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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 | #include <trace/workqueue.h> | |
37 | ||
38 | /* | |
39 | * The per-CPU workqueue (if single thread, we always use the first | |
40 | * possible cpu). | |
41 | */ | |
42 | struct cpu_workqueue_struct { | |
43 | ||
44 | spinlock_t lock; | |
45 | ||
46 | struct list_head worklist; | |
47 | wait_queue_head_t more_work; | |
48 | struct work_struct *current_work; | |
49 | ||
50 | struct workqueue_struct *wq; | |
51 | struct task_struct *thread; | |
52 | } ____cacheline_aligned; | |
53 | ||
54 | /* | |
55 | * The externally visible workqueue abstraction is an array of | |
56 | * per-CPU workqueues: | |
57 | */ | |
58 | struct workqueue_struct { | |
59 | struct cpu_workqueue_struct *cpu_wq; | |
60 | struct list_head list; | |
61 | const char *name; | |
62 | int singlethread; | |
63 | int freezeable; /* Freeze threads during suspend */ | |
64 | int rt; | |
65 | #ifdef CONFIG_LOCKDEP | |
66 | struct lockdep_map lockdep_map; | |
67 | #endif | |
68 | }; | |
69 | ||
70 | /* Serializes the accesses to the list of workqueues. */ | |
71 | static DEFINE_SPINLOCK(workqueue_lock); | |
72 | static LIST_HEAD(workqueues); | |
73 | ||
74 | static int singlethread_cpu __read_mostly; | |
75 | static const struct cpumask *cpu_singlethread_map __read_mostly; | |
76 | /* | |
77 | * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD | |
78 | * flushes cwq->worklist. This means that flush_workqueue/wait_on_work | |
79 | * which comes in between can't use for_each_online_cpu(). We could | |
80 | * use cpu_possible_map, the cpumask below is more a documentation | |
81 | * than optimization. | |
82 | */ | |
83 | static cpumask_var_t cpu_populated_map __read_mostly; | |
84 | ||
85 | /* If it's single threaded, it isn't in the list of workqueues. */ | |
86 | static inline int is_wq_single_threaded(struct workqueue_struct *wq) | |
87 | { | |
88 | return wq->singlethread; | |
89 | } | |
90 | ||
91 | static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) | |
92 | { | |
93 | return is_wq_single_threaded(wq) | |
94 | ? cpu_singlethread_map : cpu_populated_map; | |
95 | } | |
96 | ||
97 | static | |
98 | struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu) | |
99 | { | |
100 | if (unlikely(is_wq_single_threaded(wq))) | |
101 | cpu = singlethread_cpu; | |
102 | return per_cpu_ptr(wq->cpu_wq, cpu); | |
103 | } | |
104 | ||
105 | /* | |
106 | * Set the workqueue on which a work item is to be run | |
107 | * - Must *only* be called if the pending flag is set | |
108 | */ | |
109 | static inline void set_wq_data(struct work_struct *work, | |
110 | struct cpu_workqueue_struct *cwq) | |
111 | { | |
112 | unsigned long new; | |
113 | ||
114 | BUG_ON(!work_pending(work)); | |
115 | ||
116 | new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING); | |
117 | new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work); | |
118 | atomic_long_set(&work->data, new); | |
119 | } | |
120 | ||
121 | static inline | |
122 | struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) | |
123 | { | |
124 | return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK); | |
125 | } | |
126 | ||
127 | DEFINE_TRACE(workqueue_insertion); | |
128 | ||
129 | static void insert_work(struct cpu_workqueue_struct *cwq, | |
130 | struct work_struct *work, struct list_head *head) | |
131 | { | |
132 | trace_workqueue_insertion(cwq->thread, work); | |
133 | ||
134 | set_wq_data(work, cwq); | |
135 | /* | |
