kthread: rename probe_kthread_data() to kthread_probe_data()
[linux-2.6-block.git] / kernel / softirq.c
CommitLineData
1da177e4
LT
1/*
2 * linux/kernel/softirq.c
3 *
4 * Copyright (C) 1992 Linus Torvalds
5 *
b10db7f0
PM
6 * Distribute under GPLv2.
7 *
8 * Rewritten. Old one was good in 2.2, but in 2.3 it was immoral. --ANK (990903)
1da177e4
LT
9 */
10
40322764
JP
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
9984de1a 13#include <linux/export.h>
1da177e4
LT
14#include <linux/kernel_stat.h>
15#include <linux/interrupt.h>
16#include <linux/init.h>
17#include <linux/mm.h>
18#include <linux/notifier.h>
19#include <linux/percpu.h>
20#include <linux/cpu.h>
83144186 21#include <linux/freezer.h>
1da177e4
LT
22#include <linux/kthread.h>
23#include <linux/rcupdate.h>
7e49fcce 24#include <linux/ftrace.h>
78eef01b 25#include <linux/smp.h>
3e339b5d 26#include <linux/smpboot.h>
79bf2bb3 27#include <linux/tick.h>
d532676c 28#include <linux/irq.h>
a0e39ed3
HC
29
30#define CREATE_TRACE_POINTS
ad8d75ff 31#include <trace/events/irq.h>
1da177e4 32
1da177e4
LT
33/*
34 - No shared variables, all the data are CPU local.
35 - If a softirq needs serialization, let it serialize itself
36 by its own spinlocks.
37 - Even if softirq is serialized, only local cpu is marked for
38 execution. Hence, we get something sort of weak cpu binding.
39 Though it is still not clear, will it result in better locality
40 or will not.
41
42 Examples:
43 - NET RX softirq. It is multithreaded and does not require
44 any global serialization.
45 - NET TX softirq. It kicks software netdevice queues, hence
46 it is logically serialized per device, but this serialization
47 is invisible to common code.
48 - Tasklets: serialized wrt itself.
49 */
50
51#ifndef __ARCH_IRQ_STAT
52irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned;
53EXPORT_SYMBOL(irq_stat);
54#endif
55
978b0116 56static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;
1da177e4 57
4dd53d89 58DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
1da177e4 59
ce85b4f2 60const char * const softirq_to_name[NR_SOFTIRQS] = {
5dd4de58 61 "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL",
09223371 62 "TASKLET", "SCHED", "HRTIMER", "RCU"
5d592b44
JB
63};
64
1da177e4
LT
65/*
66 * we cannot loop indefinitely here to avoid userspace starvation,
67 * but we also don't want to introduce a worst case 1/HZ latency
68 * to the pending events, so lets the scheduler to balance
69 * the softirq load for us.
70 */
676cb02d 71static void wakeup_softirqd(void)
1da177e4
LT
72{
73 /* Interrupts are disabled: no need to stop preemption */
909ea964 74 struct task_struct *tsk = __this_cpu_read(ksoftirqd);
1da177e4
LT
75
76 if (tsk && tsk->state != TASK_RUNNING)
77 wake_up_process(tsk);
78}
79
4cd13c21
ED
80/*
81 * If ksoftirqd is scheduled, we do not want to process pending softirqs
82 * right now. Let ksoftirqd handle this at its own rate, to get fairness.
83 */
84static bool ksoftirqd_running(void)
85{
86 struct task_struct *tsk = __this_cpu_read(ksoftirqd);
87
88 return tsk && (tsk->state == TASK_RUNNING);
89}
90
75e1056f
VP
91/*
92 * preempt_count and SOFTIRQ_OFFSET usage:
93 * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
94 * softirq processing.
95 * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
96 * on local_bh_disable or local_bh_enable.
97 * This lets us distinguish between whether we are currently processing
98 * softirq and whether we just have bh disabled.
99 */
100
de30a2b3
IM
101/*
102 * This one is for softirq.c-internal use,
103 * where hardirqs are disabled legitimately:
104 */
3c829c36 105#ifdef CONFIG_TRACE_IRQFLAGS
0bd3a173 106void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
de30a2b3
IM
107{
108 unsigned long flags;
109
110 WARN_ON_ONCE(in_irq());
111
112 raw_local_irq_save(flags);
7e49fcce 113 /*
bdb43806 114 * The preempt tracer hooks into preempt_count_add and will break
7e49fcce
SR
115 * lockdep because it calls back into lockdep after SOFTIRQ_OFFSET
116 * is set and before current->softirq_enabled is cleared.
