]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * linux/kernel/workqueue.c | |
3 | * | |
4 | * Generic mechanism for defining kernel helper threads for running | |
5 | * arbitrary tasks in process context. | |
6 | * | |
7 | * Started by Ingo Molnar, Copyright (C) 2002 | |
8 | * | |
9 | * Derived from the taskqueue/keventd code by: | |
10 | * | |
11 | * David Woodhouse <dwmw2@infradead.org> | |
12 | * Andrew Morton | |
13 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> | |
14 | * Theodore Ts'o <tytso@mit.edu> | |
15 | * | |
16 | * Made to use alloc_percpu by Christoph Lameter. | |
17 | */ | |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/sched.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/signal.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/workqueue.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/notifier.h> | |
29 | #include <linux/kthread.h> | |
30 | #include <linux/hardirq.h> | |
31 | #include <linux/mempolicy.h> | |
32 | #include <linux/freezer.h> | |
33 | #include <linux/kallsyms.h> | |
34 | #include <linux/debug_locks.h> | |
35 | #include <linux/lockdep.h> | |
36 | #define CREATE_TRACE_POINTS | |
37 | #include <trace/events/workqueue.h> | |
38 | ||
39 | /* | |
40 | * The per-CPU workqueue (if single thread, we always use the first | |
41 | * possible cpu). | |
42 | */ | |
43 | struct cpu_workqueue_struct { | |
44 | ||
45 | spinlock_t lock; | |
46 | ||
47 | struct list_head worklist; | |
48 | wait_queue_head_t more_work; | |
49 | struct work_struct *current_work; | |
50 | ||
51 | struct workqueue_struct *wq; | |
52 | struct task_struct *thread; | |
53 | } ____cacheline_aligned; | |
54 | ||
55 | /* | |
56 | * The externally visible workqueue abstraction is an array of | |
57 | * per-CPU workqueues: | |
58 | */ | |
59 | struct workqueue_struct { | |
60 | struct cpu_workqueue_struct *cpu_wq; | |
61 | struct list_head list; | |
62 | const char *name; | |
63 | int singlethread; | |
64 | int freezeable; /* Freeze threads during suspend */ | |
65 | int rt; | |
66 | #ifdef CONFIG_LOCKDEP | |
67 | struct lockdep_map lockdep_map; | |
68 | #endif | |
69 | }; | |
70 | ||
71 | #ifdef CONFIG_LOCKDEP | |
72 | /** | |
73 | * in_workqueue_context() - in context of specified workqueue? | |
74 | * @wq: the workqueue of interest | |
75 | * | |
76 | * Checks lockdep state to see if the current task is executing from | |
77 | * within a workqueue item. This function exists only if lockdep is | |
78 | * enabled. | |
79 | */ | |
80 | int in_workqueue_context(struct workqueue_struct *wq) | |
81 | { | |
82 | return lock_is_held(&wq->lockdep_map); | |
83 | } | |
84 | #endif | |
85 | ||
86 | #ifdef CONFIG_DEBUG_OBJECTS_WORK | |
87 | ||
88 | static struct debug_obj_descr work_debug_descr; | |
89 | ||
90 | /* | |
91 | * fixup_init is called when: | |
92 | * - an active object is initialized | |
93 | */ | |
94 | static int work_fixup_init(void *addr, enum debug_obj_state state) | |
95 | { | |
96 | struct work_struct *work = addr; | |
97 | ||
98 | switch (state) { | |
99 | case ODEBUG_STATE_ACTIVE: | |
100 | cancel_work_sync(work); | |
101 | debug_object_init(work, &work_debug_descr); | |
102 | return 1; | |
103 | default: | |
104 | return 0; | |
105 | } | |
106 | } | |
107 | ||
108 | /* | |
109 | * fixup_activate is called when: | |
110 | * - an active object is activated | |
111 | * - an unknown object is activated (might be a statically initialized object) | |
112 | */ | |
113 | static int work_fixup_activate(void *addr, enum debug_obj_state state) | |
114 | { | |
115 | struct work_struct *work = addr; | |
116 | ||
117 | switch (state) { | |
118 | ||
119 | case ODEBUG_STATE_NOTAVAILABLE: | |
120 | /* | |
121 | * This is not really a fixup. The work struct was | |
122 | * statically initialized. We just make sure that it | |
123 | * is tracked in the object tracker. | |
124 | */ | |
125 | if (test_bit(WORK_STRUCT_STATIC, work_data_bits(work))) { | |
126 | debug_object_init(work, &work_debug_descr); | |
127 | debug_object_activate(work, &work_debug_descr); | |
128 | return 0; | |
129 | } | |
130 | WARN_ON_ONCE(1); | |
131 | return 0; | |
132 | ||
133 | case ODEBUG_STATE_ACTIVE: | |
134 | WARN_ON(1); | |
135 | ||
136 | default: | |
137 | return 0; | |
138 | } | |
139 | } | |
140 | ||
141 | /* | |
142 | * fixup_free is called when: | |
143 | * - an active object is freed | |
144 | */ | |
145 | static int work_fixup_free(void *addr, enum debug_obj_state state) | |
146 | { | |
147 | struct work_struct *work = addr; | |
148 | ||
149 | switch (state) { | |
150 | case ODEBUG_STATE_ACTIVE: | |
151 | cancel_work_sync(work); | |
152 | debug_object_free(work, &work_debug_descr); | |
153 | return 1; | |
154 | default: | |
155 | return 0; | |
156 | } | |
157 | } | |
158 | ||
159 | static struct debug_obj_descr work_debug_descr = { | |
160 | .name = "work_struct", | |
161 | .fixup_init = work_fixup_init, | |
162 | .fixup_activate = work_fixup_activate, | |
163 | .fixup_free = work_fixup_free, | |
164 | }; | |
165 | ||
166 | static inline void debug_work_activate(struct work_struct *work) | |
167 | { | |
168 | debug_object_activate(work, &work_debug_descr); | |
169 | } | |
170 | ||
