb(); |
| 2607 | |
| 2608 | /* |
| 2609 | * If the owning (remote) CPU is still in the middle of schedule() with |
| 2610 | * this task as prev, wait until its done referencing the task. |
| 2611 | * |
| 2612 | * Pairs with the smp_store_release() in finish_task(). |
| 2613 | * |
| 2614 | * This ensures that tasks getting woken will be fully ordered against |
| 2615 | * their previous state and preserve Program Order. |
| 2616 | */ |
| 2617 | smp_cond_load_acquire(&p->on_cpu, !VAL); |
| 2618 | |
| 2619 | p->sched_contributes_to_load = !!task_contributes_to_load(p); |
| 2620 | p->state = TASK_WAKING; |
| 2621 | |
| 2622 | if (p->in_iowait) { |
| 2623 | delayacct_blkio_end(p); |
| 2624 | atomic_dec(&task_rq(p)->nr_iowait); |
| 2625 | } |
| 2626 | |
| 2627 | cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); |
| 2628 | if (task_cpu(p) != cpu) { |
| 2629 | wake_flags |= WF_MIGRATED; |
| 2630 | psi_ttwu_dequeue(p); |
| 2631 | set_task_cpu(p, cpu); |
| 2632 | } |
| 2633 | |
| 2634 | #else /* CONFIG_SMP */ |
| 2635 | |
| 2636 | if (p->in_iowait) { |
| 2637 | delayacct_blkio_end(p); |
| 2638 | atomic_dec(&task_rq(p)->nr_iowait); |
| 2639 | } |
| 2640 | |
| 2641 | #endif /* CONFIG_SMP */ |
| 2642 | |
| 2643 | ttwu_queue(p, cpu, wake_flags); |
| 2644 | unlock: |
| 2645 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| 2646 | out: |
| 2647 | if (success) |
| 2648 | ttwu_stat(p, cpu, wake_flags); |
| 2649 | preempt_enable(); |
| 2650 | |
| 2651 | return success; |
| 2652 | } |
| 2653 | |
| 2654 | /** |
| 2655 | * wake_up_process - Wake up a specific process |
| 2656 | * @p: The process to be woken up. |
| 2657 | * |
| 2658 | * Attempt to wake up the nominated process and move it to the set of runnable |
| 2659 | * processes. |
| 2660 | * |
| 2661 | * Return: 1 if the process was woken up, 0 if it was already running. |
| 2662 | * |
| 2663 | * This function executes a full memory barrier before accessing the task state. |
| 2664 | */ |
| 2665 | int wake_up_process(struct task_struct *p) |
| 2666 | { |
| 2667 | return try_to_wake_up(p, TASK_NORMAL, 0); |
| 2668 | } |
| 2669 | EXPORT_SYMBOL(wake_up_process); |
| 2670 | |
| 2671 | int wake_up_state(struct task_struct *p, unsigned int state) |
| 2672 | { |
| 2673 | return try_to_wake_up(p, state, 0); |
| 2674 | } |
| 2675 | |
| 2676 | /* |
| 2677 | * Perform scheduler related setup for a newly forked process p. |
| 2678 | * p is forked by current. |
| 2679 | * |
| 2680 | * __sched_fork() is basic setup used by init_idle() too: |
| 2681 | */ |
| 2682 | static void __sched_fork(unsigned long clone_flags, struct task_struct *p) |
| 2683 | { |
| 2684 | p->on_rq = 0; |
| 2685 | |
| 2686 | p->se.on_rq = 0; |
| 2687 | p->se.exec_start = 0; |
| 2688 | p->se.sum_exec_runtime = 0; |
| 2689 | p->se.prev_sum_exec_runtime = 0; |
| 2690 | p->se.nr_migrations = 0; |
| 2691 | p->se.vruntime = 0; |
| 2692 | INIT_LIST_HEAD(&p->se.group_node); |
| 2693 | |
| 2694 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 2695 | p->se.cfs_rq = NULL; |
| 2696 | #endif |
| 2697 | |
| 2698 | #ifdef CONFIG_SCHEDSTATS |
| 2699 | /* Even if schedstat is disabled, there should not be garbage */ |
| 2700 | memset(&p->se.statistics, 0, sizeof(p->se.statistics)); |
| 2701 | #endif |
| 2702 | |
| 2703 | RB_CLEAR_NODE(&p->dl.rb_node); |
| 2704 | init_dl_task_timer(&p->dl); |
| 2705 | init_dl_inactive_task_timer(&p->dl); |
| 2706 | __dl_clear_params(p); |
| 2707 | |
| 2708 | INIT_LIST_HEAD(&p->rt.run_list); |
| 2709 | p->rt.timeout = 0; |
| 2710 | p->rt.time_slice = sched_rr_timeslice; |
| 2711 | p->rt.on_rq = 0; |
| 2712 | p->rt.on_list = 0; |
| 2713 | |
| 2714 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
| 2715 | INIT_HLIST_HEAD(&p->preempt_notifiers); |
| 2716 | #endif |
| 2717 | |
| 2718 | #ifdef CONFIG_COMPACTION |
| 2719 | p->capture_control = NULL; |
| 2720 | #endif |
| 2721 | init_numa_balancing(clone_flags, p); |
| 2722 | } |
| 2723 | |
| 2724 | DEFINE_STATIC_KEY_FALSE(sched_numa_balancing); |
| 2725 | |
| 2726 | #ifdef CONFIG_NUMA_BALANCING |
| 2727 | |
| 2728 | void set_numabalancing_state(bool enabled) |
| 2729 | { |
| 2730 | if (enabled) |
| 2731 | static_branch_enable(&sched_numa_balancing); |
| 2732 | else |
| 2733 | static_branch_disable(&sched_numa_balancing); |
| 2734 | } |
| 2735 | |
| 2736 | #ifdef CONFIG_PROC_SYSCTL |
| 2737 | int sysctl_numa_balancing(struct ctl_table *table, int write, |
| 2738 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 2739 | { |
| 2740 | struct ctl_table t; |
| 2741 | int err; |
| 2742 | int state = static_branch_likely(&sched_numa_balancing); |
| 2743 | |
| 2744 | if (write && !capable(CAP_SYS_ADMIN)) |
| 2745 | return -EPERM; |
| 2746 | |
| 2747 | t = *table; |
| 2748 | t.data = &state; |
| 2749 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); |
| 2750 | if (err < 0) |
| 2751 | return err; |
| 2752 | if (write) |
| 2753 | set_numabalancing_state(state); |
| 2754 | return err; |
| 2755 | } |
| 2756 | #endif |
| 2757 | #endif |
| 2758 | |
| 2759 | #ifdef CONFIG_SCHEDSTATS |
| 2760 | |
| 2761 | DEFINE_STATIC_KEY_FALSE(sched_schedstats); |
| 2762 | static bool __initdata __sched_schedstats = false; |
| 2763 | |
| 2764 | static void set_schedstats(bool enabled) |
| 2765 | { |
| 2766 | if (enabled) |
| 2767 | static_branch_enable(&sched_schedstats); |
| 2768 | else |
| 2769 | static_branch_disable(&sched_schedstats); |
| 2770 | } |
| 2771 | |
| 2772 | void force_schedstat_enabled(void) |
| 2773 | { |
| 2774 | if (!schedstat_enabled()) { |
| 2775 | pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n"); |
| 2776 | static_branch_enable(&sched_schedstats); |
| 2777 | } |
| 2778 | } |
| 2779 | |
| 2780 | static int __init setup_schedstats(char *str) |
| 2781 | { |
| 2782 | int ret = 0; |
| 2783 | if (!str) |
| 2784 | goto out; |
| 2785 | |
| 2786 | /* |
| 2787 | * This code is called before jump labels have been set up, so we can't |
| 2788 | * change the static branch directly just yet. Instead set a temporary |
| 2789 | * variable so init_schedstats() can do it later. |
| 2790 | */ |
| 2791 | if (!strcmp(str, "enable")) { |
| 2792 | __sched_schedstats = true; |
| 2793 | ret = 1; |
| 2794 | } else if (!strcmp(str, "disable")) { |
| 2795 | __sched_schedstats = false; |
| 2796 | ret = 1; |
| 2797 | } |
| 2798 | out: |
| 2799 | if (!ret) |
| 2800 | pr_warn("Unable to parse schedstats=\n"); |
| 2801 | |
| 2802 | return ret; |
| 2803 | } |
| 2804 | __setup("schedstats=", setup_schedstats); |
| 2805 | |
| 2806 | static void __init init_schedstats(void) |
| 2807 | { |
| 2808 | set_schedstats(__sched_schedstats); |
| 2809 | } |
| 2810 | |
| 2811 | #ifdef CONFIG_PROC_SYSCTL |
| 2812 | int sysctl_schedstats(struct ctl_table *table, int write, |
| 2813 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 2814 | { |
| 2815 | struct ctl_table t; |
| 2816 | int err; |
| 2817 | int state = static_branch_likely(&sched_schedstats); |
| 2818 | |
| 2819 | if (write && !capable(CAP_SYS_ADMIN)) |
| 2820 | return -EPERM; |
| 2821 | |
| 2822 | t = *table; |
| 2823 | t.data = &state; |
| 2824 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); |
| 2825 | if (err < 0) |
| 2826 | return err; |
| 2827 | if (write) |
| 2828 | set_schedstats(state); |
| 2829 | return err; |
| 2830 | } |
| 2831 | #endif /* CONFIG_PROC_SYSCTL */ |
| 2832 | #else /* !CONFIG_SCHEDSTATS */ |
| 2833 | static inline void init_schedstats(void) {} |
| 2834 | #endif /* CONFIG_SCHEDSTATS */ |
| 2835 | |
| 2836 | /* |
| 2837 | * fork()/clone()-time setup: |
| 2838 | */ |
| 2839 | int sched_fork(unsigned long clone_flags, struct task_struct *p) |
| 2840 | { |
| 2841 | unsigned long flags; |
| 2842 | |
| 2843 | __sched_fork(clone_flags, p); |
| 2844 | /* |
| 2845 | * We mark the process as NEW here. This guarantees that |
| 2846 | * nobody will actually run it, and a signal or other external |
| 2847 | * event cannot wake it up and insert it on the runqueue either. |
| 2848 | */ |
| 2849 | p->state = TASK_NEW; |
| 2850 | |
| 2851 | /* |
| 2852 | * Make sure we do not leak PI boosting priority to the child. |
| 2853 | */ |
| 2854 | p->prio = current->normal_prio; |
| 2855 | |
| 2856 | uclamp_fork(p); |
| 2857 | |
| 2858 | /* |
| 2859 | * Revert to default priority/policy on fork if requested. |
| 2860 | */ |
| 2861 | if (unlikely(p->sched_reset_on_fork)) { |
| 2862 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
| 2863 | p->policy = SCHED_NORMAL; |
| 2864 | p->static_prio = NICE_TO_PRIO(0); |
| 2865 | p->rt_priority = 0; |
| 2866 | } else if (PRIO_TO_NICE(p->static_prio) < 0) |
| 2867 | p->static_prio = NICE_TO_PRIO(0); |
| 2868 | |
| 2869 | p->prio = p->normal_prio = __normal_prio(p); |
| 2870 | set_load_weight(p, false); |
| 2871 | |
| 2872 | /* |
| 2873 | * We don't need the reset flag anymore after the fork. It has |
| 2874 | * fulfilled its duty: |
| 2875 | */ |
| 2876 | p->sched_reset_on_fork = 0; |
| 2877 | } |
| 2878 | |
| 2879 | if (dl_prio(p->prio)) |
| 2880 | return -EAGAIN; |
| 2881 | else if (rt_prio(p->prio)) |
| 2882 | p->sched_class = &rt_sched_class; |
| 2883 | else |
| 2884 | p->sched_class = &fair_sched_class; |
| 2885 | |
| 2886 | init_entity_runnable_average(&p->se); |
| 2887 | |
| 2888 | /* |
| 2889 | * The child is not yet in the pid-hash so no cgroup attach races, |
| 2890 | * and the cgroup is pinned to this child due to cgroup_fork() |
| 2891 | * is ran before sched_fork(). |
| 2892 | * |
| 2893 | * Silence PROVE_RCU. |
| 2894 | */ |
| 2895 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
| 2896 | /* |
| 2897 | * We're setting the CPU for the first time, we don't migrate, |
| 2898 | * so use __set_task_cpu(). |
| 2899 | */ |
| 2900 | __set_task_cpu(p, smp_processor_id()); |
| 2901 | if (p->sched_class->task_fork) |
| 2902 | p->sched_class->task_fork(p); |
| 2903 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| 2904 | |
| 2905 | #ifdef CONFIG_SCHED_INFO |
| 2906 | if (likely(sched_info_on())) |
| 2907 | memset(&p->sched_info, 0, sizeof(p->sched_info)); |
| 2908 | #endif |
| 2909 | #if defined(CONFIG_SMP) |
| 2910 | p->on_cpu = 0; |
| 2911 | #endif |
| 2912 | init_task_preempt_count(p); |
| 2913 | #ifdef CONFIG_SMP |
| 2914 | plist_node_init(&p->pushable_tasks, MAX_PRIO); |
| 2915 | RB_CLEAR_NODE(&p->pushable_dl_tasks); |
| 2916 | #endif |
| 2917 | return 0; |
| 2918 | } |
| 2919 | |
| 2920 | unsigned long to_ratio(u64 period, u64 runtime) |
| 2921 | { |
| 2922 | if (runtime == RUNTIME_INF) |
| 2923 | return BW_UNIT; |
| 2924 | |
| 2925 | /* |
| 2926 | * Doing this here saves a lot of checks in all |
| 2927 | * the calling paths, and returning zero seems |
| 2928 | * safe for them anyway. |
| 2929 | */ |
| 2930 | if (period == 0) |
| 2931 | return 0; |
| 2932 | |
| 2933 | return div64_u64(runtime << BW_SHIFT, period); |
| 2934 | } |
| 2935 | |
| 2936 | /* |
| 2937 | * wake_up_new_task - wake up a newly created task for the first time. |
| 2938 | * |
| 2939 | * This function will do some initial scheduler statistics housekeeping |
| 2940 | * that must be done for every newly created context, then puts the task |
| 2941 | * on the runqueue and wakes it. |
| 2942 | */ |
| 2943 | void wake_up_new_task(struct task_struct *p) |
| 2944 | { |
| 2945 | struct rq_flags rf; |
| 2946 | struct rq *rq; |
| 2947 | |
| 2948 | raw_spin_lock_irqsave(&p->pi_lock, rf.flags); |
| 2949 | p->state = TASK_RUNNING; |
| 2950 | #ifdef CONFIG_SMP |
| 2951 | /* |
| 2952 | * Fork balancing, do it here and not earlier because: |
| 2953 | * - cpus_ptr can change in the fork path |
| 2954 | * - any previously selected CPU might disappear through hotplug |
| 2955 | * |
| 2956 | * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, |
| 2957 | * as we're not fully set-up yet. |
| 2958 | */ |
| 2959 | p->recent_used_cpu = task_cpu(p); |
| 2960 | __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); |
| 2961 | #endif |
| 2962 | rq = __task_rq_lock(p, &rf); |
| 2963 | update_rq_clock(rq); |
| 2964 | post_init_entity_util_avg(p); |
| 2965 | |
| 2966 | activate_task(rq, p, ENQUEUE_NOCLOCK); |
| 2967 | trace_sched_wakeup_new(p); |
| 2968 | check_preempt_curr(rq, p, WF_FORK); |
| 2969 | #ifdef CONFIG_SMP |
| 2970 | if (p->sched_class->task_woken) { |
| 2971 | /* |
| 2972 | * Nothing relies on rq->lock after this, so its fine to |
| 2973 | * drop it. |
| 2974 | */ |
| 2975 | rq_unpin_lock(rq, &rf); |
| 2976 | p->sched_class->task_woken(rq, p); |
| 2977 | rq_repin_lock(rq, &rf); |
| 2978 | } |
| 2979 | #endif |
| 2980 | task_rq_unlock(rq, p, &rf); |
| 2981 | } |
| 2982 | |
| 2983 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
| 2984 | |
| 2985 | static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key); |
| 2986 | |
| 2987 | void preempt_notifier_inc(void) |
| 2988 | { |
| 2989 | static_branch_inc(&preempt_notifier_key); |
| 2990 | } |
| 2991 | EXPORT_SYMBOL_GPL(preempt_notifier_inc); |
| 2992 | |
| 2993 | void preempt_notifier_dec(void) |
| 2994 | { |
| 2995 | static_branch_dec(&preempt_notifier_key); |
| 2996 | } |
| 2997 | EXPORT_SYMBOL_GPL(preempt_notifier_dec); |
| 2998 | |
| 2999 | /** |
| 3000 | * preempt_notifier_register - tell me when current is being preempted & rescheduled |
| 3001 | * @notifier: notifier struct to register |
| 3002 | */ |
| 3003 | void preempt_notifier_register(struct preempt_notifier *notifier) |
| 3004 | { |
| 3005 | if (!static_branch_unlikely(&preempt_notifier_key)) |
| 3006 | WARN(1, "registering preempt_notifier while notifiers disabled\n"); |
| 3007 | |
| 3008 | hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); |
| 3009 | } |
| 3010 | EXPORT_SYMBOL_GPL(preempt_notifier_register); |
| 3011 | |
| 3012 | /** |
| 3013 | * preempt_notifier_unregister - no longer interested in preemption notifications |
| 3014 | * @notifier: notifier struct to unregister |
| 3015 | * |
| 3016 | * This is *not* safe to call from within a preemption notifier. |
| 3017 | */ |
| 3018 | void preempt_notifier_unregister(struct preempt_notifier *notifier) |
| 3019 | { |
| 3020 | hlist_del(¬ifier->link); |
| 3021 | } |
| 3022 | EXPORT_SYMBOL_GPL(preempt_notifier_unregister); |
| 3023 | |
| 3024 | static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) |
| 3025 | { |
| 3026 | struct preempt_notifier *notifier; |
| 3027 | |
| 3028 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) |
| 3029 | notifier->ops->sched_in(notifier, raw_smp_processor_id()); |
| 3030 | } |
| 3031 | |
| 3032 | static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) |
| 3033 | { |
| 3034 | if (static_branch_unlikely(&preempt_notifier_key)) |
| 3035 | __fire_sched_in_preempt_notifiers(curr); |
| 3036 | } |
| 3037 | |
| 3038 | static void |
| 3039 | __fire_sched_out_preempt_notifiers(struct task_struct *curr, |
| 3040 | struct task_struct *next) |
| 3041 | { |
| 3042 | struct preempt_notifier *notifier; |
| 3043 | |
| 3044 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) |
| 3045 | notifier->ops->sched_out(notifier, next); |
| 3046 | } |
| 3047 | |
| 3048 | static __always_inline void |
| 3049 | fire_sched_out_preempt_notifiers(struct task_struct *curr, |
| 3050 | struct task_struct *next) |
| 3051 | { |
| 3052 | if (static_branch_unlikely(&preempt_notifier_key)) |
| 3053 | __fire_sched_out_preempt_notifiers(curr, next); |
| 3054 | } |
| 3055 | |
| 3056 | #else /* !CONFIG_PREEMPT_NOTIFIERS */ |
| 3057 | |
| 3058 | static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) |
| 3059 | { |
| 3060 | } |
| 3061 | |
| 3062 | static inline void |
| 3063 | fire_sched_out_preempt_notifiers(struct task_struct *curr, |
| 3064 | struct task_struct *next) |
| 3065 | { |
| 3066 | } |
| 3067 | |
| 3068 | #endif /* CONFIG_PREEMPT_NOTIFIERS */ |
| 3069 | |
| 3070 | static inline void prepare_task(struct task_struct *next) |
| 3071 | { |
| 3072 | #ifdef CONFIG_SMP |
| 3073 | /* |
| 3074 | * Claim the task as running, we do this before switching to it |
| 3075 | * such that any running task will have this set. |
| 3076 | */ |
| 3077 | next->on_cpu = 1; |
| 3078 | #endif |
| 3079 | } |
| 3080 | |
| 3081 | static inline void finish_task(struct task_struct *prev) |
| 3082 | { |
| 3083 | #ifdef CONFIG_SMP |
| 3084 | /* |
| 3085 | * After ->on_cpu is cleared, the task can be moved to a different CPU. |
| 3086 | * We must ensure this doesn't happen until the switch is completely |
| 3087 | * finished. |
| 3088 | * |
| 3089 | * In particular, the load of prev->state in finish_task_switch() must |
| 3090 | * happen before this. |
| 3091 | * |
| 3092 | * Pairs with the smp_cond_load_acquire() in try_to_wake_up(). |
| 3093 | */ |
| 3094 | smp_store_release(&prev->on_cpu, 0); |
| 3095 | #endif |
| 3096 | } |
| 3097 | |
| 3098 | static inline void |
| 3099 | prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf) |
| 3100 | { |
| 3101 | /* |
| 3102 | * Since the runqueue lock will be released by the next |
| 3103 | * task (which is an invalid locking op but in the case |
| 3104 | * of the scheduler it's an obvious special-case), so we |
| 3105 | * do an early lockdep release here: |
| 3106 | */ |
| 3107 | rq_unpin_lock(rq, rf); |
| 3108 | spin_release(&rq->lock.dep_map, 1, _THIS_IP_); |
| 3109 | #ifdef CONFIG_DEBUG_SPINLOCK |
| 3110 | /* this is a valid case when another task releases the spinlock */ |
| 3111 | rq->lock.owner = next; |
| 3112 | #endif |
| 3113 | } |
| 3114 | |
| 3115 | static inline void finish_lock_switch(struct rq *rq) |
| 3116 | { |
| 3117 | /* |
| 3118 | * If we are tracking spinlock dependencies then we have to |
| 3119 | * fix up the runqueue lock - which gets 'carried over' from |
| 3120 | * prev into current: |
| 3121 | */ |
| 3122 | spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_); |
| 3123 | raw_spin_unlock_irq(&rq->lock); |
| 3124 | } |
| 3125 | |
| 3126 | /* |
| 3127 | * NOP if the arch has not defined these: |
| 3128 | */ |
| 3129 | |
| 3130 | #ifndef prepare_arch_switch |
| 3131 | # define prepare_arch_switch(next) do { } while (0) |
| 3132 | #endif |
| 3133 | |
| 3134 | #ifndef finish_arch_post_lock_switch |
| 3135 | # define finish_arch_post_lock_switch() do { } while (0) |
| 3136 | #endif |
| 3137 | |
| 3138 | /** |
| 3139 | * prepare_task_switch - prepare to switch tasks |
| 3140 | * @rq: the runqueue preparing to switch |
| 3141 | * @prev: the current task that is being switched out |
| 3142 | * @next: the task we are going to switch to. |
| 3143 | * |
| 3144 | * This is called with the rq lock held and interrupts off. It must |
| 3145 | * be paired with a subsequent finish_task_switch after the context |
| 3146 | * switch. |
| 3147 | * |
| 3148 | * prepare_task_switch sets up locking and calls architecture specific |
| 3149 | * hooks. |
| 3150 | */ |
| 3151 | static inline void |
| 3152 | prepare_task_switch(struct rq *rq, struct task_struct *prev, |
| 3153 | struct task_struct *next) |
| 3154 | { |
| 3155 | kcov_prepare_switch(prev); |
| 3156 | sched_info_switch(rq, prev, next); |
| 3157 | perf_event_task_sched_out(prev, next); |
| 3158 | rseq_preempt(prev); |
| 3159 | fire_sched_out_preempt_notifiers(prev, next); |
| 3160 | prepare_task(next); |
| 3161 | prepare_arch_switch(next); |
| 3162 | } |
| 3163 | |
| 3164 | /** |
| 3165 | * finish_task_switch - clean up after a task-switch |
| 3166 | * @prev: the thread we just switched away from. |
| 3167 | * |
| 3168 | * finish_task_switch must be called after the context switch, paired |
| 3169 | * with a prepare_task_switch call before the context switch. |
| 3170 | * finish_task_switch will reconcile locking set up by prepare_task_switch, |
| 3171 | * and do any other architecture-specific cleanup actions. |
| 3172 | * |
| 3173 | * Note that we may have delayed dropping an mm in context_switch(). If |
| 3174 | * so, we finish that here outside of the runqueue lock. (Doing it |
| 3175 | * with the lock held can cause deadlocks; see schedule() for |
| 3176 | * details.) |
| 3177 | * |
| 3178 | * The context switch have flipped the stack from under us and restored the |
| 3179 | * local variables which were saved when this task called schedule() in the |
| 3180 | * past. prev == current is still correct but we need to recalculate this_rq |
| 3181 | * because prev may have moved to another CPU. |
| 3182 | */ |
| 3183 | static struct rq *finish_task_switch(struct task_struct *prev) |
| 3184 | __releases(rq->lock) |
| 3185 | { |
| 3186 | struct rq *rq = this_rq(); |
| 3187 | struct mm_struct *mm = rq->prev_mm; |
| 3188 | long prev_state; |
| 3189 | |
| 3190 | /* |
| 3191 | * The previous task will have left us with a preempt_count of 2 |
| 3192 | * because it left us after: |
| 3193 | * |
| 3194 | * schedule() |
| 3195 | * preempt_disable(); // 1 |
| 3196 | * __schedule() |
| 3197 | * raw_spin_lock_irq(&rq->lock) // 2 |
| 3198 | * |
| 3199 | * Also, see FORK_PREEMPT_COUNT. |
| 3200 | */ |
| 3201 | if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET, |
| 3202 | "corrupted preempt_count: %s/%d/0x%x\n", |
| 3203 | current->comm, current->pid, preempt_count())) |
| 3204 | preempt_count_set(FORK_PREEMPT_COUNT); |
| 3205 | |
| 3206 | rq->prev_mm = NULL; |
| 3207 | |
| 3208 | /* |
| 3209 | * A task struct has one reference for the use as "current". |
| 3210 | * If a task dies, then it sets TASK_DEAD in tsk->state and calls |
| 3211 | * schedule one last time. The schedule call will never return, and |
| 3212 | * the scheduled task must drop that reference. |
| 3213 | * |
| 3214 | * We must observe prev->state before clearing prev->on_cpu (in |
| 3215 | * finish_task), otherwise a concurrent wakeup can get prev |
| 3216 | * running on another CPU and we could rave with its RUNNING -> DEAD |
| 3217 | * transition, resulting in a double drop. |
| 3218 | */ |
| 3219 | prev_state = prev->state; |
| 3220 | vtime_task_switch(prev); |
| 3221 | perf_event_task_sched_in(prev, current); |
| 3222 | finish_task(prev); |
| 3223 | finish_lock_switch(rq); |
| 3224 | finish_arch_post_lock_switch(); |
| 3225 | kcov_finish_switch(current); |
| 3226 | |
| 3227 | fire_sched_in_preempt_notifiers(current); |
| 3228 | /* |
| 3229 | * When switching through a kernel thread, the loop in |
| 3230 | * membarrier_{private,global}_expedited() may have observed that |
| 3231 | * kernel thread and not issued an IPI. It is therefore possible to |
| 3232 | * schedule between user->kernel->user threads without passing though |
| 3233 | * switch_mm(). Membarrier requires a barrier after storing to |
| 3234 | * rq->curr, before returning to userspace, so provide them here: |
| 3235 | * |
| 3236 | * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly |
| 3237 | * provided by mmdrop(), |
| 3238 | * - a sync_core for SYNC_CORE. |
| 3239 | */ |
| 3240 | if (mm) { |
| 3241 | membarrier_mm_sync_core_before_usermode(mm); |
| 3242 | mmdrop(mm); |
| 3243 | } |
| 3244 | if (unlikely(prev_state == TASK_DEAD)) { |
| 3245 | if (prev->sched_class->task_dead) |
| 3246 | prev->sched_class->task_dead(prev); |
| 3247 | |
| 3248 | /* |
| 3249 | * Remove function-return probe instances associated with this |
| 3250 | * task and put them back on the free list. |
| 3251 | */ |
| 3252 | kprobe_flush_task(prev); |
| 3253 | |
| 3254 | /* Task is done with its stack. */ |
| 3255 | put_task_stack(prev); |
| 3256 | |