117 * We must manually increment preempt_count here and manually
118 * call the trace_preempt_off later.
119 */
bdb43806 120 __preempt_count_add(cnt);
de30a2b3
IM
121 /*
122 * Were softirqs turned off above:
123 */
9ea4c380 124 if (softirq_count() == (cnt & SOFTIRQ_MASK))
de30a2b3
IM
125 trace_softirqs_off(ip);
126 raw_local_irq_restore(flags);
7e49fcce 127
0f1ba9a2
HC
128 if (preempt_count() == cnt) {
129#ifdef CONFIG_DEBUG_PREEMPT
f904f582 130 current->preempt_disable_ip = get_lock_parent_ip();
0f1ba9a2 131#endif
f904f582 132 trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip());
0f1ba9a2 133 }
de30a2b3 134}
0bd3a173 135EXPORT_SYMBOL(__local_bh_disable_ip);
3c829c36 136#endif /* CONFIG_TRACE_IRQFLAGS */
de30a2b3 137
75e1056f
VP
138static void __local_bh_enable(unsigned int cnt)
139{
75e1056f
VP
140 WARN_ON_ONCE(!irqs_disabled());
141
9ea4c380 142 if (softirq_count() == (cnt & SOFTIRQ_MASK))
d2e08473 143 trace_softirqs_on(_RET_IP_);
bdb43806 144 preempt_count_sub(cnt);
75e1056f
VP
145}
146
de30a2b3
IM
147/*
148 * Special-case - softirqs can safely be enabled in
149 * cond_resched_softirq(), or by __do_softirq(),
150 * without processing still-pending softirqs:
151 */
152void _local_bh_enable(void)
153{
5d60d3e7 154 WARN_ON_ONCE(in_irq());
75e1056f 155 __local_bh_enable(SOFTIRQ_DISABLE_OFFSET);
de30a2b3 156}
de30a2b3
IM
157EXPORT_SYMBOL(_local_bh_enable);
158
0bd3a173 159void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
de30a2b3 160{
0f476b6d 161 WARN_ON_ONCE(in_irq() || irqs_disabled());
3c829c36 162#ifdef CONFIG_TRACE_IRQFLAGS
0f476b6d 163 local_irq_disable();
3c829c36 164#endif
de30a2b3
IM
165 /*
166 * Are softirqs going to be turned on now:
167 */
75e1056f 168 if (softirq_count() == SOFTIRQ_DISABLE_OFFSET)
0f476b6d 169 trace_softirqs_on(ip);
de30a2b3
IM
170 /*
171 * Keep preemption disabled until we are done with
172 * softirq processing:
ce85b4f2 173 */
0bd3a173 174 preempt_count_sub(cnt - 1);
de30a2b3 175
0bed698a
FW
176 if (unlikely(!in_interrupt() && local_softirq_pending())) {
177 /*
178 * Run softirq if any pending. And do it in its own stack
179 * as we may be calling this deep in a task call stack already.
180 */
de30a2b3 181 do_softirq();
0bed698a 182 }
de30a2b3 183
bdb43806 184 preempt_count_dec();
3c829c36 185#ifdef CONFIG_TRACE_IRQFLAGS
0f476b6d 186 local_irq_enable();
3c829c36 187#endif
de30a2b3
IM
188 preempt_check_resched();
189}
0bd3a173 190EXPORT_SYMBOL(__local_bh_enable_ip);
de30a2b3 191
1da177e4 192/*
34376a50
BG
193 * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
194 * but break the loop if need_resched() is set or after 2 ms.
195 * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in
196 * certain cases, such as stop_machine(), jiffies may cease to
197 * increment and so we need the MAX_SOFTIRQ_RESTART limit as
198 * well to make sure we eventually return from this method.
1da177e4 199 *
c10d7367 200 * These limits have been established via experimentation.
1da177e4
LT
201 * The two things to balance is latency against fairness -
202 * we want to handle softirqs as soon as possible, but they
203 * should not be able to lock up the box.
