| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * linux/kernel/exit.c |
| 4 | * |
| 5 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 6 | */ |
| 7 | |
| 8 | #include <linux/mm.h> |
| 9 | #include <linux/slab.h> |
| 10 | #include <linux/sched/autogroup.h> |
| 11 | #include <linux/sched/mm.h> |
| 12 | #include <linux/sched/stat.h> |
| 13 | #include <linux/sched/task.h> |
| 14 | #include <linux/sched/task_stack.h> |
| 15 | #include <linux/sched/cputime.h> |
| 16 | #include <linux/interrupt.h> |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/capability.h> |
| 19 | #include <linux/completion.h> |
| 20 | #include <linux/personality.h> |
| 21 | #include <linux/tty.h> |
| 22 | #include <linux/iocontext.h> |
| 23 | #include <linux/key.h> |
| 24 | #include <linux/cpu.h> |
| 25 | #include <linux/acct.h> |
| 26 | #include <linux/tsacct_kern.h> |
| 27 | #include <linux/file.h> |
| 28 | #include <linux/fdtable.h> |
| 29 | #include <linux/freezer.h> |
| 30 | #include <linux/binfmts.h> |
| 31 | #include <linux/nsproxy.h> |
| 32 | #include <linux/pid_namespace.h> |
| 33 | #include <linux/ptrace.h> |
| 34 | #include <linux/profile.h> |
| 35 | #include <linux/mount.h> |
| 36 | #include <linux/proc_fs.h> |
| 37 | #include <linux/kthread.h> |
| 38 | #include <linux/mempolicy.h> |
| 39 | #include <linux/taskstats_kern.h> |
| 40 | #include <linux/delayacct.h> |
| 41 | #include <linux/cgroup.h> |
| 42 | #include <linux/syscalls.h> |
| 43 | #include <linux/signal.h> |
| 44 | #include <linux/posix-timers.h> |
| 45 | #include <linux/cn_proc.h> |
| 46 | #include <linux/mutex.h> |
| 47 | #include <linux/futex.h> |
| 48 | #include <linux/pipe_fs_i.h> |
| 49 | #include <linux/audit.h> /* for audit_free() */ |
| 50 | #include <linux/resource.h> |
| 51 | #include <linux/blkdev.h> |
| 52 | #include <linux/task_io_accounting_ops.h> |
| 53 | #include <linux/tracehook.h> |
| 54 | #include <linux/fs_struct.h> |
| 55 | #include <linux/init_task.h> |
| 56 | #include <linux/perf_event.h> |
| 57 | #include <trace/events/sched.h> |
| 58 | #include <linux/hw_breakpoint.h> |
| 59 | #include <linux/oom.h> |
| 60 | #include <linux/writeback.h> |
| 61 | #include <linux/shm.h> |
| 62 | #include <linux/kcov.h> |
| 63 | #include <linux/random.h> |
| 64 | #include <linux/rcuwait.h> |
| 65 | #include <linux/compat.h> |
| 66 | |
| 67 | #include <linux/uaccess.h> |
| 68 | #include <asm/unistd.h> |
| 69 | #include <asm/mmu_context.h> |
| 70 | |
| 71 | static void __unhash_process(struct task_struct *p, bool group_dead) |
| 72 | { |
| 73 | nr_threads--; |
| 74 | detach_pid(p, PIDTYPE_PID); |
| 75 | if (group_dead) { |
| 76 | detach_pid(p, PIDTYPE_TGID); |
| 77 | detach_pid(p, PIDTYPE_PGID); |
| 78 | detach_pid(p, PIDTYPE_SID); |
| 79 | |
| 80 | list_del_rcu(&p->tasks); |
| 81 | list_del_init(&p->sibling); |
| 82 | __this_cpu_dec(process_counts); |
| 83 | } |
| 84 | list_del_rcu(&p->thread_group); |
| 85 | list_del_rcu(&p->thread_node); |
| 86 | } |
| 87 | |
| 88 | /* |
| 89 | * This function expects the tasklist_lock write-locked. |
| 90 | */ |
| 91 | static void __exit_signal(struct task_struct *tsk) |
| 92 | { |
| 93 | struct signal_struct *sig = tsk->signal; |
| 94 | bool group_dead = thread_group_leader(tsk); |
| 95 | struct sighand_struct *sighand; |
| 96 | struct tty_struct *tty; |
| 97 | u64 utime, stime; |
| 98 | |
| 99 | sighand = rcu_dereference_check(tsk->sighand, |
| 100 | lockdep_tasklist_lock_is_held()); |
| 101 | spin_lock(&sighand->siglock); |
| 102 | |
| 103 | #ifdef CONFIG_POSIX_TIMERS |
| 104 | posix_cpu_timers_exit(tsk); |
| 105 | if (group_dead) |
| 106 | posix_cpu_timers_exit_group(tsk); |
| 107 | #endif |
| 108 | |
| 109 | if (group_dead) { |
| 110 | tty = sig->tty; |
| 111 | sig->tty = NULL; |
| 112 | } else { |
| 113 | /* |
| 114 | * If there is any task waiting for the group exit |
| 115 | * then notify it: |
| 116 | */ |
| 117 | if (sig->notify_count > 0 && !--sig->notify_count) |
| 118 | wake_up_process(sig->group_exit_task); |
| 119 | |
| 120 | if (tsk == sig->curr_target) |
| 121 | sig->curr_target = next_thread(tsk); |
| 122 | } |
| 123 | |
| 124 | add_device_randomness((const void*) &tsk->se.sum_exec_runtime, |
| 125 | sizeof(unsigned long long)); |
| 126 | |
| 127 | /* |
| 128 | * Accumulate here the counters for all threads as they die. We could |
| 129 | * skip the group leader because it is the last user of signal_struct, |
| 130 | * but we want to avoid the race with thread_group_cputime() which can |
| 131 | * see the empty ->thread_head list. |
| 132 | */ |
| 133 | task_cputime(tsk, &utime, &stime); |
| 134 | write_seqlock(&sig->stats_lock); |
| 135 | sig->utime += utime; |
| 136 | sig->stime += stime; |
| 137 | sig->gtime += task_gtime(tsk); |
| 138 | sig->min_flt += tsk->min_flt; |
| 139 | sig->maj_flt += tsk->maj_flt; |
| 140 | sig->nvcsw += tsk->nvcsw; |
| 141 | sig->nivcsw += tsk->nivcsw; |
| 142 | sig->inblock += task_io_get_inblock(tsk); |
| 143 | sig->oublock += task_io_get_oublock(tsk); |
| 144 | task_io_accounting_add(&sig->ioac, &tsk->ioac); |
| 145 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
| 146 | sig->nr_threads--; |
| 147 | __unhash_process(tsk, group_dead); |
| 148 | write_sequnlock(&sig->stats_lock); |
| 149 | |
| 150 | /* |
| 151 | * Do this under ->siglock, we can race with another thread |
| 152 | * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
| 153 | */ |
| 154 | flush_sigqueue(&tsk->pending); |
| 155 | tsk->sighand = NULL; |
| 156 | spin_unlock(&sighand->siglock); |
| 157 | |
| 158 | __cleanup_sighand(sighand); |
| 159 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
| 160 | if (group_dead) { |
| 161 | flush_sigqueue(&sig->shared_pending); |
| 162 | tty_kref_put(tty); |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | static void delayed_put_task_struct(struct rcu_head *rhp) |
| 167 | { |
| 168 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
| 169 | |
| 170 | perf_event_delayed_put(tsk); |
| 171 | trace_sched_process_free(tsk); |
| 172 | put_task_struct(tsk); |
| 173 | } |
| 174 | |
| 175 | void put_task_struct_rcu_user(struct task_struct *task) |
| 176 | { |
| 177 | if (refcount_dec_and_test(&task->rcu_users)) |
| 178 | call_rcu(&task->rcu, delayed_put_task_struct); |
| 179 | } |
| 180 | |
| 181 | void release_task(struct task_struct *p) |
| 182 | { |
| 183 | struct task_struct *leader; |
| 184 | struct pid *thread_pid; |
| 185 | int zap_leader; |
| 186 | repeat: |
| 187 | /* don't need to get the RCU readlock here - the process is dead and |
| 188 | * can't be modifying its own credentials. But shut RCU-lockdep up */ |
| 189 | rcu_read_lock(); |
| 190 | atomic_dec(&__task_cred(p)->user->processes); |
| 191 | rcu_read_unlock(); |
| 192 | |
| 193 | cgroup_release(p); |
| 194 | |
| 195 | write_lock_irq(&tasklist_lock); |
| 196 | ptrace_release_task(p); |
| 197 | thread_pid = get_pid(p->thread_pid); |
| 198 | __exit_signal(p); |
| 199 | |
| 200 | /* |
| 201 | * If we are the last non-leader member of the thread |
| 202 | * group, and the leader is zombie, then notify the |
| 203 | * group leader's parent process. (if it wants notification.) |
| 204 | */ |
| 205 | zap_leader = 0; |
| 206 | leader = p->group_leader; |
| 207 | if (leader != p && thread_group_empty(leader) |
| 208 | && leader->exit_state == EXIT_ZOMBIE) { |
| 209 | /* |
| 210 | * If we were the last child thread and the leader has |