| 3257 | put_task_struct_rcu_user(prev); |
| 3258 | } |
| 3259 | |
| 3260 | tick_nohz_task_switch(); |
| 3261 | return rq; |
| 3262 | } |
| 3263 | |
| 3264 | #ifdef CONFIG_SMP |
| 3265 | |
| 3266 | /* rq->lock is NOT held, but preemption is disabled */ |
| 3267 | static void __balance_callback(struct rq *rq) |
| 3268 | { |
| 3269 | struct callback_head *head, *next; |
| 3270 | void (*func)(struct rq *rq); |
| 3271 | unsigned long flags; |
| 3272 | |
| 3273 | raw_spin_lock_irqsave(&rq->lock, flags); |
| 3274 | head = rq->balance_callback; |
| 3275 | rq->balance_callback = NULL; |
| 3276 | while (head) { |
| 3277 | func = (void (*)(struct rq *))head->func; |
| 3278 | next = head->next; |
| 3279 | head->next = NULL; |
| 3280 | head = next; |
| 3281 | |
| 3282 | func(rq); |
| 3283 | } |
| 3284 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
| 3285 | } |
| 3286 | |
| 3287 | static inline void balance_callback(struct rq *rq) |
| 3288 | { |
| 3289 | if (unlikely(rq->balance_callback)) |
| 3290 | __balance_callback(rq); |
| 3291 | } |
| 3292 | |
| 3293 | #else |
| 3294 | |
| 3295 | static inline void balance_callback(struct rq *rq) |
| 3296 | { |
| 3297 | } |
| 3298 | |
| 3299 | #endif |
| 3300 | |
| 3301 | /** |
| 3302 | * schedule_tail - first thing a freshly forked thread must call. |
| 3303 | * @prev: the thread we just switched away from. |
| 3304 | */ |
| 3305 | asmlinkage __visible void schedule_tail(struct task_struct *prev) |
| 3306 | __releases(rq->lock) |
| 3307 | { |
| 3308 | struct rq *rq; |
| 3309 | |
| 3310 | /* |
| 3311 | * New tasks start with FORK_PREEMPT_COUNT, see there and |
| 3312 | * finish_task_switch() for details. |
| 3313 | * |
| 3314 | * finish_task_switch() will drop rq->lock() and lower preempt_count |
| 3315 | * and the preempt_enable() will end up enabling preemption (on |
| 3316 | * PREEMPT_COUNT kernels). |
| 3317 | */ |
| 3318 | |
| 3319 | rq = finish_task_switch(prev); |
| 3320 | balance_callback(rq); |
| 3321 | preempt_enable(); |
| 3322 | |
| 3323 | if (current->set_child_tid) |
| 3324 | put_user(task_pid_vnr(current), current->set_child_tid); |
| 3325 | |
| 3326 | calculate_sigpending(); |
| 3327 | } |
| 3328 | |
| 3329 | /* |
| 3330 | * context_switch - switch to the new MM and the new thread's register state. |
| 3331 | */ |
| 3332 | static __always_inline struct rq * |
| 3333 | context_switch(struct rq *rq, struct task_struct *prev, |
| 3334 | struct task_struct *next, struct rq_flags *rf) |
| 3335 | { |
| 3336 | prepare_task_switch(rq, prev, next); |
| 3337 | |
| 3338 | /* |
| 3339 | * For paravirt, this is coupled with an exit in switch_to to |
| 3340 | * combine the page table reload and the switch backend into |
| 3341 | * one hypercall. |
| 3342 | */ |
| 3343 | arch_start_context_switch(prev); |
| 3344 | |
| 3345 | /* |
| 3346 | * kernel -> kernel lazy + transfer active |
| 3347 | * user -> kernel lazy + mmgrab() active |
| 3348 | * |
| 3349 | * kernel -> user switch + mmdrop() active |
| 3350 | * user -> user switch |
| 3351 | */ |
| 3352 | if (!next->mm) { // to kernel |
| 3353 | enter_lazy_tlb(prev->active_mm, next); |
| 3354 | |
| 3355 | next->active_mm = prev->active_mm; |
| 3356 | if (prev->mm) // from user |
| 3357 | mmgrab(prev->active_mm); |
| 3358 | else |
| 3359 | prev->active_mm = NULL; |
| 3360 | } else { // to user |
| 3361 | membarrier_switch_mm(rq, prev->active_mm, next->mm); |
| 3362 | /* |
| 3363 | * sys_membarrier() requires an smp_mb() between setting |
| 3364 | * rq->curr / membarrier_switch_mm() and returning to userspace. |
| 3365 | * |
| 3366 | * The below provides this either through switch_mm(), or in |
| 3367 | * case 'prev->active_mm == next->mm' through |
| 3368 | * finish_task_switch()'s mmdrop(). |
| 3369 | */ |
| 3370 | switch_mm_irqs_off(prev->active_mm, next->mm, next); |
| 3371 | |
| 3372 | if (!prev->mm) { // from kernel |
| 3373 | /* will mmdrop() in finish_task_switch(). */ |
| 3374 | rq->prev_mm = prev->active_mm; |
| 3375 | prev->active_mm = NULL; |
| 3376 | } |
| 3377 | } |
| 3378 | |
| 3379 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
| 3380 | |
| 3381 | prepare_lock_switch(rq, next, rf); |
| 3382 | |
| 3383 | /* Here we just switch the register state and the stack. */ |
| 3384 | switch_to(prev, next, prev); |
| 3385 | barrier(); |
| 3386 | |
| 3387 | return finish_task_switch(prev); |
| 3388 | } |
| 3389 | |
| 3390 | /* |
| 3391 | * nr_running and nr_context_switches: |
| 3392 | * |
| 3393 | * externally visible scheduler statistics: current number of runnable |
| 3394 | * threads, total number of context switches performed since bootup. |
| 3395 | */ |
| 3396 | unsigned long nr_running(void) |
| 3397 | { |
| 3398 | unsigned long i, sum = 0; |
| 3399 | |
| 3400 | for_each_online_cpu(i) |
| 3401 | sum += cpu_rq(i)->nr_running; |
| 3402 | |
| 3403 | return sum; |
| 3404 | } |
| 3405 | |
| 3406 | /* |
| 3407 | * Check if only the current task is running on the CPU. |
| 3408 | * |
| 3409 | * Caution: this function does not check that the caller has disabled |
| 3410 | * preemption, thus the result might have a time-of-check-to-time-of-use |
| 3411 | * race. The caller is responsible to use it correctly, for example: |
| 3412 | * |
| 3413 | * - from a non-preemptible section (of course) |
| 3414 | * |
| 3415 | * - from a thread that is bound to a single CPU |
| 3416 | * |
| 3417 | * - in a loop with very short iterations (e.g. a polling loop) |
| 3418 | */ |
| 3419 | bool single_task_running(void) |
| 3420 | { |
| 3421 | return raw_rq()->nr_running == 1; |
| 3422 | } |
| 3423 | EXPORT_SYMBOL(single_task_running); |
| 3424 | |
| 3425 | unsigned long long nr_context_switches(void) |
| 3426 | { |
| 3427 | int i; |
| 3428 | unsigned long long sum = 0; |
| 3429 | |
| 3430 | for_each_possible_cpu(i) |
| 3431 | sum += cpu_rq(i)->nr_switches; |
| 3432 | |
| 3433 | return sum; |
| 3434 | } |
| 3435 | |
| 3436 | /* |
| 3437 | * Consumers of these two interfaces, like for example the cpuidle menu |
| 3438 | * governor, are using nonsensical data. Preferring shallow idle state selection |
| 3439 | * for a CPU that has IO-wait which might not even end up running the task when |
| 3440 | * it does become runnable. |
| 3441 | */ |
| 3442 | |
| 3443 | unsigned long nr_iowait_cpu(int cpu) |
| 3444 | { |
| 3445 | return atomic_read(&cpu_rq(cpu)->nr_iowait); |
| 3446 | } |
| 3447 | |
| 3448 | /* |
| 3449 | * IO-wait accounting, and how its mostly bollocks (on SMP). |
| 3450 | * |
| 3451 | * The idea behind IO-wait account is to account the idle time that we could |
| 3452 | * have spend running if it were not for IO. That is, if we were to improve the |
| 3453 | * storage performance, we'd have a proportional reduction in IO-wait time. |
| 3454 | * |
| 3455 | * This all works nicely on UP, where, when a task blocks on IO, we account |
| 3456 | * idle time as IO-wait, because if the storage were faster, it could've been |
| 3457 | * running and we'd not be idle. |
| 3458 | * |
| 3459 | * This has been extended to SMP, by doing the same for each CPU. This however |
| 3460 | * is broken. |
| 3461 | * |
| 3462 | * Imagine for instance the case where two tasks block on one CPU, only the one |
| 3463 | * CPU will have IO-wait accounted, while the other has regular idle. Even |
| 3464 | * though, if the storage were faster, both could've ran at the same time, |
| 3465 | * utilising both CPUs. |
| 3466 | * |
| 3467 | * This means, that when looking globally, the current IO-wait accounting on |
| 3468 | * SMP is a lower bound, by reason of under accounting. |
| 3469 | * |
| 3470 | * Worse, since the numbers are provided per CPU, they are sometimes |
| 3471 | * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly |
| 3472 | * associated with any one particular CPU, it can wake to another CPU than it |
| 3473 | * blocked on. This means the per CPU IO-wait number is meaningless. |
| 3474 | * |
| 3475 | * Task CPU affinities can make all that even more 'interesting'. |
| 3476 | */ |
| 3477 | |
| 3478 | unsigned long nr_iowait(void) |
| 3479 | { |
| 3480 | unsigned long i, sum = 0; |
| 3481 | |
| 3482 | for_each_possible_cpu(i) |
| 3483 | sum += nr_iowait_cpu(i); |
| 3484 | |
| 3485 | return sum; |
| 3486 | } |
| 3487 | |
| 3488 | #ifdef CONFIG_SMP |
| 3489 | |
| 3490 | /* |
| 3491 | * sched_exec - execve() is a valuable balancing opportunity, because at |
| 3492 | * this point the task has the smallest effective memory and cache footprint. |
| 3493 | */ |
| 3494 | void sched_exec(void) |
| 3495 | { |
| 3496 | struct task_struct *p = current; |
| 3497 | unsigned long flags; |
| 3498 | int dest_cpu; |
| 3499 | |
| 3500 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
| 3501 | dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); |
| 3502 | if (dest_cpu == smp_processor_id()) |
| 3503 | goto unlock; |
| 3504 | |
| 3505 | if (likely(cpu_active(dest_cpu))) { |
| 3506 | struct migration_arg arg = { p, dest_cpu }; |
| 3507 | |
| 3508 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| 3509 | stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); |
| 3510 | return; |
| 3511 | } |
| 3512 | unlock: |
| 3513 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| 3514 | } |
| 3515 | |
| 3516 | #endif |
| 3517 | |
| 3518 | DEFINE_PER_CPU(struct kernel_stat, kstat); |
| 3519 | DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); |
| 3520 | |
| 3521 | EXPORT_PER_CPU_SYMBOL(kstat); |
| 3522 | EXPORT_PER_CPU_SYMBOL(kernel_cpustat); |
| 3523 | |
| 3524 | /* |
| 3525 | * The function fair_sched_class.update_curr accesses the struct curr |
| 3526 | * and its field curr->exec_start; when called from task_sched_runtime(), |
| 3527 | * we observe a high rate of cache misses in practice. |
| 3528 | * Prefetching this data results in improved performance. |
| 3529 | */ |
| 3530 | static inline void prefetch_curr_exec_start(struct task_struct *p) |
| 3531 | { |
| 3532 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 3533 | struct sched_entity *curr = (&p->se)->cfs_rq->curr; |
| 3534 | #else |
| 3535 | struct sched_entity *curr = (&task_rq(p)->cfs)->curr; |
| 3536 | #endif |
| 3537 | prefetch(curr); |
| 3538 | prefetch(&curr->exec_start); |
| 3539 | } |
| 3540 | |
| 3541 | /* |
| 3542 | * Return accounted runtime for the task. |
| 3543 | * In case the task is currently running, return the runtime plus current's |
| 3544 | * pending runtime that have not been accounted yet. |
| 3545 | */ |
| 3546 | unsigned long long task_sched_runtime(struct task_struct *p) |
| 3547 | { |
| 3548 | struct rq_flags rf; |
| 3549 | struct rq *rq; |
| 3550 | u64 ns; |
| 3551 | |
| 3552 | #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) |
| 3553 | /* |
| 3554 | * 64-bit doesn't need locks to atomically read a 64-bit value. |
| 3555 | * So we have a optimization chance when the task's delta_exec is 0. |
| 3556 | * Reading ->on_cpu is racy, but this is ok. |
| 3557 | * |
| 3558 | * If we race with it leaving CPU, we'll take a lock. So we're correct. |
| 3559 | * If we race with it entering CPU, unaccounted time is 0. This is |
| 3560 | * indistinguishable from the read occurring a few cycles earlier. |
| 3561 | * If we see ->on_cpu without ->on_rq, the task is leaving, and has |
| 3562 | * been accounted, so we're correct here as well. |
| 3563 | */ |
| 3564 | if (!p->on_cpu || !task_on_rq_queued(p)) |
| 3565 | return p->se.sum_exec_runtime; |
| 3566 | #endif |
| 3567 | |
| 3568 | rq = task_rq_lock(p, &rf); |
| 3569 | /* |
| 3570 | * Must be ->curr _and_ ->on_rq. If dequeued, we would |
| 3571 | * project cycles that may never be accounted to this |
| 3572 | * thread, breaking clock_gettime(). |
| 3573 | */ |
| 3574 | if (task_current(rq, p) && task_on_rq_queued(p)) { |
| 3575 | prefetch_curr_exec_start(p); |
| 3576 | update_rq_clock(rq); |
| 3577 | p->sched_class->update_curr(rq); |
| 3578 | } |
| 3579 | ns = p->se.sum_exec_runtime; |
| 3580 | task_rq_unlock(rq, p, &rf); |
| 3581 | |
| 3582 | return ns; |
| 3583 | } |
| 3584 | |
| 3585 | /* |
| 3586 | * This function gets called by the timer code, with HZ frequency. |
| 3587 | * We call it with interrupts disabled. |
| 3588 | */ |
| 3589 | void scheduler_tick(void) |
| 3590 | { |
| 3591 | int cpu = smp_processor_id(); |
| 3592 | struct rq *rq = cpu_rq(cpu); |
| 3593 | struct task_struct *curr = rq->curr; |
| 3594 | struct rq_flags rf; |
| 3595 | |
| 3596 | sched_clock_tick(); |
| 3597 | |
| 3598 | rq_lock(rq, &rf); |
| 3599 | |
| 3600 | update_rq_clock(rq); |
| 3601 | curr->sched_class->task_tick(rq, curr, 0); |
| 3602 | calc_global_load_tick(rq); |
| 3603 | psi_task_tick(rq); |
| 3604 | |
| 3605 | rq_unlock(rq, &rf); |
| 3606 | |
| 3607 | perf_event_task_tick(); |
| 3608 | |
| 3609 | #ifdef CONFIG_SMP |
| 3610 | rq->idle_balance = idle_cpu(cpu); |
| 3611 | trigger_load_balance(rq); |
| 3612 | #endif |
| 3613 | } |
| 3614 | |
| 3615 | #ifdef CONFIG_NO_HZ_FULL |
| 3616 | |
| 3617 | struct tick_work { |
| 3618 | int cpu; |
| 3619 | atomic_t state; |
| 3620 | struct delayed_work work; |
| 3621 | }; |
| 3622 | /* Values for ->state, see diagram below. */ |
| 3623 | #define TICK_SCHED_REMOTE_OFFLINE 0 |
| 3624 | #define TICK_SCHED_REMOTE_OFFLINING 1 |
| 3625 | #define TICK_SCHED_REMOTE_RUNNING 2 |
| 3626 | |
| 3627 | /* |
| 3628 | * State diagram for ->state: |
| 3629 | * |
| 3630 | * |
| 3631 | * TICK_SCHED_REMOTE_OFFLINE |
| 3632 | * | ^ |
| 3633 | * | | |
| 3634 | * | | sched_tick_remote() |
| 3635 | * | | |
| 3636 | * | | |
| 3637 | * +--TICK_SCHED_REMOTE_OFFLINING |
| 3638 | * | ^ |
| 3639 | * | | |
| 3640 | * sched_tick_start() | | sched_tick_stop() |
| 3641 | * | | |
| 3642 | * V | |
| 3643 | * TICK_SCHED_REMOTE_RUNNING |
| 3644 | * |
| 3645 | * |
| 3646 | * Other transitions get WARN_ON_ONCE(), except that sched_tick_remote() |
| 3647 | * and sched_tick_start() are happy to leave the state in RUNNING. |
| 3648 | */ |
| 3649 | |
| 3650 | static struct tick_work __percpu *tick_work_cpu; |
| 3651 | |
| 3652 | static void sched_tick_remote(struct work_struct *work) |
| 3653 | { |
| 3654 | struct delayed_work *dwork = to_delayed_work(work); |
| 3655 | struct tick_work *twork = container_of(dwork, struct tick_work, work); |
| 3656 | int cpu = twork->cpu; |
| 3657 | struct rq *rq = cpu_rq(cpu); |
| 3658 | struct task_struct *curr; |
| 3659 | struct rq_flags rf; |
| 3660 | u64 delta; |
| 3661 | int os; |
| 3662 | |
| 3663 | /* |
| 3664 | * Handle the tick only if it appears the remote CPU is running in full |
| 3665 | * dynticks mode. The check is racy by nature, but missing a tick or |
| 3666 | * having one too much is no big deal because the scheduler tick updates |
| 3667 | * statistics and checks timeslices in a time-independent way, regardless |
| 3668 | * of when exactly it is running. |
| 3669 | */ |
| 3670 | if (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu)) |
| 3671 | goto out_requeue; |
| 3672 | |
| 3673 | rq_lock_irq(rq, &rf); |
| 3674 | curr = rq->curr; |
| 3675 | if (is_idle_task(curr) || cpu_is_offline(cpu)) |
| 3676 | goto out_unlock; |
| 3677 | |
| 3678 | update_rq_clock(rq); |
| 3679 | delta = rq_clock_task(rq) - curr->se.exec_start; |
| 3680 | |
| 3681 | /* |
| 3682 | * Make sure the next tick runs within a reasonable |
| 3683 | * amount of time. |
| 3684 | */ |
| 3685 | WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); |
| 3686 | curr->sched_class->task_tick(rq, curr, 0); |
| 3687 | |
| 3688 | out_unlock: |
| 3689 | rq_unlock_irq(rq, &rf); |
| 3690 | |
| 3691 | out_requeue: |
| 3692 | /* |
| 3693 | * Run the remote tick once per second (1Hz). This arbitrary |
| 3694 | * frequency is large enough to avoid overload but short enough |
| 3695 | * to keep scheduler internal stats reasonably up to date. But |
| 3696 | * first update state to reflect hotplug activity if required. |
| 3697 | */ |
| 3698 | os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING); |
| 3699 | WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE); |
| 3700 | if (os == TICK_SCHED_REMOTE_RUNNING) |
| 3701 | queue_delayed_work(system_unbound_wq, dwork, HZ); |
| 3702 | } |
| 3703 | |
| 3704 | static void sched_tick_start(int cpu) |
| 3705 | { |
| 3706 | int os; |
| 3707 | struct tick_work *twork; |
| 3708 | |
| 3709 | if (housekeeping_cpu(cpu, HK_FLAG_TICK)) |
| 3710 | return; |
| 3711 | |
| 3712 | WARN_ON_ONCE(!tick_work_cpu); |
| 3713 | |
| 3714 | twork = per_cpu_ptr(tick_work_cpu, cpu); |
| 3715 | os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING); |
| 3716 | WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING); |
| 3717 | if (os == TICK_SCHED_REMOTE_OFFLINE) { |
| 3718 | twork->cpu = cpu; |
| 3719 | INIT_DELAYED_WORK(&twork->work, sched_tick_remote); |
| 3720 | queue_delayed_work(system_unbound_wq, &twork->work, HZ); |
| 3721 | } |
| 3722 | } |
| 3723 | |
| 3724 | #ifdef CONFIG_HOTPLUG_CPU |
| 3725 | static void sched_tick_stop(int cpu) |
| 3726 | { |
| 3727 | struct tick_work *twork; |
| 3728 | int os; |
| 3729 | |
| 3730 | if (housekeeping_cpu(cpu, HK_FLAG_TICK)) |
| 3731 | return; |
| 3732 | |
| 3733 | WARN_ON_ONCE(!tick_work_cpu); |
| 3734 | |
| 3735 | twork = per_cpu_ptr(tick_work_cpu, cpu); |
| 3736 | /* There cannot be competing actions, but don't rely on stop-machine. */ |
| 3737 | os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING); |
| 3738 | WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING); |
| 3739 | /* Don't cancel, as this would mess up the state machine. */ |
| 3740 | } |
| 3741 | #endif /* CONFIG_HOTPLUG_CPU */ |
| 3742 | |
| 3743 | int __init sched_tick_offload_init(void) |
| 3744 | { |
| 3745 | tick_work_cpu = alloc_percpu(struct tick_work); |
| 3746 | BUG_ON(!tick_work_cpu); |
| 3747 | return 0; |
| 3748 | } |
| 3749 | |
| 3750 | #else /* !CONFIG_NO_HZ_FULL */ |
| 3751 | static inline void sched_tick_start(int cpu) { } |
| 3752 | static inline void sched_tick_stop(int cpu) { } |
| 3753 | #endif |
| 3754 | |
| 3755 | #if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \ |
| 3756 | defined(CONFIG_TRACE_PREEMPT_TOGGLE)) |
| 3757 | /* |
| 3758 | * If the value passed in is equal to the current preempt count |
| 3759 | * then we just disabled preemption. Start timing the latency. |
| 3760 | */ |
| 3761 | static inline void preempt_latency_start(int val) |
| 3762 | { |
| 3763 | if (preempt_count() == val) { |
| 3764 | unsigned long ip = get_lock_parent_ip(); |
| 3765 | #ifdef CONFIG_DEBUG_PREEMPT |
| 3766 | current->preempt_disable_ip = ip; |
| 3767 | #endif |
| 3768 | trace_preempt_off(CALLER_ADDR0, ip); |
| 3769 | } |
| 3770 | } |
| 3771 | |
| 3772 | void preempt_count_add(int val) |
| 3773 | { |
| 3774 | #ifdef CONFIG_DEBUG_PREEMPT |
| 3775 | /* |
| 3776 | * Underflow? |
| 3777 | */ |
| 3778 | if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) |
| 3779 | return; |
| 3780 | #endif |
| 3781 | __preempt_count_add(val); |
| 3782 | #ifdef CONFIG_DEBUG_PREEMPT |
| 3783 | /* |
| 3784 | * Spinlock count overflowing soon? |
| 3785 | */ |
| 3786 | DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= |
| 3787 | PREEMPT_MASK - 10); |
| 3788 | #endif |
| 3789 | preempt_latency_start(val); |
| 3790 | } |
| 3791 | EXPORT_SYMBOL(preempt_count_add); |
| 3792 | NOKPROBE_SYMBOL(preempt_count_add); |
| 3793 | |
| 3794 | /* |
| 3795 | * If the value passed in equals to the current preempt count |
| 3796 | * then we just enabled preemption. Stop timing the latency. |
| 3797 | */ |
| 3798 | static inline void preempt_latency_stop(int val) |
| 3799 | { |
| 3800 | if (preempt_count() == val) |
| 3801 | trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); |
| 3802 | } |
| 3803 | |
| 3804 | void preempt_count_sub(int val) |
| 3805 | { |
| 3806 | #ifdef CONFIG_DEBUG_PREEMPT |
| 3807 | /* |
| 3808 | * Underflow? |
| 3809 | */ |
| 3810 | if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) |
| 3811 | return; |
| 3812 | /* |
| 3813 | * Is the spinlock portion underflowing? |
| 3814 | */ |
| 3815 | if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && |
| 3816 | !(preempt_count() & PREEMPT_MASK))) |
| 3817 | return; |
| 3818 | #endif |
| 3819 | |
| 3820 | preempt_latency_stop(val); |
| 3821 | __preempt_count_sub(val); |
| 3822 | } |
| 3823 | EXPORT_SYMBOL(preempt_count_sub); |
| 3824 | NOKPROBE_SYMBOL(preempt_count_sub); |
| 3825 | |
| 3826 | #else |
| 3827 | static inline void preempt_latency_start(int val) { } |
| 3828 | static inline void preempt_latency_stop(int val) { } |
| 3829 | #endif |
| 3830 | |
| 3831 | static inline unsigned long get_preempt_disable_ip(struct task_struct *p) |
| 3832 | { |
| 3833 | #ifdef CONFIG_DEBUG_PREEMPT |
| 3834 | return p->preempt_disable_ip; |
| 3835 | #else |
| 3836 | return 0; |
| 3837 | #endif |
| 3838 | } |
| 3839 | |
| 3840 | /* |
| 3841 | * Print scheduling while atomic bug: |
| 3842 | */ |
| 3843 | static noinline void __schedule_bug(struct task_struct *prev) |
| 3844 | { |
| 3845 | /* Save this before calling printk(), since that will clobber it */ |
| 3846 | unsigned long preempt_disable_ip = get_preempt_disable_ip(current); |
| 3847 | |
| 3848 | if (oops_in_progress) |
| 3849 | return; |
| 3850 | |
| 3851 | printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", |
| 3852 | prev->comm, prev->pid, preempt_count()); |
| 3853 | |
| 3854 | debug_show_held_locks(prev); |
| 3855 | print_modules(); |
| 3856 | if (irqs_disabled()) |
| 3857 | print_irqtrace_events(prev); |
| 3858 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
| 3859 | && in_atomic_preempt_off()) { |
| 3860 | pr_err("Preemption disabled at:"); |
| 3861 | print_ip_sym(preempt_disable_ip); |
| 3862 | pr_cont("\n"); |
| 3863 | } |
| 3864 | if (panic_on_warn) |
| 3865 | panic("scheduling while atomic\n"); |
| 3866 | |
| 3867 | dump_stack(); |
| 3868 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
| 3869 | } |
| 3870 | |
| 3871 | /* |
| 3872 | * Various schedule()-time debugging checks and statistics: |
| 3873 | */ |
| 3874 | static inline void schedule_debug(struct task_struct *prev, bool preempt) |
| 3875 | { |
| 3876 | #ifdef CONFIG_SCHED_STACK_END_CHECK |
| 3877 | if (task_stack_end_corrupted(prev)) |
| 3878 | panic("corrupted stack end detected inside scheduler\n"); |
| 3879 | #endif |
| 3880 | |
| 3881 | #ifdef CONFIG_DEBUG_ATOMIC_SLEEP |
| 3882 | if (!preempt && prev->state && prev->non_block_count) { |
| 3883 | printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n", |
| 3884 | prev->comm, prev->pid, prev->non_block_count); |
| 3885 | dump_stack(); |
| 3886 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
| 3887 | } |
| 3888 | #endif |
| 3889 | |
| 3890 | if (unlikely(in_atomic_preempt_off())) { |
| 3891 | __schedule_bug(prev); |
| 3892 | preempt_count_set(PREEMPT_DISABLED); |
| 3893 | } |
| 3894 | rcu_sleep_check(); |
| 3895 | |
| 3896 | profile_hit(SCHED_PROFILING, __builtin_return_address(0)); |
| 3897 | |
| 3898 | schedstat_inc(this_rq()->sched_count); |
| 3899 | } |
| 3900 | |
| 3901 | /* |
| 3902 | * Pick up the highest-prio task: |
| 3903 | */ |
| 3904 | static inline struct task_struct * |
| 3905 | pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
| 3906 | { |
| 3907 | const struct sched_class *class; |
| 3908 | struct task_struct *p; |
| 3909 | |
| 3910 | /* |