204 */
c10d7367 205#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
34376a50 206#define MAX_SOFTIRQ_RESTART 10
1da177e4 207
f1a83e65
PZ
208#ifdef CONFIG_TRACE_IRQFLAGS
209/*
f1a83e65
PZ
210 * When we run softirqs from irq_exit() and thus on the hardirq stack we need
211 * to keep the lockdep irq context tracking as tight as possible in order to
212 * not miss-qualify lock contexts and miss possible deadlocks.
213 */
f1a83e65 214
5c4853b6 215static inline bool lockdep_softirq_start(void)
f1a83e65 216{
5c4853b6 217 bool in_hardirq = false;
f1a83e65 218
5c4853b6
FW
219 if (trace_hardirq_context(current)) {
220 in_hardirq = true;
f1a83e65 221 trace_hardirq_exit();
5c4853b6
FW
222 }
223
f1a83e65 224 lockdep_softirq_enter();
5c4853b6
FW
225
226 return in_hardirq;
f1a83e65
PZ
227}
228
5c4853b6 229static inline void lockdep_softirq_end(bool in_hardirq)
f1a83e65
PZ
230{
231 lockdep_softirq_exit();
5c4853b6
FW
232
233 if (in_hardirq)
f1a83e65 234 trace_hardirq_enter();
f1a83e65 235}
f1a83e65 236#else
5c4853b6
FW
237static inline bool lockdep_softirq_start(void) { return false; }
238static inline void lockdep_softirq_end(bool in_hardirq) { }
f1a83e65
PZ
239#endif
240
be7635e7 241asmlinkage __visible void __softirq_entry __do_softirq(void)
1da177e4 242{
c10d7367 243 unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
907aed48 244 unsigned long old_flags = current->flags;
34376a50 245 int max_restart = MAX_SOFTIRQ_RESTART;
f1a83e65 246 struct softirq_action *h;
5c4853b6 247 bool in_hardirq;
f1a83e65 248 __u32 pending;
2e702b9f 249 int softirq_bit;
907aed48
MG
250
251 /*
252 * Mask out PF_MEMALLOC s current task context is borrowed for the
253 * softirq. A softirq handled such as network RX might set PF_MEMALLOC
254 * again if the socket is related to swap
255 */
256 current->flags &= ~PF_MEMALLOC;
1da177e4
LT
257
258 pending = local_softirq_pending();
6a61671b 259 account_irq_enter_time(current);
829035fd 260
0bd3a173 261 __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
5c4853b6 262 in_hardirq = lockdep_softirq_start();
1da177e4 263
1da177e4
LT
264restart:
265 /* Reset the pending bitmask before enabling irqs */
3f74478b 266 set_softirq_pending(0);
1da177e4 267
c70f5d66 268 local_irq_enable();
1da177e4
LT
269
270 h = softirq_vec;
271
2e702b9f
JP
272 while ((softirq_bit = ffs(pending))) {
273 unsigned int vec_nr;
274 int prev_count;
275
276 h += softirq_bit - 1;
277
278 vec_nr = h - softirq_vec;
279 prev_count = preempt_count();
280
281 kstat_incr_softirqs_this_cpu(vec_nr);
282
283 trace_softirq_entry(vec_nr);
284 h->action(h);
285 trace_softirq_exit(vec_nr);
286 if (unlikely(prev_count != preempt_count())) {
40322764 287 pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
2e702b9f
JP
288 vec_nr, softirq_to_name[vec_nr], h->action,
289 prev_count, preempt_count());
290 preempt_count_set(prev_count);
1da177e4
LT
291 }
292 h++;
2e702b9f
JP
293 pending >>= softirq_bit;
294 }
1da177e4 295
284a8c93 296 rcu_bh_qs();
c70f5d66 297 local_irq_disable();
1da177e4
LT
298
299 pending = local_softirq_pending();
c10d7367 300 if (pending) {
34376a50
BG
301 if (time_before(jiffies, end) && !need_resched() &&
302 --max_restart)
c10d7367 303 goto restart;
1da177e4 304
1da177e4 305 wakeup_softirqd();
c10d7367 306 }
1da177e4 307
5c4853b6 308 lockdep_softirq_end(in_hardirq);
6a61671b 309 account_irq_exit_time(current);
75e1056f 310 __local_bh_enable(SOFTIRQ_OFFSET);
5d60d3e7 311 WARN_ON_ONCE(in_interrupt());
907aed48 312 tsk_restore_flags(current, old_flags, PF_MEMALLOC);
1da177e4
LT
313}
314
722a9f92 315asmlinkage __visible void do_softirq(void)
1da177e4
LT
316{
317 __u32 pending;
318 unsigned long flags;
319
320 if (in_interrupt())
321 return;
322
323 local_irq_save(flags);
324
325 pending = local_softirq_pending();
326
4cd13c21 327 if (pending && !ksoftirqd_running())
7d65f4a6 328 do_softirq_own_stack();
1da177e4
LT
329
330 local_irq_restore(flags);
331}
332
dde4b2b5
IM
333/*
334 * Enter an interrupt context.