171 | static inline void debug_work_deactivate(struct work_struct *work) | |
172 | { | |
173 | debug_object_deactivate(work, &work_debug_descr); | |
174 | } | |
175 | ||
176 | void __init_work(struct work_struct *work, int onstack) | |
177 | { | |
178 | if (onstack) | |
179 | debug_object_init_on_stack(work, &work_debug_descr); | |
180 | else | |
181 | debug_object_init(work, &work_debug_descr); | |
182 | } | |
183 | EXPORT_SYMBOL_GPL(__init_work); | |
184 | ||
185 | void destroy_work_on_stack(struct work_struct *work) | |
186 | { | |
187 | debug_object_free(work, &work_debug_descr); | |
188 | } | |
189 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
190 | ||
191 | #else | |
192 | static inline void debug_work_activate(struct work_struct *work) { } | |
193 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
194 | #endif | |
195 | ||
196 | /* Serializes the accesses to the list of workqueues. */ | |
197 | static DEFINE_SPINLOCK(workqueue_lock); | |
198 | static LIST_HEAD(workqueues); | |
199 | ||
200 | static int singlethread_cpu __read_mostly; | |
201 | static const struct cpumask *cpu_singlethread_map __read_mostly; | |
202 | /* | |
203 | * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD | |
204 | * flushes cwq->worklist. This means that flush_workqueue/wait_on_work | |
205 | * which comes in between can't use for_each_online_cpu(). We could | |
206 | * use cpu_possible_map, the cpumask below is more a documentation | |
207 | * than optimization. | |
208 | */ | |
209 | static cpumask_var_t cpu_populated_map __read_mostly; | |
210 | ||
211 | /* If it's single threaded, it isn't in the list of workqueues. */ | |
212 | static inline int is_wq_single_threaded(struct workqueue_struct *wq) | |
213 | { | |
214 | return wq->singlethread; | |
215 | } | |
216 | ||
217 | static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) | |
218 | { | |
219 | return is_wq_single_threaded(wq) | |
220 | ? cpu_singlethread_map : cpu_populated_map; | |
221 | } | |
222 | ||
223 | static | |
224 | struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu) | |
225 | { | |
226 | if (unlikely(is_wq_single_threaded(wq))) | |
227 | cpu = singlethread_cpu; | |
228 | return per_cpu_ptr(wq->cpu_wq, cpu); | |
229 | } | |
230 | ||
231 | /* | |
232 | * Set the workqueue on which a work item is to be run | |
233 | * - Must *only* be called if the pending flag is set | |
234 | */ | |
235 | static inline void set_wq_data(struct work_struct *work, | |
236 | struct cpu_workqueue_struct *cwq) | |
237 | { | |
238 | unsigned long new; | |
239 | ||
240 | BUG_ON(!work_pending(work)); | |
241 | ||
242 | new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING); | |
243 | new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work); | |
244 | atomic_long_set(&work->data, new); | |
245 | } | |
246 | ||
247 | /* | |
248 | * Clear WORK_STRUCT_PENDING and the workqueue on which it was queued. | |
249 | */ | |
250 | static inline void clear_wq_data(struct work_struct *work) | |
251 | { | |
252 | unsigned long flags = *work_data_bits(work) & | |
253 | (1UL << WORK_STRUCT_STATIC); | |
254 | atomic_long_set(&work->data, flags); | |
255 | } | |
256 | ||
257 | static inline | |
258 | struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) | |
259 | { | |
260 | return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK); | |
261 | } | |
262 | ||
263 | static void insert_work(struct cpu_workqueue_struct *cwq, | |
264 | struct work_struct *work, struct list_head *head) | |
265 | { | |
266 | trace_workqueue_insertion(cwq->thread, work); | |
267 | ||
268 | set_wq_data(work, cwq); | |
269 | /* | |
270 | * Ensure that we get the right work->data if we see the | |
271 | * result of list_add() below, see try_to_grab_pending(). | |
272 | */ | |
273 | smp_wmb(); | |
274 | list_add_tail(&work->entry, head); | |
275 | wake_up(&cwq->more_work); | |
276 | } | |
277 | ||
278 | static void __queue_work(struct cpu_workqueue_struct *cwq, | |
279 | struct work_struct *work) | |
280 | { | |
281 | unsigned long flags; | |
282 | ||
283 | debug_work_activate(work); | |
284 | spin_lock_irqsave(&cwq->lock, flags); | |
285 | insert_work(cwq, work, &cwq->worklist); | |
286 | spin_unlock_irqrestore(&cwq->lock, flags); | |
287 | } | |
288 | ||
289 | /** | |
290 | * queue_work - queue work on a workqueue | |
291 | * @wq: workqueue to use | |
292 | * @work: work to queue | |
293 | * | |
294 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
295 | * | |
296 | * We queue the work to the CPU on which it was submitted, but if the CPU dies | |
297 | * it can be processed by another CPU. | |
298 | */ | |
299 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) | |
300 | { | |
301 | int ret; | |
302 | ||
303 | ret = queue_work_on(get_cpu(), wq, work); | |
304 | put_cpu(); | |
305 | ||
306 | return ret; | |
307 | } | |
308 | EXPORT_SYMBOL_GPL(queue_work); | |
309 | ||
310 | /** | |
311 | * queue_work_on - queue work on specific cpu | |
312 | * @cpu: CPU number to execute work on | |
313 | * @wq: workqueue to use | |
314 | * @work: work to queue | |
315 | * | |
316 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
317 | * | |
318 | * We queue the work to a specific CPU, the caller must ensure it | |