| 3911 | * Optimization: we know that if all tasks are in the fair class we can |
| 3912 | * call that function directly, but only if the @prev task wasn't of a |
| 3913 | * higher scheduling class, because otherwise those loose the |
| 3914 | * opportunity to pull in more work from other CPUs. |
| 3915 | */ |
| 3916 | if (likely((prev->sched_class == &idle_sched_class || |
| 3917 | prev->sched_class == &fair_sched_class) && |
| 3918 | rq->nr_running == rq->cfs.h_nr_running)) { |
| 3919 | |
| 3920 | p = fair_sched_class.pick_next_task(rq, prev, rf); |
| 3921 | if (unlikely(p == RETRY_TASK)) |
| 3922 | goto restart; |
| 3923 | |
| 3924 | /* Assumes fair_sched_class->next == idle_sched_class */ |
| 3925 | if (unlikely(!p)) |
| 3926 | p = idle_sched_class.pick_next_task(rq, prev, rf); |
| 3927 | |
| 3928 | return p; |
| 3929 | } |
| 3930 | |
| 3931 | restart: |
| 3932 | /* |
| 3933 | * Ensure that we put DL/RT tasks before the pick loop, such that they |
| 3934 | * can PULL higher prio tasks when we lower the RQ 'priority'. |
| 3935 | */ |
| 3936 | prev->sched_class->put_prev_task(rq, prev, rf); |
| 3937 | if (!rq->nr_running) |
| 3938 | newidle_balance(rq, rf); |
| 3939 | |
| 3940 | for_each_class(class) { |
| 3941 | p = class->pick_next_task(rq, NULL, NULL); |
| 3942 | if (p) |
| 3943 | return p; |
| 3944 | } |
| 3945 | |
| 3946 | /* The idle class should always have a runnable task: */ |
| 3947 | BUG(); |
| 3948 | } |
| 3949 | |
| 3950 | /* |
| 3951 | * __schedule() is the main scheduler function. |
| 3952 | * |
| 3953 | * The main means of driving the scheduler and thus entering this function are: |
| 3954 | * |
| 3955 | * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. |
| 3956 | * |
| 3957 | * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return |
| 3958 | * paths. For example, see arch/x86/entry_64.S. |
| 3959 | * |
| 3960 | * To drive preemption between tasks, the scheduler sets the flag in timer |
| 3961 | * interrupt handler scheduler_tick(). |
| 3962 | * |
| 3963 | * 3. Wakeups don't really cause entry into schedule(). They add a |
| 3964 | * task to the run-queue and that's it. |
| 3965 | * |
| 3966 | * Now, if the new task added to the run-queue preempts the current |
| 3967 | * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets |
| 3968 | * called on the nearest possible occasion: |
| 3969 | * |
| 3970 | * - If the kernel is preemptible (CONFIG_PREEMPTION=y): |
| 3971 | * |
| 3972 | * - in syscall or exception context, at the next outmost |
| 3973 | * preempt_enable(). (this might be as soon as the wake_up()'s |
| 3974 | * spin_unlock()!) |
| 3975 | * |
| 3976 | * - in IRQ context, return from interrupt-handler to |
| 3977 | * preemptible context |
| 3978 | * |
| 3979 | * - If the kernel is not preemptible (CONFIG_PREEMPTION is not set) |
| 3980 | * then at the next: |
| 3981 | * |
| 3982 | * - cond_resched() call |
| 3983 | * - explicit schedule() call |
| 3984 | * - return from syscall or exception to user-space |
| 3985 | * - return from interrupt-handler to user-space |
| 3986 | * |
| 3987 | * WARNING: must be called with preemption disabled! |
| 3988 | */ |
| 3989 | static void __sched notrace __schedule(bool preempt) |
| 3990 | { |
| 3991 | struct task_struct *prev, *next; |
| 3992 | unsigned long *switch_count; |
| 3993 | struct rq_flags rf; |
| 3994 | struct rq *rq; |
| 3995 | int cpu; |
| 3996 | |
| 3997 | cpu = smp_processor_id(); |
| 3998 | rq = cpu_rq(cpu); |
| 3999 | prev = rq->curr; |
| 4000 | |
| 4001 | schedule_debug(prev, preempt); |
| 4002 | |
| 4003 | if (sched_feat(HRTICK)) |
| 4004 | hrtick_clear(rq); |
| 4005 | |
| 4006 | local_irq_disable(); |
| 4007 | rcu_note_context_switch(preempt); |
| 4008 | |
| 4009 | /* |
| 4010 | * Make sure that signal_pending_state()->signal_pending() below |
| 4011 | * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) |
| 4012 | * done by the caller to avoid the race with signal_wake_up(). |
| 4013 | * |
| 4014 | * The membarrier system call requires a full memory barrier |
| 4015 | * after coming from user-space, before storing to rq->curr. |
| 4016 | */ |
| 4017 | rq_lock(rq, &rf); |
| 4018 | smp_mb__after_spinlock(); |
| 4019 | |
| 4020 | /* Promote REQ to ACT */ |
| 4021 | rq->clock_update_flags <<= 1; |
| 4022 | update_rq_clock(rq); |
| 4023 | |
| 4024 | switch_count = &prev->nivcsw; |
| 4025 | if (!preempt && prev->state) { |
| 4026 | if (signal_pending_state(prev->state, prev)) { |
| 4027 | prev->state = TASK_RUNNING; |
| 4028 | } else { |
| 4029 | deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK); |
| 4030 | |
| 4031 | if (prev->in_iowait) { |
| 4032 | atomic_inc(&rq->nr_iowait); |
| 4033 | delayacct_blkio_start(); |
| 4034 | } |
| 4035 | } |
| 4036 | switch_count = &prev->nvcsw; |
| 4037 | } |
| 4038 | |
| 4039 | next = pick_next_task(rq, prev, &rf); |
| 4040 | clear_tsk_need_resched(prev); |
| 4041 | clear_preempt_need_resched(); |
| 4042 | |
| 4043 | if (likely(prev != next)) { |
| 4044 | rq->nr_switches++; |
| 4045 | /* |
| 4046 | * RCU users of rcu_dereference(rq->curr) may not see |
| 4047 | * changes to task_struct made by pick_next_task(). |
| 4048 | */ |
| 4049 | RCU_INIT_POINTER(rq->curr, next); |
| 4050 | /* |
| 4051 | * The membarrier system call requires each architecture |
| 4052 | * to have a full memory barrier after updating |
| 4053 | * rq->curr, before returning to user-space. |
| 4054 | * |
| 4055 | * Here are the schemes providing that barrier on the |
| 4056 | * various architectures: |
| 4057 | * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC. |
| 4058 | * switch_mm() rely on membarrier_arch_switch_mm() on PowerPC. |
| 4059 | * - finish_lock_switch() for weakly-ordered |
| 4060 | * architectures where spin_unlock is a full barrier, |
| 4061 | * - switch_to() for arm64 (weakly-ordered, spin_unlock |
| 4062 | * is a RELEASE barrier), |
| 4063 | */ |
| 4064 | ++*switch_count; |
| 4065 | |
| 4066 | trace_sched_switch(preempt, prev, next); |
| 4067 | |
| 4068 | /* Also unlocks the rq: */ |
| 4069 | rq = context_switch(rq, prev, next, &rf); |
| 4070 | } else { |
| 4071 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
| 4072 | rq_unlock_irq(rq, &rf); |
| 4073 | } |
| 4074 | |
| 4075 | balance_callback(rq); |
| 4076 | } |
| 4077 | |
| 4078 | void __noreturn do_task_dead(void) |
| 4079 | { |
| 4080 | /* Causes final put_task_struct in finish_task_switch(): */ |
| 4081 | set_special_state(TASK_DEAD); |
| 4082 | |
| 4083 | /* Tell freezer to ignore us: */ |
| 4084 | current->flags |= PF_NOFREEZE; |
| 4085 | |
| 4086 | __schedule(false); |
| 4087 | BUG(); |
| 4088 | |
| 4089 | /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */ |
| 4090 | for (;;) |
| 4091 | cpu_relax(); |
| 4092 | } |
| 4093 | |
| 4094 | static inline void sched_submit_work(struct task_struct *tsk) |
| 4095 | { |
| 4096 | if (!tsk->state) |
| 4097 | return; |
| 4098 | |
| 4099 | /* |
| 4100 | * If a worker went to sleep, notify and ask workqueue whether |
| 4101 | * it wants to wake up a task to maintain concurrency. |
| 4102 | * As this function is called inside the schedule() context, |
| 4103 | * we disable preemption to avoid it calling schedule() again |
| 4104 | * in the possible wakeup of a kworker. |
| 4105 | */ |
| 4106 | if (tsk->flags & PF_WQ_WORKER) { |
| 4107 | preempt_disable(); |
| 4108 | wq_worker_sleeping(tsk); |
| 4109 | preempt_enable_no_resched(); |
| 4110 | } |
| 4111 | |
| 4112 | if (tsk_is_pi_blocked(tsk)) |
| 4113 | return; |
| 4114 | |
| 4115 | /* |
| 4116 | * If we are going to sleep and we have plugged IO queued, |
| 4117 | * make sure to submit it to avoid deadlocks. |
| 4118 | */ |
| 4119 | if (blk_needs_flush_plug(tsk)) |
| 4120 | blk_schedule_flush_plug(tsk); |
| 4121 | } |
| 4122 | |
| 4123 | static void sched_update_worker(struct task_struct *tsk) |
| 4124 | { |
| 4125 | if (tsk->flags & PF_WQ_WORKER) |
| 4126 | wq_worker_running(tsk); |
| 4127 | } |
| 4128 | |
| 4129 | asmlinkage __visible void __sched schedule(void) |
| 4130 | { |
| 4131 | struct task_struct *tsk = current; |
| 4132 | |
| 4133 | sched_submit_work(tsk); |
| 4134 | do { |
| 4135 | preempt_disable(); |
| 4136 | __schedule(false); |
| 4137 | sched_preempt_enable_no_resched(); |
| 4138 | } while (need_resched()); |
| 4139 | sched_update_worker(tsk); |
| 4140 | } |
| 4141 | EXPORT_SYMBOL(schedule); |
| 4142 | |
| 4143 | /* |
| 4144 | * synchronize_rcu_tasks() makes sure that no task is stuck in preempted |
| 4145 | * state (have scheduled out non-voluntarily) by making sure that all |
| 4146 | * tasks have either left the run queue or have gone into user space. |
| 4147 | * As idle tasks do not do either, they must not ever be preempted |
| 4148 | * (schedule out non-voluntarily). |
| 4149 | * |
| 4150 | * schedule_idle() is similar to schedule_preempt_disable() except that it |
| 4151 | * never enables preemption because it does not call sched_submit_work(). |
| 4152 | */ |
| 4153 | void __sched schedule_idle(void) |
| 4154 | { |
| 4155 | /* |
| 4156 | * As this skips calling sched_submit_work(), which the idle task does |
| 4157 | * regardless because that function is a nop when the task is in a |
| 4158 | * TASK_RUNNING state, make sure this isn't used someplace that the |
| 4159 | * current task can be in any other state. Note, idle is always in the |
| 4160 | * TASK_RUNNING state. |
| 4161 | */ |
| 4162 | WARN_ON_ONCE(current->state); |
| 4163 | do { |
| 4164 | __schedule(false); |
| 4165 | } while (need_resched()); |
| 4166 | } |
| 4167 | |
| 4168 | #ifdef CONFIG_CONTEXT_TRACKING |
| 4169 | asmlinkage __visible void __sched schedule_user(void) |
| 4170 | { |
| 4171 | /* |
| 4172 | * If we come here after a random call to set_need_resched(), |
| 4173 | * or we have been woken up remotely but the IPI has not yet arrived, |
| 4174 | * we haven't yet exited the RCU idle mode. Do it here manually until |
| 4175 | * we find a better solution. |
| 4176 | * |
| 4177 | * NB: There are buggy callers of this function. Ideally we |
| 4178 | * should warn if prev_state != CONTEXT_USER, but that will trigger |
| 4179 | * too frequently to make sense yet. |
| 4180 | */ |
| 4181 | enum ctx_state prev_state = exception_enter(); |
| 4182 | schedule(); |
| 4183 | exception_exit(prev_state); |
| 4184 | } |
| 4185 | #endif |
| 4186 | |
| 4187 | /** |
| 4188 | * schedule_preempt_disabled - called with preemption disabled |
| 4189 | * |
| 4190 | * Returns with preemption disabled. Note: preempt_count must be 1 |
| 4191 | */ |
| 4192 | void __sched schedule_preempt_disabled(void) |
| 4193 | { |
| 4194 | sched_preempt_enable_no_resched(); |
| 4195 | schedule(); |
| 4196 | preempt_disable(); |
| 4197 | } |
| 4198 | |
| 4199 | static void __sched notrace preempt_schedule_common(void) |
| 4200 | { |
| 4201 | do { |
| 4202 | /* |
| 4203 | * Because the function tracer can trace preempt_count_sub() |
| 4204 | * and it also uses preempt_enable/disable_notrace(), if |
| 4205 | * NEED_RESCHED is set, the preempt_enable_notrace() called |
| 4206 | * by the function tracer will call this function again and |
| 4207 | * cause infinite recursion. |
| 4208 | * |
| 4209 | * Preemption must be disabled here before the function |
| 4210 | * tracer can trace. Break up preempt_disable() into two |
| 4211 | * calls. One to disable preemption without fear of being |
| 4212 | * traced. The other to still record the preemption latency, |
| 4213 | * which can also be traced by the function tracer. |
| 4214 | */ |
| 4215 | preempt_disable_notrace(); |
| 4216 | preempt_latency_start(1); |
| 4217 | __schedule(true); |
| 4218 | preempt_latency_stop(1); |
| 4219 | preempt_enable_no_resched_notrace(); |
| 4220 | |
| 4221 | /* |
| 4222 | * Check again in case we missed a preemption opportunity |
| 4223 | * between schedule and now. |
| 4224 | */ |
| 4225 | } while (need_resched()); |
| 4226 | } |
| 4227 | |
| 4228 | #ifdef CONFIG_PREEMPTION |
| 4229 | /* |
| 4230 | * This is the entry point to schedule() from in-kernel preemption |
| 4231 | * off of preempt_enable. |
| 4232 | */ |
| 4233 | asmlinkage __visible void __sched notrace preempt_schedule(void) |
| 4234 | { |
| 4235 | /* |
| 4236 | * If there is a non-zero preempt_count or interrupts are disabled, |
| 4237 | * we do not want to preempt the current task. Just return.. |
| 4238 | */ |
| 4239 | if (likely(!preemptible())) |
| 4240 | return; |
| 4241 | |
| 4242 | preempt_schedule_common(); |
| 4243 | } |
| 4244 | NOKPROBE_SYMBOL(preempt_schedule); |
| 4245 | EXPORT_SYMBOL(preempt_schedule); |
| 4246 | |
| 4247 | /** |
| 4248 | * preempt_schedule_notrace - preempt_schedule called by tracing |
| 4249 | * |
| 4250 | * The tracing infrastructure uses preempt_enable_notrace to prevent |
| 4251 | * recursion and tracing preempt enabling caused by the tracing |
| 4252 | * infrastructure itself. But as tracing can happen in areas coming |
| 4253 | * from userspace or just about to enter userspace, a preempt enable |
| 4254 | * can occur before user_exit() is called. This will cause the scheduler |
| 4255 | * to be called when the system is still in usermode. |
| 4256 | * |
| 4257 | * To prevent this, the preempt_enable_notrace will use this function |
| 4258 | * instead of preempt_schedule() to exit user context if needed before |
| 4259 | * calling the scheduler. |
| 4260 | */ |
| 4261 | asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) |
| 4262 | { |
| 4263 | enum ctx_state prev_ctx; |
| 4264 | |
| 4265 | if (likely(!preemptible())) |
| 4266 | return; |
| 4267 | |
| 4268 | do { |
| 4269 | /* |
| 4270 | * Because the function tracer can trace preempt_count_sub() |
| 4271 | * and it also uses preempt_enable/disable_notrace(), if |
| 4272 | * NEED_RESCHED is set, the preempt_enable_notrace() called |
| 4273 | * by the function tracer will call this function again and |
| 4274 | * cause infinite recursion. |
| 4275 | * |
| 4276 | * Preemption must be disabled here before the function |
| 4277 | * tracer can trace. Break up preempt_disable() into two |
| 4278 | * calls. One to disable preemption without fear of being |
| 4279 | * traced. The other to still record the preemption latency, |
| 4280 | * which can also be traced by the function tracer. |
| 4281 | */ |
| 4282 | preempt_disable_notrace(); |
| 4283 | preempt_latency_start(1); |
| 4284 | /* |
| 4285 | * Needs preempt disabled in case user_exit() is traced |
| 4286 | * and the tracer calls preempt_enable_notrace() causing |
| 4287 | * an infinite recursion. |
| 4288 | */ |
| 4289 | prev_ctx = exception_enter(); |
| 4290 | __schedule(true); |
| 4291 | exception_exit(prev_ctx); |
| 4292 | |
| 4293 | preempt_latency_stop(1); |
| 4294 | preempt_enable_no_resched_notrace(); |
| 4295 | } while (need_resched()); |
| 4296 | } |
| 4297 | EXPORT_SYMBOL_GPL(preempt_schedule_notrace); |
| 4298 | |
| 4299 | #endif /* CONFIG_PREEMPTION */ |
| 4300 | |
| 4301 | /* |
| 4302 | * This is the entry point to schedule() from kernel preemption |
| 4303 | * off of irq context. |
| 4304 | * Note, that this is called and return with irqs disabled. This will |
| 4305 | * protect us against recursive calling from irq. |
| 4306 | */ |
| 4307 | asmlinkage __visible void __sched preempt_schedule_irq(void) |
| 4308 | { |
| 4309 | enum ctx_state prev_state; |
| 4310 | |
| 4311 | /* Catch callers which need to be fixed */ |
| 4312 | BUG_ON(preempt_count() || !irqs_disabled()); |
| 4313 | |
| 4314 | prev_state = exception_enter(); |
| 4315 | |
| 4316 | do { |
| 4317 | preempt_disable(); |
| 4318 | local_irq_enable(); |
| 4319 | __schedule(true); |
| 4320 | local_irq_disable(); |
| 4321 | sched_preempt_enable_no_resched(); |
| 4322 | } while (need_resched()); |
| 4323 | |
| 4324 | exception_exit(prev_state); |
| 4325 | } |
| 4326 | |
| 4327 | int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags, |
| 4328 | void *key) |
| 4329 | { |
| 4330 | return try_to_wake_up(curr->private, mode, wake_flags); |
| 4331 | } |
| 4332 | EXPORT_SYMBOL(default_wake_function); |
| 4333 | |
| 4334 | #ifdef CONFIG_RT_MUTEXES |
| 4335 | |
| 4336 | static inline int __rt_effective_prio(struct task_struct *pi_task, int prio) |
| 4337 | { |
| 4338 | if (pi_task) |
| 4339 | prio = min(prio, pi_task->prio); |
| 4340 | |
| 4341 | return prio; |
| 4342 | } |
| 4343 | |
| 4344 | static inline int rt_effective_prio(struct task_struct *p, int prio) |
| 4345 | { |
| 4346 | struct task_struct *pi_task = rt_mutex_get_top_task(p); |
| 4347 | |
| 4348 | return __rt_effective_prio(pi_task, prio); |
| 4349 | } |
| 4350 | |
| 4351 | /* |
| 4352 | * rt_mutex_setprio - set the current priority of a task |
| 4353 | * @p: task to boost |
| 4354 | * @pi_task: donor task |
| 4355 | * |
| 4356 | * This function changes the 'effective' priority of a task. It does |
| 4357 | * not touch ->normal_prio like __setscheduler(). |
| 4358 | * |
| 4359 | * Used by the rt_mutex code to implement priority inheritance |
| 4360 | * logic. Call site only calls if the priority of the task changed. |
| 4361 | */ |
| 4362 | void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) |
| 4363 | { |
| 4364 | int prio, oldprio, queued, running, queue_flag = |
| 4365 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
| 4366 | const struct sched_class *prev_class; |
| 4367 | struct rq_flags rf; |
| 4368 | struct rq *rq; |
| 4369 | |
| 4370 | /* XXX used to be waiter->prio, not waiter->task->prio */ |
| 4371 | prio = __rt_effective_prio(pi_task, p->normal_prio); |
| 4372 | |
| 4373 | /* |
| 4374 | * If nothing changed; bail early. |
| 4375 | */ |
| 4376 | if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio)) |
| 4377 | return; |
| 4378 | |
| 4379 | rq = __task_rq_lock(p, &rf); |
| 4380 | update_rq_clock(rq); |
| 4381 | /* |
| 4382 | * Set under pi_lock && rq->lock, such that the value can be used under |
| 4383 | * either lock. |
| 4384 | * |
| 4385 | * Note that there is loads of tricky to make this pointer cache work |
| 4386 | * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to |
| 4387 | * ensure a task is de-boosted (pi_task is set to NULL) before the |
| 4388 | * task is allowed to run again (and can exit). This ensures the pointer |
| 4389 | * points to a blocked task -- which guaratees the task is present. |
| 4390 | */ |
| 4391 | p->pi_top_task = pi_task; |
| 4392 | |
| 4393 | /* |
| 4394 | * For FIFO/RR we only need to set prio, if that matches we're done. |
| 4395 | */ |
| 4396 | if (prio == p->prio && !dl_prio(prio)) |
| 4397 | goto out_unlock; |
| 4398 | |
| 4399 | /* |
| 4400 | * Idle task boosting is a nono in general. There is one |
| 4401 | * exception, when PREEMPT_RT and NOHZ is active: |
| 4402 | * |
| 4403 | * The idle task calls get_next_timer_interrupt() and holds |
| 4404 | * the timer wheel base->lock on the CPU and another CPU wants |
| 4405 | * to access the timer (probably to cancel it). We can safely |
| 4406 | * ignore the boosting request, as the idle CPU runs this code |
| 4407 | * with interrupts disabled and will complete the lock |
| 4408 | * protected section without being interrupted. So there is no |
| 4409 | * real need to boost. |
| 4410 | */ |
| 4411 | if (unlikely(p == rq->idle)) { |
| 4412 | WARN_ON(p != rq->curr); |
| 4413 | WARN_ON(p->pi_blocked_on); |
| 4414 | goto out_unlock; |
| 4415 | } |
| 4416 | |
| 4417 | trace_sched_pi_setprio(p, pi_task); |
| 4418 | oldprio = p->prio; |
| 4419 | |
| 4420 | if (oldprio == prio) |
| 4421 | queue_flag &= ~DEQUEUE_MOVE; |
| 4422 | |
| 4423 | prev_class = p->sched_class; |
| 4424 | queued = task_on_rq_queued(p); |
| 4425 | running = task_current(rq, p); |
| 4426 | if (queued) |
| 4427 | dequeue_task(rq, p, queue_flag); |
| 4428 | if (running) |
| 4429 | put_prev_task(rq, p); |
| 4430 | |
| 4431 | /* |
| 4432 | * Boosting condition are: |
| 4433 | * 1. -rt task is running and holds mutex A |
| 4434 | * --> -dl task blocks on mutex A |
| 4435 | * |
| 4436 | * 2. -dl task is running and holds mutex A |
| 4437 | * --> -dl task blocks on mutex A and could preempt the |
| 4438 | * running task |
| 4439 | */ |
| 4440 | if (dl_prio(prio)) { |
| 4441 | if (!dl_prio(p->normal_prio) || |
| 4442 | (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { |
| 4443 | p->dl.dl_boosted = 1; |
| 4444 | queue_flag |= ENQUEUE_REPLENISH; |
| 4445 | } else |
| 4446 | p->dl.dl_boosted = 0; |
| 4447 | p->sched_class = &dl_sched_class; |
| 4448 | } else if (rt_prio(prio)) { |
| 4449 | if (dl_prio(oldprio)) |
| 4450 | p->dl.dl_boosted = 0; |
| 4451 | if (oldprio < prio) |
| 4452 | queue_flag |= ENQUEUE_HEAD; |
| 4453 | p->sched_class = &rt_sched_class; |
| 4454 | } else { |
| 4455 | if (dl_prio(oldprio)) |
| 4456 | p->dl.dl_boosted = 0; |
| 4457 | if (rt_prio(oldprio)) |
| 4458 | p->rt.timeout = 0; |
| 4459 | p->sched_class = &fair_sched_class; |
| 4460 | } |
| 4461 | |
| 4462 | p->prio = prio; |
| 4463 | |
| 4464 | if (queued) |
| 4465 | enqueue_task(rq, p, queue_flag); |
| 4466 | if (running) |
| 4467 | set_next_task(rq, p); |
| 4468 | |
| 4469 | check_class_changed(rq, p, prev_class, oldprio); |
| 4470 | out_unlock: |
| 4471 | /* Avoid rq from going away on us: */ |
| 4472 | preempt_disable(); |
| 4473 | __task_rq_unlock(rq, &rf); |
| 4474 | |
| 4475 | balance_callback(rq); |
| 4476 | preempt_enable(); |
| 4477 | } |
| 4478 | #else |
| 4479 | static inline int rt_effective_prio(struct task_struct *p, int prio) |
| 4480 | { |
| 4481 | return prio; |
| 4482 | } |
| 4483 | #endif |
| 4484 | |
| 4485 | void set_user_nice(struct task_struct *p, long nice) |
| 4486 | { |
| 4487 | bool queued, running; |
| 4488 | int old_prio, delta; |
| 4489 | struct rq_flags rf; |
| 4490 | struct rq *rq; |
| 4491 | |
| 4492 | if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) |
| 4493 | return; |
| 4494 | /* |
| 4495 | * We have to be careful, if called from sys_setpriority(), |
| 4496 | * the task might be in the middle of scheduling on another CPU. |
| 4497 | */ |
| 4498 | rq = task_rq_lock(p, &rf); |
| 4499 | update_rq_clock(rq); |
| 4500 | |
| 4501 | /* |
| 4502 | * The RT priorities are set via sched_setscheduler(), but we still |
| 4503 | * allow the 'normal' nice value to be set - but as expected |
| 4504 | * it wont have any effect on scheduling until the task is |
| 4505 | * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: |
| 4506 | */ |
| 4507 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
| 4508 | p->static_prio = NICE_TO_PRIO(nice); |
| 4509 | goto out_unlock; |
| 4510 | } |
| 4511 | queued = task_on_rq_queued(p); |
| 4512 | running = task_current(rq, p); |
| 4513 | if (queued) |
| 4514 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
| 4515 | if (running) |
| 4516 | put_prev_task(rq, p); |
| 4517 | |
| 4518 | p->static_prio = NICE_TO_PRIO(nice); |
| 4519 | set_load_weight(p, true); |
| 4520 | old_prio = p->prio; |
| 4521 | p->prio = effective_prio(p); |
| 4522 | delta = p->prio - old_prio; |
| 4523 | |
| 4524 | if (queued) { |
| 4525 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
| 4526 | /* |
| 4527 | * If the task increased its priority or is running and |
| 4528 | * lowered its priority, then reschedule its CPU: |
| 4529 | */ |
| 4530 | if (delta < 0 || (delta > 0 && task_running(rq, p))) |