| 211 | * exited already, and the leader's parent ignores SIGCHLD, |
| 212 | * then we are the one who should release the leader. |
| 213 | */ |
| 214 | zap_leader = do_notify_parent(leader, leader->exit_signal); |
| 215 | if (zap_leader) |
| 216 | leader->exit_state = EXIT_DEAD; |
| 217 | } |
| 218 | |
| 219 | write_unlock_irq(&tasklist_lock); |
| 220 | seccomp_filter_release(p); |
| 221 | proc_flush_pid(thread_pid); |
| 222 | put_pid(thread_pid); |
| 223 | release_thread(p); |
| 224 | put_task_struct_rcu_user(p); |
| 225 | |
| 226 | p = leader; |
| 227 | if (unlikely(zap_leader)) |
| 228 | goto repeat; |
| 229 | } |
| 230 | |
| 231 | int rcuwait_wake_up(struct rcuwait *w) |
| 232 | { |
| 233 | int ret = 0; |
| 234 | struct task_struct *task; |
| 235 | |
| 236 | rcu_read_lock(); |
| 237 | |
| 238 | /* |
| 239 | * Order condition vs @task, such that everything prior to the load |
| 240 | * of @task is visible. This is the condition as to why the user called |
| 241 | * rcuwait_wake() in the first place. Pairs with set_current_state() |
| 242 | * barrier (A) in rcuwait_wait_event(). |
| 243 | * |
| 244 | * WAIT WAKE |
| 245 | * [S] tsk = current [S] cond = true |
| 246 | * MB (A) MB (B) |
| 247 | * [L] cond [L] tsk |
| 248 | */ |
| 249 | smp_mb(); /* (B) */ |
| 250 | |
| 251 | task = rcu_dereference(w->task); |
| 252 | if (task) |
| 253 | ret = wake_up_process(task); |
| 254 | rcu_read_unlock(); |
| 255 | |
| 256 | return ret; |
| 257 | } |
| 258 | EXPORT_SYMBOL_GPL(rcuwait_wake_up); |
| 259 | |
| 260 | /* |
| 261 | * Determine if a process group is "orphaned", according to the POSIX |
| 262 | * definition in 2.2.2.52. Orphaned process groups are not to be affected |
| 263 | * by terminal-generated stop signals. Newly orphaned process groups are |
| 264 | * to receive a SIGHUP and a SIGCONT. |
| 265 | * |
| 266 | * "I ask you, have you ever known what it is to be an orphan?" |
| 267 | */ |
| 268 | static int will_become_orphaned_pgrp(struct pid *pgrp, |
| 269 | struct task_struct *ignored_task) |
| 270 | { |
| 271 | struct task_struct *p; |
| 272 | |
| 273 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| 274 | if ((p == ignored_task) || |
| 275 | (p->exit_state && thread_group_empty(p)) || |
| 276 | is_global_init(p->real_parent)) |
| 277 | continue; |
| 278 | |
| 279 | if (task_pgrp(p->real_parent) != pgrp && |
| 280 | task_session(p->real_parent) == task_session(p)) |
| 281 | return 0; |
| 282 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| 283 | |
| 284 | return 1; |
| 285 | } |
| 286 | |
| 287 | int is_current_pgrp_orphaned(void) |
| 288 | { |
| 289 | int retval; |
| 290 | |
| 291 | read_lock(&tasklist_lock); |
| 292 | retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
| 293 | read_unlock(&tasklist_lock); |
| 294 | |
| 295 | return retval; |
| 296 | } |
| 297 | |
| 298 | static bool has_stopped_jobs(struct pid *pgrp) |
| 299 | { |
| 300 | struct task_struct *p; |
| 301 | |
| 302 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| 303 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
| 304 | return true; |
| 305 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| 306 | |
| 307 | return false; |
| 308 | } |
| 309 | |
| 310 | /* |
| 311 | * Check to see if any process groups have become orphaned as |
| 312 | * a result of our exiting, and if they have any stopped jobs, |
| 313 | * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| 314 | */ |
| 315 | static void |
| 316 | kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
| 317 | { |
| 318 | struct pid *pgrp = task_pgrp(tsk); |
| 319 | struct task_struct *ignored_task = tsk; |
| 320 | |
| 321 | if (!parent) |
| 322 | /* exit: our father is in a different pgrp than |
| 323 | * we are and we were the only connection outside. |
| 324 | */ |
| 325 | parent = tsk->real_parent; |
| 326 | else |
| 327 | /* reparent: our child is in a different pgrp than |
| 328 | * we are, and it was the only connection outside. |
| 329 | */ |
| 330 | ignored_task = NULL; |
| 331 | |
| 332 | if (task_pgrp(parent) != pgrp && |
| 333 | task_session(parent) == task_session(tsk) && |
| 334 | will_become_orphaned_pgrp(pgrp, ignored_task) && |
| 335 | has_stopped_jobs(pgrp)) { |
| 336 | __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
| 337 | __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
| 338 | } |
| 339 | } |
| 340 | |
| 341 | #ifdef CONFIG_MEMCG |
| 342 | /* |
| 343 | * A task is exiting. If it owned this mm, find a new owner for the mm. |
| 344 | */ |
| 345 | void mm_update_next_owner(struct mm_struct *mm) |
| 346 | { |
| 347 | struct task_struct *c, *g, *p = current; |
| 348 | |
| 349 | retry: |
| 350 | /* |
| 351 | * If the exiting or execing task is not the owner, it's |
| 352 | * someone else's problem. |
| 353 | */ |
| 354 | if (mm->owner != p) |
| 355 | return; |
| 356 | /* |
| 357 | * The current owner is exiting/execing and there are no other |
| 358 | * candidates. Do not leave the mm pointing to a possibly |
| 359 | * freed task structure. |
| 360 | */ |
| 361 | if (atomic_read(&mm->mm_users) <= 1) { |
| 362 | WRITE_ONCE(mm->owner, NULL); |
| 363 | return; |
| 364 | } |
| 365 | |
| 366 | read_lock(&tasklist_lock); |
| 367 | /* |
| 368 | * Search in the children |
| 369 | */ |
| 370 | list_for_each_entry(c, &p->children, sibling) { |
| 371 | if (c->mm == mm) |
| 372 | goto assign_new_owner; |
| 373 | } |
| 374 | |
| 375 | /* |
| 376 | * Search in the siblings |
| 377 | */ |
| 378 | list_for_each_entry(c, &p->real_parent->children, sibling) { |
| 379 | if (c->mm == mm) |
| 380 | goto assign_new_owner; |
| 381 | } |
| 382 | |
| 383 | /* |
| 384 | * Search through everything else, we should not get here often. |
| 385 | */ |
| 386 | for_each_process(g) { |
| 387 | if (g->flags & PF_KTHREAD) |
| 388 | continue; |
| 389 | for_each_thread(g, c) { |
| 390 | if (c->mm == mm) |
| 391 | goto assign_new_owner; |
| 392 | if (c->mm) |
| 393 | break; |
| 394 | } |
| 395 | } |
| 396 | read_unlock(&tasklist_lock); |
| 397 | /* |
| 398 | * We found no owner yet mm_users > 1: this implies that we are |
| 399 | * most likely racing with swapoff (try_to_unuse()) or /proc or |
| 400 | * ptrace or page migration (get_task_mm()). Mark owner as NULL. |
| 401 | */ |
| 402 | WRITE_ONCE(mm->owner, NULL); |
| 403 | return; |
| 404 | |
| 405 | assign_new_owner: |
| 406 | BUG_ON(c == p); |
| 407 | get_task_struct(c); |
| 408 | /* |
| 409 | * The task_lock protects c->mm from changing. |
| 410 | * We always want mm->owner->mm == mm |
| 411 | */ |
| 412 | task_lock(c); |
| 413 | /* |
| 414 | * Delay read_unlock() till we have the task_lock() |
| 415 | * to ensure that c does not slip away underneath us |
| 416 | */ |
| 417 | read_unlock(&tasklist_lock); |
| 418 | if (c->mm != mm) { |
| 419 | task_unlock(c); |
| 420 | put_task_struct(c); |
| 421 | goto retry; |
| 422 | } |
| 423 | WRITE_ONCE(mm->owner, c); |
| 424 | task_unlock(c); |
| 425 | put_task_struct(c); |
| 426 | } |
| 427 | #endif /* CONFIG_MEMCG */ |
| 428 | |
| 429 | /* |
| 430 | * Turn us into a lazy TLB process if we |
| 431 | * aren't already.. |
| 432 | */ |
| 433 | static void exit_mm(void) |
| 434 | { |
| 435 | struct mm_struct *mm = current->mm; |
| 436 | struct core_state *core_state; |
| 437 | |
| 438 | exit_mm_release(current, mm); |
| 439 | if (!mm) |
| 440 | return; |
| 441 | sync_mm_rss(mm); |