319 | * can't go away. | |
320 | */ | |
321 | int | |
322 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) | |
323 | { | |
324 | int ret = 0; | |
325 | ||
326 | if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { | |
327 | BUG_ON(!list_empty(&work->entry)); | |
328 | __queue_work(wq_per_cpu(wq, cpu), work); | |
329 | ret = 1; | |
330 | } | |
331 | return ret; | |
332 | } | |
333 | EXPORT_SYMBOL_GPL(queue_work_on); | |
334 | ||
335 | static void delayed_work_timer_fn(unsigned long __data) | |
336 | { | |
337 | struct delayed_work *dwork = (struct delayed_work *)__data; | |
338 | struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); | |
339 | struct workqueue_struct *wq = cwq->wq; | |
340 | ||
341 | __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work); | |
342 | } | |
343 | ||
344 | /** | |
345 | * queue_delayed_work - queue work on a workqueue after delay | |
346 | * @wq: workqueue to use | |
347 | * @dwork: delayable work to queue | |
348 | * @delay: number of jiffies to wait before queueing | |
349 | * | |
350 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
351 | */ | |
352 | int queue_delayed_work(struct workqueue_struct *wq, | |
353 | struct delayed_work *dwork, unsigned long delay) | |
354 | { | |
355 | if (delay == 0) | |
356 | return queue_work(wq, &dwork->work); | |
357 | ||
358 | return queue_delayed_work_on(-1, wq, dwork, delay); | |
359 | } | |
360 | EXPORT_SYMBOL_GPL(queue_delayed_work); | |
361 | ||
362 | /** | |
363 | * queue_delayed_work_on - queue work on specific CPU after delay | |
364 | * @cpu: CPU number to execute work on | |
365 | * @wq: workqueue to use | |
366 | * @dwork: work to queue | |
367 | * @delay: number of jiffies to wait before queueing | |
368 | * | |
369 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
370 | */ | |
371 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, | |
372 | struct delayed_work *dwork, unsigned long delay) | |
373 | { | |
374 | int ret = 0; | |
375 | struct timer_list *timer = &dwork->timer; | |
376 | struct work_struct *work = &dwork->work; | |
377 | ||
378 | if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { | |
379 | BUG_ON(timer_pending(timer)); | |
380 | BUG_ON(!list_empty(&work->entry)); | |
381 | ||
382 | timer_stats_timer_set_start_info(&dwork->timer); | |
383 | ||
384 | /* This stores cwq for the moment, for the timer_fn */ | |
385 | set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id())); | |
386 | timer->expires = jiffies + delay; | |
387 | timer->data = (unsigned long)dwork; | |
388 | timer->function = delayed_work_timer_fn; | |
389 | ||
390 | if (unlikely(cpu >= 0)) | |
391 | add_timer_on(timer, cpu); | |
392 | else | |
393 | add_timer(timer); | |
394 | ret = 1; | |
395 | } | |
396 | return ret; | |
397 | } | |
398 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); | |
399 | ||
400 | static void run_workqueue(struct cpu_workqueue_struct *cwq) | |
401 | { | |
402 | spin_lock_irq(&cwq->lock); | |
403 | while (!list_empty(&cwq->worklist)) { | |
404 | struct work_struct *work = list_entry(cwq->worklist.next, | |
405 | struct work_struct, entry); | |
406 | work_func_t f = work->func; | |
407 | #ifdef CONFIG_LOCKDEP | |
408 | /* | |
409 | * It is permissible to free the struct work_struct | |
410 | * from inside the function that is called from it, | |
411 | * this we need to take into account for lockdep too. | |
412 | * To avoid bogus "held lock freed" warnings as well | |
413 | * as problems when looking into work->lockdep_map, | |
414 | * make a copy and use that here. | |
415 | */ | |
416 | struct lockdep_map lockdep_map = work->lockdep_map; | |
417 | #endif | |
418 | trace_workqueue_execution(cwq->thread, work); | |
419 | debug_work_deactivate(work); | |
420 | cwq->current_work = work; | |
421 | list_del_init(cwq->worklist.next); | |
422 | spin_unlock_irq(&cwq->lock); | |
423 | ||
424 | BUG_ON(get_wq_data(work) != cwq); | |
425 | work_clear_pending(work); | |
426 | lock_map_acquire(&cwq->wq->lockdep_map); | |
427 | lock_map_acquire(&lockdep_map); | |
428 | f(work); | |
429 | lock_map_release(&lockdep_map); | |
430 | lock_map_release(&cwq->wq->lockdep_map); | |
431 | ||
432 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
433 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " | |
434 | "%s/0x%08x/%d\n", | |
435 | current->comm, preempt_count(), | |
436 | task_pid_nr(current)); | |
437 | printk(KERN_ERR " last function: "); | |
438 | print_symbol("%s\n", (unsigned long)f); | |
439 | debug_show_held_locks(current); | |
440 | dump_stack(); | |
441 | } | |
442 | ||
443 | spin_lock_irq(&cwq->lock); | |
444 | cwq->current_work = NULL; | |
445 | } | |
446 | spin_unlock_irq(&cwq->lock); | |
447 | } | |
448 | ||
449 | static int worker_thread(void *__cwq) | |
450 | { | |
451 | struct cpu_workqueue_struct *cwq = __cwq; | |
452 | DEFINE_WAIT(wait); | |
453 | ||
454 | if (cwq->wq->freezeable) | |
455 | set_freezable(); | |
456 | ||
457 | for (;;) { | |
458 | prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); | |
459 | if (!freezing(current) && | |
460 | !kthread_should_stop() && | |
461 | list_empty(&cwq->worklist)) | |
462 | schedule(); | |