| 4531 | resched_curr(rq); |
| 4532 | } |
| 4533 | if (running) |
| 4534 | set_next_task(rq, p); |
| 4535 | out_unlock: |
| 4536 | task_rq_unlock(rq, p, &rf); |
| 4537 | } |
| 4538 | EXPORT_SYMBOL(set_user_nice); |
| 4539 | |
| 4540 | /* |
| 4541 | * can_nice - check if a task can reduce its nice value |
| 4542 | * @p: task |
| 4543 | * @nice: nice value |
| 4544 | */ |
| 4545 | int can_nice(const struct task_struct *p, const int nice) |
| 4546 | { |
| 4547 | /* Convert nice value [19,-20] to rlimit style value [1,40]: */ |
| 4548 | int nice_rlim = nice_to_rlimit(nice); |
| 4549 | |
| 4550 | return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || |
| 4551 | capable(CAP_SYS_NICE)); |
| 4552 | } |
| 4553 | |
| 4554 | #ifdef __ARCH_WANT_SYS_NICE |
| 4555 | |
| 4556 | /* |
| 4557 | * sys_nice - change the priority of the current process. |
| 4558 | * @increment: priority increment |
| 4559 | * |
| 4560 | * sys_setpriority is a more generic, but much slower function that |
| 4561 | * does similar things. |
| 4562 | */ |
| 4563 | SYSCALL_DEFINE1(nice, int, increment) |
| 4564 | { |
| 4565 | long nice, retval; |
| 4566 | |
| 4567 | /* |
| 4568 | * Setpriority might change our priority at the same moment. |
| 4569 | * We don't have to worry. Conceptually one call occurs first |
| 4570 | * and we have a single winner. |
| 4571 | */ |
| 4572 | increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); |
| 4573 | nice = task_nice(current) + increment; |
| 4574 | |
| 4575 | nice = clamp_val(nice, MIN_NICE, MAX_NICE); |
| 4576 | if (increment < 0 && !can_nice(current, nice)) |
| 4577 | return -EPERM; |
| 4578 | |
| 4579 | retval = security_task_setnice(current, nice); |
| 4580 | if (retval) |
| 4581 | return retval; |
| 4582 | |
| 4583 | set_user_nice(current, nice); |
| 4584 | return 0; |
| 4585 | } |
| 4586 | |
| 4587 | #endif |
| 4588 | |
| 4589 | /** |
| 4590 | * task_prio - return the priority value of a given task. |
| 4591 | * @p: the task in question. |
| 4592 | * |
| 4593 | * Return: The priority value as seen by users in /proc. |
| 4594 | * RT tasks are offset by -200. Normal tasks are centered |
| 4595 | * around 0, value goes from -16 to +15. |
| 4596 | */ |
| 4597 | int task_prio(const struct task_struct *p) |
| 4598 | { |
| 4599 | return p->prio - MAX_RT_PRIO; |
| 4600 | } |
| 4601 | |
| 4602 | /** |
| 4603 | * idle_cpu - is a given CPU idle currently? |
| 4604 | * @cpu: the processor in question. |
| 4605 | * |
| 4606 | * Return: 1 if the CPU is currently idle. 0 otherwise. |
| 4607 | */ |
| 4608 | int idle_cpu(int cpu) |
| 4609 | { |
| 4610 | struct rq *rq = cpu_rq(cpu); |
| 4611 | |
| 4612 | if (rq->curr != rq->idle) |
| 4613 | return 0; |
| 4614 | |
| 4615 | if (rq->nr_running) |
| 4616 | return 0; |
| 4617 | |
| 4618 | #ifdef CONFIG_SMP |
| 4619 | if (!llist_empty(&rq->wake_list)) |
| 4620 | return 0; |
| 4621 | #endif |
| 4622 | |
| 4623 | return 1; |
| 4624 | } |
| 4625 | |
| 4626 | /** |
| 4627 | * available_idle_cpu - is a given CPU idle for enqueuing work. |
| 4628 | * @cpu: the CPU in question. |
| 4629 | * |
| 4630 | * Return: 1 if the CPU is currently idle. 0 otherwise. |
| 4631 | */ |
| 4632 | int available_idle_cpu(int cpu) |
| 4633 | { |
| 4634 | if (!idle_cpu(cpu)) |
| 4635 | return 0; |
| 4636 | |
| 4637 | if (vcpu_is_preempted(cpu)) |
| 4638 | return 0; |
| 4639 | |
| 4640 | return 1; |
| 4641 | } |
| 4642 | |
| 4643 | /** |
| 4644 | * idle_task - return the idle task for a given CPU. |
| 4645 | * @cpu: the processor in question. |
| 4646 | * |
| 4647 | * Return: The idle task for the CPU @cpu. |
| 4648 | */ |
| 4649 | struct task_struct *idle_task(int cpu) |
| 4650 | { |
| 4651 | return cpu_rq(cpu)->idle; |
| 4652 | } |
| 4653 | |
| 4654 | /** |
| 4655 | * find_process_by_pid - find a process with a matching PID value. |
| 4656 | * @pid: the pid in question. |
| 4657 | * |
| 4658 | * The task of @pid, if found. %NULL otherwise. |
| 4659 | */ |
| 4660 | static struct task_struct *find_process_by_pid(pid_t pid) |
| 4661 | { |
| 4662 | return pid ? find_task_by_vpid(pid) : current; |
| 4663 | } |
| 4664 | |
| 4665 | /* |
| 4666 | * sched_setparam() passes in -1 for its policy, to let the functions |
| 4667 | * it calls know not to change it. |
| 4668 | */ |
| 4669 | #define SETPARAM_POLICY -1 |
| 4670 | |
| 4671 | static void __setscheduler_params(struct task_struct *p, |
| 4672 | const struct sched_attr *attr) |
| 4673 | { |
| 4674 | int policy = attr->sched_policy; |
| 4675 | |
| 4676 | if (policy == SETPARAM_POLICY) |
| 4677 | policy = p->policy; |
| 4678 | |
| 4679 | p->policy = policy; |
| 4680 | |
| 4681 | if (dl_policy(policy)) |
| 4682 | __setparam_dl(p, attr); |
| 4683 | else if (fair_policy(policy)) |
| 4684 | p->static_prio = NICE_TO_PRIO(attr->sched_nice); |
| 4685 | |
| 4686 | /* |
| 4687 | * __sched_setscheduler() ensures attr->sched_priority == 0 when |
| 4688 | * !rt_policy. Always setting this ensures that things like |
| 4689 | * getparam()/getattr() don't report silly values for !rt tasks. |
| 4690 | */ |
| 4691 | p->rt_priority = attr->sched_priority; |
| 4692 | p->normal_prio = normal_prio(p); |
| 4693 | set_load_weight(p, true); |
| 4694 | } |
| 4695 | |
| 4696 | /* Actually do priority change: must hold pi & rq lock. */ |
| 4697 | static void __setscheduler(struct rq *rq, struct task_struct *p, |
| 4698 | const struct sched_attr *attr, bool keep_boost) |
| 4699 | { |
| 4700 | /* |
| 4701 | * If params can't change scheduling class changes aren't allowed |
| 4702 | * either. |
| 4703 | */ |
| 4704 | if (attr->sched_flags & SCHED_FLAG_KEEP_PARAMS) |
| 4705 | return; |
| 4706 | |
| 4707 | __setscheduler_params(p, attr); |
| 4708 | |
| 4709 | /* |
| 4710 | * Keep a potential priority boosting if called from |
| 4711 | * sched_setscheduler(). |
| 4712 | */ |
| 4713 | p->prio = normal_prio(p); |
| 4714 | if (keep_boost) |
| 4715 | p->prio = rt_effective_prio(p, p->prio); |
| 4716 | |
| 4717 | if (dl_prio(p->prio)) |
| 4718 | p->sched_class = &dl_sched_class; |
| 4719 | else if (rt_prio(p->prio)) |
| 4720 | p->sched_class = &rt_sched_class; |
| 4721 | else |
| 4722 | p->sched_class = &fair_sched_class; |
| 4723 | } |
| 4724 | |
| 4725 | /* |
| 4726 | * Check the target process has a UID that matches the current process's: |
| 4727 | */ |
| 4728 | static bool check_same_owner(struct task_struct *p) |
| 4729 | { |
| 4730 | const struct cred *cred = current_cred(), *pcred; |
| 4731 | bool match; |
| 4732 | |
| 4733 | rcu_read_lock(); |
| 4734 | pcred = __task_cred(p); |
| 4735 | match = (uid_eq(cred->euid, pcred->euid) || |
| 4736 | uid_eq(cred->euid, pcred->uid)); |
| 4737 | rcu_read_unlock(); |
| 4738 | return match; |
| 4739 | } |
| 4740 | |
| 4741 | static int __sched_setscheduler(struct task_struct *p, |
| 4742 | const struct sched_attr *attr, |
| 4743 | bool user, bool pi) |
| 4744 | { |
| 4745 | int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : |
| 4746 | MAX_RT_PRIO - 1 - attr->sched_priority; |
| 4747 | int retval, oldprio, oldpolicy = -1, queued, running; |
| 4748 | int new_effective_prio, policy = attr->sched_policy; |
| 4749 | const struct sched_class *prev_class; |
| 4750 | struct rq_flags rf; |
| 4751 | int reset_on_fork; |
| 4752 | int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
| 4753 | struct rq *rq; |
| 4754 | |
| 4755 | /* The pi code expects interrupts enabled */ |
| 4756 | BUG_ON(pi && in_interrupt()); |
| 4757 | recheck: |
| 4758 | /* Double check policy once rq lock held: */ |
| 4759 | if (policy < 0) { |
| 4760 | reset_on_fork = p->sched_reset_on_fork; |
| 4761 | policy = oldpolicy = p->policy; |
| 4762 | } else { |
| 4763 | reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK); |
| 4764 | |
| 4765 | if (!valid_policy(policy)) |
| 4766 | return -EINVAL; |
| 4767 | } |
| 4768 | |
| 4769 | if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV)) |
| 4770 | return -EINVAL; |
| 4771 | |
| 4772 | /* |
| 4773 | * Valid priorities for SCHED_FIFO and SCHED_RR are |
| 4774 | * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, |
| 4775 | * SCHED_BATCH and SCHED_IDLE is 0. |
| 4776 | */ |
| 4777 | if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || |
| 4778 | (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) |
| 4779 | return -EINVAL; |
| 4780 | if ((dl_policy(policy) && !__checkparam_dl(attr)) || |
| 4781 | (rt_policy(policy) != (attr->sched_priority != 0))) |
| 4782 | return -EINVAL; |
| 4783 | |
| 4784 | /* |
| 4785 | * Allow unprivileged RT tasks to decrease priority: |
| 4786 | */ |
| 4787 | if (user && !capable(CAP_SYS_NICE)) { |
| 4788 | if (fair_policy(policy)) { |
| 4789 | if (attr->sched_nice < task_nice(p) && |
| 4790 | !can_nice(p, attr->sched_nice)) |
| 4791 | return -EPERM; |
| 4792 | } |
| 4793 | |
| 4794 | if (rt_policy(policy)) { |
| 4795 | unsigned long rlim_rtprio = |
| 4796 | task_rlimit(p, RLIMIT_RTPRIO); |
| 4797 | |
| 4798 | /* Can't set/change the rt policy: */ |
| 4799 | if (policy != p->policy && !rlim_rtprio) |
| 4800 | return -EPERM; |
| 4801 | |
| 4802 | /* Can't increase priority: */ |
| 4803 | if (attr->sched_priority > p->rt_priority && |
| 4804 | attr->sched_priority > rlim_rtprio) |
| 4805 | return -EPERM; |
| 4806 | } |
| 4807 | |
| 4808 | /* |
| 4809 | * Can't set/change SCHED_DEADLINE policy at all for now |
| 4810 | * (safest behavior); in the future we would like to allow |
| 4811 | * unprivileged DL tasks to increase their relative deadline |
| 4812 | * or reduce their runtime (both ways reducing utilization) |
| 4813 | */ |
| 4814 | if (dl_policy(policy)) |
| 4815 | return -EPERM; |
| 4816 | |
| 4817 | /* |
| 4818 | * Treat SCHED_IDLE as nice 20. Only allow a switch to |
| 4819 | * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. |
| 4820 | */ |
| 4821 | if (task_has_idle_policy(p) && !idle_policy(policy)) { |
| 4822 | if (!can_nice(p, task_nice(p))) |
| 4823 | return -EPERM; |
| 4824 | } |
| 4825 | |
| 4826 | /* Can't change other user's priorities: */ |
| 4827 | if (!check_same_owner(p)) |
| 4828 | return -EPERM; |
| 4829 | |
| 4830 | /* Normal users shall not reset the sched_reset_on_fork flag: */ |
| 4831 | if (p->sched_reset_on_fork && !reset_on_fork) |
| 4832 | return -EPERM; |
| 4833 | } |
| 4834 | |
| 4835 | if (user) { |
| 4836 | if (attr->sched_flags & SCHED_FLAG_SUGOV) |
| 4837 | return -EINVAL; |
| 4838 | |
| 4839 | retval = security_task_setscheduler(p); |
| 4840 | if (retval) |
| 4841 | return retval; |
| 4842 | } |
| 4843 | |
| 4844 | /* Update task specific "requested" clamps */ |
| 4845 | if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) { |
| 4846 | retval = uclamp_validate(p, attr); |
| 4847 | if (retval) |
| 4848 | return retval; |
| 4849 | } |
| 4850 | |
| 4851 | if (pi) |
| 4852 | cpuset_read_lock(); |
| 4853 | |
| 4854 | /* |
| 4855 | * Make sure no PI-waiters arrive (or leave) while we are |
| 4856 | * changing the priority of the task: |
| 4857 | * |
| 4858 | * To be able to change p->policy safely, the appropriate |
| 4859 | * runqueue lock must be held. |
| 4860 | */ |
| 4861 | rq = task_rq_lock(p, &rf); |
| 4862 | update_rq_clock(rq); |
| 4863 | |
| 4864 | /* |
| 4865 | * Changing the policy of the stop threads its a very bad idea: |
| 4866 | */ |
| 4867 | if (p == rq->stop) { |
| 4868 | retval = -EINVAL; |
| 4869 | goto unlock; |
| 4870 | } |
| 4871 | |
| 4872 | /* |
| 4873 | * If not changing anything there's no need to proceed further, |
| 4874 | * but store a possible modification of reset_on_fork. |
| 4875 | */ |
| 4876 | if (unlikely(policy == p->policy)) { |
| 4877 | if (fair_policy(policy) && attr->sched_nice != task_nice(p)) |
| 4878 | goto change; |
| 4879 | if (rt_policy(policy) && attr->sched_priority != p->rt_priority) |
| 4880 | goto change; |
| 4881 | if (dl_policy(policy) && dl_param_changed(p, attr)) |
| 4882 | goto change; |
| 4883 | if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) |
| 4884 | goto change; |
| 4885 | |
| 4886 | p->sched_reset_on_fork = reset_on_fork; |
| 4887 | retval = 0; |
| 4888 | goto unlock; |
| 4889 | } |
| 4890 | change: |
| 4891 | |
| 4892 | if (user) { |
| 4893 | #ifdef CONFIG_RT_GROUP_SCHED |
| 4894 | /* |
| 4895 | * Do not allow realtime tasks into groups that have no runtime |
| 4896 | * assigned. |
| 4897 | */ |
| 4898 | if (rt_bandwidth_enabled() && rt_policy(policy) && |
| 4899 | task_group(p)->rt_bandwidth.rt_runtime == 0 && |
| 4900 | !task_group_is_autogroup(task_group(p))) { |
| 4901 | retval = -EPERM; |
| 4902 | goto unlock; |
| 4903 | } |
| 4904 | #endif |
| 4905 | #ifdef CONFIG_SMP |
| 4906 | if (dl_bandwidth_enabled() && dl_policy(policy) && |
| 4907 | !(attr->sched_flags & SCHED_FLAG_SUGOV)) { |
| 4908 | cpumask_t *span = rq->rd->span; |
| 4909 | |
| 4910 | /* |
| 4911 | * Don't allow tasks with an affinity mask smaller than |
| 4912 | * the entire root_domain to become SCHED_DEADLINE. We |
| 4913 | * will also fail if there's no bandwidth available. |
| 4914 | */ |
| 4915 | if (!cpumask_subset(span, p->cpus_ptr) || |
| 4916 | rq->rd->dl_bw.bw == 0) { |
| 4917 | retval = -EPERM; |
| 4918 | goto unlock; |
| 4919 | } |
| 4920 | } |
| 4921 | #endif |
| 4922 | } |
| 4923 | |
| 4924 | /* Re-check policy now with rq lock held: */ |
| 4925 | if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { |
| 4926 | policy = oldpolicy = -1; |
| 4927 | task_rq_unlock(rq, p, &rf); |
| 4928 | if (pi) |
| 4929 | cpuset_read_unlock(); |
| 4930 | goto recheck; |
| 4931 | } |
| 4932 | |
| 4933 | /* |
| 4934 | * If setscheduling to SCHED_DEADLINE (or changing the parameters |
| 4935 | * of a SCHED_DEADLINE task) we need to check if enough bandwidth |
| 4936 | * is available. |
| 4937 | */ |
| 4938 | if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) { |
| 4939 | retval = -EBUSY; |
| 4940 | goto unlock; |
| 4941 | } |
| 4942 | |
| 4943 | p->sched_reset_on_fork = reset_on_fork; |
| 4944 | oldprio = p->prio; |
| 4945 | |
| 4946 | if (pi) { |
| 4947 | /* |
| 4948 | * Take priority boosted tasks into account. If the new |
| 4949 | * effective priority is unchanged, we just store the new |
| 4950 | * normal parameters and do not touch the scheduler class and |
| 4951 | * the runqueue. This will be done when the task deboost |
| 4952 | * itself. |
| 4953 | */ |
| 4954 | new_effective_prio = rt_effective_prio(p, newprio); |
| 4955 | if (new_effective_prio == oldprio) |
| 4956 | queue_flags &= ~DEQUEUE_MOVE; |
| 4957 | } |
| 4958 | |
| 4959 | queued = task_on_rq_queued(p); |
| 4960 | running = task_current(rq, p); |
| 4961 | if (queued) |
| 4962 | dequeue_task(rq, p, queue_flags); |
| 4963 | if (running) |
| 4964 | put_prev_task(rq, p); |
| 4965 | |
| 4966 | prev_class = p->sched_class; |
| 4967 | |
| 4968 | __setscheduler(rq, p, attr, pi); |
| 4969 | __setscheduler_uclamp(p, attr); |
| 4970 | |
| 4971 | if (queued) { |
| 4972 | /* |
| 4973 | * We enqueue to tail when the priority of a task is |
| 4974 | * increased (user space view). |
| 4975 | */ |
| 4976 | if (oldprio < p->prio) |
| 4977 | queue_flags |= ENQUEUE_HEAD; |
| 4978 | |
| 4979 | enqueue_task(rq, p, queue_flags); |
| 4980 | } |
| 4981 | if (running) |
| 4982 | set_next_task(rq, p); |
| 4983 | |
| 4984 | check_class_changed(rq, p, prev_class, oldprio); |
| 4985 | |
| 4986 | /* Avoid rq from going away on us: */ |
| 4987 | preempt_disable(); |
| 4988 | task_rq_unlock(rq, p, &rf); |
| 4989 | |
| 4990 | if (pi) { |
| 4991 | cpuset_read_unlock(); |
| 4992 | rt_mutex_adjust_pi(p); |
| 4993 | } |
| 4994 | |
| 4995 | /* Run balance callbacks after we've adjusted the PI chain: */ |
| 4996 | balance_callback(rq); |
| 4997 | preempt_enable(); |
| 4998 | |
| 4999 | return 0; |
| 5000 | |
| 5001 | unlock: |
| 5002 | task_rq_unlock(rq, p, &rf); |
| 5003 | if (pi) |
| 5004 | cpuset_read_unlock(); |
| 5005 | return retval; |
| 5006 | } |
| 5007 | |
| 5008 | static int _sched_setscheduler(struct task_struct *p, int policy, |
| 5009 | const struct sched_param *param, bool check) |
| 5010 | { |
| 5011 | struct sched_attr attr = { |
| 5012 | .sched_policy = policy, |
| 5013 | .sched_priority = param->sched_priority, |
| 5014 | .sched_nice = PRIO_TO_NICE(p->static_prio), |
| 5015 | }; |
| 5016 | |
| 5017 | /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ |
| 5018 | if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { |
| 5019 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; |
| 5020 | policy &= ~SCHED_RESET_ON_FORK; |
| 5021 | attr.sched_policy = policy; |
| 5022 | } |
| 5023 | |
| 5024 | return __sched_setscheduler(p, &attr, check, true); |
| 5025 | } |
| 5026 | /** |
| 5027 | * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. |
| 5028 | * @p: the task in question. |
| 5029 | * @policy: new policy. |
| 5030 | * @param: structure containing the new RT priority. |
| 5031 | * |
| 5032 | * Return: 0 on success. An error code otherwise. |
| 5033 | * |
| 5034 | * NOTE that the task may be already dead. |
| 5035 | */ |
| 5036 | int sched_setscheduler(struct task_struct *p, int policy, |
| 5037 | const struct sched_param *param) |
| 5038 | { |
| 5039 | return _sched_setscheduler(p, policy, param, true); |
| 5040 | } |
| 5041 | EXPORT_SYMBOL_GPL(sched_setscheduler); |
| 5042 | |
| 5043 | int sched_setattr(struct task_struct *p, const struct sched_attr *attr) |
| 5044 | { |
| 5045 | return __sched_setscheduler(p, attr, true, true); |
| 5046 | } |
| 5047 | EXPORT_SYMBOL_GPL(sched_setattr); |
| 5048 | |
| 5049 | int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr) |
| 5050 | { |
| 5051 | return __sched_setscheduler(p, attr, false, true); |
| 5052 | } |
| 5053 | |
| 5054 | /** |
| 5055 | * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. |
| 5056 | * @p: the task in question. |
| 5057 | * @policy: new policy. |
| 5058 | * @param: structure containing the new RT priority. |
| 5059 | * |
| 5060 | * Just like sched_setscheduler, only don't bother checking if the |
| 5061 | * current context has permission. For example, this is needed in |
| 5062 | * stop_machine(): we create temporary high priority worker threads, |
| 5063 | * but our caller might not have that capability. |
| 5064 | * |
| 5065 | * Return: 0 on success. An error code otherwise. |
| 5066 | */ |
| 5067 | int sched_setscheduler_nocheck(struct task_struct *p, int policy, |
| 5068 | const struct sched_param *param) |
| 5069 | { |
| 5070 | return _sched_setscheduler(p, policy, param, false); |
| 5071 | } |
| 5072 | EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck); |
| 5073 | |
| 5074 | static int |
| 5075 | do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) |
| 5076 | { |
| 5077 | struct sched_param lparam; |
| 5078 | struct task_struct *p; |
| 5079 | int retval; |
| 5080 | |
| 5081 | if (!param || pid < 0) |
| 5082 | return -EINVAL; |
| 5083 | if (copy_from_user(&lparam, param, sizeof(struct sched_param))) |
| 5084 | return -EFAULT; |
| 5085 | |
| 5086 | rcu_read_lock(); |
| 5087 | retval = -ESRCH; |
| 5088 | p = find_process_by_pid(pid); |
| 5089 | if (likely(p)) |
| 5090 | get_task_struct(p); |
| 5091 | rcu_read_unlock(); |
| 5092 | |
| 5093 | if (likely(p)) { |
| 5094 | retval = sched_setscheduler(p, policy, &lparam); |
| 5095 | put_task_struct(p); |
| 5096 | } |
| 5097 | |
| 5098 | return retval; |
| 5099 | } |
| 5100 | |
| 5101 | /* |
| 5102 | * Mimics kernel/events/core.c perf_copy_attr(). |
| 5103 | */ |
| 5104 | static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr) |
| 5105 | { |
| 5106 | u32 size; |
| 5107 | int ret; |
| 5108 | |
| 5109 | /* Zero the full structure, so that a short copy will be nice: */ |
| 5110 | memset(attr, 0, sizeof(*attr)); |
| 5111 | |
| 5112 | ret = get_user(size, &uattr->size); |
| 5113 | if (ret) |
| 5114 | return ret; |
| 5115 | |
| 5116 | /* ABI compatibility quirk: */ |
| 5117 | if (!size) |
| 5118 | size = SCHED_ATTR_SIZE_VER0; |
| 5119 | if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE) |
| 5120 | goto err_size; |
| 5121 | |
| 5122 | ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size); |
| 5123 | if (ret) { |
| 5124 | if (ret == -E2BIG) |
| 5125 | goto err_size; |
| 5126 | return ret; |
| 5127 | } |
| 5128 | |
| 5129 | if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) && |
| 5130 | size < SCHED_ATTR_SIZE_VER1) |
| 5131 | return -EINVAL; |
| 5132 | |
| 5133 | /* |
| 5134 | * XXX: Do we want to be lenient like existing syscalls; or do we want |
| 5135 | * to be strict and return an error on out-of-bounds values? |
| 5136 | */ |
| 5137 | attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); |
| 5138 | |
| 5139 | return 0; |
| 5140 | |
| 5141 | err_size: |
| 5142 | put_user(sizeof(*attr), &uattr->size); |
| 5143 | return -E2BIG; |
| 5144 | } |
| 5145 | |
| 5146 | /** |
| 5147 | * sys_sched_setscheduler - set/change the scheduler policy and RT priority |
| 5148 | * @pid: the pid in question. |
| 5149 | * @policy: new policy. |
| 5150 | * @param: structure containing the new RT priority. |
| 5151 | * |
| 5152 | * Return: 0 on success. An error code otherwise. |
| 5153 | */ |
| 5154 | SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param) |
| 5155 | { |
| 5156 | if (policy < 0) |
| 5157 | return -EINVAL; |
| 5158 | |
| 5159 | return do_sched_setscheduler(pid, policy, param); |
| 5160 | } |
| 5161 | |
| 5162 | /** |
| 5163 | * sys_sched_setparam - set/change the RT priority of a thread |
| 5164 | * @pid: the pid in question. |
| 5165 | * @param: structure containing the new RT priority. |
| 5166 | * |
| 5167 | * Return: 0 on success. An error code otherwise. |
| 5168 | */ |
| 5169 | SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) |
| 5170 | { |
| 5171 | return do_sched_setscheduler(pid, SETPARAM_POLICY, param); |
| 5172 | } |
| 5173 | |
| 5174 | /** |
| 5175 | * sys_sched_setattr - same as above, but with extended sched_attr |
| 5176 | * @pid: the pid in question. |
| 5177 | * @uattr: structure containing the extended parameters. |
| 5178 | * @flags: for future extension. |
| 5179 | */ |
| 5180 | SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, |
| 5181 | unsigned int, flags) |
| 5182 | { |
| 5183 | struct sched_attr attr; |
| 5184 | struct task_struct *p; |
| 5185 | int retval; |
| 5186 | |
| 5187 | if (!uattr || pid < 0 || flags) |
| 5188 | return -EINVAL; |
| 5189 | |
| 5190 | retval = sched_copy_attr(uattr, &attr); |
| 5191 | if (retval) |
| 5192 | return retval; |
| 5193 | |
| 5194 | if ((int)attr.sched_policy < 0) |
| 5195 | return -EINVAL; |
| 5196 | if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY) |
| 5197 | attr.sched_policy = SETPARAM_POLICY; |
| 5198 | |
| 5199 | rcu_read_lock(); |
| 5200 | retval = -ESRCH; |
| 5201 | p = find_process_by_pid(pid); |
| 5202 | if (likely(p)) |
| 5203 | get_task_struct(p); |
| 5204 | rcu_read_unlock(); |
| 5205 | |
| 5206 | if (likely(p)) { |
| 5207 | retval = sched_setattr(p, &attr); |
| 5208 | put_task_struct(p); |
| 5209 | } |
| 5210 | |
| 5211 | return retval; |
| 5212 | } |
| 5213 | |
| 5214 | /** |
| 5215 | * sys_sched_getscheduler - get the policy (scheduling class) of a thread |
| 5216 | * @pid: the pid in question. |
| 5217 | * |
| 5218 | * Return: On success, the policy of the thread. Otherwise, a negative error |
| 5219 | * code. |
| 5220 | */ |
