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