463 | finish_wait(&cwq->more_work, &wait); | |
464 | ||
465 | try_to_freeze(); | |
466 | ||
467 | if (kthread_should_stop()) | |
468 | break; | |
469 | ||
470 | run_workqueue(cwq); | |
471 | } | |
472 | ||
473 | return 0; | |
474 | } | |
475 | ||
476 | struct wq_barrier { | |
477 | struct work_struct work; | |
478 | struct completion done; | |
479 | }; | |
480 | ||
481 | static void wq_barrier_func(struct work_struct *work) | |
482 | { | |
483 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
484 | complete(&barr->done); | |
485 | } | |
486 | ||
487 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, | |
488 | struct wq_barrier *barr, struct list_head *head) | |
489 | { | |
490 | /* | |
491 | * debugobject calls are safe here even with cwq->lock locked | |
492 | * as we know for sure that this will not trigger any of the | |
493 | * checks and call back into the fixup functions where we | |
494 | * might deadlock. | |
495 | */ | |
496 | INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); | |
497 | __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work)); | |
498 | ||
499 | init_completion(&barr->done); | |
500 | ||
501 | debug_work_activate(&barr->work); | |
502 | insert_work(cwq, &barr->work, head); | |
503 | } | |
504 | ||
505 | static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) | |
506 | { | |
507 | int active = 0; | |
508 | struct wq_barrier barr; | |
509 | ||
510 | WARN_ON(cwq->thread == current); | |
511 | ||
512 | spin_lock_irq(&cwq->lock); | |
513 | if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { | |
514 | insert_wq_barrier(cwq, &barr, &cwq->worklist); | |
515 | active = 1; | |
516 | } | |
517 | spin_unlock_irq(&cwq->lock); | |
518 | ||
519 | if (active) { | |
520 | wait_for_completion(&barr.done); | |
521 | destroy_work_on_stack(&barr.work); | |
522 | } | |
523 | ||
524 | return active; | |
525 | } | |
526 | ||
527 | /** | |
528 | * flush_workqueue - ensure that any scheduled work has run to completion. | |
529 | * @wq: workqueue to flush | |
530 | * | |
531 | * Forces execution of the workqueue and blocks until its completion. | |
532 | * This is typically used in driver shutdown handlers. | |
533 | * | |
534 | * We sleep until all works which were queued on entry have been handled, | |
535 | * but we are not livelocked by new incoming ones. | |
536 | * | |
537 | * This function used to run the workqueues itself. Now we just wait for the | |
538 | * helper threads to do it. | |
539 | */ | |
540 | void flush_workqueue(struct workqueue_struct *wq) | |
541 | { | |
542 | const struct cpumask *cpu_map = wq_cpu_map(wq); | |
543 | int cpu; | |
544 | ||
545 | might_sleep(); | |
546 | lock_map_acquire(&wq->lockdep_map); | |
547 | lock_map_release(&wq->lockdep_map); | |
548 | for_each_cpu(cpu, cpu_map) | |
549 | flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu)); | |
550 | } | |
551 | EXPORT_SYMBOL_GPL(flush_workqueue); | |
552 | ||
553 | /** | |
554 | * flush_work - block until a work_struct's callback has terminated | |
555 | * @work: the work which is to be flushed | |
556 | * | |
557 | * Returns false if @work has already terminated. | |
558 | * | |
559 | * It is expected that, prior to calling flush_work(), the caller has | |
560 | * arranged for the work to not be requeued, otherwise it doesn't make | |
561 | * sense to use this function. | |
562 | */ | |
563 | int flush_work(struct work_struct *work) | |
564 | { | |
565 | struct cpu_workqueue_struct *cwq; | |
566 | struct list_head *prev; | |
567 | struct wq_barrier barr; | |
568 | ||
569 | might_sleep(); | |
570 | cwq = get_wq_data(work); | |
571 | if (!cwq) | |
572 | return 0; | |
573 | ||
574 | lock_map_acquire(&cwq->wq->lockdep_map); | |
575 | lock_map_release(&cwq->wq->lockdep_map); | |
576 | ||
577 | prev = NULL; | |
578 | spin_lock_irq(&cwq->lock); | |
579 | if (!list_empty(&work->entry)) { | |
580 | /* | |
581 | * See the comment near try_to_grab_pending()->smp_rmb(). | |
582 | * If it was re-queued under us we are not going to wait. | |
583 | */ | |
584 | smp_rmb(); | |
585 | if (unlikely(cwq != get_wq_data(work))) | |
586 | goto out; | |
587 | prev = &work->entry; | |
588 | } else { | |
589 | if (cwq->current_work != work) | |
590 | goto out; | |
591 | prev = &cwq->worklist; | |
592 | } | |
593 | insert_wq_barrier(cwq, &barr, prev->next); | |
594 | out: | |
595 | spin_unlock_irq(&cwq->lock); | |
596 | if (!prev) | |
597 | return 0; | |
598 | ||
599 | wait_for_completion(&barr.done); | |
600 | destroy_work_on_stack(&barr.work); | |
601 | return 1; | |
602 | } | |
603 | EXPORT_SYMBOL_GPL(flush_work); | |
604 | ||
605 | /* | |
606 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, | |
607 | * so this work can't be re-armed in any way. | |
608 | */ | |
609 | static int try_to_grab_pending(struct work_struct *work) | |
610 | { | |
611 | struct cpu_workqueue_struct *cwq; | |
612 | int ret = -1; | |
613 | ||
614 | if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) | |
615 | return 0; | |
616 | ||
617 | /* | |
618 | * The queueing is in progress, or it is already queued. Try to | |
619 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
620 | */ | |
621 | ||
622 | cwq = get_wq_data(work); | |