| 5221 | SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) |
| 5222 | { |
| 5223 | struct task_struct *p; |
| 5224 | int retval; |
| 5225 | |
| 5226 | if (pid < 0) |
| 5227 | return -EINVAL; |
| 5228 | |
| 5229 | retval = -ESRCH; |
| 5230 | rcu_read_lock(); |
| 5231 | p = find_process_by_pid(pid); |
| 5232 | if (p) { |
| 5233 | retval = security_task_getscheduler(p); |
| 5234 | if (!retval) |
| 5235 | retval = p->policy |
| 5236 | | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); |
| 5237 | } |
| 5238 | rcu_read_unlock(); |
| 5239 | return retval; |
| 5240 | } |
| 5241 | |
| 5242 | /** |
| 5243 | * sys_sched_getparam - get the RT priority of a thread |
| 5244 | * @pid: the pid in question. |
| 5245 | * @param: structure containing the RT priority. |
| 5246 | * |
| 5247 | * Return: On success, 0 and the RT priority is in @param. Otherwise, an error |
| 5248 | * code. |
| 5249 | */ |
| 5250 | SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) |
| 5251 | { |
| 5252 | struct sched_param lp = { .sched_priority = 0 }; |
| 5253 | struct task_struct *p; |
| 5254 | int retval; |
| 5255 | |
| 5256 | if (!param || pid < 0) |
| 5257 | return -EINVAL; |
| 5258 | |
| 5259 | rcu_read_lock(); |
| 5260 | p = find_process_by_pid(pid); |
| 5261 | retval = -ESRCH; |
| 5262 | if (!p) |
| 5263 | goto out_unlock; |
| 5264 | |
| 5265 | retval = security_task_getscheduler(p); |
| 5266 | if (retval) |
| 5267 | goto out_unlock; |
| 5268 | |
| 5269 | if (task_has_rt_policy(p)) |
| 5270 | lp.sched_priority = p->rt_priority; |
| 5271 | rcu_read_unlock(); |
| 5272 | |
| 5273 | /* |
| 5274 | * This one might sleep, we cannot do it with a spinlock held ... |
| 5275 | */ |
| 5276 | retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; |
| 5277 | |
| 5278 | return retval; |
| 5279 | |
| 5280 | out_unlock: |
| 5281 | rcu_read_unlock(); |
| 5282 | return retval; |
| 5283 | } |
| 5284 | |
| 5285 | /* |
| 5286 | * Copy the kernel size attribute structure (which might be larger |
| 5287 | * than what user-space knows about) to user-space. |
| 5288 | * |
| 5289 | * Note that all cases are valid: user-space buffer can be larger or |
| 5290 | * smaller than the kernel-space buffer. The usual case is that both |
| 5291 | * have the same size. |
| 5292 | */ |
| 5293 | static int |
| 5294 | sched_attr_copy_to_user(struct sched_attr __user *uattr, |
| 5295 | struct sched_attr *kattr, |
| 5296 | unsigned int usize) |
| 5297 | { |
| 5298 | unsigned int ksize = sizeof(*kattr); |
| 5299 | |
| 5300 | if (!access_ok(uattr, usize)) |
| 5301 | return -EFAULT; |
| 5302 | |
| 5303 | /* |
| 5304 | * sched_getattr() ABI forwards and backwards compatibility: |
| 5305 | * |
| 5306 | * If usize == ksize then we just copy everything to user-space and all is good. |
| 5307 | * |
| 5308 | * If usize < ksize then we only copy as much as user-space has space for, |
| 5309 | * this keeps ABI compatibility as well. We skip the rest. |
| 5310 | * |
| 5311 | * If usize > ksize then user-space is using a newer version of the ABI, |
| 5312 | * which part the kernel doesn't know about. Just ignore it - tooling can |
| 5313 | * detect the kernel's knowledge of attributes from the attr->size value |
| 5314 | * which is set to ksize in this case. |
| 5315 | */ |
| 5316 | kattr->size = min(usize, ksize); |
| 5317 | |
| 5318 | if (copy_to_user(uattr, kattr, kattr->size)) |
| 5319 | return -EFAULT; |
| 5320 | |
| 5321 | return 0; |
| 5322 | } |
| 5323 | |
| 5324 | /** |
| 5325 | * sys_sched_getattr - similar to sched_getparam, but with sched_attr |
| 5326 | * @pid: the pid in question. |
| 5327 | * @uattr: structure containing the extended parameters. |
| 5328 | * @usize: sizeof(attr) for fwd/bwd comp. |
| 5329 | * @flags: for future extension. |
| 5330 | */ |
| 5331 | SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, |
| 5332 | unsigned int, usize, unsigned int, flags) |
| 5333 | { |
| 5334 | struct sched_attr kattr = { }; |
| 5335 | struct task_struct *p; |
| 5336 | int retval; |
| 5337 | |
| 5338 | if (!uattr || pid < 0 || usize > PAGE_SIZE || |
| 5339 | usize < SCHED_ATTR_SIZE_VER0 || flags) |
| 5340 | return -EINVAL; |
| 5341 | |
| 5342 | rcu_read_lock(); |
| 5343 | p = find_process_by_pid(pid); |
| 5344 | retval = -ESRCH; |
| 5345 | if (!p) |
| 5346 | goto out_unlock; |
| 5347 | |
| 5348 | retval = security_task_getscheduler(p); |
| 5349 | if (retval) |
| 5350 | goto out_unlock; |
| 5351 | |
| 5352 | kattr.sched_policy = p->policy; |
| 5353 | if (p->sched_reset_on_fork) |
| 5354 | kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; |
| 5355 | if (task_has_dl_policy(p)) |
| 5356 | __getparam_dl(p, &kattr); |
| 5357 | else if (task_has_rt_policy(p)) |
| 5358 | kattr.sched_priority = p->rt_priority; |
| 5359 | else |
| 5360 | kattr.sched_nice = task_nice(p); |
| 5361 | |
| 5362 | #ifdef CONFIG_UCLAMP_TASK |
| 5363 | kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value; |
| 5364 | kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value; |
| 5365 | #endif |
| 5366 | |
| 5367 | rcu_read_unlock(); |
| 5368 | |
| 5369 | return sched_attr_copy_to_user(uattr, &kattr, usize); |
| 5370 | |
| 5371 | out_unlock: |
| 5372 | rcu_read_unlock(); |
| 5373 | return retval; |
| 5374 | } |
| 5375 | |
| 5376 | long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) |
| 5377 | { |
| 5378 | cpumask_var_t cpus_allowed, new_mask; |
| 5379 | struct task_struct *p; |
| 5380 | int retval; |
| 5381 | |
| 5382 | rcu_read_lock(); |
| 5383 | |
| 5384 | p = find_process_by_pid(pid); |
| 5385 | if (!p) { |
| 5386 | rcu_read_unlock(); |
| 5387 | return -ESRCH; |
| 5388 | } |
| 5389 | |
| 5390 | /* Prevent p going away */ |
| 5391 | get_task_struct(p); |
| 5392 | rcu_read_unlock(); |
| 5393 | |
| 5394 | if (p->flags & PF_NO_SETAFFINITY) { |
| 5395 | retval = -EINVAL; |
| 5396 | goto out_put_task; |
| 5397 | } |
| 5398 | if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { |
| 5399 | retval = -ENOMEM; |
| 5400 | goto out_put_task; |
| 5401 | } |
| 5402 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { |
| 5403 | retval = -ENOMEM; |
| 5404 | goto out_free_cpus_allowed; |
| 5405 | } |
| 5406 | retval = -EPERM; |
| 5407 | if (!check_same_owner(p)) { |
| 5408 | rcu_read_lock(); |
| 5409 | if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { |
| 5410 | rcu_read_unlock(); |
| 5411 | goto out_free_new_mask; |
| 5412 | } |
| 5413 | rcu_read_unlock(); |
| 5414 | } |
| 5415 | |
| 5416 | retval = security_task_setscheduler(p); |
| 5417 | if (retval) |
| 5418 | goto out_free_new_mask; |
| 5419 | |
| 5420 | |
| 5421 | cpuset_cpus_allowed(p, cpus_allowed); |
| 5422 | cpumask_and(new_mask, in_mask, cpus_allowed); |
| 5423 | |
| 5424 | /* |
| 5425 | * Since bandwidth control happens on root_domain basis, |
| 5426 | * if admission test is enabled, we only admit -deadline |
| 5427 | * tasks allowed to run on all the CPUs in the task's |
| 5428 | * root_domain. |
| 5429 | */ |
| 5430 | #ifdef CONFIG_SMP |
| 5431 | if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { |
| 5432 | rcu_read_lock(); |
| 5433 | if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { |
| 5434 | retval = -EBUSY; |
| 5435 | rcu_read_unlock(); |
| 5436 | goto out_free_new_mask; |
| 5437 | } |
| 5438 | rcu_read_unlock(); |
| 5439 | } |
| 5440 | #endif |
| 5441 | again: |
| 5442 | retval = __set_cpus_allowed_ptr(p, new_mask, true); |
| 5443 | |
| 5444 | if (!retval) { |
| 5445 | cpuset_cpus_allowed(p, cpus_allowed); |
| 5446 | if (!cpumask_subset(new_mask, cpus_allowed)) { |
| 5447 | /* |
| 5448 | * We must have raced with a concurrent cpuset |
| 5449 | * update. Just reset the cpus_allowed to the |
| 5450 | * cpuset's cpus_allowed |
| 5451 | */ |
| 5452 | cpumask_copy(new_mask, cpus_allowed); |
| 5453 | goto again; |
| 5454 | } |
| 5455 | } |
| 5456 | out_free_new_mask: |
| 5457 | free_cpumask_var(new_mask); |
| 5458 | out_free_cpus_allowed: |
| 5459 | free_cpumask_var(cpus_allowed); |
| 5460 | out_put_task: |
| 5461 | put_task_struct(p); |
| 5462 | return retval; |
| 5463 | } |
| 5464 | |
| 5465 | static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, |
| 5466 | struct cpumask *new_mask) |
| 5467 | { |
| 5468 | if (len < cpumask_size()) |
| 5469 | cpumask_clear(new_mask); |
| 5470 | else if (len > cpumask_size()) |
| 5471 | len = cpumask_size(); |
| 5472 | |
| 5473 | return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; |
| 5474 | } |
| 5475 | |
| 5476 | /** |
| 5477 | * sys_sched_setaffinity - set the CPU affinity of a process |
| 5478 | * @pid: pid of the process |
| 5479 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr |
| 5480 | * @user_mask_ptr: user-space pointer to the new CPU mask |
| 5481 | * |
| 5482 | * Return: 0 on success. An error code otherwise. |
| 5483 | */ |
| 5484 | SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, |
| 5485 | unsigned long __user *, user_mask_ptr) |
| 5486 | { |
| 5487 | cpumask_var_t new_mask; |
| 5488 | int retval; |
| 5489 | |
| 5490 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) |
| 5491 | return -ENOMEM; |
| 5492 | |
| 5493 | retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); |
| 5494 | if (retval == 0) |
| 5495 | retval = sched_setaffinity(pid, new_mask); |
| 5496 | free_cpumask_var(new_mask); |
| 5497 | return retval; |
| 5498 | } |
| 5499 | |
| 5500 | long sched_getaffinity(pid_t pid, struct cpumask *mask) |
| 5501 | { |
| 5502 | struct task_struct *p; |
| 5503 | unsigned long flags; |
| 5504 | int retval; |
| 5505 | |
| 5506 | rcu_read_lock(); |
| 5507 | |
| 5508 | retval = -ESRCH; |
| 5509 | p = find_process_by_pid(pid); |
| 5510 | if (!p) |
| 5511 | goto out_unlock; |
| 5512 | |
| 5513 | retval = security_task_getscheduler(p); |
| 5514 | if (retval) |
| 5515 | goto out_unlock; |
| 5516 | |
| 5517 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
| 5518 | cpumask_and(mask, &p->cpus_mask, cpu_active_mask); |
| 5519 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| 5520 | |
| 5521 | out_unlock: |
| 5522 | rcu_read_unlock(); |
| 5523 | |
| 5524 | return retval; |
| 5525 | } |
| 5526 | |
| 5527 | /** |
| 5528 | * sys_sched_getaffinity - get the CPU affinity of a process |
| 5529 | * @pid: pid of the process |
| 5530 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr |
| 5531 | * @user_mask_ptr: user-space pointer to hold the current CPU mask |
| 5532 | * |
| 5533 | * Return: size of CPU mask copied to user_mask_ptr on success. An |
| 5534 | * error code otherwise. |
| 5535 | */ |
| 5536 | SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, |
| 5537 | unsigned long __user *, user_mask_ptr) |
| 5538 | { |
| 5539 | int ret; |
| 5540 | cpumask_var_t mask; |
| 5541 | |
| 5542 | if ((len * BITS_PER_BYTE) < nr_cpu_ids) |
| 5543 | return -EINVAL; |
| 5544 | if (len & (sizeof(unsigned long)-1)) |
| 5545 | return -EINVAL; |
| 5546 | |
| 5547 | if (!alloc_cpumask_var(&mask, GFP_KERNEL)) |
| 5548 | return -ENOMEM; |
| 5549 | |
| 5550 | ret = sched_getaffinity(pid, mask); |
| 5551 | if (ret == 0) { |
| 5552 | unsigned int retlen = min(len, cpumask_size()); |
| 5553 | |
| 5554 | if (copy_to_user(user_mask_ptr, mask, retlen)) |
| 5555 | ret = -EFAULT; |
| 5556 | else |
| 5557 | ret = retlen; |
| 5558 | } |
| 5559 | free_cpumask_var(mask); |
| 5560 | |
| 5561 | return ret; |
| 5562 | } |
| 5563 | |
| 5564 | /** |
| 5565 | * sys_sched_yield - yield the current processor to other threads. |
| 5566 | * |
| 5567 | * This function yields the current CPU to other tasks. If there are no |
| 5568 | * other threads running on this CPU then this function will return. |
| 5569 | * |
| 5570 | * Return: 0. |
| 5571 | */ |
| 5572 | static void do_sched_yield(void) |
| 5573 | { |
| 5574 | struct rq_flags rf; |
| 5575 | struct rq *rq; |
| 5576 | |
| 5577 | rq = this_rq_lock_irq(&rf); |
| 5578 | |
| 5579 | schedstat_inc(rq->yld_count); |
| 5580 | current->sched_class->yield_task(rq); |
| 5581 | |
| 5582 | /* |
| 5583 | * Since we are going to call schedule() anyway, there's |
| 5584 | * no need to preempt or enable interrupts: |
| 5585 | */ |
| 5586 | preempt_disable(); |
| 5587 | rq_unlock(rq, &rf); |
| 5588 | sched_preempt_enable_no_resched(); |
| 5589 | |
| 5590 | schedule(); |
| 5591 | } |
| 5592 | |
| 5593 | SYSCALL_DEFINE0(sched_yield) |
| 5594 | { |
| 5595 | do_sched_yield(); |
| 5596 | return 0; |
| 5597 | } |
| 5598 | |
| 5599 | #ifndef CONFIG_PREEMPTION |
| 5600 | int __sched _cond_resched(void) |
| 5601 | { |
| 5602 | if (should_resched(0)) { |
| 5603 | preempt_schedule_common(); |
| 5604 | return 1; |
| 5605 | } |
| 5606 | rcu_all_qs(); |
| 5607 | return 0; |
| 5608 | } |
| 5609 | EXPORT_SYMBOL(_cond_resched); |
| 5610 | #endif |
| 5611 | |
| 5612 | /* |
| 5613 | * __cond_resched_lock() - if a reschedule is pending, drop the given lock, |
| 5614 | * call schedule, and on return reacquire the lock. |
| 5615 | * |
| 5616 | * This works OK both with and without CONFIG_PREEMPTION. We do strange low-level |
| 5617 | * operations here to prevent schedule() from being called twice (once via |
| 5618 | * spin_unlock(), once by hand). |
| 5619 | */ |
| 5620 | int __cond_resched_lock(spinlock_t *lock) |
| 5621 | { |
| 5622 | int resched = should_resched(PREEMPT_LOCK_OFFSET); |
| 5623 | int ret = 0; |
| 5624 | |
| 5625 | lockdep_assert_held(lock); |
| 5626 | |
| 5627 | if (spin_needbreak(lock) || resched) { |
| 5628 | spin_unlock(lock); |
| 5629 | if (resched) |
| 5630 | preempt_schedule_common(); |
| 5631 | else |
| 5632 | cpu_relax(); |
| 5633 | ret = 1; |
| 5634 | spin_lock(lock); |
| 5635 | } |
| 5636 | return ret; |
| 5637 | } |
| 5638 | EXPORT_SYMBOL(__cond_resched_lock); |
| 5639 | |
| 5640 | /** |
| 5641 | * yield - yield the current processor to other threads. |
| 5642 | * |
| 5643 | * Do not ever use this function, there's a 99% chance you're doing it wrong. |
| 5644 | * |
| 5645 | * The scheduler is at all times free to pick the calling task as the most |
| 5646 | * eligible task to run, if removing the yield() call from your code breaks |
| 5647 | * it, its already broken. |
| 5648 | * |
| 5649 | * Typical broken usage is: |
| 5650 | * |
| 5651 | * while (!event) |
| 5652 | * yield(); |
| 5653 | * |
| 5654 | * where one assumes that yield() will let 'the other' process run that will |
| 5655 | * make event true. If the current task is a SCHED_FIFO task that will never |
| 5656 | * happen. Never use yield() as a progress guarantee!! |
| 5657 | * |
| 5658 | * If you want to use yield() to wait for something, use wait_event(). |
| 5659 | * If you want to use yield() to be 'nice' for others, use cond_resched(). |
| 5660 | * If you still want to use yield(), do not! |
| 5661 | */ |
| 5662 | void __sched yield(void) |
| 5663 | { |
| 5664 | set_current_state(TASK_RUNNING); |
| 5665 | do_sched_yield(); |
| 5666 | } |
| 5667 | EXPORT_SYMBOL(yield); |
| 5668 | |
| 5669 | /** |
| 5670 | * yield_to - yield the current processor to another thread in |
| 5671 | * your thread group, or accelerate that thread toward the |
| 5672 | * processor it's on. |
| 5673 | * @p: target task |
| 5674 | * @preempt: whether task preemption is allowed or not |
| 5675 | * |
| 5676 | * It's the caller's job to ensure that the target task struct |
| 5677 | * can't go away on us before we can do any checks. |
| 5678 | * |
| 5679 | * Return: |
| 5680 | * true (>0) if we indeed boosted the target task. |
| 5681 | * false (0) if we failed to boost the target. |
| 5682 | * -ESRCH if there's no task to yield to. |
| 5683 | */ |
| 5684 | int __sched yield_to(struct task_struct *p, bool preempt) |
| 5685 | { |
| 5686 | struct task_struct *curr = current; |
| 5687 | struct rq *rq, *p_rq; |
| 5688 | unsigned long flags; |
| 5689 | int yielded = 0; |
| 5690 | |
| 5691 | local_irq_save(flags); |
| 5692 | rq = this_rq(); |
| 5693 | |
| 5694 | again: |
| 5695 | p_rq = task_rq(p); |
| 5696 | /* |
| 5697 | * If we're the only runnable task on the rq and target rq also |
| 5698 | * has only one task, there's absolutely no point in yielding. |
| 5699 | */ |
| 5700 | if (rq->nr_running == 1 && p_rq->nr_running == 1) { |
| 5701 | yielded = -ESRCH; |
| 5702 | goto out_irq; |
| 5703 | } |
| 5704 | |
| 5705 | double_rq_lock(rq, p_rq); |
| 5706 | if (task_rq(p) != p_rq) { |
| 5707 | double_rq_unlock(rq, p_rq); |
| 5708 | goto again; |
| 5709 | } |
| 5710 | |
| 5711 | if (!curr->sched_class->yield_to_task) |
| 5712 | goto out_unlock; |
| 5713 | |
| 5714 | if (curr->sched_class != p->sched_class) |
| 5715 | goto out_unlock; |
| 5716 | |
| 5717 | if (task_running(p_rq, p) || p->state) |
| 5718 | goto out_unlock; |
| 5719 | |
| 5720 | yielded = curr->sched_class->yield_to_task(rq, p, preempt); |
| 5721 | if (yielded) { |
| 5722 | schedstat_inc(rq->yld_count); |
| 5723 | /* |
| 5724 | * Make p's CPU reschedule; pick_next_entity takes care of |
| 5725 | * fairness. |
| 5726 | */ |
| 5727 | if (preempt && rq != p_rq) |
| 5728 | resched_curr(p_rq); |
| 5729 | } |
| 5730 | |
| 5731 | out_unlock: |
| 5732 | double_rq_unlock(rq, p_rq); |
| 5733 | out_irq: |
| 5734 | local_irq_restore(flags); |
| 5735 | |
| 5736 | if (yielded > 0) |
| 5737 | schedule(); |
| 5738 | |
| 5739 | return yielded; |
| 5740 | } |
| 5741 | EXPORT_SYMBOL_GPL(yield_to); |
| 5742 | |
| 5743 | int io_schedule_prepare(void) |
| 5744 | { |
| 5745 | int old_iowait = current->in_iowait; |
| 5746 | |
| 5747 | current->in_iowait = 1; |
| 5748 | blk_schedule_flush_plug(current); |
| 5749 | |
| 5750 | return old_iowait; |
| 5751 | } |
| 5752 | |
| 5753 | void io_schedule_finish(int token) |
| 5754 | { |
| 5755 | current->in_iowait = token; |
| 5756 | } |
| 5757 | |
| 5758 | /* |
| 5759 | * This task is about to go to sleep on IO. Increment rq->nr_iowait so |
| 5760 | * that process accounting knows that this is a task in IO wait state. |
| 5761 | */ |
| 5762 | long __sched io_schedule_timeout(long timeout) |
| 5763 | { |
| 5764 | int token; |
| 5765 | long ret; |
| 5766 | |
| 5767 | token = io_schedule_prepare(); |
| 5768 | ret = schedule_timeout(timeout); |
| 5769 | io_schedule_finish(token); |
| 5770 | |
| 5771 | return ret; |
| 5772 | } |
| 5773 | EXPORT_SYMBOL(io_schedule_timeout); |
| 5774 | |
| 5775 | void __sched io_schedule(void) |
| 5776 | { |
| 5777 | int token; |
| 5778 | |
| 5779 | token = io_schedule_prepare(); |
| 5780 | schedule(); |
| 5781 | io_schedule_finish(token); |
| 5782 | } |
| 5783 | EXPORT_SYMBOL(io_schedule); |
| 5784 | |
| 5785 | /** |
| 5786 | * sys_sched_get_priority_max - return maximum RT priority. |
| 5787 | * @policy: scheduling class. |
| 5788 | * |
| 5789 | * Return: On success, this syscall returns the maximum |
| 5790 | * rt_priority that can be used by a given scheduling class. |
| 5791 | * On failure, a negative error code is returned. |
| 5792 | */ |
| 5793 | SYSCALL_DEFINE1(sched_get_priority_max, int, policy) |
| 5794 | { |
| 5795 | int ret = -EINVAL; |
| 5796 | |
| 5797 | switch (policy) { |
| 5798 | case SCHED_FIFO: |
| 5799 | case SCHED_RR: |
| 5800 | ret = MAX_USER_RT_PRIO-1; |
| 5801 | break; |
| 5802 | case SCHED_DEADLINE: |
| 5803 | case SCHED_NORMAL: |
| 5804 | case SCHED_BATCH: |
| 5805 | case SCHED_IDLE: |
| 5806 | ret = 0; |
| 5807 | break; |
| 5808 | } |
| 5809 | return ret; |
| 5810 | } |
| 5811 | |
| 5812 | /** |
| 5813 | * sys_sched_get_priority_min - return minimum RT priority. |
| 5814 | * @policy: scheduling class. |
| 5815 | * |
| 5816 | * Return: On success, this syscall returns the minimum |
| 5817 | * rt_priority that can be used by a given scheduling class. |
| 5818 | * On failure, a negative error code is returned. |
| 5819 | */ |
| 5820 | SYSCALL_DEFINE1(sched_get_priority_min, int, policy) |
| 5821 | { |
| 5822 | int ret = -EINVAL; |
| 5823 | |
| 5824 | switch (policy) { |
| 5825 | case SCHED_FIFO: |
| 5826 | case SCHED_RR: |
| 5827 | ret = 1; |
| 5828 | break; |
| 5829 | case SCHED_DEADLINE: |
| 5830 | case SCHED_NORMAL: |
| 5831 | case SCHED_BATCH: |
| 5832 | case SCHED_IDLE: |
| 5833 | ret = 0; |
| 5834 | } |
| 5835 | return ret; |
| 5836 | } |
| 5837 | |
| 5838 | static int sched_rr_get_interval(pid_t pid, struct timespec64 *t) |
| 5839 | { |
| 5840 | struct task_struct *p; |
| 5841 | unsigned int time_slice; |
| 5842 | struct rq_flags rf; |
| 5843 | struct rq *rq; |
| 5844 | int retval; |
| 5845 | |
| 5846 | if (pid < 0) |
| 5847 | return -EINVAL; |
| 5848 | |
| 5849 | retval = -ESRCH; |
| 5850 | rcu_read_lock(); |
| 5851 | p = find_process_by_pid(pid); |
| 5852 | if (!p) |
| 5853 | goto out_unlock; |
| 5854 | |
| 5855 | retval = security_task_getscheduler(p); |
| 5856 | if (retval) |
| 5857 | goto out_unlock; |
| 5858 | |
| 5859 | rq = task_rq_lock(p, &rf); |
| 5860 | time_slice = 0; |
| 5861 | if (p->sched_class->get_rr_interval) |
| 5862 | time_slice = p->sched_class->get_rr_interval(rq, p); |
| 5863 | task_rq_unlock(rq, p, &rf); |
| 5864 | |
| 5865 | rcu_read_unlock(); |
| 5866 | jiffies_to_timespec64(time_slice, t); |
| 5867 | return 0; |
| 5868 | |
| 5869 | out_unlock: |
| 5870 | rcu_read_unlock(); |
| 5871 | return retval; |
| 5872 | } |
| 5873 | |
| 5874 | /** |
| 5875 | * sys_sched_rr_get_interval - return the default timeslice of a process. |
| 5876 | * @pid: pid of the process. |
| 5877 | * @interval: userspace pointer to the timeslice value. |
| 5878 | * |
| 5879 | * this syscall writes the default timeslice value of a given process |
| 5880 | * into the user-space timespec buffer. A value of '0' means infinity. |
| 5881 | * |
| 5882 | * Return: On success, 0 and the timeslice is in @interval. Otherwise, |
| 5883 | * an error code. |
| 5884 | */ |
| 5885 | SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, |
| 5886 | struct __kernel_timespec __user *, interval) |
| 5887 | { |
| 5888 | struct timespec64 t; |
| 5889 | int retval = sched_rr_get_interval(pid, &t); |
| 5890 | |
| 5891 | if (retval == 0) |
| 5892 | retval = put_timespec64(&t, interval); |
| 5893 | |
| 5894 | return retval; |
| 5895 | } |
| 5896 | |
| 5897 | #ifdef CONFIG_COMPAT_32BIT_TIME |
| 5898 | SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, pid, |
| 5899 | struct old_timespec32 __user *, interval) |
| 5900 | { |
| 5901 | struct timespec64 t; |
| 5902 | int retval = sched_rr_get_interval(pid, &t); |
| 5903 | |
| 5904 | if (retval == 0) |
| 5905 | retval = put_old_timespec32(&t, interval); |
| 5906 | return retval; |
| 5907 | } |
| 5908 | #endif |
| 5909 | |
| 5910 | void sched_show_task(struct task_struct *p) |
| 5911 | { |
| 5912 | unsigned long free = 0; |
| 5913 | int ppid; |
| 5914 | |
| 5915 | if (!try_get_task_stack(p)) |
| 5916 | return; |
| 5917 | |
| 5918 | printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p)); |
| 5919 | |
| 5920 | if (p->state == TASK_RUNNING) |
| 5921 | printk(KERN_CONT " running task "); |
| 5922 | #ifdef CONFIG_DEBUG_STACK_USAGE |
| 5923 | free = stack_not_used(p); |
| 5924 | #endif |
| 5925 | ppid = 0; |
| 5926 | rcu_read_lock(); |
| 5927 | if (pid_alive(p)) |
| 5928 | ppid = task_pid_nr(rcu_dereference(p->real_parent)); |
| 5929 | rcu_read_unlock(); |
| 5930 | printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, |
| 5931 | task_pid_nr(p), ppid, |
| 5932 | (unsigned long)task_thread_info(p)->flags); |
| 5933 | |
| 5934 | print_worker_info(KERN_INFO, p); |