335 */
336void irq_enter(void)
337{
64db4cff 338 rcu_irq_enter();
0a8a2e78 339 if (is_idle_task(current) && !in_interrupt()) {
d267f87f
VP
340 /*
341 * Prevent raise_softirq from needlessly waking up ksoftirqd
342 * here, as softirq will be serviced on return from interrupt.
343 */
344 local_bh_disable();
5acac1be 345 tick_irq_enter();
d267f87f
VP
346 _local_bh_enable();
347 }
348
349 __irq_enter();
dde4b2b5
IM
350}
351
8d32a307
TG
352static inline void invoke_softirq(void)
353{
4cd13c21
ED
354 if (ksoftirqd_running())
355 return;
356
ded79754 357 if (!force_irqthreads) {
cc1f0274 358#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
ded79754
FW
359 /*
360 * We can safely execute softirq on the current stack if
361 * it is the irq stack, because it should be near empty
cc1f0274
FW
362 * at this stage.
363 */
364 __do_softirq();
365#else
366 /*
367 * Otherwise, irq_exit() is called on the task stack that can
368 * be potentially deep already. So call softirq in its own stack
369 * to prevent from any overrun.
ded79754 370 */
be6e1016 371 do_softirq_own_stack();
cc1f0274 372#endif
ded79754 373 } else {
8d32a307 374 wakeup_softirqd();
ded79754 375 }
8d32a307 376}
1da177e4 377
67826eae
FW
378static inline void tick_irq_exit(void)
379{
380#ifdef CONFIG_NO_HZ_COMMON
381 int cpu = smp_processor_id();
382
383 /* Make sure that timer wheel updates are propagated */
384 if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) {
385 if (!in_interrupt())
386 tick_nohz_irq_exit();
387 }
388#endif
389}
390
1da177e4
LT
391/*
392 * Exit an interrupt context. Process softirqs if needed and possible:
393 */
394void irq_exit(void)
395{
74eed016 396#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
4cd5d111 397 local_irq_disable();
74eed016
TG
398#else
399 WARN_ON_ONCE(!irqs_disabled());
400#endif
401
6a61671b 402 account_irq_exit_time(current);
bdb43806 403 preempt_count_sub(HARDIRQ_OFFSET);
1da177e4
LT
404 if (!in_interrupt() && local_softirq_pending())
405 invoke_softirq();
79bf2bb3 406
67826eae 407 tick_irq_exit();
416eb33c 408 rcu_irq_exit();
f1a83e65 409 trace_hardirq_exit(); /* must be last! */
1da177e4
LT
410}
411
412/*
413 * This function must run with irqs disabled!
414 */
7ad5b3a5 415inline void raise_softirq_irqoff(unsigned int nr)
1da177e4
LT
416{
417 __raise_softirq_irqoff(nr);
418
419 /*
420 * If we're in an interrupt or softirq, we're done
421 * (this also catches softirq-disabled code). We will
422 * actually run the softirq once we return from
423 * the irq or softirq.
424 *
425 * Otherwise we wake up ksoftirqd to make sure we
426 * schedule the softirq soon.