623 | if (!cwq) | |
624 | return ret; | |
625 | ||
626 | spin_lock_irq(&cwq->lock); | |
627 | if (!list_empty(&work->entry)) { | |
628 | /* | |
629 | * This work is queued, but perhaps we locked the wrong cwq. | |
630 | * In that case we must see the new value after rmb(), see | |
631 | * insert_work()->wmb(). | |
632 | */ | |
633 | smp_rmb(); | |
634 | if (cwq == get_wq_data(work)) { | |
635 | debug_work_deactivate(work); | |
636 | list_del_init(&work->entry); | |
637 | ret = 1; | |
638 | } | |
639 | } | |
640 | spin_unlock_irq(&cwq->lock); | |
641 | ||
642 | return ret; | |
643 | } | |
644 | ||
645 | static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, | |
646 | struct work_struct *work) | |
647 | { | |
648 | struct wq_barrier barr; | |
649 | int running = 0; | |
650 | ||
651 | spin_lock_irq(&cwq->lock); | |
652 | if (unlikely(cwq->current_work == work)) { | |
653 | insert_wq_barrier(cwq, &barr, cwq->worklist.next); | |
654 | running = 1; | |
655 | } | |
656 | spin_unlock_irq(&cwq->lock); | |
657 | ||
658 | if (unlikely(running)) { | |
659 | wait_for_completion(&barr.done); | |
660 | destroy_work_on_stack(&barr.work); | |
661 | } | |
662 | } | |
663 | ||
664 | static void wait_on_work(struct work_struct *work) | |
665 | { | |
666 | struct cpu_workqueue_struct *cwq; | |
667 | struct workqueue_struct *wq; | |
668 | const struct cpumask *cpu_map; | |
669 | int cpu; | |
670 | ||
671 | might_sleep(); | |
672 | ||
673 | lock_map_acquire(&work->lockdep_map); | |
674 | lock_map_release(&work->lockdep_map); | |
675 | ||
676 | cwq = get_wq_data(work); | |
677 | if (!cwq) | |
678 | return; | |
679 | ||
680 | wq = cwq->wq; | |
681 | cpu_map = wq_cpu_map(wq); | |
682 | ||
683 | for_each_cpu(cpu, cpu_map) | |
684 | wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work); | |
685 | } | |
686 | ||
687 | static int __cancel_work_timer(struct work_struct *work, | |
688 | struct timer_list* timer) | |
689 | { | |
690 | int ret; | |
691 | ||
692 | do { | |
693 | ret = (timer && likely(del_timer(timer))); | |
694 | if (!ret) | |
695 | ret = try_to_grab_pending(work); | |
696 | wait_on_work(work); | |
697 | } while (unlikely(ret < 0)); | |
698 | ||
699 | clear_wq_data(work); | |
700 | return ret; | |
701 | } | |
702 | ||
703 | /** | |
704 | * cancel_work_sync - block until a work_struct's callback has terminated | |
705 | * @work: the work which is to be flushed | |
706 | * | |
707 | * Returns true if @work was pending. | |
708 | * | |
709 | * cancel_work_sync() will cancel the work if it is queued. If the work's | |
710 | * callback appears to be running, cancel_work_sync() will block until it | |
711 | * has completed. | |
712 | * | |
713 | * It is possible to use this function if the work re-queues itself. It can | |
714 | * cancel the work even if it migrates to another workqueue, however in that | |
715 | * case it only guarantees that work->func() has completed on the last queued | |
716 | * workqueue. | |
717 | * | |
718 | * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not | |
719 | * pending, otherwise it goes into a busy-wait loop until the timer expires. | |
720 | * | |
721 | * The caller must ensure that workqueue_struct on which this work was last | |
722 | * queued can't be destroyed before this function returns. | |
723 | */ | |
724 | int cancel_work_sync(struct work_struct *work) | |
725 | { | |
726 | return __cancel_work_timer(work, NULL); | |
727 | } | |
728 | EXPORT_SYMBOL_GPL(cancel_work_sync); | |
729 | ||
730 | /** | |
731 | * cancel_delayed_work_sync - reliably kill off a delayed work. | |
732 | * @dwork: the delayed work struct | |
733 | * | |
734 | * Returns true if @dwork was pending. | |
735 | * | |
736 | * It is possible to use this function if @dwork rearms itself via queue_work() | |
737 | * or queue_delayed_work(). See also the comment for cancel_work_sync(). | |
738 | */ | |
739 | int cancel_delayed_work_sync(struct delayed_work *dwork) | |
740 | { | |
741 | return __cancel_work_timer(&dwork->work, &dwork->timer); | |
742 | } | |
743 | EXPORT_SYMBOL(cancel_delayed_work_sync); | |
744 | ||
745 | static struct workqueue_struct *keventd_wq __read_mostly; | |
746 | ||
747 | /** | |
748 | * schedule_work - put work task in global workqueue | |
749 | * @work: job to be done | |
750 | * | |
751 | * Returns zero if @work was already on the kernel-global workqueue and | |
752 | * non-zero otherwise. | |
753 | * | |
754 | * This puts a job in the kernel-global workqueue if it was not already | |
755 | * queued and leaves it in the same position on the kernel-global | |
756 | * workqueue otherwise. | |
757 | */ | |
758 | int schedule_work(struct work_struct *work) | |
759 | { | |
760 | return queue_work(keventd_wq, work); | |
761 | } | |
762 | EXPORT_SYMBOL(schedule_work); | |
763 | ||
764 | /* | |
765 | * schedule_work_on - put work task on a specific cpu | |
766 | * @cpu: cpu to put the work task on | |
767 | * @work: job to be done | |
768 | * | |
769 | * This puts a job on a specific cpu | |
770 | */ | |
771 | int schedule_work_on(int cpu, struct work_struct *work) | |
772 | { | |
773 | return queue_work_on(cpu, keventd_wq, work); | |
774 | } | |