| 442 | /* |
| 443 | * Serialize with any possible pending coredump. |
| 444 | * We must hold mmap_lock around checking core_state |
| 445 | * and clearing tsk->mm. The core-inducing thread |
| 446 | * will increment ->nr_threads for each thread in the |
| 447 | * group with ->mm != NULL. |
| 448 | */ |
| 449 | mmap_read_lock(mm); |
| 450 | core_state = mm->core_state; |
| 451 | if (core_state) { |
| 452 | struct core_thread self; |
| 453 | |
| 454 | mmap_read_unlock(mm); |
| 455 | |
| 456 | self.task = current; |
| 457 | self.next = xchg(&core_state->dumper.next, &self); |
| 458 | /* |
| 459 | * Implies mb(), the result of xchg() must be visible |
| 460 | * to core_state->dumper. |
| 461 | */ |
| 462 | if (atomic_dec_and_test(&core_state->nr_threads)) |
| 463 | complete(&core_state->startup); |
| 464 | |
| 465 | for (;;) { |
| 466 | set_current_state(TASK_UNINTERRUPTIBLE); |
| 467 | if (!self.task) /* see coredump_finish() */ |
| 468 | break; |
| 469 | freezable_schedule(); |
| 470 | } |
| 471 | __set_current_state(TASK_RUNNING); |
| 472 | mmap_read_lock(mm); |
| 473 | } |
| 474 | mmgrab(mm); |
| 475 | BUG_ON(mm != current->active_mm); |
| 476 | /* more a memory barrier than a real lock */ |
| 477 | task_lock(current); |
| 478 | current->mm = NULL; |
| 479 | mmap_read_unlock(mm); |
| 480 | enter_lazy_tlb(mm, current); |
| 481 | task_unlock(current); |
| 482 | mm_update_next_owner(mm); |
| 483 | mmput(mm); |
| 484 | if (test_thread_flag(TIF_MEMDIE)) |
| 485 | exit_oom_victim(); |
| 486 | } |
| 487 | |
| 488 | static struct task_struct *find_alive_thread(struct task_struct *p) |
| 489 | { |
| 490 | struct task_struct *t; |
| 491 | |
| 492 | for_each_thread(p, t) { |
| 493 | if (!(t->flags & PF_EXITING)) |
| 494 | return t; |
| 495 | } |
| 496 | return NULL; |
| 497 | } |
| 498 | |
| 499 | static struct task_struct *find_child_reaper(struct task_struct *father, |
| 500 | struct list_head *dead) |
| 501 | __releases(&tasklist_lock) |
| 502 | __acquires(&tasklist_lock) |
| 503 | { |
| 504 | struct pid_namespace *pid_ns = task_active_pid_ns(father); |
| 505 | struct task_struct *reaper = pid_ns->child_reaper; |
| 506 | struct task_struct *p, *n; |
| 507 | |
| 508 | if (likely(reaper != father)) |
| 509 | return reaper; |
| 510 | |
| 511 | reaper = find_alive_thread(father); |
| 512 | if (reaper) { |
| 513 | pid_ns->child_reaper = reaper; |
| 514 | return reaper; |
| 515 | } |
| 516 | |
| 517 | write_unlock_irq(&tasklist_lock); |
| 518 | |
| 519 | list_for_each_entry_safe(p, n, dead, ptrace_entry) { |
| 520 | list_del_init(&p->ptrace_entry); |
| 521 | release_task(p); |
| 522 | } |
| 523 | |
| 524 | zap_pid_ns_processes(pid_ns); |
| 525 | write_lock_irq(&tasklist_lock); |
| 526 | |
| 527 | return father; |
| 528 | } |
| 529 | |
| 530 | /* |
| 531 | * When we die, we re-parent all our children, and try to: |
| 532 | * 1. give them to another thread in our thread group, if such a member exists |
| 533 | * 2. give it to the first ancestor process which prctl'd itself as a |
| 534 | * child_subreaper for its children (like a service manager) |
| 535 | * 3. give it to the init process (PID 1) in our pid namespace |
| 536 | */ |
| 537 | static struct task_struct *find_new_reaper(struct task_struct *father, |
| 538 | struct task_struct *child_reaper) |
| 539 | { |
| 540 | struct task_struct *thread, *reaper; |
| 541 | |
| 542 | thread = find_alive_thread(father); |
| 543 | if (thread) |
| 544 | return thread; |
| 545 | |
| 546 | if (father->signal->has_child_subreaper) { |
| 547 | unsigned int ns_level = task_pid(father)->level; |
| 548 | /* |
| 549 | * Find the first ->is_child_subreaper ancestor in our pid_ns. |
| 550 | * We can't check reaper != child_reaper to ensure we do not |
| 551 | * cross the namespaces, the exiting parent could be injected |
| 552 | * by setns() + fork(). |
| 553 | * We check pid->level, this is slightly more efficient than |
| 554 | * task_active_pid_ns(reaper) != task_active_pid_ns(father). |
| 555 | */ |
| 556 | for (reaper = father->real_parent; |
| 557 | task_pid(reaper)->level == ns_level; |
| 558 | reaper = reaper->real_parent) { |
| 559 | if (reaper == &init_task) |
| 560 | break; |
| 561 | if (!reaper->signal->is_child_subreaper) |
| 562 | continue; |
| 563 | thread = find_alive_thread(reaper); |
| 564 | if (thread) |
| 565 | return thread; |
| 566 | } |
| 567 | } |
| 568 | |
| 569 | return child_reaper; |
| 570 | } |
| 571 | |
| 572 | /* |
| 573 | * Any that need to be release_task'd are put on the @dead list. |
| 574 | */ |
| 575 | static void reparent_leader(struct task_struct *father, struct task_struct *p, |
| 576 | struct list_head *dead) |
| 577 | { |
| 578 | if (unlikely(p->exit_state == EXIT_DEAD)) |
| 579 | return; |
| 580 | |
| 581 | /* We don't want people slaying init. */ |
| 582 | p->exit_signal = SIGCHLD; |
| 583 | |
| 584 | /* If it has exited notify the new parent about this child's death. */ |
| 585 | if (!p->ptrace && |
| 586 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
| 587 | if (do_notify_parent(p, p->exit_signal)) { |
| 588 | p->exit_state = EXIT_DEAD; |
| 589 | list_add(&p->ptrace_entry, dead); |
| 590 | } |
| 591 | } |
| 592 | |
| 593 | kill_orphaned_pgrp(p, father); |
| 594 | } |
| 595 | |
| 596 | /* |
| 597 | * This does two things: |
| 598 | * |
| 599 | * A. Make init inherit all the child processes |
| 600 | * B. Check to see if any process groups have become orphaned |
| 601 | * as a result of our exiting, and if they have any stopped |
| 602 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| 603 | */ |
| 604 | static void forget_original_parent(struct task_struct *father, |
| 605 | struct list_head *dead) |
| 606 | { |
| 607 | struct task_struct *p, *t, *reaper; |
| 608 | |
| 609 | if (unlikely(!list_empty(&father->ptraced))) |
| 610 | exit_ptrace(father, dead); |
| 611 | |
| 612 | /* Can drop and reacquire tasklist_lock */ |
| 613 | reaper = find_child_reaper(father, dead); |
| 614 | if (list_empty(&father->children)) |
| 615 | return; |
| 616 | |
| 617 | reaper = find_new_reaper(father, reaper); |
| 618 | list_for_each_entry(p, &father->children, sibling) { |
| 619 | for_each_thread(p, t) { |
| 620 | RCU_INIT_POINTER(t->real_parent, reaper); |
| 621 | BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); |
| 622 | if (likely(!t->ptrace)) |
| 623 | t->parent = t->real_parent; |
| 624 | if (t->pdeath_signal) |
| 625 | group_send_sig_info(t->pdeath_signal, |
| 626 | SEND_SIG_NOINFO, t, |
| 627 | PIDTYPE_TGID); |
| 628 | } |
| 629 | /* |
| 630 | * If this is a threaded reparent there is no need to |
| 631 | * notify anyone anything has happened. |
| 632 | */ |
| 633 | if (!same_thread_group(reaper, father)) |
| 634 | reparent_leader(father, p, dead); |
| 635 | } |
| 636 | list_splice_tail_init(&father->children, &reaper->children); |
| 637 | } |
| 638 | |
| 639 | /* |
| 640 | * Send signals to all our closest relatives so that they know |
| 641 | * to properly mourn us.. |
| 642 | */ |
| 643 | static void exit_notify(struct task_struct *tsk, int group_dead) |
| 644 | { |
| 645 | bool autoreap; |
| 646 | struct task_struct *p, *n; |
| 647 | LIST_HEAD(dead); |
| 648 | |
| 649 | write_lock_irq(&tasklist_lock); |
| 650 | forget_original_parent(tsk, &dead); |
| 651 | |
| 652 | if (group_dead) |
| 653 | kill_orphaned_pgrp(tsk->group_leader, NULL); |
| 654 | |