427 */
428 if (!in_interrupt())
429 wakeup_softirqd();
430}
431
7ad5b3a5 432void raise_softirq(unsigned int nr)
1da177e4
LT
433{
434 unsigned long flags;
435
436 local_irq_save(flags);
437 raise_softirq_irqoff(nr);
438 local_irq_restore(flags);
439}
440
f069686e
SR
441void __raise_softirq_irqoff(unsigned int nr)
442{
443 trace_softirq_raise(nr);
444 or_softirq_pending(1UL << nr);
445}
446
962cf36c 447void open_softirq(int nr, void (*action)(struct softirq_action *))
1da177e4 448{
1da177e4
LT
449 softirq_vec[nr].action = action;
450}
451
9ba5f005
PZ
452/*
453 * Tasklets
454 */
ce85b4f2 455struct tasklet_head {
48f20a9a
OJ
456 struct tasklet_struct *head;
457 struct tasklet_struct **tail;
1da177e4
LT
458};
459
4620b49f
VN
460static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
461static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);
1da177e4 462
7ad5b3a5 463void __tasklet_schedule(struct tasklet_struct *t)
1da177e4
LT
464{
465 unsigned long flags;
466
467 local_irq_save(flags);
48f20a9a 468 t->next = NULL;
909ea964
CL
469 *__this_cpu_read(tasklet_vec.tail) = t;
470 __this_cpu_write(tasklet_vec.tail, &(t->next));
1da177e4
LT
471 raise_softirq_irqoff(TASKLET_SOFTIRQ);
472 local_irq_restore(flags);
473}
1da177e4
LT
474EXPORT_SYMBOL(__tasklet_schedule);
475
7ad5b3a5 476void __tasklet_hi_schedule(struct tasklet_struct *t)
1da177e4
LT
477{
478 unsigned long flags;
479
480 local_irq_save(flags);
48f20a9a 481 t->next = NULL;
909ea964
CL
482 *__this_cpu_read(tasklet_hi_vec.tail) = t;
483 __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
1da177e4
LT
484 raise_softirq_irqoff(HI_SOFTIRQ);
485 local_irq_restore(flags);
486}
1da177e4
LT
487EXPORT_SYMBOL(__tasklet_hi_schedule);
488
7c692cba
VN
489void __tasklet_hi_schedule_first(struct tasklet_struct *t)
490{
491 BUG_ON(!irqs_disabled());
492
909ea964
CL
493 t->next = __this_cpu_read(tasklet_hi_vec.head);
494 __this_cpu_write(tasklet_hi_vec.head, t);
7c692cba
VN
495 __raise_softirq_irqoff(HI_SOFTIRQ);
496}
7c692cba
VN
497EXPORT_SYMBOL(__tasklet_hi_schedule_first);
498
1da177e4
LT
499static void tasklet_action(struct softirq_action *a)
500{
501 struct tasklet_struct *list;
502
503 local_irq_disable();
909ea964
CL
504 list = __this_cpu_read(tasklet_vec.head);
505 __this_cpu_write(tasklet_vec.head, NULL);
22127e93 506 __this_cpu_write(tasklet_vec.tail, this_cpu_ptr(&tasklet_vec.head));
1da177e4
LT
507 local_irq_enable();
508
509 while (list) {
510 struct tasklet_struct *t = list;
511
512 list = list->next;
513
514 if (tasklet_trylock(t)) {
515 if (!atomic_read(&t->count)) {
ce85b4f2
JP
516 if (!test_and_clear_bit(TASKLET_STATE_SCHED,
517 &t->state))
1da177e4
LT
518 BUG();
519 t->func(t->data);
520 tasklet_unlock(t);
521 continue;
522 }
523 tasklet_unlock(t);
524 }
525
526 local_irq_disable();
48f20a9a 527 t->next = NULL;
909ea964
CL
528 *__this_cpu_read(tasklet_vec.tail) = t;
529 __this_cpu_write(tasklet_vec.tail, &(t->next));
1da177e4
LT
530 __raise_softirq_irqoff(TASKLET_SOFTIRQ);
531 local_irq_enable();
532 }
533}
534
535static void tasklet_hi_action(struct softirq_action *a)
536{
537 struct tasklet_struct *list;
538
539 local_irq_disable();
909ea964
CL
540 list = __this_cpu_read(tasklet_hi_vec.head);
541 __this_cpu_write(tasklet_hi_vec.head, NULL);
22127e93 542 __this_cpu_write(tasklet_hi_vec.tail, this_cpu_ptr(&tasklet_hi_vec.head));
1da177e4
LT
543 local_irq_enable();
544
545 while (list) {
546 struct tasklet_struct *t = list;
547
548 list = list->next;
549
550 if (tasklet_trylock(t)) {
551 if (!atomic_read(&t->count)) {
ce85b4f2
JP
552 if (!test_and_clear_bit(TASKLET_STATE_SCHED,
553 &t->state))
1da177e4
LT
554 BUG();
555 t->func(t->data);