775 | EXPORT_SYMBOL(schedule_work_on); | |
776 | ||
777 | /** | |
778 | * schedule_delayed_work - put work task in global workqueue after delay | |
779 | * @dwork: job to be done | |
780 | * @delay: number of jiffies to wait or 0 for immediate execution | |
781 | * | |
782 | * After waiting for a given time this puts a job in the kernel-global | |
783 | * workqueue. | |
784 | */ | |
785 | int schedule_delayed_work(struct delayed_work *dwork, | |
786 | unsigned long delay) | |
787 | { | |
788 | return queue_delayed_work(keventd_wq, dwork, delay); | |
789 | } | |
790 | EXPORT_SYMBOL(schedule_delayed_work); | |
791 | ||
792 | /** | |
793 | * flush_delayed_work - block until a dwork_struct's callback has terminated | |
794 | * @dwork: the delayed work which is to be flushed | |
795 | * | |
796 | * Any timeout is cancelled, and any pending work is run immediately. | |
797 | */ | |
798 | void flush_delayed_work(struct delayed_work *dwork) | |
799 | { | |
800 | if (del_timer_sync(&dwork->timer)) { | |
801 | struct cpu_workqueue_struct *cwq; | |
802 | cwq = wq_per_cpu(get_wq_data(&dwork->work)->wq, get_cpu()); | |
803 | __queue_work(cwq, &dwork->work); | |
804 | put_cpu(); | |
805 | } | |
806 | flush_work(&dwork->work); | |
807 | } | |
808 | EXPORT_SYMBOL(flush_delayed_work); | |
809 | ||
810 | /** | |
811 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay | |
812 | * @cpu: cpu to use | |
813 | * @dwork: job to be done | |
814 | * @delay: number of jiffies to wait | |
815 | * | |
816 | * After waiting for a given time this puts a job in the kernel-global | |
817 | * workqueue on the specified CPU. | |
818 | */ | |
819 | int schedule_delayed_work_on(int cpu, | |
820 | struct delayed_work *dwork, unsigned long delay) | |
821 | { | |
822 | return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); | |
823 | } | |
824 | EXPORT_SYMBOL(schedule_delayed_work_on); | |
825 | ||
826 | /** | |
827 | * schedule_on_each_cpu - call a function on each online CPU from keventd | |
828 | * @func: the function to call | |
829 | * | |
830 | * Returns zero on success. | |
831 | * Returns -ve errno on failure. | |
832 | * | |
833 | * schedule_on_each_cpu() is very slow. | |
834 | */ | |
835 | int schedule_on_each_cpu(work_func_t func) | |
836 | { | |
837 | int cpu; | |
838 | int orig = -1; | |
839 | struct work_struct *works; | |
840 | ||
841 | works = alloc_percpu(struct work_struct); | |
842 | if (!works) | |
843 | return -ENOMEM; | |
844 | ||
845 | get_online_cpus(); | |
846 | ||
847 | /* | |
848 | * When running in keventd don't schedule a work item on | |
849 | * itself. Can just call directly because the work queue is | |
850 | * already bound. This also is faster. | |
851 | */ | |
852 | if (current_is_keventd()) | |
853 | orig = raw_smp_processor_id(); | |
854 | ||
855 | for_each_online_cpu(cpu) { | |
856 | struct work_struct *work = per_cpu_ptr(works, cpu); | |
857 | ||
858 | INIT_WORK(work, func); | |
859 | if (cpu != orig) | |
860 | schedule_work_on(cpu, work); | |
861 | } | |
862 | if (orig >= 0) | |
863 | func(per_cpu_ptr(works, orig)); | |
864 | ||
865 | for_each_online_cpu(cpu) | |
866 | flush_work(per_cpu_ptr(works, cpu)); | |
867 | ||
868 | put_online_cpus(); | |
869 | free_percpu(works); | |
870 | return 0; | |
871 | } | |
872 | ||
873 | /** | |
874 | * flush_scheduled_work - ensure that any scheduled work has run to completion. | |
875 | * | |
876 | * Forces execution of the kernel-global workqueue and blocks until its | |
877 | * completion. | |
878 | * | |
879 | * Think twice before calling this function! It's very easy to get into | |
880 | * trouble if you don't take great care. Either of the following situations | |
881 | * will lead to deadlock: | |
882 | * | |
883 | * One of the work items currently on the workqueue needs to acquire | |
884 | * a lock held by your code or its caller. | |
885 | * | |
886 | * Your code is running in the context of a work routine. | |
887 | * | |
888 | * They will be detected by lockdep when they occur, but the first might not | |
889 | * occur very often. It depends on what work items are on the workqueue and | |
890 | * what locks they need, which you have no control over. | |
891 | * | |
892 | * In most situations flushing the entire workqueue is overkill; you merely | |
893 | * need to know that a particular work item isn't queued and isn't running. | |
894 | * In such cases you should use cancel_delayed_work_sync() or | |
895 | * cancel_work_sync() instead. | |
896 | */ | |
897 | void flush_scheduled_work(void) | |
898 | { | |
899 | flush_workqueue(keventd_wq); | |
900 | } | |
901 | EXPORT_SYMBOL(flush_scheduled_work); | |
902 | ||
903 | /** | |
904 | * execute_in_process_context - reliably execute the routine with user context | |
905 | * @fn: the function to execute | |
906 | * @ew: guaranteed storage for the execute work structure (must | |
907 | * be available when the work executes) | |
908 | * | |
909 | * Executes the function immediately if process context is available, | |
910 | * otherwise schedules the function for delayed execution. | |
911 | * | |
912 | * Returns: 0 - function was executed | |
913 | * 1 - function was scheduled for execution | |
914 | */ | |