| 655 | tsk->exit_state = EXIT_ZOMBIE; |
| 656 | if (unlikely(tsk->ptrace)) { |
| 657 | int sig = thread_group_leader(tsk) && |
| 658 | thread_group_empty(tsk) && |
| 659 | !ptrace_reparented(tsk) ? |
| 660 | tsk->exit_signal : SIGCHLD; |
| 661 | autoreap = do_notify_parent(tsk, sig); |
| 662 | } else if (thread_group_leader(tsk)) { |
| 663 | autoreap = thread_group_empty(tsk) && |
| 664 | do_notify_parent(tsk, tsk->exit_signal); |
| 665 | } else { |
| 666 | autoreap = true; |
| 667 | } |
| 668 | |
| 669 | if (autoreap) { |
| 670 | tsk->exit_state = EXIT_DEAD; |
| 671 | list_add(&tsk->ptrace_entry, &dead); |
| 672 | } |
| 673 | |
| 674 | /* mt-exec, de_thread() is waiting for group leader */ |
| 675 | if (unlikely(tsk->signal->notify_count < 0)) |
| 676 | wake_up_process(tsk->signal->group_exit_task); |
| 677 | write_unlock_irq(&tasklist_lock); |
| 678 | |
| 679 | list_for_each_entry_safe(p, n, &dead, ptrace_entry) { |
| 680 | list_del_init(&p->ptrace_entry); |
| 681 | release_task(p); |
| 682 | } |
| 683 | } |
| 684 | |
| 685 | #ifdef CONFIG_DEBUG_STACK_USAGE |
| 686 | static void check_stack_usage(void) |
| 687 | { |
| 688 | static DEFINE_SPINLOCK(low_water_lock); |
| 689 | static int lowest_to_date = THREAD_SIZE; |
| 690 | unsigned long free; |
| 691 | |
| 692 | free = stack_not_used(current); |
| 693 | |
| 694 | if (free >= lowest_to_date) |
| 695 | return; |
| 696 | |
| 697 | spin_lock(&low_water_lock); |
| 698 | if (free < lowest_to_date) { |
| 699 | pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", |
| 700 | current->comm, task_pid_nr(current), free); |
| 701 | lowest_to_date = free; |
| 702 | } |
| 703 | spin_unlock(&low_water_lock); |
| 704 | } |
| 705 | #else |
| 706 | static inline void check_stack_usage(void) {} |
| 707 | #endif |
| 708 | |
| 709 | void __noreturn do_exit(long code) |
| 710 | { |
| 711 | struct task_struct *tsk = current; |
| 712 | int group_dead; |
| 713 | |
| 714 | /* |
| 715 | * We can get here from a kernel oops, sometimes with preemption off. |
| 716 | * Start by checking for critical errors. |
| 717 | * Then fix up important state like USER_DS and preemption. |
| 718 | * Then do everything else. |
| 719 | */ |
| 720 | |
| 721 | WARN_ON(blk_needs_flush_plug(tsk)); |
| 722 | |
| 723 | if (unlikely(in_interrupt())) |
| 724 | panic("Aiee, killing interrupt handler!"); |
| 725 | if (unlikely(!tsk->pid)) |
| 726 | panic("Attempted to kill the idle task!"); |
| 727 | |
| 728 | /* |
| 729 | * If do_exit is called because this processes oopsed, it's possible |
| 730 | * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before |
| 731 | * continuing. Amongst other possible reasons, this is to prevent |
| 732 | * mm_release()->clear_child_tid() from writing to a user-controlled |
| 733 | * kernel address. |
| 734 | */ |
| 735 | set_fs(USER_DS); |
| 736 | |
| 737 | if (unlikely(in_atomic())) { |
| 738 | pr_info("note: %s[%d] exited with preempt_count %d\n", |
| 739 | current->comm, task_pid_nr(current), |
| 740 | preempt_count()); |
| 741 | preempt_count_set(PREEMPT_ENABLED); |
| 742 | } |
| 743 | |
| 744 | profile_task_exit(tsk); |
| 745 | kcov_task_exit(tsk); |
| 746 | |
| 747 | ptrace_event(PTRACE_EVENT_EXIT, code); |
| 748 | |
| 749 | validate_creds_for_do_exit(tsk); |
| 750 | |
| 751 | /* |
| 752 | * We're taking recursive faults here in do_exit. Safest is to just |
| 753 | * leave this task alone and wait for reboot. |
| 754 | */ |
| 755 | if (unlikely(tsk->flags & PF_EXITING)) { |
| 756 | pr_alert("Fixing recursive fault but reboot is needed!\n"); |
| 757 | futex_exit_recursive(tsk); |
| 758 | set_current_state(TASK_UNINTERRUPTIBLE); |
| 759 | schedule(); |
| 760 | } |
| 761 | |
| 762 | exit_signals(tsk); /* sets PF_EXITING */ |
| 763 | |
| 764 | /* sync mm's RSS info before statistics gathering */ |
| 765 | if (tsk->mm) |
| 766 | sync_mm_rss(tsk->mm); |
| 767 | acct_update_integrals(tsk); |
| 768 | group_dead = atomic_dec_and_test(&tsk->signal->live); |
| 769 | if (group_dead) { |
| 770 | /* |
| 771 | * If the last thread of global init has exited, panic |
| 772 | * immediately to get a useable coredump. |
| 773 | */ |
| 774 | if (unlikely(is_global_init(tsk))) |
| 775 | panic("Attempted to kill init! exitcode=0x%08x\n", |
| 776 | tsk->signal->group_exit_code ?: (int)code); |
| 777 | |
| 778 | #ifdef CONFIG_POSIX_TIMERS |
| 779 | hrtimer_cancel(&tsk->signal->real_timer); |
| 780 | exit_itimers(tsk->signal); |
| 781 | #endif |
| 782 | if (tsk->mm) |
| 783 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); |
| 784 | } |
| 785 | acct_collect(code, group_dead); |
| 786 | if (group_dead) |
| 787 | tty_audit_exit(); |
| 788 | audit_free(tsk); |
| 789 | |
| 790 | tsk->exit_code = code; |
| 791 | taskstats_exit(tsk, group_dead); |
| 792 | |
| 793 | exit_mm(); |
| 794 | |
| 795 | if (group_dead) |
| 796 | acct_process(); |
| 797 | trace_sched_process_exit(tsk); |
| 798 | |
| 799 | exit_sem(tsk); |
| 800 | exit_shm(tsk); |
| 801 | exit_files(tsk); |
| 802 | exit_fs(tsk); |
| 803 | if (group_dead) |
| 804 | disassociate_ctty(1); |
| 805 | exit_task_namespaces(tsk); |
| 806 | exit_task_work(tsk); |
| 807 | exit_thread(tsk); |
| 808 | |
| 809 | /* |
| 810 | * Flush inherited counters to the parent - before the parent |
| 811 | * gets woken up by child-exit notifications. |
| 812 | * |
| 813 | * because of cgroup mode, must be called before cgroup_exit() |
| 814 | */ |
| 815 | perf_event_exit_task(tsk); |
| 816 | |
| 817 | sched_autogroup_exit_task(tsk); |
| 818 | cgroup_exit(tsk); |
| 819 | |
| 820 | /* |
| 821 | * FIXME: do that only when needed, using sched_exit tracepoint |
| 822 | */ |
| 823 | flush_ptrace_hw_breakpoint(tsk); |
| 824 | |
| 825 | exit_tasks_rcu_start(); |
| 826 | exit_notify(tsk, group_dead); |
| 827 | proc_exit_connector(tsk); |
| 828 | mpol_put_task_policy(tsk); |
| 829 | #ifdef CONFIG_FUTEX |
| 830 | if (unlikely(current->pi_state_cache)) |
| 831 | kfree(current->pi_state_cache); |
| 832 | #endif |
| 833 | /* |
| 834 | * Make sure we are holding no locks: |
| 835 | */ |
| 836 | debug_check_no_locks_held(); |
| 837 | |
| 838 | if (tsk->io_context) |
| 839 | exit_io_context(tsk); |
| 840 | |
| 841 | if (tsk->splice_pipe) |
| 842 | free_pipe_info(tsk->splice_pipe); |
| 843 | |
| 844 | if (tsk->task_frag.page) |
| 845 | put_page(tsk->task_frag.page); |
| 846 | |
| 847 | validate_creds_for_do_exit(tsk); |
| 848 | |
| 849 | check_stack_usage(); |
| 850 | preempt_disable(); |
| 851 | if (tsk->nr_dirtied) |
| 852 | __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
| 853 | exit_rcu(); |
| 854 | exit_tasks_rcu_finish(); |
| 855 | |
| 856 | lockdep_free_task(tsk); |
| 857 | do_task_dead(); |
| 858 | } |
| 859 | EXPORT_SYMBOL_GPL(do_exit); |
| 860 | |
| 861 | void complete_and_exit(struct completion *comp, long code) |
| 862 | { |
| 863 | if (comp) |
| 864 | complete(comp); |
| 865 | |
| 866 | do_exit(code); |
| 867 | } |
| 868 | EXPORT_SYMBOL(complete_and_exit); |
| 869 | |
| 870 | SYSCALL_DEFINE1(exit, int, error_code) |
| 871 | { |
| 872 | do_exit((error_code&0xff)<<8); |
| 873 | } |
| 874 | |
| 875 | /* |
| 876 | * Take down every thread in the group. This is called by fatal signals |
| 877 | * as well as by sys_exit_group (below). |
| 878 | */ |
| 879 | void |
| 880 | do_group_exit(int exit_code) |
| 881 | { |
| 882 | struct signal_struct *sig = current->signal; |
| 883 | |