556 tasklet_unlock(t);
557 continue;
558 }
559 tasklet_unlock(t);
560 }
561
562 local_irq_disable();
48f20a9a 563 t->next = NULL;
909ea964
CL
564 *__this_cpu_read(tasklet_hi_vec.tail) = t;
565 __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
1da177e4
LT
566 __raise_softirq_irqoff(HI_SOFTIRQ);
567 local_irq_enable();
568 }
569}
570
1da177e4
LT
571void tasklet_init(struct tasklet_struct *t,
572 void (*func)(unsigned long), unsigned long data)
573{
574 t->next = NULL;
575 t->state = 0;
576 atomic_set(&t->count, 0);
577 t->func = func;
578 t->data = data;
579}
1da177e4
LT
580EXPORT_SYMBOL(tasklet_init);
581
582void tasklet_kill(struct tasklet_struct *t)
583{
584 if (in_interrupt())
40322764 585 pr_notice("Attempt to kill tasklet from interrupt\n");
1da177e4
LT
586
587 while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
79d381c9 588 do {
1da177e4 589 yield();
79d381c9 590 } while (test_bit(TASKLET_STATE_SCHED, &t->state));
1da177e4
LT
591 }
592 tasklet_unlock_wait(t);
593 clear_bit(TASKLET_STATE_SCHED, &t->state);
594}
1da177e4
LT
595EXPORT_SYMBOL(tasklet_kill);
596
9ba5f005
PZ
597/*
598 * tasklet_hrtimer
599 */
600
601/*
b9c30322
PZ
602 * The trampoline is called when the hrtimer expires. It schedules a tasklet
603 * to run __tasklet_hrtimer_trampoline() which in turn will call the intended
604 * hrtimer callback, but from softirq context.
9ba5f005
PZ
605 */
606static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
607{
608 struct tasklet_hrtimer *ttimer =
609 container_of(timer, struct tasklet_hrtimer, timer);
610
b9c30322
PZ
611 tasklet_hi_schedule(&ttimer->tasklet);
612 return HRTIMER_NORESTART;
9ba5f005
PZ
613}
614
615/*
616 * Helper function which calls the hrtimer callback from
617 * tasklet/softirq context
618 */
619static void __tasklet_hrtimer_trampoline(unsigned long data)
620{
621 struct tasklet_hrtimer *ttimer = (void *)data;
622 enum hrtimer_restart restart;
623
624 restart = ttimer->function(&ttimer->timer);
625 if (restart != HRTIMER_NORESTART)
626 hrtimer_restart(&ttimer->timer);
627}
628
629/**
630 * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks
631 * @ttimer: tasklet_hrtimer which is initialized
25985edc 632 * @function: hrtimer callback function which gets called from softirq context
9ba5f005
PZ
633 * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
634 * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
635 */
636void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
637 enum hrtimer_restart (*function)(struct hrtimer *),
638 clockid_t which_clock, enum hrtimer_mode mode)
639{
640 hrtimer_init(&ttimer->timer, which_clock, mode);
641 ttimer->timer.function = __hrtimer_tasklet_trampoline;
642 tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
643 (unsigned long)ttimer);
644 ttimer->function = function;
645}
646EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
647
1da177e4
LT
648void __init softirq_init(void)
649{
48f20a9a
OJ
650 int cpu;
651
652 for_each_possible_cpu(cpu) {
653 per_cpu(tasklet_vec, cpu).tail =
654 &per_cpu(tasklet_vec, cpu).head;
655 per_cpu(tasklet_hi_vec, cpu).tail =
656 &per_cpu(tasklet_hi_vec, cpu).head;
657 }
658
962cf36c
CM
659 open_softirq(TASKLET_SOFTIRQ, tasklet_action);
660 open_softirq(HI_SOFTIRQ, tasklet_hi_action);
1da177e4
LT
661}
662
3e339b5d 663static int ksoftirqd_should_run(unsigned int cpu)
1da177e4 664{
3e339b5d
TG
665 return local_softirq_pending();
666}
1da177e4 667
3e339b5d
TG
668static void run_ksoftirqd(unsigned int cpu)
669{
670 local_irq_disable();
671 if (local_softirq_pending()) {
0bed698a
FW
672 /*
673 * We can safely run softirq on inline stack, as we are not deep
674 * in the task stack here.