915 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) | |
916 | { | |
917 | if (!in_interrupt()) { | |
918 | fn(&ew->work); | |
919 | return 0; | |
920 | } | |
921 | ||
922 | INIT_WORK(&ew->work, fn); | |
923 | schedule_work(&ew->work); | |
924 | ||
925 | return 1; | |
926 | } | |
927 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
928 | ||
929 | int keventd_up(void) | |
930 | { | |
931 | return keventd_wq != NULL; | |
932 | } | |
933 | ||
934 | int current_is_keventd(void) | |
935 | { | |
936 | struct cpu_workqueue_struct *cwq; | |
937 | int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ | |
938 | int ret = 0; | |
939 | ||
940 | BUG_ON(!keventd_wq); | |
941 | ||
942 | cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu); | |
943 | if (current == cwq->thread) | |
944 | ret = 1; | |
945 | ||
946 | return ret; | |
947 | ||
948 | } | |
949 | ||
950 | static struct cpu_workqueue_struct * | |
951 | init_cpu_workqueue(struct workqueue_struct *wq, int cpu) | |
952 | { | |
953 | struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); | |
954 | ||
955 | cwq->wq = wq; | |
956 | spin_lock_init(&cwq->lock); | |
957 | INIT_LIST_HEAD(&cwq->worklist); | |
958 | init_waitqueue_head(&cwq->more_work); | |
959 | ||
960 | return cwq; | |
961 | } | |
962 | ||
963 | static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) | |
964 | { | |
965 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
966 | struct workqueue_struct *wq = cwq->wq; | |
967 | const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d"; | |
968 | struct task_struct *p; | |
969 | ||
970 | p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu); | |
971 | /* | |
972 | * Nobody can add the work_struct to this cwq, | |
973 | * if (caller is __create_workqueue) | |
974 | * nobody should see this wq | |
975 | * else // caller is CPU_UP_PREPARE | |
976 | * cpu is not on cpu_online_map | |
977 | * so we can abort safely. | |
978 | */ | |
979 | if (IS_ERR(p)) | |
980 | return PTR_ERR(p); | |
981 | if (cwq->wq->rt) | |
982 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); | |
983 | cwq->thread = p; | |
984 | ||
985 | trace_workqueue_creation(cwq->thread, cpu); | |
986 | ||
987 | return 0; | |
988 | } | |
989 | ||
990 | static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) | |
991 | { | |
992 | struct task_struct *p = cwq->thread; | |
993 | ||
994 | if (p != NULL) { | |
995 | if (cpu >= 0) | |
996 | kthread_bind(p, cpu); | |
997 | wake_up_process(p); | |
998 | } | |
999 | } | |
1000 | ||
1001 | struct workqueue_struct *__create_workqueue_key(const char *name, | |
1002 | int singlethread, | |
1003 | int freezeable, | |
1004 | int rt, | |
1005 | struct lock_class_key *key, | |
1006 | const char *lock_name) | |
1007 | { | |
1008 | struct workqueue_struct *wq; | |
1009 | struct cpu_workqueue_struct *cwq; | |
1010 | int err = 0, cpu; | |
1011 | ||
1012 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); | |
1013 | if (!wq) | |
1014 | return NULL; | |
1015 | ||
1016 | wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); | |
1017 | if (!wq->cpu_wq) { | |
1018 | kfree(wq); | |
1019 | return NULL; | |
1020 | } | |
1021 | ||
1022 | wq->name = name; | |
1023 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); | |
1024 | wq->singlethread = singlethread; | |
1025 | wq->freezeable = freezeable; | |
1026 | wq->rt = rt; | |
1027 | INIT_LIST_HEAD(&wq->list); | |
1028 | ||
1029 | if (singlethread) { | |
1030 | cwq = init_cpu_workqueue(wq, singlethread_cpu); | |
1031 | err = create_workqueue_thread(cwq, singlethread_cpu); | |
1032 | start_workqueue_thread(cwq, -1); | |
1033 | } else { | |
1034 | cpu_maps_update_begin(); | |
1035 | /* | |
1036 | * We must place this wq on list even if the code below fails. | |
1037 | * cpu_down(cpu) can remove cpu from cpu_populated_map before | |
1038 | * destroy_workqueue() takes the lock, in that case we leak | |
1039 | * cwq[cpu]->thread. | |
1040 | */ | |
1041 | spin_lock(&workqueue_lock); | |
1042 | list_add(&wq->list, &workqueues); | |
1043 | spin_unlock(&workqueue_lock); | |
1044 | /* | |
1045 | * We must initialize cwqs for each possible cpu even if we | |
1046 | * are going to call destroy_workqueue() finally. Otherwise | |
1047 | * cpu_up() can hit the uninitialized cwq once we drop the | |
1048 | * lock. | |
1049 | */ | |
1050 | for_each_possible_cpu(cpu) { | |
1051 | cwq = init_cpu_workqueue(wq, cpu); | |
1052 | if (err || !cpu_online(cpu)) | |
1053 | continue; | |
1054 | err = create_workqueue_thread(cwq, cpu); | |
1055 | start_workqueue_thread(cwq, cpu); | |
1056 | } | |
1057 | cpu_maps_update_done(); | |
1058 | } | |
1059 | ||
1060 | if (err) { | |
1061 | destroy_workqueue(wq); | |
1062 | wq = NULL; | |
1063 | } | |
1064 | return wq; | |
1065 | } | |
1066 | EXPORT_SYMBOL_GPL(__create_workqueue_key); | |
1067 | ||
1068 | static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) | |
1069 | { | |
1070 | /* | |
1071 | * Our caller is either destroy_workqueue() or CPU_POST_DEAD, | |
1072 | * cpu_add_remove_lock protects cwq->thread. | |
1073 | */ | |
1074 | if (cwq->thread == NULL) | |
1075 | return; | |
1076 | ||
1077 | lock_map_acquire(&cwq->wq->lockdep_map); | |