| 884 | BUG_ON(exit_code & 0x80); /* core dumps don't get here */ |
| 885 | |
| 886 | if (signal_group_exit(sig)) |
| 887 | exit_code = sig->group_exit_code; |
| 888 | else if (!thread_group_empty(current)) { |
| 889 | struct sighand_struct *const sighand = current->sighand; |
| 890 | |
| 891 | spin_lock_irq(&sighand->siglock); |
| 892 | if (signal_group_exit(sig)) |
| 893 | /* Another thread got here before we took the lock. */ |
| 894 | exit_code = sig->group_exit_code; |
| 895 | else { |
| 896 | sig->group_exit_code = exit_code; |
| 897 | sig->flags = SIGNAL_GROUP_EXIT; |
| 898 | zap_other_threads(current); |
| 899 | } |
| 900 | spin_unlock_irq(&sighand->siglock); |
| 901 | } |
| 902 | |
| 903 | do_exit(exit_code); |
| 904 | /* NOTREACHED */ |
| 905 | } |
| 906 | |
| 907 | /* |
| 908 | * this kills every thread in the thread group. Note that any externally |
| 909 | * wait4()-ing process will get the correct exit code - even if this |
| 910 | * thread is not the thread group leader. |
| 911 | */ |
| 912 | SYSCALL_DEFINE1(exit_group, int, error_code) |
| 913 | { |
| 914 | do_group_exit((error_code & 0xff) << 8); |
| 915 | /* NOTREACHED */ |
| 916 | return 0; |
| 917 | } |
| 918 | |
| 919 | struct waitid_info { |
| 920 | pid_t pid; |
| 921 | uid_t uid; |
| 922 | int status; |
| 923 | int cause; |
| 924 | }; |
| 925 | |
| 926 | struct wait_opts { |
| 927 | enum pid_type wo_type; |
| 928 | int wo_flags; |
| 929 | struct pid *wo_pid; |
| 930 | |
| 931 | struct waitid_info *wo_info; |
| 932 | int wo_stat; |
| 933 | struct rusage *wo_rusage; |
| 934 | |
| 935 | wait_queue_entry_t child_wait; |
| 936 | int notask_error; |
| 937 | }; |
| 938 | |
| 939 | static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
| 940 | { |
| 941 | return wo->wo_type == PIDTYPE_MAX || |
| 942 | task_pid_type(p, wo->wo_type) == wo->wo_pid; |
| 943 | } |
| 944 | |
| 945 | static int |
| 946 | eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) |
| 947 | { |
| 948 | if (!eligible_pid(wo, p)) |
| 949 | return 0; |
| 950 | |
| 951 | /* |
| 952 | * Wait for all children (clone and not) if __WALL is set or |
| 953 | * if it is traced by us. |
| 954 | */ |
| 955 | if (ptrace || (wo->wo_flags & __WALL)) |
| 956 | return 1; |
| 957 | |
| 958 | /* |
| 959 | * Otherwise, wait for clone children *only* if __WCLONE is set; |
| 960 | * otherwise, wait for non-clone children *only*. |
| 961 | * |
| 962 | * Note: a "clone" child here is one that reports to its parent |
| 963 | * using a signal other than SIGCHLD, or a non-leader thread which |
| 964 | * we can only see if it is traced by us. |
| 965 | */ |
| 966 | if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
| 967 | return 0; |
| 968 | |
| 969 | return 1; |
| 970 | } |
| 971 | |
| 972 | /* |
| 973 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
| 974 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
| 975 | * the lock and this task is uninteresting. If we return nonzero, we have |
| 976 | * released the lock and the system call should return. |
| 977 | */ |
| 978 | static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
| 979 | { |
| 980 | int state, status; |
| 981 | pid_t pid = task_pid_vnr(p); |
| 982 | uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| 983 | struct waitid_info *infop; |
| 984 | |
| 985 | if (!likely(wo->wo_flags & WEXITED)) |
| 986 | return 0; |
| 987 | |
| 988 | if (unlikely(wo->wo_flags & WNOWAIT)) { |
| 989 | status = p->exit_code; |
| 990 | get_task_struct(p); |
| 991 | read_unlock(&tasklist_lock); |
| 992 | sched_annotate_sleep(); |
| 993 | if (wo->wo_rusage) |
| 994 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 995 | put_task_struct(p); |
| 996 | goto out_info; |
| 997 | } |
| 998 | /* |
| 999 | * Move the task's state to DEAD/TRACE, only one thread can do this. |
| 1000 | */ |
| 1001 | state = (ptrace_reparented(p) && thread_group_leader(p)) ? |
| 1002 | EXIT_TRACE : EXIT_DEAD; |
| 1003 | if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
| 1004 | return 0; |
| 1005 | /* |
| 1006 | * We own this thread, nobody else can reap it. |
| 1007 | */ |
| 1008 | read_unlock(&tasklist_lock); |
| 1009 | sched_annotate_sleep(); |
| 1010 | |
| 1011 | /* |
| 1012 | * Check thread_group_leader() to exclude the traced sub-threads. |
| 1013 | */ |
| 1014 | if (state == EXIT_DEAD && thread_group_leader(p)) { |
| 1015 | struct signal_struct *sig = p->signal; |
| 1016 | struct signal_struct *psig = current->signal; |
| 1017 | unsigned long maxrss; |
| 1018 | u64 tgutime, tgstime; |
| 1019 | |
| 1020 | /* |
| 1021 | * The resource counters for the group leader are in its |
| 1022 | * own task_struct. Those for dead threads in the group |
| 1023 | * are in its signal_struct, as are those for the child |
| 1024 | * processes it has previously reaped. All these |
| 1025 | * accumulate in the parent's signal_struct c* fields. |
| 1026 | * |
| 1027 | * We don't bother to take a lock here to protect these |
| 1028 | * p->signal fields because the whole thread group is dead |
| 1029 | * and nobody can change them. |
| 1030 | * |
| 1031 | * psig->stats_lock also protects us from our sub-theads |
| 1032 | * which can reap other children at the same time. Until |
| 1033 | * we change k_getrusage()-like users to rely on this lock |
| 1034 | * we have to take ->siglock as well. |
| 1035 | * |
| 1036 | * We use thread_group_cputime_adjusted() to get times for |
| 1037 | * the thread group, which consolidates times for all threads |
| 1038 | * in the group including the group leader. |
| 1039 | */ |
| 1040 | thread_group_cputime_adjusted(p, &tgutime, &tgstime); |
| 1041 | spin_lock_irq(¤t->sighand->siglock); |
| 1042 | write_seqlock(&psig->stats_lock); |
| 1043 | psig->cutime += tgutime + sig->cutime; |
| 1044 | psig->cstime += tgstime + sig->cstime; |
| 1045 | psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; |
| 1046 | psig->cmin_flt += |
| 1047 | p->min_flt + sig->min_flt + sig->cmin_flt; |
| 1048 | psig->cmaj_flt += |
| 1049 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
| 1050 | psig->cnvcsw += |
| 1051 | p->nvcsw + sig->nvcsw + sig->cnvcsw; |
| 1052 | psig->cnivcsw += |
| 1053 | p->nivcsw + sig->nivcsw + sig->cnivcsw; |
| 1054 | psig->cinblock += |
| 1055 | task_io_get_inblock(p) + |
| 1056 | sig->inblock + sig->cinblock; |
| 1057 | psig->coublock += |
| 1058 | task_io_get_oublock(p) + |
| 1059 | sig->oublock + sig->coublock; |
| 1060 | maxrss = max(sig->maxrss, sig->cmaxrss); |
| 1061 | if (psig->cmaxrss < maxrss) |
| 1062 | psig->cmaxrss = maxrss; |
| 1063 | task_io_accounting_add(&psig->ioac, &p->ioac); |
| 1064 | task_io_accounting_add(&psig->ioac, &sig->ioac); |
| 1065 | write_sequnlock(&psig->stats_lock); |
| 1066 | spin_unlock_irq(¤t->sighand->siglock); |
| 1067 | } |
| 1068 | |
| 1069 | if (wo->wo_rusage) |
| 1070 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1071 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
| 1072 | ? p->signal->group_exit_code : p->exit_code; |
| 1073 | wo->wo_stat = status; |
| 1074 | |
| 1075 | if (state == EXIT_TRACE) { |
| 1076 | write_lock_irq(&tasklist_lock); |
| 1077 | /* We dropped tasklist, ptracer could die and untrace */ |
| 1078 | ptrace_unlink(p); |
| 1079 | |
| 1080 | /* If parent wants a zombie, don't release it now */ |
| 1081 | state = EXIT_ZOMBIE; |
| 1082 | if (do_notify_parent(p, p->exit_signal)) |
| 1083 | state = EXIT_DEAD; |