675 */
3e339b5d 676 __do_softirq();
3e339b5d 677 local_irq_enable();
60479676 678 cond_resched_rcu_qs();
3e339b5d 679 return;
1da177e4 680 }
3e339b5d 681 local_irq_enable();
1da177e4
LT
682}
683
684#ifdef CONFIG_HOTPLUG_CPU
685/*
686 * tasklet_kill_immediate is called to remove a tasklet which can already be
687 * scheduled for execution on @cpu.
688 *
689 * Unlike tasklet_kill, this function removes the tasklet
690 * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state.
691 *
692 * When this function is called, @cpu must be in the CPU_DEAD state.
693 */
694void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
695{
696 struct tasklet_struct **i;
697
698 BUG_ON(cpu_online(cpu));
699 BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state));
700
701 if (!test_bit(TASKLET_STATE_SCHED, &t->state))
702 return;
703
704 /* CPU is dead, so no lock needed. */
48f20a9a 705 for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
1da177e4
LT
706 if (*i == t) {
707 *i = t->next;
48f20a9a
OJ
708 /* If this was the tail element, move the tail ptr */
709 if (*i == NULL)
710 per_cpu(tasklet_vec, cpu).tail = i;
1da177e4
LT
711 return;
712 }
713 }
714 BUG();
715}
716
c4544dbc 717static int takeover_tasklets(unsigned int cpu)
1da177e4 718{
1da177e4
LT
719 /* CPU is dead, so no lock needed. */
720 local_irq_disable();
721
722 /* Find end, append list for that CPU. */
e5e41723 723 if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
909ea964
CL
724 *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head;
725 this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail);
e5e41723
CB
726 per_cpu(tasklet_vec, cpu).head = NULL;
727 per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
728 }
1da177e4
LT
729 raise_softirq_irqoff(TASKLET_SOFTIRQ);
730
e5e41723 731 if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
909ea964
CL
732 *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head;
733 __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail);
e5e41723
CB
734 per_cpu(tasklet_hi_vec, cpu).head = NULL;
735 per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
736 }
1da177e4
LT
737 raise_softirq_irqoff(HI_SOFTIRQ);
738
739 local_irq_enable();
c4544dbc 740 return 0;
1da177e4 741}
c4544dbc
SAS
742#else
743#define takeover_tasklets NULL
1da177e4
LT
744#endif /* CONFIG_HOTPLUG_CPU */
745
3e339b5d
TG
746static struct smp_hotplug_thread softirq_threads = {
747 .store = &ksoftirqd,
748 .thread_should_run = ksoftirqd_should_run,
749 .thread_fn = run_ksoftirqd,
750 .thread_comm = "ksoftirqd/%u",
751};
752
7babe8db 753static __init int spawn_ksoftirqd(void)
1da177e4 754{
c4544dbc
SAS
755 cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL,
756 takeover_tasklets);
3e339b5d
TG
757 BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
758
1da177e4
LT
759 return 0;
760}
7babe8db 761early_initcall(spawn_ksoftirqd);
78eef01b 762
43a25632
YL
763/*
764 * [ These __weak aliases are kept in a separate compilation unit, so that
765 * GCC does not inline them incorrectly. ]
766 */
767
768int __init __weak early_irq_init(void)
769{
770 return 0;
771}
772
4a046d17
YL
773int __init __weak arch_probe_nr_irqs(void)
774{
b683de2b 775 return NR_IRQS_LEGACY;
4a046d17
YL
776}
777
43a25632
YL
778int __init __weak arch_early_irq_init(void)
779{
780 return 0;
781}
62a08ae2
TG
782
783unsigned int __weak arch_dynirq_lower_bound(unsigned int from)
784{
785 return from;
786}