| 5935 | show_stack(p, NULL); |
| 5936 | put_task_stack(p); |
| 5937 | } |
| 5938 | EXPORT_SYMBOL_GPL(sched_show_task); |
| 5939 | |
| 5940 | static inline bool |
| 5941 | state_filter_match(unsigned long state_filter, struct task_struct *p) |
| 5942 | { |
| 5943 | /* no filter, everything matches */ |
| 5944 | if (!state_filter) |
| 5945 | return true; |
| 5946 | |
| 5947 | /* filter, but doesn't match */ |
| 5948 | if (!(p->state & state_filter)) |
| 5949 | return false; |
| 5950 | |
| 5951 | /* |
| 5952 | * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows |
| 5953 | * TASK_KILLABLE). |
| 5954 | */ |
| 5955 | if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE) |
| 5956 | return false; |
| 5957 | |
| 5958 | return true; |
| 5959 | } |
| 5960 | |
| 5961 | |
| 5962 | void show_state_filter(unsigned long state_filter) |
| 5963 | { |
| 5964 | struct task_struct *g, *p; |
| 5965 | |
| 5966 | #if BITS_PER_LONG == 32 |
| 5967 | printk(KERN_INFO |
| 5968 | " task PC stack pid father\n"); |
| 5969 | #else |
| 5970 | printk(KERN_INFO |
| 5971 | " task PC stack pid father\n"); |
| 5972 | #endif |
| 5973 | rcu_read_lock(); |
| 5974 | for_each_process_thread(g, p) { |
| 5975 | /* |
| 5976 | * reset the NMI-timeout, listing all files on a slow |
| 5977 | * console might take a lot of time: |
| 5978 | * Also, reset softlockup watchdogs on all CPUs, because |
| 5979 | * another CPU might be blocked waiting for us to process |
| 5980 | * an IPI. |
| 5981 | */ |
| 5982 | touch_nmi_watchdog(); |
| 5983 | touch_all_softlockup_watchdogs(); |
| 5984 | if (state_filter_match(state_filter, p)) |
| 5985 | sched_show_task(p); |
| 5986 | } |
| 5987 | |
| 5988 | #ifdef CONFIG_SCHED_DEBUG |
| 5989 | if (!state_filter) |
| 5990 | sysrq_sched_debug_show(); |
| 5991 | #endif |
| 5992 | rcu_read_unlock(); |
| 5993 | /* |
| 5994 | * Only show locks if all tasks are dumped: |
| 5995 | */ |
| 5996 | if (!state_filter) |
| 5997 | debug_show_all_locks(); |
| 5998 | } |
| 5999 | |
| 6000 | /** |
| 6001 | * init_idle - set up an idle thread for a given CPU |
| 6002 | * @idle: task in question |
| 6003 | * @cpu: CPU the idle task belongs to |
| 6004 | * |
| 6005 | * NOTE: this function does not set the idle thread's NEED_RESCHED |
| 6006 | * flag, to make booting more robust. |
| 6007 | */ |
| 6008 | void init_idle(struct task_struct *idle, int cpu) |
| 6009 | { |
| 6010 | struct rq *rq = cpu_rq(cpu); |
| 6011 | unsigned long flags; |
| 6012 | |
| 6013 | raw_spin_lock_irqsave(&idle->pi_lock, flags); |
| 6014 | raw_spin_lock(&rq->lock); |
| 6015 | |
| 6016 | __sched_fork(0, idle); |
| 6017 | idle->state = TASK_RUNNING; |
| 6018 | idle->se.exec_start = sched_clock(); |
| 6019 | idle->flags |= PF_IDLE; |
| 6020 | |
| 6021 | kasan_unpoison_task_stack(idle); |
| 6022 | |
| 6023 | #ifdef CONFIG_SMP |
| 6024 | /* |
| 6025 | * Its possible that init_idle() gets called multiple times on a task, |
| 6026 | * in that case do_set_cpus_allowed() will not do the right thing. |
| 6027 | * |
| 6028 | * And since this is boot we can forgo the serialization. |
| 6029 | */ |
| 6030 | set_cpus_allowed_common(idle, cpumask_of(cpu)); |
| 6031 | #endif |
| 6032 | /* |
| 6033 | * We're having a chicken and egg problem, even though we are |
| 6034 | * holding rq->lock, the CPU isn't yet set to this CPU so the |
| 6035 | * lockdep check in task_group() will fail. |
| 6036 | * |
| 6037 | * Similar case to sched_fork(). / Alternatively we could |
| 6038 | * use task_rq_lock() here and obtain the other rq->lock. |
| 6039 | * |
| 6040 | * Silence PROVE_RCU |
| 6041 | */ |
| 6042 | rcu_read_lock(); |
| 6043 | __set_task_cpu(idle, cpu); |
| 6044 | rcu_read_unlock(); |
| 6045 | |
| 6046 | rq->idle = idle; |
| 6047 | rcu_assign_pointer(rq->curr, idle); |
| 6048 | idle->on_rq = TASK_ON_RQ_QUEUED; |
| 6049 | #ifdef CONFIG_SMP |
| 6050 | idle->on_cpu = 1; |
| 6051 | #endif |
| 6052 | raw_spin_unlock(&rq->lock); |
| 6053 | raw_spin_unlock_irqrestore(&idle->pi_lock, flags); |
| 6054 | |
| 6055 | /* Set the preempt count _outside_ the spinlocks! */ |
| 6056 | init_idle_preempt_count(idle, cpu); |
| 6057 | |
| 6058 | /* |
| 6059 | * The idle tasks have their own, simple scheduling class: |
| 6060 | */ |
| 6061 | idle->sched_class = &idle_sched_class; |
| 6062 | ftrace_graph_init_idle_task(idle, cpu); |
| 6063 | vtime_init_idle(idle, cpu); |
| 6064 | #ifdef CONFIG_SMP |
| 6065 | sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); |
| 6066 | #endif |
| 6067 | } |
| 6068 | |
| 6069 | #ifdef CONFIG_SMP |
| 6070 | |
| 6071 | int cpuset_cpumask_can_shrink(const struct cpumask *cur, |
| 6072 | const struct cpumask *trial) |
| 6073 | { |
| 6074 | int ret = 1; |
| 6075 | |
| 6076 | if (!cpumask_weight(cur)) |
| 6077 | return ret; |
| 6078 | |
| 6079 | ret = dl_cpuset_cpumask_can_shrink(cur, trial); |
| 6080 | |
| 6081 | return ret; |
| 6082 | } |
| 6083 | |
| 6084 | int task_can_attach(struct task_struct *p, |
| 6085 | const struct cpumask *cs_cpus_allowed) |
| 6086 | { |
| 6087 | int ret = 0; |
| 6088 | |
| 6089 | /* |
| 6090 | * Kthreads which disallow setaffinity shouldn't be moved |
| 6091 | * to a new cpuset; we don't want to change their CPU |
| 6092 | * affinity and isolating such threads by their set of |
| 6093 | * allowed nodes is unnecessary. Thus, cpusets are not |
| 6094 | * applicable for such threads. This prevents checking for |
| 6095 | * success of set_cpus_allowed_ptr() on all attached tasks |
| 6096 | * before cpus_mask may be changed. |
| 6097 | */ |
| 6098 | if (p->flags & PF_NO_SETAFFINITY) { |
| 6099 | ret = -EINVAL; |
| 6100 | goto out; |
| 6101 | } |
| 6102 | |
| 6103 | if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, |
| 6104 | cs_cpus_allowed)) |
| 6105 | ret = dl_task_can_attach(p, cs_cpus_allowed); |
| 6106 | |
| 6107 | out: |
| 6108 | return ret; |
| 6109 | } |
| 6110 | |
| 6111 | bool sched_smp_initialized __read_mostly; |
| 6112 | |
| 6113 | #ifdef CONFIG_NUMA_BALANCING |
| 6114 | /* Migrate current task p to target_cpu */ |
| 6115 | int migrate_task_to(struct task_struct *p, int target_cpu) |
| 6116 | { |
| 6117 | struct migration_arg arg = { p, target_cpu }; |
| 6118 | int curr_cpu = task_cpu(p); |
| 6119 | |
| 6120 | if (curr_cpu == target_cpu) |
| 6121 | return 0; |
| 6122 | |
| 6123 | if (!cpumask_test_cpu(target_cpu, p->cpus_ptr)) |
| 6124 | return -EINVAL; |
| 6125 | |
| 6126 | /* TODO: This is not properly updating schedstats */ |
| 6127 | |
| 6128 | trace_sched_move_numa(p, curr_cpu, target_cpu); |
| 6129 | return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); |
| 6130 | } |
| 6131 | |
| 6132 | /* |
| 6133 | * Requeue a task on a given node and accurately track the number of NUMA |
| 6134 | * tasks on the runqueues |
| 6135 | */ |
| 6136 | void sched_setnuma(struct task_struct *p, int nid) |
| 6137 | { |
| 6138 | bool queued, running; |
| 6139 | struct rq_flags rf; |
| 6140 | struct rq *rq; |
| 6141 | |
| 6142 | rq = task_rq_lock(p, &rf); |
| 6143 | queued = task_on_rq_queued(p); |
| 6144 | running = task_current(rq, p); |
| 6145 | |
| 6146 | if (queued) |
| 6147 | dequeue_task(rq, p, DEQUEUE_SAVE); |
| 6148 | if (running) |
| 6149 | put_prev_task(rq, p); |
| 6150 | |
| 6151 | p->numa_preferred_nid = nid; |
| 6152 | |
| 6153 | if (queued) |
| 6154 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
| 6155 | if (running) |
| 6156 | set_next_task(rq, p); |
| 6157 | task_rq_unlock(rq, p, &rf); |
| 6158 | } |
| 6159 | #endif /* CONFIG_NUMA_BALANCING */ |
| 6160 | |
| 6161 | #ifdef CONFIG_HOTPLUG_CPU |
| 6162 | /* |
| 6163 | * Ensure that the idle task is using init_mm right before its CPU goes |
| 6164 | * offline. |
| 6165 | */ |
| 6166 | void idle_task_exit(void) |
| 6167 | { |
| 6168 | struct mm_struct *mm = current->active_mm; |
| 6169 | |
| 6170 | BUG_ON(cpu_online(smp_processor_id())); |
| 6171 | |
| 6172 | if (mm != &init_mm) { |
| 6173 | switch_mm(mm, &init_mm, current); |
| 6174 | current->active_mm = &init_mm; |
| 6175 | finish_arch_post_lock_switch(); |
| 6176 | } |
| 6177 | mmdrop(mm); |
| 6178 | } |
| 6179 | |
| 6180 | /* |
| 6181 | * Since this CPU is going 'away' for a while, fold any nr_active delta |
| 6182 | * we might have. Assumes we're called after migrate_tasks() so that the |
| 6183 | * nr_active count is stable. We need to take the teardown thread which |
| 6184 | * is calling this into account, so we hand in adjust = 1 to the load |
| 6185 | * calculation. |
| 6186 | * |
| 6187 | * Also see the comment "Global load-average calculations". |
| 6188 | */ |
| 6189 | static void calc_load_migrate(struct rq *rq) |
| 6190 | { |
| 6191 | long delta = calc_load_fold_active(rq, 1); |
| 6192 | if (delta) |
| 6193 | atomic_long_add(delta, &calc_load_tasks); |
| 6194 | } |
| 6195 | |
| 6196 | static struct task_struct *__pick_migrate_task(struct rq *rq) |
| 6197 | { |
| 6198 | const struct sched_class *class; |
| 6199 | struct task_struct *next; |
| 6200 | |
| 6201 | for_each_class(class) { |
| 6202 | next = class->pick_next_task(rq, NULL, NULL); |
| 6203 | if (next) { |
| 6204 | next->sched_class->put_prev_task(rq, next, NULL); |
| 6205 | return next; |
| 6206 | } |
| 6207 | } |
| 6208 | |
| 6209 | /* The idle class should always have a runnable task */ |
| 6210 | BUG(); |
| 6211 | } |
| 6212 | |
| 6213 | /* |
| 6214 | * Migrate all tasks from the rq, sleeping tasks will be migrated by |
| 6215 | * try_to_wake_up()->select_task_rq(). |
| 6216 | * |
| 6217 | * Called with rq->lock held even though we'er in stop_machine() and |
| 6218 | * there's no concurrency possible, we hold the required locks anyway |
| 6219 | * because of lock validation efforts. |
| 6220 | */ |
| 6221 | static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf) |
| 6222 | { |
| 6223 | struct rq *rq = dead_rq; |
| 6224 | struct task_struct *next, *stop = rq->stop; |
| 6225 | struct rq_flags orf = *rf; |
| 6226 | int dest_cpu; |
| 6227 | |
| 6228 | /* |
| 6229 | * Fudge the rq selection such that the below task selection loop |
| 6230 | * doesn't get stuck on the currently eligible stop task. |
| 6231 | * |
| 6232 | * We're currently inside stop_machine() and the rq is either stuck |
| 6233 | * in the stop_machine_cpu_stop() loop, or we're executing this code, |
| 6234 | * either way we should never end up calling schedule() until we're |
| 6235 | * done here. |
| 6236 | */ |
| 6237 | rq->stop = NULL; |
| 6238 | |
| 6239 | /* |
| 6240 | * put_prev_task() and pick_next_task() sched |
| 6241 | * class method both need to have an up-to-date |
| 6242 | * value of rq->clock[_task] |
| 6243 | */ |
| 6244 | update_rq_clock(rq); |
| 6245 | |
| 6246 | for (;;) { |
| 6247 | /* |
| 6248 | * There's this thread running, bail when that's the only |
| 6249 | * remaining thread: |
| 6250 | */ |
| 6251 | if (rq->nr_running == 1) |
| 6252 | break; |
| 6253 | |
| 6254 | next = __pick_migrate_task(rq); |
| 6255 | |
| 6256 | /* |
| 6257 | * Rules for changing task_struct::cpus_mask are holding |
| 6258 | * both pi_lock and rq->lock, such that holding either |
| 6259 | * stabilizes the mask. |
| 6260 | * |
| 6261 | * Drop rq->lock is not quite as disastrous as it usually is |
| 6262 | * because !cpu_active at this point, which means load-balance |
| 6263 | * will not interfere. Also, stop-machine. |
| 6264 | */ |
| 6265 | rq_unlock(rq, rf); |
| 6266 | raw_spin_lock(&next->pi_lock); |
| 6267 | rq_relock(rq, rf); |
| 6268 | |
| 6269 | /* |
| 6270 | * Since we're inside stop-machine, _nothing_ should have |
| 6271 | * changed the task, WARN if weird stuff happened, because in |
| 6272 | * that case the above rq->lock drop is a fail too. |
| 6273 | */ |
| 6274 | if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) { |
| 6275 | raw_spin_unlock(&next->pi_lock); |
| 6276 | continue; |
| 6277 | } |
| 6278 | |
| 6279 | /* Find suitable destination for @next, with force if needed. */ |
| 6280 | dest_cpu = select_fallback_rq(dead_rq->cpu, next); |
| 6281 | rq = __migrate_task(rq, rf, next, dest_cpu); |
| 6282 | if (rq != dead_rq) { |
| 6283 | rq_unlock(rq, rf); |
| 6284 | rq = dead_rq; |
| 6285 | *rf = orf; |
| 6286 | rq_relock(rq, rf); |
| 6287 | } |
| 6288 | raw_spin_unlock(&next->pi_lock); |
| 6289 | } |
| 6290 | |
| 6291 | rq->stop = stop; |
| 6292 | } |
| 6293 | #endif /* CONFIG_HOTPLUG_CPU */ |
| 6294 | |
| 6295 | void set_rq_online(struct rq *rq) |
| 6296 | { |
| 6297 | if (!rq->online) { |
| 6298 | const struct sched_class *class; |
| 6299 | |
| 6300 | cpumask_set_cpu(rq->cpu, rq->rd->online); |
| 6301 | rq->online = 1; |
| 6302 | |
| 6303 | for_each_class(class) { |
| 6304 | if (class->rq_online) |
| 6305 | class->rq_online(rq); |
| 6306 | } |
| 6307 | } |
| 6308 | } |
| 6309 | |
| 6310 | void set_rq_offline(struct rq *rq) |
| 6311 | { |
| 6312 | if (rq->online) { |
| 6313 | const struct sched_class *class; |
| 6314 | |
| 6315 | for_each_class(class) { |
| 6316 | if (class->rq_offline) |
| 6317 | class->rq_offline(rq); |
| 6318 | } |
| 6319 | |
| 6320 | cpumask_clear_cpu(rq->cpu, rq->rd->online); |
| 6321 | rq->online = 0; |
| 6322 | } |
| 6323 | } |
| 6324 | |
| 6325 | /* |
| 6326 | * used to mark begin/end of suspend/resume: |
| 6327 | */ |
| 6328 | static int num_cpus_frozen; |
| 6329 | |
| 6330 | /* |
| 6331 | * Update cpusets according to cpu_active mask. If cpusets are |
| 6332 | * disabled, cpuset_update_active_cpus() becomes a simple wrapper |
| 6333 | * around partition_sched_domains(). |
| 6334 | * |
| 6335 | * If we come here as part of a suspend/resume, don't touch cpusets because we |
| 6336 | * want to restore it back to its original state upon resume anyway. |
| 6337 | */ |
| 6338 | static void cpuset_cpu_active(void) |
| 6339 | { |
| 6340 | if (cpuhp_tasks_frozen) { |
| 6341 | /* |
| 6342 | * num_cpus_frozen tracks how many CPUs are involved in suspend |
| 6343 | * resume sequence. As long as this is not the last online |
| 6344 | * operation in the resume sequence, just build a single sched |
| 6345 | * domain, ignoring cpusets. |
| 6346 | */ |
| 6347 | partition_sched_domains(1, NULL, NULL); |
| 6348 | if (--num_cpus_frozen) |
| 6349 | return; |
| 6350 | /* |
| 6351 | * This is the last CPU online operation. So fall through and |
| 6352 | * restore the original sched domains by considering the |
| 6353 | * cpuset configurations. |
| 6354 | */ |
| 6355 | cpuset_force_rebuild(); |
| 6356 | } |
| 6357 | cpuset_update_active_cpus(); |
| 6358 | } |
| 6359 | |
| 6360 | static int cpuset_cpu_inactive(unsigned int cpu) |
| 6361 | { |
| 6362 | if (!cpuhp_tasks_frozen) { |
| 6363 | if (dl_cpu_busy(cpu)) |
| 6364 | return -EBUSY; |
| 6365 | cpuset_update_active_cpus(); |
| 6366 | } else { |
| 6367 | num_cpus_frozen++; |
| 6368 | partition_sched_domains(1, NULL, NULL); |
| 6369 | } |
| 6370 | return 0; |
| 6371 | } |
| 6372 | |
| 6373 | int sched_cpu_activate(unsigned int cpu) |
| 6374 | { |
| 6375 | struct rq *rq = cpu_rq(cpu); |
| 6376 | struct rq_flags rf; |
| 6377 | |
| 6378 | #ifdef CONFIG_SCHED_SMT |
| 6379 | /* |
| 6380 | * When going up, increment the number of cores with SMT present. |
| 6381 | */ |
| 6382 | if (cpumask_weight(cpu_smt_mask(cpu)) == 2) |
| 6383 | static_branch_inc_cpuslocked(&sched_smt_present); |
| 6384 | #endif |
| 6385 | set_cpu_active(cpu, true); |
| 6386 | |
| 6387 | if (sched_smp_initialized) { |
| 6388 | sched_domains_numa_masks_set(cpu); |
| 6389 | cpuset_cpu_active(); |
| 6390 | } |
| 6391 | |
| 6392 | /* |
| 6393 | * Put the rq online, if not already. This happens: |
| 6394 | * |
| 6395 | * 1) In the early boot process, because we build the real domains |
| 6396 | * after all CPUs have been brought up. |
| 6397 | * |
| 6398 | * 2) At runtime, if cpuset_cpu_active() fails to rebuild the |
| 6399 | * domains. |
| 6400 | */ |
| 6401 | rq_lock_irqsave(rq, &rf); |
| 6402 | if (rq->rd) { |
| 6403 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); |
| 6404 | set_rq_online(rq); |
| 6405 | } |
| 6406 | rq_unlock_irqrestore(rq, &rf); |
| 6407 | |
| 6408 | return 0; |
| 6409 | } |
| 6410 | |
| 6411 | int sched_cpu_deactivate(unsigned int cpu) |
| 6412 | { |
| 6413 | int ret; |
| 6414 | |
| 6415 | set_cpu_active(cpu, false); |
| 6416 | /* |
| 6417 | * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU |
| 6418 | * users of this state to go away such that all new such users will |
| 6419 | * observe it. |
| 6420 | * |
| 6421 | * Do sync before park smpboot threads to take care the rcu boost case. |
| 6422 | */ |
| 6423 | synchronize_rcu(); |
| 6424 | |
| 6425 | #ifdef CONFIG_SCHED_SMT |
| 6426 | /* |
| 6427 | * When going down, decrement the number of cores with SMT present. |
| 6428 | */ |
| 6429 | if (cpumask_weight(cpu_smt_mask(cpu)) == 2) |
| 6430 | static_branch_dec_cpuslocked(&sched_smt_present); |
| 6431 | #endif |
| 6432 | |
| 6433 | if (!sched_smp_initialized) |
| 6434 | return 0; |
| 6435 | |
| 6436 | ret = cpuset_cpu_inactive(cpu); |
| 6437 | if (ret) { |
| 6438 | set_cpu_active(cpu, true); |
| 6439 | return ret; |
| 6440 | } |
| 6441 | sched_domains_numa_masks_clear(cpu); |
| 6442 | return 0; |
| 6443 | } |
| 6444 | |
| 6445 | static void sched_rq_cpu_starting(unsigned int cpu) |
| 6446 | { |
| 6447 | struct rq *rq = cpu_rq(cpu); |
| 6448 | |
| 6449 | rq->calc_load_update = calc_load_update; |
| 6450 | update_max_interval(); |
| 6451 | } |
| 6452 | |
| 6453 | int sched_cpu_starting(unsigned int cpu) |
| 6454 | { |
| 6455 | sched_rq_cpu_starting(cpu); |
| 6456 | sched_tick_start(cpu); |
| 6457 | return 0; |
| 6458 | } |
| 6459 | |
| 6460 | #ifdef CONFIG_HOTPLUG_CPU |
| 6461 | int sched_cpu_dying(unsigned int cpu) |
| 6462 | { |
| 6463 | struct rq *rq = cpu_rq(cpu); |
| 6464 | struct rq_flags rf; |
| 6465 | |
| 6466 | /* Handle pending wakeups and then migrate everything off */ |
| 6467 | sched_ttwu_pending(); |
| 6468 | sched_tick_stop(cpu); |
| 6469 | |
| 6470 | rq_lock_irqsave(rq, &rf); |
| 6471 | if (rq->rd) { |
| 6472 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); |
| 6473 | set_rq_offline(rq); |
| 6474 | } |
| 6475 | migrate_tasks(rq, &rf); |
| 6476 | BUG_ON(rq->nr_running != 1); |
| 6477 | rq_unlock_irqrestore(rq, &rf); |
| 6478 | |
| 6479 | calc_load_migrate(rq); |
| 6480 | update_max_interval(); |
| 6481 | nohz_balance_exit_idle(rq); |
| 6482 | hrtick_clear(rq); |
| 6483 | return 0; |
| 6484 | } |
| 6485 | #endif |
| 6486 | |
| 6487 | void __init sched_init_smp(void) |
| 6488 | { |
| 6489 | sched_init_numa(); |
| 6490 | |
| 6491 | /* |
| 6492 | * There's no userspace yet to cause hotplug operations; hence all the |
| 6493 | * CPU masks are stable and all blatant races in the below code cannot |
| 6494 | * happen. |
| 6495 | */ |
| 6496 | mutex_lock(&sched_domains_mutex); |
| 6497 | sched_init_domains(cpu_active_mask); |
| 6498 | mutex_unlock(&sched_domains_mutex); |
| 6499 | |
| 6500 | /* Move init over to a non-isolated CPU */ |
| 6501 | if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0) |
| 6502 | BUG(); |
| 6503 | sched_init_granularity(); |
| 6504 | |
| 6505 | init_sched_rt_class(); |
| 6506 | init_sched_dl_class(); |
| 6507 | |
| 6508 | sched_smp_initialized = true; |
| 6509 | } |
| 6510 | |
| 6511 | static int __init migration_init(void) |
| 6512 | { |
| 6513 | sched_cpu_starting(smp_processor_id()); |
| 6514 | return 0; |
| 6515 | } |
| 6516 | early_initcall(migration_init); |
| 6517 | |
| 6518 | #else |
| 6519 | void __init sched_init_smp(void) |
| 6520 | { |
| 6521 | sched_init_granularity(); |
| 6522 | } |
| 6523 | #endif /* CONFIG_SMP */ |
| 6524 | |
| 6525 | int in_sched_functions(unsigned long addr) |
| 6526 | { |
| 6527 | return in_lock_functions(addr) || |
| 6528 | (addr >= (unsigned long)__sched_text_start |
| 6529 | && addr < (unsigned long)__sched_text_end); |
| 6530 | } |
| 6531 | |
| 6532 | #ifdef CONFIG_CGROUP_SCHED |
| 6533 | /* |
| 6534 | * Default task group. |
| 6535 | * Every task in system belongs to this group at bootup. |
| 6536 | */ |
| 6537 | struct task_group root_task_group; |
| 6538 | LIST_HEAD(task_groups); |
| 6539 | |
| 6540 | /* Cacheline aligned slab cache for task_group */ |
| 6541 | static struct kmem_cache *task_group_cache __read_mostly; |
| 6542 | #endif |
| 6543 | |
| 6544 | DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); |
| 6545 | DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); |
| 6546 | |
| 6547 | void __init sched_init(void) |
| 6548 | { |
| 6549 | unsigned long ptr = 0; |
| 6550 | int i; |
| 6551 | |
| 6552 | wait_bit_init(); |
| 6553 | |
| 6554 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 6555 | ptr += 2 * nr_cpu_ids * sizeof(void **); |
| 6556 | #endif |
| 6557 | #ifdef CONFIG_RT_GROUP_SCHED |
| 6558 | ptr += 2 * nr_cpu_ids * sizeof(void **); |
| 6559 | #endif |
| 6560 | if (ptr) { |
| 6561 | ptr = (unsigned long)kzalloc(ptr, GFP_NOWAIT); |
| 6562 | |
| 6563 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 6564 | root_task_group.se = (struct sched_entity **)ptr; |
| 6565 | ptr += nr_cpu_ids * sizeof(void **); |
| 6566 | |
| 6567 | root_task_group.cfs_rq = (struct cfs_rq **)ptr; |
| 6568 | ptr += nr_cpu_ids * sizeof(void **); |
| 6569 | |
| 6570 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| 6571 | #ifdef CONFIG_RT_GROUP_SCHED |
| 6572 | root_task_group.rt_se = (struct sched_rt_entity **)ptr; |
| 6573 | ptr += nr_cpu_ids * sizeof(void **); |
| 6574 | |
| 6575 | root_task_group.rt_rq = (struct rt_rq **)ptr; |
| 6576 | ptr += nr_cpu_ids * sizeof(void **); |
| 6577 | |
| 6578 | #endif /* CONFIG_RT_GROUP_SCHED */ |
| 6579 | } |
| 6580 | #ifdef CONFIG_CPUMASK_OFFSTACK |
| 6581 | for_each_possible_cpu(i) { |
| 6582 | per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( |
| 6583 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); |
| 6584 | per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( |
| 6585 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); |
| 6586 | } |
| 6587 | #endif /* CONFIG_CPUMASK_OFFSTACK */ |
| 6588 | |
| 6589 | init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); |
| 6590 | init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime()); |
| 6591 | |
| 6592 | #ifdef CONFIG_SMP |
| 6593 | init_defrootdomain(); |
| 6594 | #endif |
| 6595 | |
| 6596 | #ifdef CONFIG_RT_GROUP_SCHED |
| 6597 | init_rt_bandwidth(&root_task_group.rt_bandwidth, |
| 6598 | global_rt_period(), global_rt_runtime()); |
| 6599 | #endif /* CONFIG_RT_GROUP_SCHED */ |
| 6600 | |
| 6601 | #ifdef CONFIG_CGROUP_SCHED |
| 6602 | task_group_cache = KMEM_CACHE(task_group, 0); |
| 6603 | |
| 6604 | list_add(&root_task_group.list, &task_groups); |
| 6605 | INIT_LIST_HEAD(&root_task_group.children); |
| 6606 | INIT_LIST_HEAD(&root_task_group.siblings); |
| 6607 | autogroup_init(&init_task); |
| 6608 | #endif /* CONFIG_CGROUP_SCHED */ |
| 6609 | |
| 6610 | for_each_possible_cpu(i) { |
| 6611 | struct rq *rq; |
| 6612 | |
| 6613 | rq = cpu_rq(i); |
| 6614 | raw_spin_lock_init(&rq->lock); |
| 6615 | rq->nr_running = 0; |
| 6616 | rq->calc_load_active = 0; |
| 6617 | rq->calc_load_update = jiffies + LOAD_FREQ; |
| 6618 | init_cfs_rq(&rq->cfs); |
| 6619 | init_rt_rq(&rq->rt); |
| 6620 | init_dl_rq(&rq->dl); |
| 6621 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 6622 | root_task_group.shares = ROOT_TASK_GROUP_LOAD; |