| 1084 | p->exit_state = state; |
| 1085 | write_unlock_irq(&tasklist_lock); |
| 1086 | } |
| 1087 | if (state == EXIT_DEAD) |
| 1088 | release_task(p); |
| 1089 | |
| 1090 | out_info: |
| 1091 | infop = wo->wo_info; |
| 1092 | if (infop) { |
| 1093 | if ((status & 0x7f) == 0) { |
| 1094 | infop->cause = CLD_EXITED; |
| 1095 | infop->status = status >> 8; |
| 1096 | } else { |
| 1097 | infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
| 1098 | infop->status = status & 0x7f; |
| 1099 | } |
| 1100 | infop->pid = pid; |
| 1101 | infop->uid = uid; |
| 1102 | } |
| 1103 | |
| 1104 | return pid; |
| 1105 | } |
| 1106 | |
| 1107 | static int *task_stopped_code(struct task_struct *p, bool ptrace) |
| 1108 | { |
| 1109 | if (ptrace) { |
| 1110 | if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) |
| 1111 | return &p->exit_code; |
| 1112 | } else { |
| 1113 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
| 1114 | return &p->signal->group_exit_code; |
| 1115 | } |
| 1116 | return NULL; |
| 1117 | } |
| 1118 | |
| 1119 | /** |
| 1120 | * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
| 1121 | * @wo: wait options |
| 1122 | * @ptrace: is the wait for ptrace |
| 1123 | * @p: task to wait for |
| 1124 | * |
| 1125 | * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
| 1126 | * |
| 1127 | * CONTEXT: |
| 1128 | * read_lock(&tasklist_lock), which is released if return value is |
| 1129 | * non-zero. Also, grabs and releases @p->sighand->siglock. |
| 1130 | * |
| 1131 | * RETURNS: |
| 1132 | * 0 if wait condition didn't exist and search for other wait conditions |
| 1133 | * should continue. Non-zero return, -errno on failure and @p's pid on |
| 1134 | * success, implies that tasklist_lock is released and wait condition |
| 1135 | * search should terminate. |
| 1136 | */ |
| 1137 | static int wait_task_stopped(struct wait_opts *wo, |
| 1138 | int ptrace, struct task_struct *p) |
| 1139 | { |
| 1140 | struct waitid_info *infop; |
| 1141 | int exit_code, *p_code, why; |
| 1142 | uid_t uid = 0; /* unneeded, required by compiler */ |
| 1143 | pid_t pid; |
| 1144 | |
| 1145 | /* |
| 1146 | * Traditionally we see ptrace'd stopped tasks regardless of options. |
| 1147 | */ |
| 1148 | if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
| 1149 | return 0; |
| 1150 | |
| 1151 | if (!task_stopped_code(p, ptrace)) |
| 1152 | return 0; |
| 1153 | |
| 1154 | exit_code = 0; |
| 1155 | spin_lock_irq(&p->sighand->siglock); |
| 1156 | |
| 1157 | p_code = task_stopped_code(p, ptrace); |
| 1158 | if (unlikely(!p_code)) |
| 1159 | goto unlock_sig; |
| 1160 | |
| 1161 | exit_code = *p_code; |
| 1162 | if (!exit_code) |
| 1163 | goto unlock_sig; |
| 1164 | |
| 1165 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
| 1166 | *p_code = 0; |
| 1167 | |
| 1168 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| 1169 | unlock_sig: |
| 1170 | spin_unlock_irq(&p->sighand->siglock); |
| 1171 | if (!exit_code) |
| 1172 | return 0; |
| 1173 | |
| 1174 | /* |
| 1175 | * Now we are pretty sure this task is interesting. |
| 1176 | * Make sure it doesn't get reaped out from under us while we |
| 1177 | * give up the lock and then examine it below. We don't want to |
| 1178 | * keep holding onto the tasklist_lock while we call getrusage and |
| 1179 | * possibly take page faults for user memory. |
| 1180 | */ |
| 1181 | get_task_struct(p); |
| 1182 | pid = task_pid_vnr(p); |
| 1183 | why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
| 1184 | read_unlock(&tasklist_lock); |
| 1185 | sched_annotate_sleep(); |
| 1186 | if (wo->wo_rusage) |
| 1187 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1188 | put_task_struct(p); |
| 1189 | |
| 1190 | if (likely(!(wo->wo_flags & WNOWAIT))) |
| 1191 | wo->wo_stat = (exit_code << 8) | 0x7f; |
| 1192 | |
| 1193 | infop = wo->wo_info; |
| 1194 | if (infop) { |
| 1195 | infop->cause = why; |
| 1196 | infop->status = exit_code; |
| 1197 | infop->pid = pid; |
| 1198 | infop->uid = uid; |
| 1199 | } |
| 1200 | return pid; |
| 1201 | } |
| 1202 | |
| 1203 | /* |
| 1204 | * Handle do_wait work for one task in a live, non-stopped state. |
| 1205 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
| 1206 | * the lock and this task is uninteresting. If we return nonzero, we have |
| 1207 | * released the lock and the system call should return. |
| 1208 | */ |
| 1209 | static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
| 1210 | { |
| 1211 | struct waitid_info *infop; |
| 1212 | pid_t pid; |
| 1213 | uid_t uid; |
| 1214 | |
| 1215 | if (!unlikely(wo->wo_flags & WCONTINUED)) |
| 1216 | return 0; |
| 1217 | |
| 1218 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
| 1219 | return 0; |
| 1220 | |
| 1221 | spin_lock_irq(&p->sighand->siglock); |
| 1222 | /* Re-check with the lock held. */ |
| 1223 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
| 1224 | spin_unlock_irq(&p->sighand->siglock); |
| 1225 | return 0; |
| 1226 | } |
| 1227 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
| 1228 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
| 1229 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| 1230 | spin_unlock_irq(&p->sighand->siglock); |
| 1231 | |
| 1232 | pid = task_pid_vnr(p); |
| 1233 | get_task_struct(p); |
| 1234 | read_unlock(&tasklist_lock); |
| 1235 | sched_annotate_sleep(); |
| 1236 | if (wo->wo_rusage) |
| 1237 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1238 | put_task_struct(p); |
| 1239 | |
| 1240 | infop = wo->wo_info; |
| 1241 | if (!infop) { |
| 1242 | wo->wo_stat = 0xffff; |
| 1243 | } else { |
| 1244 | infop->cause = CLD_CONTINUED; |
| 1245 | infop->pid = pid; |
| 1246 | infop->uid = uid; |
| 1247 | infop->status = SIGCONT; |
| 1248 | } |
| 1249 | return pid; |
| 1250 | } |
| 1251 | |
| 1252 | /* |
| 1253 | * Consider @p for a wait by @parent. |
| 1254 | * |
| 1255 | * -ECHILD should be in ->notask_error before the first call. |
| 1256 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
| 1257 | * Returns zero if the search for a child should continue; |
| 1258 | * then ->notask_error is 0 if @p is an eligible child, |
| 1259 | * or still -ECHILD. |
| 1260 | */ |
| 1261 | static int wait_consider_task(struct wait_opts *wo, int ptrace, |
| 1262 | struct task_struct *p) |
| 1263 | { |
| 1264 | /* |
| 1265 | * We can race with wait_task_zombie() from another thread. |
| 1266 | * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition |
| 1267 | * can't confuse the checks below. |
| 1268 | */ |
| 1269 | int exit_state = READ_ONCE(p->exit_state); |
| 1270 | int ret; |
| 1271 | |
| 1272 | if (unlikely(exit_state == EXIT_DEAD)) |
| 1273 | return 0; |
| 1274 | |
| 1275 | ret = eligible_child(wo, ptrace, p); |
| 1276 | if (!ret) |
| 1277 | return ret; |
| 1278 | |
| 1279 | if (unlikely(exit_state == EXIT_TRACE)) { |
| 1280 | /* |
| 1281 | * ptrace == 0 means we are the natural parent. In this case |
| 1282 | * we should clear notask_error, debugger will notify us. |
| 1283 | */ |
| 1284 | if (likely(!ptrace)) |
| 1285 | wo->notask_error = 0; |
| 1286 | return 0; |
| 1287 | } |
| 1288 | |
| 1289 | if (likely(!ptrace) && unlikely(p->ptrace)) { |
| 1290 | /* |
| 1291 | * If it is traced by its real parent's group, just pretend |
| 1292 | * the caller is ptrace_do_wait() and reap this child if it |
| 1293 | * is zombie. |
| 1294 | * |