1078 | lock_map_release(&cwq->wq->lockdep_map); | |
1079 | ||
1080 | flush_cpu_workqueue(cwq); | |
1081 | /* | |
1082 | * If the caller is CPU_POST_DEAD and cwq->worklist was not empty, | |
1083 | * a concurrent flush_workqueue() can insert a barrier after us. | |
1084 | * However, in that case run_workqueue() won't return and check | |
1085 | * kthread_should_stop() until it flushes all work_struct's. | |
1086 | * When ->worklist becomes empty it is safe to exit because no | |
1087 | * more work_structs can be queued on this cwq: flush_workqueue | |
1088 | * checks list_empty(), and a "normal" queue_work() can't use | |
1089 | * a dead CPU. | |
1090 | */ | |
1091 | trace_workqueue_destruction(cwq->thread); | |
1092 | kthread_stop(cwq->thread); | |
1093 | cwq->thread = NULL; | |
1094 | } | |
1095 | ||
1096 | /** | |
1097 | * destroy_workqueue - safely terminate a workqueue | |
1098 | * @wq: target workqueue | |
1099 | * | |
1100 | * Safely destroy a workqueue. All work currently pending will be done first. | |
1101 | */ | |
1102 | void destroy_workqueue(struct workqueue_struct *wq) | |
1103 | { | |
1104 | const struct cpumask *cpu_map = wq_cpu_map(wq); | |
1105 | int cpu; | |
1106 | ||
1107 | cpu_maps_update_begin(); | |
1108 | spin_lock(&workqueue_lock); | |
1109 | list_del(&wq->list); | |
1110 | spin_unlock(&workqueue_lock); | |
1111 | ||
1112 | for_each_cpu(cpu, cpu_map) | |
1113 | cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); | |
1114 | cpu_maps_update_done(); | |
1115 | ||
1116 | free_percpu(wq->cpu_wq); | |
1117 | kfree(wq); | |
1118 | } | |
1119 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
1120 | ||
1121 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, | |
1122 | unsigned long action, | |
1123 | void *hcpu) | |
1124 | { | |
1125 | unsigned int cpu = (unsigned long)hcpu; | |
1126 | struct cpu_workqueue_struct *cwq; | |
1127 | struct workqueue_struct *wq; | |
1128 | int err = 0; | |
1129 | ||
1130 | action &= ~CPU_TASKS_FROZEN; | |
1131 | ||
1132 | switch (action) { | |
1133 | case CPU_UP_PREPARE: | |
1134 | cpumask_set_cpu(cpu, cpu_populated_map); | |
1135 | } | |
1136 | undo: | |
1137 | list_for_each_entry(wq, &workqueues, list) { | |
1138 | cwq = per_cpu_ptr(wq->cpu_wq, cpu); | |
1139 | ||
1140 | switch (action) { | |
1141 | case CPU_UP_PREPARE: | |
1142 | err = create_workqueue_thread(cwq, cpu); | |
1143 | if (!err) | |
1144 | break; | |
1145 | printk(KERN_ERR "workqueue [%s] for %i failed\n", | |
1146 | wq->name, cpu); | |
1147 | action = CPU_UP_CANCELED; | |
1148 | err = -ENOMEM; | |
1149 | goto undo; | |
1150 | ||
1151 | case CPU_ONLINE: | |
1152 | start_workqueue_thread(cwq, cpu); | |
1153 | break; | |
1154 | ||
1155 | case CPU_UP_CANCELED: | |
1156 | start_workqueue_thread(cwq, -1); | |
1157 | case CPU_POST_DEAD: | |
1158 | cleanup_workqueue_thread(cwq); | |
1159 | break; | |
1160 | } | |
1161 | } | |
1162 | ||
1163 | switch (action) { | |
1164 | case CPU_UP_CANCELED: | |
1165 | case CPU_POST_DEAD: | |
1166 | cpumask_clear_cpu(cpu, cpu_populated_map); | |
1167 | } | |
1168 | ||
1169 | return notifier_from_errno(err); | |
1170 | } | |
1171 | ||
1172 | #ifdef CONFIG_SMP | |
1173 | ||
1174 | struct work_for_cpu { | |
1175 | struct completion completion; | |
1176 | long (*fn)(void *); | |
1177 | void *arg; | |
1178 | long ret; | |
1179 | }; | |
1180 | ||
1181 | static int do_work_for_cpu(void *_wfc) | |
1182 | { | |
1183 | struct work_for_cpu *wfc = _wfc; | |
1184 | wfc->ret = wfc->fn(wfc->arg); | |
1185 | complete(&wfc->completion); | |
1186 | return 0; | |
1187 | } | |
1188 | ||
1189 | /** | |
1190 | * work_on_cpu - run a function in user context on a particular cpu | |
1191 | * @cpu: the cpu to run on | |
1192 | * @fn: the function to run | |
1193 | * @arg: the function arg | |
1194 | * | |
1195 | * This will return the value @fn returns. | |
1196 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
1197 | * The caller must not hold any locks which would prevent @fn from completing. | |
1198 | */ | |
1199 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) | |
1200 | { | |
1201 | struct task_struct *sub_thread; | |
1202 | struct work_for_cpu wfc = { | |
1203 | .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), | |
1204 | .fn = fn, | |
1205 | .arg = arg, | |
1206 | }; | |
1207 | ||
1208 | sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); | |
1209 | if (IS_ERR(sub_thread)) | |
1210 | return PTR_ERR(sub_thread); | |
1211 | kthread_bind(sub_thread, cpu); | |
1212 | wake_up_process(sub_thread); | |
1213 | wait_for_completion(&wfc.completion); | |
1214 | return wfc.ret; | |
1215 | } | |
1216 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
1217 | #endif /* CONFIG_SMP */ | |
1218 | ||
1219 | void __init init_workqueues(void) | |
1220 | { | |
1221 | alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL); | |
1222 | ||
1223 | cpumask_copy(cpu_populated_map, cpu_online_mask); | |
1224 | singlethread_cpu = cpumask_first(cpu_possible_mask); | |
1225 | cpu_singlethread_map = cpumask_of(singlethread_cpu); | |
1226 | hotcpu_notifier(workqueue_cpu_callback, 0); | |
1227 | keventd_wq = create_workqueue("events"); | |
1228 | BUG_ON(!keventd_wq); | |
1229 | } |