136 | * Ensure that we get the right work->data if we see the | |
137 | * result of list_add() below, see try_to_grab_pending(). | |
138 | */ | |
139 | smp_wmb(); | |
140 | list_add_tail(&work->entry, head); | |
141 | wake_up(&cwq->more_work); | |
142 | } | |
143 | ||
144 | static void __queue_work(struct cpu_workqueue_struct *cwq, | |
145 | struct work_struct *work) | |
146 | { | |
147 | unsigned long flags; | |
148 | ||
149 | spin_lock_irqsave(&cwq->lock, flags); | |
150 | insert_work(cwq, work, &cwq->worklist); | |
151 | spin_unlock_irqrestore(&cwq->lock, flags); | |
152 | } | |
153 | ||
154 | /** | |
155 | * queue_work - queue work on a workqueue | |
156 | * @wq: workqueue to use | |
157 | * @work: work to queue | |
158 | * | |
159 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
160 | * | |
161 | * We queue the work to the CPU on which it was submitted, but if the CPU dies | |
162 | * it can be processed by another CPU. | |
163 | */ | |
164 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) | |
165 | { | |
166 | int ret; | |
167 | ||
168 | ret = queue_work_on(get_cpu(), wq, work); | |
169 | put_cpu(); | |
170 | ||
171 | return ret; | |
172 | } | |
173 | EXPORT_SYMBOL_GPL(queue_work); | |
174 | ||
175 | /** | |
176 | * queue_work_on - queue work on specific cpu | |
177 | * @cpu: CPU number to execute work on | |
178 | * @wq: workqueue to use | |
179 | * @work: work to queue | |
180 | * | |
181 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
182 | * | |
183 | * We queue the work to a specific CPU, the caller must ensure it | |
184 | * can't go away. | |
185 | */ | |
186 | int | |
187 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) | |
188 | { | |
189 | int ret = 0; | |
190 | ||
191 | if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { | |
192 | BUG_ON(!list_empty(&work->entry)); | |
193 | __queue_work(wq_per_cpu(wq, cpu), work); | |
194 | ret = 1; | |
195 | } | |
196 | return ret; | |
197 | } | |
198 | EXPORT_SYMBOL_GPL(queue_work_on); | |
199 | ||
200 | static void delayed_work_timer_fn(unsigned long __data) | |
201 | { | |
202 | struct delayed_work *dwork = (struct delayed_work *)__data; | |
203 | struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); | |
204 | struct workqueue_struct *wq = cwq->wq; | |
205 | ||
206 | __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work); | |
207 | } | |
208 | ||
209 | /** | |
210 | * queue_delayed_work - queue work on a workqueue after delay | |
211 | * @wq: workqueue to use | |
212 | * @dwork: delayable work to queue | |
213 | * @delay: number of jiffies to wait before queueing | |
214 | * | |
215 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
216 | */ | |
217 | int queue_delayed_work(struct workqueue_struct *wq, | |
218 | struct delayed_work *dwork, unsigned long delay) | |
219 | { | |
220 | if (delay == 0) | |
221 | return queue_work(wq, &dwork->work); | |
222 | ||
223 | return queue_delayed_work_on(-1, wq, dwork, delay); | |
224 | } | |
225 | EXPORT_SYMBOL_GPL(queue_delayed_work); | |
226 | ||
227 | /** | |
228 | * queue_delayed_work_on - queue work on specific CPU after delay | |
229 | * @cpu: CPU number to execute work on | |
230 | * @wq: workqueue to use | |
231 | * @dwork: work to queue | |
232 | * @delay: number of jiffies to wait before queueing | |
233 | * | |
234 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
235 | */ | |
236 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, | |
237 | struct delayed_work *dwork, unsigned long delay) | |
238 | { | |
239 | int ret = 0; | |