| 1295 | * This also hides group stop state from real parent; otherwise |
| 1296 | * a single stop can be reported twice as group and ptrace stop. |
| 1297 | * If a ptracer wants to distinguish these two events for its |
| 1298 | * own children it should create a separate process which takes |
| 1299 | * the role of real parent. |
| 1300 | */ |
| 1301 | if (!ptrace_reparented(p)) |
| 1302 | ptrace = 1; |
| 1303 | } |
| 1304 | |
| 1305 | /* slay zombie? */ |
| 1306 | if (exit_state == EXIT_ZOMBIE) { |
| 1307 | /* we don't reap group leaders with subthreads */ |
| 1308 | if (!delay_group_leader(p)) { |
| 1309 | /* |
| 1310 | * A zombie ptracee is only visible to its ptracer. |
| 1311 | * Notification and reaping will be cascaded to the |
| 1312 | * real parent when the ptracer detaches. |
| 1313 | */ |
| 1314 | if (unlikely(ptrace) || likely(!p->ptrace)) |
| 1315 | return wait_task_zombie(wo, p); |
| 1316 | } |
| 1317 | |
| 1318 | /* |
| 1319 | * Allow access to stopped/continued state via zombie by |
| 1320 | * falling through. Clearing of notask_error is complex. |
| 1321 | * |
| 1322 | * When !@ptrace: |
| 1323 | * |
| 1324 | * If WEXITED is set, notask_error should naturally be |
| 1325 | * cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
| 1326 | * so, if there are live subthreads, there are events to |
| 1327 | * wait for. If all subthreads are dead, it's still safe |
| 1328 | * to clear - this function will be called again in finite |
| 1329 | * amount time once all the subthreads are released and |
| 1330 | * will then return without clearing. |
| 1331 | * |
| 1332 | * When @ptrace: |
| 1333 | * |
| 1334 | * Stopped state is per-task and thus can't change once the |
| 1335 | * target task dies. Only continued and exited can happen. |
| 1336 | * Clear notask_error if WCONTINUED | WEXITED. |
| 1337 | */ |
| 1338 | if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
| 1339 | wo->notask_error = 0; |
| 1340 | } else { |
| 1341 | /* |
| 1342 | * @p is alive and it's gonna stop, continue or exit, so |
| 1343 | * there always is something to wait for. |
| 1344 | */ |
| 1345 | wo->notask_error = 0; |
| 1346 | } |
| 1347 | |
| 1348 | /* |
| 1349 | * Wait for stopped. Depending on @ptrace, different stopped state |
| 1350 | * is used and the two don't interact with each other. |
| 1351 | */ |
| 1352 | ret = wait_task_stopped(wo, ptrace, p); |
| 1353 | if (ret) |
| 1354 | return ret; |
| 1355 | |
| 1356 | /* |
| 1357 | * Wait for continued. There's only one continued state and the |
| 1358 | * ptracer can consume it which can confuse the real parent. Don't |
| 1359 | * use WCONTINUED from ptracer. You don't need or want it. |
| 1360 | */ |
| 1361 | return wait_task_continued(wo, p); |
| 1362 | } |
| 1363 | |
| 1364 | /* |
| 1365 | * Do the work of do_wait() for one thread in the group, @tsk. |
| 1366 | * |
| 1367 | * -ECHILD should be in ->notask_error before the first call. |
| 1368 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
| 1369 | * Returns zero if the search for a child should continue; then |
| 1370 | * ->notask_error is 0 if there were any eligible children, |
| 1371 | * or still -ECHILD. |
| 1372 | */ |
| 1373 | static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
| 1374 | { |
| 1375 | struct task_struct *p; |
| 1376 | |
| 1377 | list_for_each_entry(p, &tsk->children, sibling) { |
| 1378 | int ret = wait_consider_task(wo, 0, p); |
| 1379 | |
| 1380 | if (ret) |
| 1381 | return ret; |
| 1382 | } |
| 1383 | |
| 1384 | return 0; |
| 1385 | } |
| 1386 | |
| 1387 | static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
| 1388 | { |
| 1389 | struct task_struct *p; |
| 1390 | |
| 1391 | list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
| 1392 | int ret = wait_consider_task(wo, 1, p); |
| 1393 | |
| 1394 | if (ret) |
| 1395 | return ret; |
| 1396 | } |
| 1397 | |
| 1398 | return 0; |
| 1399 | } |
| 1400 | |
| 1401 | static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, |
| 1402 | int sync, void *key) |
| 1403 | { |
| 1404 | struct wait_opts *wo = container_of(wait, struct wait_opts, |
| 1405 | child_wait); |
| 1406 | struct task_struct *p = key; |
| 1407 | |
| 1408 | if (!eligible_pid(wo, p)) |
| 1409 | return 0; |
| 1410 | |
| 1411 | if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) |
| 1412 | return 0; |
| 1413 | |
| 1414 | return default_wake_function(wait, mode, sync, key); |
| 1415 | } |
| 1416 | |
| 1417 | void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
| 1418 | { |
| 1419 | __wake_up_sync_key(&parent->signal->wait_chldexit, |
| 1420 | TASK_INTERRUPTIBLE, p); |
| 1421 | } |
| 1422 | |
| 1423 | static long do_wait(struct wait_opts *wo) |
| 1424 | { |
| 1425 | struct task_struct *tsk; |
| 1426 | int retval; |
| 1427 | |
| 1428 | trace_sched_process_wait(wo->wo_pid); |
| 1429 | |
| 1430 | init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); |
| 1431 | wo->child_wait.private = current; |
| 1432 | add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| 1433 | repeat: |
| 1434 | /* |
| 1435 | * If there is nothing that can match our criteria, just get out. |
| 1436 | * We will clear ->notask_error to zero if we see any child that |
| 1437 | * might later match our criteria, even if we are not able to reap |
| 1438 | * it yet. |
| 1439 | */ |
| 1440 | wo->notask_error = -ECHILD; |
| 1441 | if ((wo->wo_type < PIDTYPE_MAX) && |
| 1442 | (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) |
| 1443 | goto notask; |
| 1444 | |
| 1445 | set_current_state(TASK_INTERRUPTIBLE); |
| 1446 | read_lock(&tasklist_lock); |
| 1447 | tsk = current; |
| 1448 | do { |
| 1449 | retval = do_wait_thread(wo, tsk); |
| 1450 | if (retval) |
| 1451 | goto end; |
| 1452 | |
| 1453 | retval = ptrace_do_wait(wo, tsk); |
| 1454 | if (retval) |
| 1455 | goto end; |
| 1456 | |
| 1457 | if (wo->wo_flags & __WNOTHREAD) |
| 1458 | break; |
| 1459 | } while_each_thread(current, tsk); |
| 1460 | read_unlock(&tasklist_lock); |
| 1461 | |
| 1462 | notask: |
| 1463 | retval = wo->notask_error; |
| 1464 | if (!retval && !(wo->wo_flags & WNOHANG)) { |
| 1465 | retval = -ERESTARTSYS; |
| 1466 | if (!signal_pending(current)) { |
| 1467 | schedule(); |
| 1468 | goto repeat; |
| 1469 | } |
| 1470 | } |
| 1471 | end: |
| 1472 | __set_current_state(TASK_RUNNING); |
| 1473 | remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| 1474 | return retval; |
| 1475 | } |
| 1476 | |
| 1477 | static struct pid *pidfd_get_pid(unsigned int fd) |
| 1478 | { |
| 1479 | struct fd f; |
| 1480 | struct pid *pid; |
| 1481 | |
| 1482 | f = fdget(fd); |
| 1483 | if (!f.file) |
| 1484 | return ERR_PTR(-EBADF); |
| 1485 | |
| 1486 | pid = pidfd_pid(f.file); |
| 1487 | if (!IS_ERR(pid)) |
| 1488 | get_pid(pid); |
| 1489 | |
| 1490 | fdput(f); |
| 1491 | return pid; |
| 1492 | } |
| 1493 | |
| 1494 | static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, |
| 1495 | int options, struct rusage *ru) |
| 1496 | { |
| 1497 | struct wait_opts wo; |
| 1498 | struct pid *pid = NULL; |
| 1499 | enum pid_type type; |
| 1500 | long ret; |
| 1501 | |
| 1502 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| |
| 1503 | __WNOTHREAD|__WCLONE|__WALL)) |
| 1504 | return -EINVAL; |
| 1505 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
| 1506 | return -EINVAL; |
| 1507 | |
| 1508 | switch (which) { |
| 1509 | case P_ALL: |
| 1510 | type = PIDTYPE_MAX; |
| 1511 | break; |