| 6623 | INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); |
| 6624 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; |
| 6625 | /* |
| 6626 | * How much CPU bandwidth does root_task_group get? |
| 6627 | * |
| 6628 | * In case of task-groups formed thr' the cgroup filesystem, it |
| 6629 | * gets 100% of the CPU resources in the system. This overall |
| 6630 | * system CPU resource is divided among the tasks of |
| 6631 | * root_task_group and its child task-groups in a fair manner, |
| 6632 | * based on each entity's (task or task-group's) weight |
| 6633 | * (se->load.weight). |
| 6634 | * |
| 6635 | * In other words, if root_task_group has 10 tasks of weight |
| 6636 | * 1024) and two child groups A0 and A1 (of weight 1024 each), |
| 6637 | * then A0's share of the CPU resource is: |
| 6638 | * |
| 6639 | * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% |
| 6640 | * |
| 6641 | * We achieve this by letting root_task_group's tasks sit |
| 6642 | * directly in rq->cfs (i.e root_task_group->se[] = NULL). |
| 6643 | */ |
| 6644 | init_cfs_bandwidth(&root_task_group.cfs_bandwidth); |
| 6645 | init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); |
| 6646 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| 6647 | |
| 6648 | rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; |
| 6649 | #ifdef CONFIG_RT_GROUP_SCHED |
| 6650 | init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); |
| 6651 | #endif |
| 6652 | #ifdef CONFIG_SMP |
| 6653 | rq->sd = NULL; |
| 6654 | rq->rd = NULL; |
| 6655 | rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; |
| 6656 | rq->balance_callback = NULL; |
| 6657 | rq->active_balance = 0; |
| 6658 | rq->next_balance = jiffies; |
| 6659 | rq->push_cpu = 0; |
| 6660 | rq->cpu = i; |
| 6661 | rq->online = 0; |
| 6662 | rq->idle_stamp = 0; |
| 6663 | rq->avg_idle = 2*sysctl_sched_migration_cost; |
| 6664 | rq->max_idle_balance_cost = sysctl_sched_migration_cost; |
| 6665 | |
| 6666 | INIT_LIST_HEAD(&rq->cfs_tasks); |
| 6667 | |
| 6668 | rq_attach_root(rq, &def_root_domain); |
| 6669 | #ifdef CONFIG_NO_HZ_COMMON |
| 6670 | rq->last_load_update_tick = jiffies; |
| 6671 | rq->last_blocked_load_update_tick = jiffies; |
| 6672 | atomic_set(&rq->nohz_flags, 0); |
| 6673 | #endif |
| 6674 | #endif /* CONFIG_SMP */ |
| 6675 | hrtick_rq_init(rq); |
| 6676 | atomic_set(&rq->nr_iowait, 0); |
| 6677 | } |
| 6678 | |
| 6679 | set_load_weight(&init_task, false); |
| 6680 | |
| 6681 | /* |
| 6682 | * The boot idle thread does lazy MMU switching as well: |
| 6683 | */ |
| 6684 | mmgrab(&init_mm); |
| 6685 | enter_lazy_tlb(&init_mm, current); |
| 6686 | |
| 6687 | /* |
| 6688 | * Make us the idle thread. Technically, schedule() should not be |
| 6689 | * called from this thread, however somewhere below it might be, |
| 6690 | * but because we are the idle thread, we just pick up running again |
| 6691 | * when this runqueue becomes "idle". |
| 6692 | */ |
| 6693 | init_idle(current, smp_processor_id()); |
| 6694 | |
| 6695 | calc_load_update = jiffies + LOAD_FREQ; |
| 6696 | |
| 6697 | #ifdef CONFIG_SMP |
| 6698 | idle_thread_set_boot_cpu(); |
| 6699 | #endif |
| 6700 | init_sched_fair_class(); |
| 6701 | |
| 6702 | init_schedstats(); |
| 6703 | |
| 6704 | psi_init(); |
| 6705 | |
| 6706 | init_uclamp(); |
| 6707 | |
| 6708 | scheduler_running = 1; |
| 6709 | } |
| 6710 | |
| 6711 | #ifdef CONFIG_DEBUG_ATOMIC_SLEEP |
| 6712 | static inline int preempt_count_equals(int preempt_offset) |
| 6713 | { |
| 6714 | int nested = preempt_count() + rcu_preempt_depth(); |
| 6715 | |
| 6716 | return (nested == preempt_offset); |
| 6717 | } |
| 6718 | |
| 6719 | void __might_sleep(const char *file, int line, int preempt_offset) |
| 6720 | { |
| 6721 | /* |
| 6722 | * Blocking primitives will set (and therefore destroy) current->state, |
| 6723 | * since we will exit with TASK_RUNNING make sure we enter with it, |
| 6724 | * otherwise we will destroy state. |
| 6725 | */ |
| 6726 | WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change, |
| 6727 | "do not call blocking ops when !TASK_RUNNING; " |
| 6728 | "state=%lx set at [<%p>] %pS\n", |
| 6729 | current->state, |
| 6730 | (void *)current->task_state_change, |
| 6731 | (void *)current->task_state_change); |
| 6732 | |
| 6733 | ___might_sleep(file, line, preempt_offset); |
| 6734 | } |
| 6735 | EXPORT_SYMBOL(__might_sleep); |
| 6736 | |
| 6737 | void ___might_sleep(const char *file, int line, int preempt_offset) |
| 6738 | { |
| 6739 | /* Ratelimiting timestamp: */ |
| 6740 | static unsigned long prev_jiffy; |
| 6741 | |
| 6742 | unsigned long preempt_disable_ip; |
| 6743 | |
| 6744 | /* WARN_ON_ONCE() by default, no rate limit required: */ |
| 6745 | rcu_sleep_check(); |
| 6746 | |
| 6747 | if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && |
| 6748 | !is_idle_task(current) && !current->non_block_count) || |
| 6749 | system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING || |
| 6750 | oops_in_progress) |
| 6751 | return; |
| 6752 | |
| 6753 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) |
| 6754 | return; |
| 6755 | prev_jiffy = jiffies; |
| 6756 | |
| 6757 | /* Save this before calling printk(), since that will clobber it: */ |
| 6758 | preempt_disable_ip = get_preempt_disable_ip(current); |
| 6759 | |
| 6760 | printk(KERN_ERR |
| 6761 | "BUG: sleeping function called from invalid context at %s:%d\n", |
| 6762 | file, line); |
| 6763 | printk(KERN_ERR |
| 6764 | "in_atomic(): %d, irqs_disabled(): %d, non_block: %d, pid: %d, name: %s\n", |
| 6765 | in_atomic(), irqs_disabled(), current->non_block_count, |
| 6766 | current->pid, current->comm); |
| 6767 | |
| 6768 | if (task_stack_end_corrupted(current)) |
| 6769 | printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); |
| 6770 | |
| 6771 | debug_show_held_locks(current); |
| 6772 | if (irqs_disabled()) |
| 6773 | print_irqtrace_events(current); |
| 6774 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
| 6775 | && !preempt_count_equals(preempt_offset)) { |
| 6776 | pr_err("Preemption disabled at:"); |
| 6777 | print_ip_sym(preempt_disable_ip); |
| 6778 | pr_cont("\n"); |
| 6779 | } |
| 6780 | dump_stack(); |
| 6781 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
| 6782 | } |
| 6783 | EXPORT_SYMBOL(___might_sleep); |
| 6784 | |
| 6785 | void __cant_sleep(const char *file, int line, int preempt_offset) |
| 6786 | { |
| 6787 | static unsigned long prev_jiffy; |
| 6788 | |
| 6789 | if (irqs_disabled()) |
| 6790 | return; |
| 6791 | |
| 6792 | if (!IS_ENABLED(CONFIG_PREEMPT_COUNT)) |
| 6793 | return; |
| 6794 | |
| 6795 | if (preempt_count() > preempt_offset) |
| 6796 | return; |
| 6797 | |
| 6798 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) |
| 6799 | return; |
| 6800 | prev_jiffy = jiffies; |
| 6801 | |
| 6802 | printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line); |
| 6803 | printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", |
| 6804 | in_atomic(), irqs_disabled(), |
| 6805 | current->pid, current->comm); |
| 6806 | |
| 6807 | debug_show_held_locks(current); |
| 6808 | dump_stack(); |
| 6809 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
| 6810 | } |
| 6811 | EXPORT_SYMBOL_GPL(__cant_sleep); |
| 6812 | #endif |
| 6813 | |
| 6814 | #ifdef CONFIG_MAGIC_SYSRQ |
| 6815 | void normalize_rt_tasks(void) |
| 6816 | { |
| 6817 | struct task_struct *g, *p; |
| 6818 | struct sched_attr attr = { |
| 6819 | .sched_policy = SCHED_NORMAL, |
| 6820 | }; |
| 6821 | |
| 6822 | read_lock(&tasklist_lock); |
| 6823 | for_each_process_thread(g, p) { |
| 6824 | /* |
| 6825 | * Only normalize user tasks: |
| 6826 | */ |
| 6827 | if (p->flags & PF_KTHREAD) |
| 6828 | continue; |
| 6829 | |
| 6830 | p->se.exec_start = 0; |
| 6831 | schedstat_set(p->se.statistics.wait_start, 0); |
| 6832 | schedstat_set(p->se.statistics.sleep_start, 0); |
| 6833 | schedstat_set(p->se.statistics.block_start, 0); |
| 6834 | |
| 6835 | if (!dl_task(p) && !rt_task(p)) { |
| 6836 | /* |
| 6837 | * Renice negative nice level userspace |
| 6838 | * tasks back to 0: |
| 6839 | */ |
| 6840 | if (task_nice(p) < 0) |
| 6841 | set_user_nice(p, 0); |
| 6842 | continue; |
| 6843 | } |
| 6844 | |
| 6845 | __sched_setscheduler(p, &attr, false, false); |
| 6846 | } |
| 6847 | read_unlock(&tasklist_lock); |
| 6848 | } |
| 6849 | |
| 6850 | #endif /* CONFIG_MAGIC_SYSRQ */ |
| 6851 | |
| 6852 | #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) |
| 6853 | /* |
| 6854 | * These functions are only useful for the IA64 MCA handling, or kdb. |
| 6855 | * |
| 6856 | * They can only be called when the whole system has been |
| 6857 | * stopped - every CPU needs to be quiescent, and no scheduling |
| 6858 | * activity can take place. Using them for anything else would |
| 6859 | * be a serious bug, and as a result, they aren't even visible |
| 6860 | * under any other configuration. |
| 6861 | */ |
| 6862 | |
| 6863 | /** |
| 6864 | * curr_task - return the current task for a given CPU. |
| 6865 | * @cpu: the processor in question. |
| 6866 | * |
| 6867 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! |
| 6868 | * |
| 6869 | * Return: The current task for @cpu. |
| 6870 | */ |
| 6871 | struct task_struct *curr_task(int cpu) |
| 6872 | { |
| 6873 | return cpu_curr(cpu); |
| 6874 | } |
| 6875 | |
| 6876 | #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ |
| 6877 | |
| 6878 | #ifdef CONFIG_IA64 |
| 6879 | /** |
| 6880 | * ia64_set_curr_task - set the current task for a given CPU. |
| 6881 | * @cpu: the processor in question. |
| 6882 | * @p: the task pointer to set. |
| 6883 | * |
| 6884 | * Description: This function must only be used when non-maskable interrupts |
| 6885 | * are serviced on a separate stack. It allows the architecture to switch the |
| 6886 | * notion of the current task on a CPU in a non-blocking manner. This function |
| 6887 | * must be called with all CPU's synchronized, and interrupts disabled, the |
| 6888 | * and caller must save the original value of the current task (see |
| 6889 | * curr_task() above) and restore that value before reenabling interrupts and |
| 6890 | * re-starting the system. |
| 6891 | * |
| 6892 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! |
| 6893 | */ |
| 6894 | void ia64_set_curr_task(int cpu, struct task_struct *p) |
| 6895 | { |
| 6896 | cpu_curr(cpu) = p; |
| 6897 | } |
| 6898 | |
| 6899 | #endif |
| 6900 | |
| 6901 | #ifdef CONFIG_CGROUP_SCHED |
| 6902 | /* task_group_lock serializes the addition/removal of task groups */ |
| 6903 | static DEFINE_SPINLOCK(task_group_lock); |
| 6904 | |
| 6905 | static inline void alloc_uclamp_sched_group(struct task_group *tg, |
| 6906 | struct task_group *parent) |
| 6907 | { |
| 6908 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 6909 | enum uclamp_id clamp_id; |
| 6910 | |
| 6911 | for_each_clamp_id(clamp_id) { |
| 6912 | uclamp_se_set(&tg->uclamp_req[clamp_id], |
| 6913 | uclamp_none(clamp_id), false); |
| 6914 | tg->uclamp[clamp_id] = parent->uclamp[clamp_id]; |
| 6915 | } |
| 6916 | #endif |
| 6917 | } |
| 6918 | |
| 6919 | static void sched_free_group(struct task_group *tg) |
| 6920 | { |
| 6921 | free_fair_sched_group(tg); |
| 6922 | free_rt_sched_group(tg); |
| 6923 | autogroup_free(tg); |
| 6924 | kmem_cache_free(task_group_cache, tg); |
| 6925 | } |
| 6926 | |
| 6927 | /* allocate runqueue etc for a new task group */ |
| 6928 | struct task_group *sched_create_group(struct task_group *parent) |
| 6929 | { |
| 6930 | struct task_group *tg; |
| 6931 | |
| 6932 | tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO); |
| 6933 | if (!tg) |
| 6934 | return ERR_PTR(-ENOMEM); |
| 6935 | |
| 6936 | if (!alloc_fair_sched_group(tg, parent)) |
| 6937 | goto err; |
| 6938 | |
| 6939 | if (!alloc_rt_sched_group(tg, parent)) |
| 6940 | goto err; |
| 6941 | |
| 6942 | alloc_uclamp_sched_group(tg, parent); |
| 6943 | |
| 6944 | return tg; |
| 6945 | |
| 6946 | err: |
| 6947 | sched_free_group(tg); |
| 6948 | return ERR_PTR(-ENOMEM); |
| 6949 | } |
| 6950 | |
| 6951 | void sched_online_group(struct task_group *tg, struct task_group *parent) |
| 6952 | { |
| 6953 | unsigned long flags; |
| 6954 | |
| 6955 | spin_lock_irqsave(&task_group_lock, flags); |
| 6956 | list_add_rcu(&tg->list, &task_groups); |
| 6957 | |
| 6958 | /* Root should already exist: */ |
| 6959 | WARN_ON(!parent); |
| 6960 | |
| 6961 | tg->parent = parent; |
| 6962 | INIT_LIST_HEAD(&tg->children); |
| 6963 | list_add_rcu(&tg->siblings, &parent->children); |
| 6964 | spin_unlock_irqrestore(&task_group_lock, flags); |
| 6965 | |
| 6966 | online_fair_sched_group(tg); |
| 6967 | } |
| 6968 | |
| 6969 | /* rcu callback to free various structures associated with a task group */ |
| 6970 | static void sched_free_group_rcu(struct rcu_head *rhp) |
| 6971 | { |
| 6972 | /* Now it should be safe to free those cfs_rqs: */ |
| 6973 | sched_free_group(container_of(rhp, struct task_group, rcu)); |
| 6974 | } |
| 6975 | |
| 6976 | void sched_destroy_group(struct task_group *tg) |
| 6977 | { |
| 6978 | /* Wait for possible concurrent references to cfs_rqs complete: */ |
| 6979 | call_rcu(&tg->rcu, sched_free_group_rcu); |
| 6980 | } |
| 6981 | |
| 6982 | void sched_offline_group(struct task_group *tg) |
| 6983 | { |
| 6984 | unsigned long flags; |
| 6985 | |
| 6986 | /* End participation in shares distribution: */ |
| 6987 | unregister_fair_sched_group(tg); |
| 6988 | |
| 6989 | spin_lock_irqsave(&task_group_lock, flags); |
| 6990 | list_del_rcu(&tg->list); |
| 6991 | list_del_rcu(&tg->siblings); |
| 6992 | spin_unlock_irqrestore(&task_group_lock, flags); |
| 6993 | } |
| 6994 | |
| 6995 | static void sched_change_group(struct task_struct *tsk, int type) |
| 6996 | { |
| 6997 | struct task_group *tg; |
| 6998 | |
| 6999 | /* |
| 7000 | * All callers are synchronized by task_rq_lock(); we do not use RCU |
| 7001 | * which is pointless here. Thus, we pass "true" to task_css_check() |
| 7002 | * to prevent lockdep warnings. |
| 7003 | */ |
| 7004 | tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), |
| 7005 | struct task_group, css); |
| 7006 | tg = autogroup_task_group(tsk, tg); |
| 7007 | tsk->sched_task_group = tg; |
| 7008 | |
| 7009 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 7010 | if (tsk->sched_class->task_change_group) |
| 7011 | tsk->sched_class->task_change_group(tsk, type); |
| 7012 | else |
| 7013 | #endif |
| 7014 | set_task_rq(tsk, task_cpu(tsk)); |
| 7015 | } |
| 7016 | |
| 7017 | /* |
| 7018 | * Change task's runqueue when it moves between groups. |
| 7019 | * |
| 7020 | * The caller of this function should have put the task in its new group by |
| 7021 | * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect |
| 7022 | * its new group. |
| 7023 | */ |
| 7024 | void sched_move_task(struct task_struct *tsk) |
| 7025 | { |
| 7026 | int queued, running, queue_flags = |
| 7027 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
| 7028 | struct rq_flags rf; |
| 7029 | struct rq *rq; |
| 7030 | |
| 7031 | rq = task_rq_lock(tsk, &rf); |
| 7032 | update_rq_clock(rq); |
| 7033 | |
| 7034 | running = task_current(rq, tsk); |
| 7035 | queued = task_on_rq_queued(tsk); |
| 7036 | |
| 7037 | if (queued) |
| 7038 | dequeue_task(rq, tsk, queue_flags); |
| 7039 | if (running) |
| 7040 | put_prev_task(rq, tsk); |
| 7041 | |
| 7042 | sched_change_group(tsk, TASK_MOVE_GROUP); |
| 7043 | |
| 7044 | if (queued) |
| 7045 | enqueue_task(rq, tsk, queue_flags); |
| 7046 | if (running) |
| 7047 | set_next_task(rq, tsk); |
| 7048 | |
| 7049 | task_rq_unlock(rq, tsk, &rf); |
| 7050 | } |
| 7051 | |
| 7052 | static inline struct task_group *css_tg(struct cgroup_subsys_state *css) |
| 7053 | { |
| 7054 | return css ? container_of(css, struct task_group, css) : NULL; |
| 7055 | } |
| 7056 | |
| 7057 | static struct cgroup_subsys_state * |
| 7058 | cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) |
| 7059 | { |
| 7060 | struct task_group *parent = css_tg(parent_css); |
| 7061 | struct task_group *tg; |
| 7062 | |
| 7063 | if (!parent) { |
| 7064 | /* This is early initialization for the top cgroup */ |
| 7065 | return &root_task_group.css; |
| 7066 | } |
| 7067 | |
| 7068 | tg = sched_create_group(parent); |
| 7069 | if (IS_ERR(tg)) |
| 7070 | return ERR_PTR(-ENOMEM); |
| 7071 | |
| 7072 | return &tg->css; |
| 7073 | } |
| 7074 | |
| 7075 | /* Expose task group only after completing cgroup initialization */ |
| 7076 | static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) |
| 7077 | { |
| 7078 | struct task_group *tg = css_tg(css); |
| 7079 | struct task_group *parent = css_tg(css->parent); |
| 7080 | |
| 7081 | if (parent) |
| 7082 | sched_online_group(tg, parent); |
| 7083 | return 0; |
| 7084 | } |
| 7085 | |
| 7086 | static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) |
| 7087 | { |
| 7088 | struct task_group *tg = css_tg(css); |
| 7089 | |
| 7090 | sched_offline_group(tg); |
| 7091 | } |
| 7092 | |
| 7093 | static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) |
| 7094 | { |
| 7095 | struct task_group *tg = css_tg(css); |
| 7096 | |
| 7097 | /* |
| 7098 | * Relies on the RCU grace period between css_released() and this. |
| 7099 | */ |
| 7100 | sched_free_group(tg); |
| 7101 | } |
| 7102 | |
| 7103 | /* |
| 7104 | * This is called before wake_up_new_task(), therefore we really only |
| 7105 | * have to set its group bits, all the other stuff does not apply. |
| 7106 | */ |
| 7107 | static void cpu_cgroup_fork(struct task_struct *task) |
| 7108 | { |
| 7109 | struct rq_flags rf; |
| 7110 | struct rq *rq; |
| 7111 | |
| 7112 | rq = task_rq_lock(task, &rf); |
| 7113 | |
| 7114 | update_rq_clock(rq); |
| 7115 | sched_change_group(task, TASK_SET_GROUP); |
| 7116 | |
| 7117 | task_rq_unlock(rq, task, &rf); |
| 7118 | } |
| 7119 | |
| 7120 | static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) |
| 7121 | { |
| 7122 | struct task_struct *task; |
| 7123 | struct cgroup_subsys_state *css; |
| 7124 | int ret = 0; |
| 7125 | |
| 7126 | cgroup_taskset_for_each(task, css, tset) { |
| 7127 | #ifdef CONFIG_RT_GROUP_SCHED |
| 7128 | if (!sched_rt_can_attach(css_tg(css), task)) |
| 7129 | return -EINVAL; |
| 7130 | #endif |
| 7131 | /* |
| 7132 | * Serialize against wake_up_new_task() such that if its |
| 7133 | * running, we're sure to observe its full state. |
| 7134 | */ |
| 7135 | raw_spin_lock_irq(&task->pi_lock); |
| 7136 | /* |
| 7137 | * Avoid calling sched_move_task() before wake_up_new_task() |
| 7138 | * has happened. This would lead to problems with PELT, due to |
| 7139 | * move wanting to detach+attach while we're not attached yet. |
| 7140 | */ |
| 7141 | if (task->state == TASK_NEW) |
| 7142 | ret = -EINVAL; |
| 7143 | raw_spin_unlock_irq(&task->pi_lock); |
| 7144 | |
| 7145 | if (ret) |
| 7146 | break; |
| 7147 | } |
| 7148 | return ret; |
| 7149 | } |
| 7150 | |
| 7151 | static void cpu_cgroup_attach(struct cgroup_taskset *tset) |
| 7152 | { |
| 7153 | struct task_struct *task; |
| 7154 | struct cgroup_subsys_state *css; |
| 7155 | |
| 7156 | cgroup_taskset_for_each(task, css, tset) |
| 7157 | sched_move_task(task); |
| 7158 | } |
| 7159 | |
| 7160 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 7161 | static void cpu_util_update_eff(struct cgroup_subsys_state *css) |
| 7162 | { |
| 7163 | struct cgroup_subsys_state *top_css = css; |
| 7164 | struct uclamp_se *uc_parent = NULL; |
| 7165 | struct uclamp_se *uc_se = NULL; |
| 7166 | unsigned int eff[UCLAMP_CNT]; |
| 7167 | enum uclamp_id clamp_id; |
| 7168 | unsigned int clamps; |
| 7169 | |
| 7170 | css_for_each_descendant_pre(css, top_css) { |
| 7171 | uc_parent = css_tg(css)->parent |
| 7172 | ? css_tg(css)->parent->uclamp : NULL; |
| 7173 | |
| 7174 | for_each_clamp_id(clamp_id) { |
| 7175 | /* Assume effective clamps matches requested clamps */ |
| 7176 | eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value; |
| 7177 | /* Cap effective clamps with parent's effective clamps */ |
| 7178 | if (uc_parent && |
| 7179 | eff[clamp_id] > uc_parent[clamp_id].value) { |
| 7180 | eff[clamp_id] = uc_parent[clamp_id].value; |
| 7181 | } |
| 7182 | } |
| 7183 | /* Ensure protection is always capped by limit */ |
| 7184 | eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]); |
| 7185 | |
| 7186 | /* Propagate most restrictive effective clamps */ |
| 7187 | clamps = 0x0; |
| 7188 | uc_se = css_tg(css)->uclamp; |
| 7189 | for_each_clamp_id(clamp_id) { |
| 7190 | if (eff[clamp_id] == uc_se[clamp_id].value) |
| 7191 | continue; |
| 7192 | uc_se[clamp_id].value = eff[clamp_id]; |
| 7193 | uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]); |
| 7194 | clamps |= (0x1 << clamp_id); |
| 7195 | } |
| 7196 | if (!clamps) { |
| 7197 | css = css_rightmost_descendant(css); |
| 7198 | continue; |
| 7199 | } |
| 7200 | |
| 7201 | /* Immediately update descendants RUNNABLE tasks */ |
| 7202 | uclamp_update_active_tasks(css, clamps); |
| 7203 | } |
| 7204 | } |
| 7205 | |
| 7206 | /* |
| 7207 | * Integer 10^N with a given N exponent by casting to integer the literal "1eN" |
| 7208 | * C expression. Since there is no way to convert a macro argument (N) into a |
| 7209 | * character constant, use two levels of macros. |
| 7210 | */ |
| 7211 | #define _POW10(exp) ((unsigned int)1e##exp) |
| 7212 | #define POW10(exp) _POW10(exp) |
| 7213 | |
| 7214 | struct uclamp_request { |
| 7215 | #define UCLAMP_PERCENT_SHIFT 2 |
| 7216 | #define UCLAMP_PERCENT_SCALE (100 * POW10(UCLAMP_PERCENT_SHIFT)) |
| 7217 | s64 percent; |
| 7218 | u64 util; |
| 7219 | int ret; |
| 7220 | }; |
| 7221 | |
| 7222 | static inline struct uclamp_request |
| 7223 | capacity_from_percent(char *buf) |
| 7224 | { |
| 7225 | struct uclamp_request req = { |
| 7226 | .percent = UCLAMP_PERCENT_SCALE, |
| 7227 | .util = SCHED_CAPACITY_SCALE, |
| 7228 | .ret = 0, |
| 7229 | }; |
| 7230 | |
| 7231 | buf = strim(buf); |
| 7232 | if (strcmp(buf, "max")) { |
| 7233 | req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT, |
| 7234 | &req.percent); |
| 7235 | if (req.ret) |
| 7236 | return req; |
| 7237 | if (req.percent > UCLAMP_PERCENT_SCALE) { |
| 7238 | req.ret = -ERANGE; |
| 7239 | return req; |
| 7240 | } |
| 7241 | |
| 7242 | req.util = req.percent << SCHED_CAPACITY_SHIFT; |
| 7243 | req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE); |
| 7244 | } |
| 7245 | |
| 7246 | return req; |
| 7247 | } |
| 7248 | |
| 7249 | static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf, |
| 7250 | size_t nbytes, loff_t off, |
| 7251 | enum uclamp_id clamp_id) |
| 7252 | { |
| 7253 | struct uclamp_request req; |
| 7254 | struct task_group *tg; |
| 7255 | |
| 7256 | req = capacity_from_percent(buf); |
| 7257 | if (req.ret) |
| 7258 | return req.ret; |
| 7259 | |
| 7260 | mutex_lock(&uclamp_mutex); |
| 7261 | rcu_read_lock(); |
| 7262 | |
| 7263 | tg = css_tg(of_css(of)); |
| 7264 | if (tg->uclamp_req[clamp_id].value != req.util) |
| 7265 | uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false); |
| 7266 | |
| 7267 | /* |
| 7268 | * Because of not recoverable conversion rounding we keep track of the |
| 7269 | * exact requested value |
| 7270 | */ |
| 7271 | tg->uclamp_pct[clamp_id] = req.percent; |
| 7272 | |