| 1512 | case P_PID: |
| 1513 | type = PIDTYPE_PID; |
| 1514 | if (upid <= 0) |
| 1515 | return -EINVAL; |
| 1516 | |
| 1517 | pid = find_get_pid(upid); |
| 1518 | break; |
| 1519 | case P_PGID: |
| 1520 | type = PIDTYPE_PGID; |
| 1521 | if (upid < 0) |
| 1522 | return -EINVAL; |
| 1523 | |
| 1524 | if (upid) |
| 1525 | pid = find_get_pid(upid); |
| 1526 | else |
| 1527 | pid = get_task_pid(current, PIDTYPE_PGID); |
| 1528 | break; |
| 1529 | case P_PIDFD: |
| 1530 | type = PIDTYPE_PID; |
| 1531 | if (upid < 0) |
| 1532 | return -EINVAL; |
| 1533 | |
| 1534 | pid = pidfd_get_pid(upid); |
| 1535 | if (IS_ERR(pid)) |
| 1536 | return PTR_ERR(pid); |
| 1537 | break; |
| 1538 | default: |
| 1539 | return -EINVAL; |
| 1540 | } |
| 1541 | |
| 1542 | wo.wo_type = type; |
| 1543 | wo.wo_pid = pid; |
| 1544 | wo.wo_flags = options; |
| 1545 | wo.wo_info = infop; |
| 1546 | wo.wo_rusage = ru; |
| 1547 | ret = do_wait(&wo); |
| 1548 | |
| 1549 | put_pid(pid); |
| 1550 | return ret; |
| 1551 | } |
| 1552 | |
| 1553 | SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
| 1554 | infop, int, options, struct rusage __user *, ru) |
| 1555 | { |
| 1556 | struct rusage r; |
| 1557 | struct waitid_info info = {.status = 0}; |
| 1558 | long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); |
| 1559 | int signo = 0; |
| 1560 | |
| 1561 | if (err > 0) { |
| 1562 | signo = SIGCHLD; |
| 1563 | err = 0; |
| 1564 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
| 1565 | return -EFAULT; |
| 1566 | } |
| 1567 | if (!infop) |
| 1568 | return err; |
| 1569 | |
| 1570 | if (!user_write_access_begin(infop, sizeof(*infop))) |
| 1571 | return -EFAULT; |
| 1572 | |
| 1573 | unsafe_put_user(signo, &infop->si_signo, Efault); |
| 1574 | unsafe_put_user(0, &infop->si_errno, Efault); |
| 1575 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
| 1576 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
| 1577 | unsafe_put_user(info.uid, &infop->si_uid, Efault); |
| 1578 | unsafe_put_user(info.status, &infop->si_status, Efault); |
| 1579 | user_write_access_end(); |
| 1580 | return err; |
| 1581 | Efault: |
| 1582 | user_write_access_end(); |
| 1583 | return -EFAULT; |
| 1584 | } |
| 1585 | |
| 1586 | long kernel_wait4(pid_t upid, int __user *stat_addr, int options, |
| 1587 | struct rusage *ru) |
| 1588 | { |
| 1589 | struct wait_opts wo; |
| 1590 | struct pid *pid = NULL; |
| 1591 | enum pid_type type; |
| 1592 | long ret; |
| 1593 | |
| 1594 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
| 1595 | __WNOTHREAD|__WCLONE|__WALL)) |
| 1596 | return -EINVAL; |
| 1597 | |
| 1598 | /* -INT_MIN is not defined */ |
| 1599 | if (upid == INT_MIN) |
| 1600 | return -ESRCH; |
| 1601 | |
| 1602 | if (upid == -1) |
| 1603 | type = PIDTYPE_MAX; |
| 1604 | else if (upid < 0) { |
| 1605 | type = PIDTYPE_PGID; |
| 1606 | pid = find_get_pid(-upid); |
| 1607 | } else if (upid == 0) { |
| 1608 | type = PIDTYPE_PGID; |
| 1609 | pid = get_task_pid(current, PIDTYPE_PGID); |
| 1610 | } else /* upid > 0 */ { |
| 1611 | type = PIDTYPE_PID; |
| 1612 | pid = find_get_pid(upid); |
| 1613 | } |
| 1614 | |
| 1615 | wo.wo_type = type; |
| 1616 | wo.wo_pid = pid; |
| 1617 | wo.wo_flags = options | WEXITED; |
| 1618 | wo.wo_info = NULL; |
| 1619 | wo.wo_stat = 0; |
| 1620 | wo.wo_rusage = ru; |
| 1621 | ret = do_wait(&wo); |
| 1622 | put_pid(pid); |
| 1623 | if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) |
| 1624 | ret = -EFAULT; |
| 1625 | |
| 1626 | return ret; |
| 1627 | } |
| 1628 | |
| 1629 | SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
| 1630 | int, options, struct rusage __user *, ru) |
| 1631 | { |
| 1632 | struct rusage r; |
| 1633 | long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); |
| 1634 | |
| 1635 | if (err > 0) { |
| 1636 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
| 1637 | return -EFAULT; |
| 1638 | } |
| 1639 | return err; |
| 1640 | } |
| 1641 | |
| 1642 | #ifdef __ARCH_WANT_SYS_WAITPID |
| 1643 | |
| 1644 | /* |
| 1645 | * sys_waitpid() remains for compatibility. waitpid() should be |
| 1646 | * implemented by calling sys_wait4() from libc.a. |
| 1647 | */ |
| 1648 | SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
| 1649 | { |
| 1650 | return kernel_wait4(pid, stat_addr, options, NULL); |
| 1651 | } |
| 1652 | |
| 1653 | #endif |
| 1654 | |
| 1655 | #ifdef CONFIG_COMPAT |
| 1656 | COMPAT_SYSCALL_DEFINE4(wait4, |
| 1657 | compat_pid_t, pid, |
| 1658 | compat_uint_t __user *, stat_addr, |
| 1659 | int, options, |
| 1660 | struct compat_rusage __user *, ru) |
| 1661 | { |
| 1662 | struct rusage r; |
| 1663 | long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); |
| 1664 | if (err > 0) { |
| 1665 | if (ru && put_compat_rusage(&r, ru)) |
| 1666 | return -EFAULT; |
| 1667 | } |
| 1668 | return err; |
| 1669 | } |
| 1670 | |
| 1671 | COMPAT_SYSCALL_DEFINE5(waitid, |
| 1672 | int, which, compat_pid_t, pid, |
| 1673 | struct compat_siginfo __user *, infop, int, options, |
| 1674 | struct compat_rusage __user *, uru) |
| 1675 | { |
| 1676 | struct rusage ru; |
| 1677 | struct waitid_info info = {.status = 0}; |
| 1678 | long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); |
| 1679 | int signo = 0; |
| 1680 | if (err > 0) { |
| 1681 | signo = SIGCHLD; |
| 1682 | err = 0; |
| 1683 | if (uru) { |
| 1684 | /* kernel_waitid() overwrites everything in ru */ |
| 1685 | if (COMPAT_USE_64BIT_TIME) |
| 1686 | err = copy_to_user(uru, &ru, sizeof(ru)); |
| 1687 | else |
| 1688 | err = put_compat_rusage(&ru, uru); |
| 1689 | if (err) |
| 1690 | return -EFAULT; |
| 1691 | } |
| 1692 | } |
| 1693 | |
| 1694 | if (!infop) |
| 1695 | return err; |
| 1696 | |
| 1697 | if (!user_write_access_begin(infop, sizeof(*infop))) |
| 1698 | return -EFAULT; |
| 1699 | |
| 1700 | unsafe_put_user(signo, &infop->si_signo, Efault); |
| 1701 | unsafe_put_user(0, &infop->si_errno, Efault); |
| 1702 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
| 1703 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
| 1704 | unsafe_put_user(info.uid, &infop->si_uid, Efault); |
| 1705 | unsafe_put_user(info.status, &infop->si_status, Efault); |
| 1706 | user_write_access_end(); |
| 1707 | return err; |
| 1708 | Efault: |
| 1709 | user_write_access_end(); |
| 1710 | return -EFAULT; |
| 1711 | } |
| 1712 | #endif |
| 1713 | |
| 1714 | /** |
| 1715 | * thread_group_exited - check that a thread group has exited |
| 1716 | * @pid: tgid of thread group to be checked. |
| 1717 | * |
| 1718 | * Test if the thread group represented by tgid has exited (all |
| 1719 | * threads are zombies, dead or completely gone). |
| 1720 | * |
| 1721 | * Return: true if the thread group has exited. false otherwise. |
| 1722 | */ |
| 1723 | bool thread_group_exited(struct pid *pid) |
| 1724 | { |
| 1725 | struct task_struct *task; |
| 1726 | bool exited; |
| 1727 | |
| 1728 | rcu_read_lock(); |
| 1729 | task = pid_task(pid, PIDTYPE_PID); |
| 1730 | exited = !task || |
| 1731 | (READ_ONCE(task->exit_state) && thread_group_empty(task)); |
| 1732 | rcu_read_unlock(); |
| 1733 | |
| 1734 | return exited; |
| 1735 | } |
| 1736 | EXPORT_SYMBOL(thread_group_exited); |
| 1737 | |
| 1738 | __weak void abort(void) |
| 1739 | { |
| 1740 | BUG(); |
| 1741 | |
| 1742 | /* if that doesn't kill us, halt */ |
| 1743 | panic("Oops failed to kill thread"); |
| 1744 | } |
| 1745 | EXPORT_SYMBOL(abort); |