| 7273 | /* Update effective clamps to track the most restrictive value */ |
| 7274 | cpu_util_update_eff(of_css(of)); |
| 7275 | |
| 7276 | rcu_read_unlock(); |
| 7277 | mutex_unlock(&uclamp_mutex); |
| 7278 | |
| 7279 | return nbytes; |
| 7280 | } |
| 7281 | |
| 7282 | static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of, |
| 7283 | char *buf, size_t nbytes, |
| 7284 | loff_t off) |
| 7285 | { |
| 7286 | return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN); |
| 7287 | } |
| 7288 | |
| 7289 | static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of, |
| 7290 | char *buf, size_t nbytes, |
| 7291 | loff_t off) |
| 7292 | { |
| 7293 | return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX); |
| 7294 | } |
| 7295 | |
| 7296 | static inline void cpu_uclamp_print(struct seq_file *sf, |
| 7297 | enum uclamp_id clamp_id) |
| 7298 | { |
| 7299 | struct task_group *tg; |
| 7300 | u64 util_clamp; |
| 7301 | u64 percent; |
| 7302 | u32 rem; |
| 7303 | |
| 7304 | rcu_read_lock(); |
| 7305 | tg = css_tg(seq_css(sf)); |
| 7306 | util_clamp = tg->uclamp_req[clamp_id].value; |
| 7307 | rcu_read_unlock(); |
| 7308 | |
| 7309 | if (util_clamp == SCHED_CAPACITY_SCALE) { |
| 7310 | seq_puts(sf, "max\n"); |
| 7311 | return; |
| 7312 | } |
| 7313 | |
| 7314 | percent = tg->uclamp_pct[clamp_id]; |
| 7315 | percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem); |
| 7316 | seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem); |
| 7317 | } |
| 7318 | |
| 7319 | static int cpu_uclamp_min_show(struct seq_file *sf, void *v) |
| 7320 | { |
| 7321 | cpu_uclamp_print(sf, UCLAMP_MIN); |
| 7322 | return 0; |
| 7323 | } |
| 7324 | |
| 7325 | static int cpu_uclamp_max_show(struct seq_file *sf, void *v) |
| 7326 | { |
| 7327 | cpu_uclamp_print(sf, UCLAMP_MAX); |
| 7328 | return 0; |
| 7329 | } |
| 7330 | #endif /* CONFIG_UCLAMP_TASK_GROUP */ |
| 7331 | |
| 7332 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 7333 | static int cpu_shares_write_u64(struct cgroup_subsys_state *css, |
| 7334 | struct cftype *cftype, u64 shareval) |
| 7335 | { |
| 7336 | if (shareval > scale_load_down(ULONG_MAX)) |
| 7337 | shareval = MAX_SHARES; |
| 7338 | return sched_group_set_shares(css_tg(css), scale_load(shareval)); |
| 7339 | } |
| 7340 | |
| 7341 | static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, |
| 7342 | struct cftype *cft) |
| 7343 | { |
| 7344 | struct task_group *tg = css_tg(css); |
| 7345 | |
| 7346 | return (u64) scale_load_down(tg->shares); |
| 7347 | } |
| 7348 | |
| 7349 | #ifdef CONFIG_CFS_BANDWIDTH |
| 7350 | static DEFINE_MUTEX(cfs_constraints_mutex); |
| 7351 | |
| 7352 | const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ |
| 7353 | static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ |
| 7354 | |
| 7355 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); |
| 7356 | |
| 7357 | static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) |
| 7358 | { |
| 7359 | int i, ret = 0, runtime_enabled, runtime_was_enabled; |
| 7360 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| 7361 | |
| 7362 | if (tg == &root_task_group) |
| 7363 | return -EINVAL; |
| 7364 | |
| 7365 | /* |
| 7366 | * Ensure we have at some amount of bandwidth every period. This is |
| 7367 | * to prevent reaching a state of large arrears when throttled via |
| 7368 | * entity_tick() resulting in prolonged exit starvation. |
| 7369 | */ |
| 7370 | if (quota < min_cfs_quota_period || period < min_cfs_quota_period) |
| 7371 | return -EINVAL; |
| 7372 | |
| 7373 | /* |
| 7374 | * Likewise, bound things on the otherside by preventing insane quota |
| 7375 | * periods. This also allows us to normalize in computing quota |
| 7376 | * feasibility. |
| 7377 | */ |
| 7378 | if (period > max_cfs_quota_period) |
| 7379 | return -EINVAL; |
| 7380 | |
| 7381 | /* |
| 7382 | * Prevent race between setting of cfs_rq->runtime_enabled and |
| 7383 | * unthrottle_offline_cfs_rqs(). |
| 7384 | */ |
| 7385 | get_online_cpus(); |
| 7386 | mutex_lock(&cfs_constraints_mutex); |
| 7387 | ret = __cfs_schedulable(tg, period, quota); |
| 7388 | if (ret) |
| 7389 | goto out_unlock; |
| 7390 | |
| 7391 | runtime_enabled = quota != RUNTIME_INF; |
| 7392 | runtime_was_enabled = cfs_b->quota != RUNTIME_INF; |
| 7393 | /* |
| 7394 | * If we need to toggle cfs_bandwidth_used, off->on must occur |
| 7395 | * before making related changes, and on->off must occur afterwards |
| 7396 | */ |
| 7397 | if (runtime_enabled && !runtime_was_enabled) |
| 7398 | cfs_bandwidth_usage_inc(); |
| 7399 | raw_spin_lock_irq(&cfs_b->lock); |
| 7400 | cfs_b->period = ns_to_ktime(period); |
| 7401 | cfs_b->quota = quota; |
| 7402 | |
| 7403 | __refill_cfs_bandwidth_runtime(cfs_b); |
| 7404 | |
| 7405 | /* Restart the period timer (if active) to handle new period expiry: */ |
| 7406 | if (runtime_enabled) |
| 7407 | start_cfs_bandwidth(cfs_b); |
| 7408 | |
| 7409 | raw_spin_unlock_irq(&cfs_b->lock); |
| 7410 | |
| 7411 | for_each_online_cpu(i) { |
| 7412 | struct cfs_rq *cfs_rq = tg->cfs_rq[i]; |
| 7413 | struct rq *rq = cfs_rq->rq; |
| 7414 | struct rq_flags rf; |
| 7415 | |
| 7416 | rq_lock_irq(rq, &rf); |
| 7417 | cfs_rq->runtime_enabled = runtime_enabled; |
| 7418 | cfs_rq->runtime_remaining = 0; |
| 7419 | |
| 7420 | if (cfs_rq->throttled) |
| 7421 | unthrottle_cfs_rq(cfs_rq); |
| 7422 | rq_unlock_irq(rq, &rf); |
| 7423 | } |
| 7424 | if (runtime_was_enabled && !runtime_enabled) |
| 7425 | cfs_bandwidth_usage_dec(); |
| 7426 | out_unlock: |
| 7427 | mutex_unlock(&cfs_constraints_mutex); |
| 7428 | put_online_cpus(); |
| 7429 | |
| 7430 | return ret; |
| 7431 | } |
| 7432 | |
| 7433 | static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) |
| 7434 | { |
| 7435 | u64 quota, period; |
| 7436 | |
| 7437 | period = ktime_to_ns(tg->cfs_bandwidth.period); |
| 7438 | if (cfs_quota_us < 0) |
| 7439 | quota = RUNTIME_INF; |
| 7440 | else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC) |
| 7441 | quota = (u64)cfs_quota_us * NSEC_PER_USEC; |
| 7442 | else |
| 7443 | return -EINVAL; |
| 7444 | |
| 7445 | return tg_set_cfs_bandwidth(tg, period, quota); |
| 7446 | } |
| 7447 | |
| 7448 | static long tg_get_cfs_quota(struct task_group *tg) |
| 7449 | { |
| 7450 | u64 quota_us; |
| 7451 | |
| 7452 | if (tg->cfs_bandwidth.quota == RUNTIME_INF) |
| 7453 | return -1; |
| 7454 | |
| 7455 | quota_us = tg->cfs_bandwidth.quota; |
| 7456 | do_div(quota_us, NSEC_PER_USEC); |
| 7457 | |
| 7458 | return quota_us; |
| 7459 | } |
| 7460 | |
| 7461 | static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) |
| 7462 | { |
| 7463 | u64 quota, period; |
| 7464 | |
| 7465 | if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC) |
| 7466 | return -EINVAL; |
| 7467 | |
| 7468 | period = (u64)cfs_period_us * NSEC_PER_USEC; |
| 7469 | quota = tg->cfs_bandwidth.quota; |
| 7470 | |
| 7471 | return tg_set_cfs_bandwidth(tg, period, quota); |
| 7472 | } |
| 7473 | |
| 7474 | static long tg_get_cfs_period(struct task_group *tg) |
| 7475 | { |
| 7476 | u64 cfs_period_us; |
| 7477 | |
| 7478 | cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); |
| 7479 | do_div(cfs_period_us, NSEC_PER_USEC); |
| 7480 | |
| 7481 | return cfs_period_us; |
| 7482 | } |
| 7483 | |
| 7484 | static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, |
| 7485 | struct cftype *cft) |
| 7486 | { |
| 7487 | return tg_get_cfs_quota(css_tg(css)); |
| 7488 | } |
| 7489 | |
| 7490 | static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, |
| 7491 | struct cftype *cftype, s64 cfs_quota_us) |
| 7492 | { |
| 7493 | return tg_set_cfs_quota(css_tg(css), cfs_quota_us); |
| 7494 | } |
| 7495 | |
| 7496 | static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, |
| 7497 | struct cftype *cft) |
| 7498 | { |
| 7499 | return tg_get_cfs_period(css_tg(css)); |
| 7500 | } |
| 7501 | |
| 7502 | static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, |
| 7503 | struct cftype *cftype, u64 cfs_period_us) |
| 7504 | { |
| 7505 | return tg_set_cfs_period(css_tg(css), cfs_period_us); |
| 7506 | } |
| 7507 | |
| 7508 | struct cfs_schedulable_data { |
| 7509 | struct task_group *tg; |
| 7510 | u64 period, quota; |
| 7511 | }; |
| 7512 | |
| 7513 | /* |
| 7514 | * normalize group quota/period to be quota/max_period |
| 7515 | * note: units are usecs |
| 7516 | */ |
| 7517 | static u64 normalize_cfs_quota(struct task_group *tg, |
| 7518 | struct cfs_schedulable_data *d) |
| 7519 | { |
| 7520 | u64 quota, period; |
| 7521 | |
| 7522 | if (tg == d->tg) { |
| 7523 | period = d->period; |
| 7524 | quota = d->quota; |
| 7525 | } else { |
| 7526 | period = tg_get_cfs_period(tg); |
| 7527 | quota = tg_get_cfs_quota(tg); |
| 7528 | } |
| 7529 | |
| 7530 | /* note: these should typically be equivalent */ |
| 7531 | if (quota == RUNTIME_INF || quota == -1) |
| 7532 | return RUNTIME_INF; |
| 7533 | |
| 7534 | return to_ratio(period, quota); |
| 7535 | } |
| 7536 | |
| 7537 | static int tg_cfs_schedulable_down(struct task_group *tg, void *data) |
| 7538 | { |
| 7539 | struct cfs_schedulable_data *d = data; |
| 7540 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| 7541 | s64 quota = 0, parent_quota = -1; |
| 7542 | |
| 7543 | if (!tg->parent) { |
| 7544 | quota = RUNTIME_INF; |
| 7545 | } else { |
| 7546 | struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; |
| 7547 | |
| 7548 | quota = normalize_cfs_quota(tg, d); |
| 7549 | parent_quota = parent_b->hierarchical_quota; |
| 7550 | |
| 7551 | /* |
| 7552 | * Ensure max(child_quota) <= parent_quota. On cgroup2, |
| 7553 | * always take the min. On cgroup1, only inherit when no |
| 7554 | * limit is set: |
| 7555 | */ |
| 7556 | if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) { |
| 7557 | quota = min(quota, parent_quota); |
| 7558 | } else { |
| 7559 | if (quota == RUNTIME_INF) |
| 7560 | quota = parent_quota; |
| 7561 | else if (parent_quota != RUNTIME_INF && quota > parent_quota) |
| 7562 | return -EINVAL; |
| 7563 | } |
| 7564 | } |
| 7565 | cfs_b->hierarchical_quota = quota; |
| 7566 | |
| 7567 | return 0; |
| 7568 | } |
| 7569 | |
| 7570 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) |
| 7571 | { |
| 7572 | int ret; |
| 7573 | struct cfs_schedulable_data data = { |
| 7574 | .tg = tg, |
| 7575 | .period = period, |
| 7576 | .quota = quota, |
| 7577 | }; |
| 7578 | |
| 7579 | if (quota != RUNTIME_INF) { |
| 7580 | do_div(data.period, NSEC_PER_USEC); |
| 7581 | do_div(data.quota, NSEC_PER_USEC); |
| 7582 | } |
| 7583 | |
| 7584 | rcu_read_lock(); |
| 7585 | ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); |
| 7586 | rcu_read_unlock(); |
| 7587 | |
| 7588 | return ret; |
| 7589 | } |
| 7590 | |
| 7591 | static int cpu_cfs_stat_show(struct seq_file *sf, void *v) |
| 7592 | { |
| 7593 | struct task_group *tg = css_tg(seq_css(sf)); |
| 7594 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| 7595 | |
| 7596 | seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); |
| 7597 | seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); |
| 7598 | seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); |
| 7599 | |
| 7600 | if (schedstat_enabled() && tg != &root_task_group) { |
| 7601 | u64 ws = 0; |
| 7602 | int i; |
| 7603 | |
| 7604 | for_each_possible_cpu(i) |
| 7605 | ws += schedstat_val(tg->se[i]->statistics.wait_sum); |
| 7606 | |
| 7607 | seq_printf(sf, "wait_sum %llu\n", ws); |
| 7608 | } |
| 7609 | |
| 7610 | return 0; |
| 7611 | } |
| 7612 | #endif /* CONFIG_CFS_BANDWIDTH */ |
| 7613 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| 7614 | |
| 7615 | #ifdef CONFIG_RT_GROUP_SCHED |
| 7616 | static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, |
| 7617 | struct cftype *cft, s64 val) |
| 7618 | { |
| 7619 | return sched_group_set_rt_runtime(css_tg(css), val); |
| 7620 | } |
| 7621 | |
| 7622 | static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, |
| 7623 | struct cftype *cft) |
| 7624 | { |
| 7625 | return sched_group_rt_runtime(css_tg(css)); |
| 7626 | } |
| 7627 | |
| 7628 | static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, |
| 7629 | struct cftype *cftype, u64 rt_period_us) |
| 7630 | { |
| 7631 | return sched_group_set_rt_period(css_tg(css), rt_period_us); |
| 7632 | } |
| 7633 | |
| 7634 | static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, |
| 7635 | struct cftype *cft) |
| 7636 | { |
| 7637 | return sched_group_rt_period(css_tg(css)); |
| 7638 | } |
| 7639 | #endif /* CONFIG_RT_GROUP_SCHED */ |
| 7640 | |
| 7641 | static struct cftype cpu_legacy_files[] = { |
| 7642 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 7643 | { |
| 7644 | .name = "shares", |
| 7645 | .read_u64 = cpu_shares_read_u64, |
| 7646 | .write_u64 = cpu_shares_write_u64, |
| 7647 | }, |
| 7648 | #endif |
| 7649 | #ifdef CONFIG_CFS_BANDWIDTH |
| 7650 | { |
| 7651 | .name = "cfs_quota_us", |
| 7652 | .read_s64 = cpu_cfs_quota_read_s64, |
| 7653 | .write_s64 = cpu_cfs_quota_write_s64, |
| 7654 | }, |
| 7655 | { |
| 7656 | .name = "cfs_period_us", |
| 7657 | .read_u64 = cpu_cfs_period_read_u64, |
| 7658 | .write_u64 = cpu_cfs_period_write_u64, |
| 7659 | }, |
| 7660 | { |
| 7661 | .name = "stat", |
| 7662 | .seq_show = cpu_cfs_stat_show, |
| 7663 | }, |
| 7664 | #endif |
| 7665 | #ifdef CONFIG_RT_GROUP_SCHED |
| 7666 | { |
| 7667 | .name = "rt_runtime_us", |
| 7668 | .read_s64 = cpu_rt_runtime_read, |
| 7669 | .write_s64 = cpu_rt_runtime_write, |
| 7670 | }, |
| 7671 | { |
| 7672 | .name = "rt_period_us", |
| 7673 | .read_u64 = cpu_rt_period_read_uint, |
| 7674 | .write_u64 = cpu_rt_period_write_uint, |
| 7675 | }, |
| 7676 | #endif |
| 7677 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 7678 | { |
| 7679 | .name = "uclamp.min", |
| 7680 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7681 | .seq_show = cpu_uclamp_min_show, |
| 7682 | .write = cpu_uclamp_min_write, |
| 7683 | }, |
| 7684 | { |
| 7685 | .name = "uclamp.max", |
| 7686 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7687 | .seq_show = cpu_uclamp_max_show, |
| 7688 | .write = cpu_uclamp_max_write, |
| 7689 | }, |
| 7690 | #endif |
| 7691 | { } /* Terminate */ |
| 7692 | }; |
| 7693 | |
| 7694 | static int cpu_extra_stat_show(struct seq_file *sf, |
| 7695 | struct cgroup_subsys_state *css) |
| 7696 | { |
| 7697 | #ifdef CONFIG_CFS_BANDWIDTH |
| 7698 | { |
| 7699 | struct task_group *tg = css_tg(css); |
| 7700 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
| 7701 | u64 throttled_usec; |
| 7702 | |
| 7703 | throttled_usec = cfs_b->throttled_time; |
| 7704 | do_div(throttled_usec, NSEC_PER_USEC); |
| 7705 | |
| 7706 | seq_printf(sf, "nr_periods %d\n" |
| 7707 | "nr_throttled %d\n" |
| 7708 | "throttled_usec %llu\n", |
| 7709 | cfs_b->nr_periods, cfs_b->nr_throttled, |
| 7710 | throttled_usec); |
| 7711 | } |
| 7712 | #endif |
| 7713 | return 0; |
| 7714 | } |
| 7715 | |
| 7716 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 7717 | static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css, |
| 7718 | struct cftype *cft) |
| 7719 | { |
| 7720 | struct task_group *tg = css_tg(css); |
| 7721 | u64 weight = scale_load_down(tg->shares); |
| 7722 | |
| 7723 | return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024); |
| 7724 | } |
| 7725 | |
| 7726 | static int cpu_weight_write_u64(struct cgroup_subsys_state *css, |
| 7727 | struct cftype *cft, u64 weight) |
| 7728 | { |
| 7729 | /* |
| 7730 | * cgroup weight knobs should use the common MIN, DFL and MAX |
| 7731 | * values which are 1, 100 and 10000 respectively. While it loses |
| 7732 | * a bit of range on both ends, it maps pretty well onto the shares |
| 7733 | * value used by scheduler and the round-trip conversions preserve |
| 7734 | * the original value over the entire range. |
| 7735 | */ |
| 7736 | if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX) |
| 7737 | return -ERANGE; |
| 7738 | |
| 7739 | weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL); |
| 7740 | |
| 7741 | return sched_group_set_shares(css_tg(css), scale_load(weight)); |
| 7742 | } |
| 7743 | |
| 7744 | static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css, |
| 7745 | struct cftype *cft) |
| 7746 | { |
| 7747 | unsigned long weight = scale_load_down(css_tg(css)->shares); |
| 7748 | int last_delta = INT_MAX; |
| 7749 | int prio, delta; |
| 7750 | |
| 7751 | /* find the closest nice value to the current weight */ |
| 7752 | for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) { |
| 7753 | delta = abs(sched_prio_to_weight[prio] - weight); |
| 7754 | if (delta >= last_delta) |
| 7755 | break; |
| 7756 | last_delta = delta; |
| 7757 | } |
| 7758 | |
| 7759 | return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO); |
| 7760 | } |
| 7761 | |
| 7762 | static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css, |
| 7763 | struct cftype *cft, s64 nice) |
| 7764 | { |
| 7765 | unsigned long weight; |
| 7766 | int idx; |
| 7767 | |
| 7768 | if (nice < MIN_NICE || nice > MAX_NICE) |
| 7769 | return -ERANGE; |
| 7770 | |
| 7771 | idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO; |
| 7772 | idx = array_index_nospec(idx, 40); |
| 7773 | weight = sched_prio_to_weight[idx]; |
| 7774 | |
| 7775 | return sched_group_set_shares(css_tg(css), scale_load(weight)); |
| 7776 | } |
| 7777 | #endif |
| 7778 | |
| 7779 | static void __maybe_unused cpu_period_quota_print(struct seq_file *sf, |
| 7780 | long period, long quota) |
| 7781 | { |
| 7782 | if (quota < 0) |
| 7783 | seq_puts(sf, "max"); |
| 7784 | else |
| 7785 | seq_printf(sf, "%ld", quota); |
| 7786 | |
| 7787 | seq_printf(sf, " %ld\n", period); |
| 7788 | } |
| 7789 | |
| 7790 | /* caller should put the current value in *@periodp before calling */ |
| 7791 | static int __maybe_unused cpu_period_quota_parse(char *buf, |
| 7792 | u64 *periodp, u64 *quotap) |
| 7793 | { |
| 7794 | char tok[21]; /* U64_MAX */ |
| 7795 | |
| 7796 | if (sscanf(buf, "%20s %llu", tok, periodp) < 1) |
| 7797 | return -EINVAL; |
| 7798 | |
| 7799 | *periodp *= NSEC_PER_USEC; |
| 7800 | |
| 7801 | if (sscanf(tok, "%llu", quotap)) |
| 7802 | *quotap *= NSEC_PER_USEC; |
| 7803 | else if (!strcmp(tok, "max")) |
| 7804 | *quotap = RUNTIME_INF; |
| 7805 | else |
| 7806 | return -EINVAL; |
| 7807 | |
| 7808 | return 0; |
| 7809 | } |
| 7810 | |
| 7811 | #ifdef CONFIG_CFS_BANDWIDTH |
| 7812 | static int cpu_max_show(struct seq_file *sf, void *v) |
| 7813 | { |
| 7814 | struct task_group *tg = css_tg(seq_css(sf)); |
| 7815 | |
| 7816 | cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg)); |
| 7817 | return 0; |
| 7818 | } |
| 7819 | |
| 7820 | static ssize_t cpu_max_write(struct kernfs_open_file *of, |
| 7821 | char *buf, size_t nbytes, loff_t off) |
| 7822 | { |
| 7823 | struct task_group *tg = css_tg(of_css(of)); |
| 7824 | u64 period = tg_get_cfs_period(tg); |
| 7825 | u64 quota; |
| 7826 | int ret; |
| 7827 | |
| 7828 | ret = cpu_period_quota_parse(buf, &period, "a); |
| 7829 | if (!ret) |
| 7830 | ret = tg_set_cfs_bandwidth(tg, period, quota); |
| 7831 | return ret ?: nbytes; |
| 7832 | } |
| 7833 | #endif |
| 7834 | |
| 7835 | static struct cftype cpu_files[] = { |
| 7836 | #ifdef CONFIG_FAIR_GROUP_SCHED |
| 7837 | { |
| 7838 | .name = "weight", |
| 7839 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7840 | .read_u64 = cpu_weight_read_u64, |
| 7841 | .write_u64 = cpu_weight_write_u64, |
| 7842 | }, |
| 7843 | { |
| 7844 | .name = "weight.nice", |
| 7845 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7846 | .read_s64 = cpu_weight_nice_read_s64, |
| 7847 | .write_s64 = cpu_weight_nice_write_s64, |
| 7848 | }, |
| 7849 | #endif |
| 7850 | #ifdef CONFIG_CFS_BANDWIDTH |
| 7851 | { |
| 7852 | .name = "max", |
| 7853 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7854 | .seq_show = cpu_max_show, |
| 7855 | .write = cpu_max_write, |
| 7856 | }, |
| 7857 | #endif |
| 7858 | #ifdef CONFIG_UCLAMP_TASK_GROUP |
| 7859 | { |
| 7860 | .name = "uclamp.min", |
| 7861 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7862 | .seq_show = cpu_uclamp_min_show, |
| 7863 | .write = cpu_uclamp_min_write, |
| 7864 | }, |
| 7865 | { |
| 7866 | .name = "uclamp.max", |
| 7867 | .flags = CFTYPE_NOT_ON_ROOT, |
| 7868 | .seq_show = cpu_uclamp_max_show, |
| 7869 | .write = cpu_uclamp_max_write, |
| 7870 | }, |
| 7871 | #endif |
| 7872 | { } /* terminate */ |
| 7873 | }; |
| 7874 | |
| 7875 | struct cgroup_subsys cpu_cgrp_subsys = { |
| 7876 | .css_alloc = cpu_cgroup_css_alloc, |
| 7877 | .css_online = cpu_cgroup_css_online, |
| 7878 | .css_released = cpu_cgroup_css_released, |
| 7879 | .css_free = cpu_cgroup_css_free, |
| 7880 | .css_extra_stat_show = cpu_extra_stat_show, |
| 7881 | .fork = cpu_cgroup_fork, |
| 7882 | .can_attach = cpu_cgroup_can_attach, |
| 7883 | .attach = cpu_cgroup_attach, |
| 7884 | .legacy_cftypes = cpu_legacy_files, |
| 7885 | .dfl_cftypes = cpu_files, |
| 7886 | .early_init = true, |
| 7887 | .threaded = true, |
| 7888 | }; |
| 7889 | |
| 7890 | #endif /* CONFIG_CGROUP_SCHED */ |
| 7891 | |
| 7892 | void dump_cpu_task(int cpu) |
| 7893 | { |
| 7894 | pr_info("Task dump for CPU %d:\n", cpu); |
| 7895 | sched_show_task(cpu_curr(cpu)); |
| 7896 | } |
| 7897 | |
| 7898 | /* |
| 7899 | * Nice levels are multiplicative, with a gentle 10% change for every |
| 7900 | * nice level changed. I.e. when a CPU-bound task goes from nice 0 to |
| 7901 | * nice 1, it will get ~10% less CPU time than another CPU-bound task |
| 7902 | * that remained on nice 0. |
| 7903 | * |
| 7904 | * The "10% effect" is relative and cumulative: from _any_ nice level, |
| 7905 | * if you go up 1 level, it's -10% CPU usage, if you go down 1 level |
| 7906 | * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. |
| 7907 | * If a task goes up by ~10% and another task goes down by ~10% then |
| 7908 | * the relative distance between them is ~25%.) |
| 7909 | */ |
| 7910 | const int sched_prio_to_weight[40] = { |
| 7911 | /* -20 */ 88761, 71755, 56483, 46273, 36291, |
| 7912 | /* -15 */ 29154, 23254, 18705, 14949, 11916, |
| 7913 | /* -10 */ 9548, 7620, 6100, 4904, 3906, |
| 7914 | /* -5 */ 3121, 2501, 1991, 1586, 1277, |
| 7915 | /* 0 */ 1024, 820, 655, 526, 423, |
| 7916 | /* 5 */ 335, 272, 215, 172, 137, |
| 7917 | /* 10 */ 110, 87, 70, 56, 45, |
| 7918 | /* 15 */ 36, 29, 23, 18, 15, |
| 7919 | }; |
| 7920 | |
| 7921 | /* |
| 7922 | * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. |
| 7923 | * |
| 7924 | * In cases where the weight does not change often, we can use the |
| 7925 | * precalculated inverse to speed up arithmetics by turning divisions |
| 7926 | * into multiplications: |
| 7927 | */ |
| 7928 | const u32 sched_prio_to_wmult[40] = { |
| 7929 | /* -20 */ 48388, 59856, 76040, 92818, 118348, |
| 7930 | /* -15 */ 147320, 184698, 229616, 287308, 360437, |
| 7931 | /* -10 */ 449829, 563644, 704093, 875809, 1099582, |
| 7932 | /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, |
| 7933 | /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, |
| 7934 | /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, |
| 7935 | /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, |
| 7936 | /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, |
| 7937 | }; |
| 7938 | |
| 7939 | #undef CREATE_TRACE_POINTS |