240 | struct timer_list *timer = &dwork->timer; | |
241 | struct work_struct *work = &dwork->work; | |
242 | ||
243 | if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { | |
244 | BUG_ON(timer_pending(timer)); | |
245 | BUG_ON(!list_empty(&work->entry)); | |
246 | ||
247 | timer_stats_timer_set_start_info(&dwork->timer); | |
248 | ||
249 | /* This stores cwq for the moment, for the timer_fn */ | |
250 | set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id())); | |
251 | timer->expires = jiffies + delay; | |
252 | timer->data = (unsigned long)dwork; | |
253 | timer->function = delayed_work_timer_fn; | |
254 | ||
255 | if (unlikely(cpu >= 0)) | |
256 | add_timer_on(timer, cpu); | |
257 | else | |
258 | add_timer(timer); | |
259 | ret = 1; | |
260 | } | |
261 | return ret; | |
262 | } | |
263 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); | |
264 | ||
265 | DEFINE_TRACE(workqueue_execution); | |
266 | ||
267 | static void run_workqueue(struct cpu_workqueue_struct *cwq) | |
268 | { | |
269 | spin_lock_irq(&cwq->lock); | |
270 | while (!list_empty(&cwq->worklist)) { | |
271 | struct work_struct *work = list_entry(cwq->worklist.next, | |
272 | struct work_struct, entry); | |
273 | work_func_t f = work->func; | |
274 | #ifdef CONFIG_LOCKDEP | |
275 | /* | |
276 | * It is permissible to free the struct work_struct | |
277 | * from inside the function that is called from it, | |
278 | * this we need to take into account for lockdep too. | |
279 | * To avoid bogus "held lock freed" warnings as well | |
280 | * as problems when looking into work->lockdep_map, | |
281 | * make a copy and use that here. | |
282 | */ | |
283 | struct lockdep_map lockdep_map = work->lockdep_map; | |
284 | #endif | |
285 | trace_workqueue_execution(cwq->thread, work); | |
286 | cwq->current_work = work; | |
287 | list_del_init(cwq->worklist.next); | |
288 | spin_unlock_irq(&cwq->lock); | |
289 | ||
290 | BUG_ON(get_wq_data(work) != cwq); | |
291 | work_clear_pending(work); | |
292 | lock_map_acquire(&cwq->wq->lockdep_map); | |
293 | lock_map_acquire(&lockdep_map); | |
294 | f(work); | |
295 | lock_map_release(&lockdep_map); | |
296 | lock_map_release(&cwq->wq->lockdep_map); | |
297 | ||
298 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
299 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " | |
300 | "%s/0x%08x/%d\n", | |
301 | current->comm, preempt_count(), | |
302 | task_pid_nr(current)); | |
303 | printk(KERN_ERR " last function: "); | |
304 | print_symbol("%s\n", (unsigned long)f); | |
305 | debug_show_held_locks(current); | |
306 | dump_stack(); | |
307 | } | |
308 | ||
309 | spin_lock_irq(&cwq->lock); | |
310 | cwq->current_work = NULL; | |
311 | } | |
312 | spin_unlock_irq(&cwq->lock); | |
313 | } | |
314 | ||
315 | static int worker_thread(void *__cwq) | |
316 | { | |
317 | struct cpu_workqueue_struct *cwq = __cwq; | |
318 | DEFINE_WAIT(wait); | |
319 | ||
320 | if (cwq->wq->freezeable) | |
321 | set_freezable(); | |
322 | ||
323 | set_user_nice(current, -5); | |
324 | ||
325 | for (;;) { | |
326 | prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); | |
327 | if (!freezing(current) && | |
328 | !kthread_should_stop() && | |
329 | list_empty(&cwq->worklist)) | |
330 | schedule(); | |
331 | finish_wait(&cwq->more_work, &wait); | |
332 | ||
333 | try_to_freeze(); | |
334 | ||
335 | if (kthread_should_stop()) | |
336 | break; | |
337 | ||
338 | run_workqueue(cwq); | |
339 | } | |
340 | ||
341 | return 0; | |
342 | } | |
343 | ||
344 | struct wq_barrier { | |
345 | struct work_struct work; | |
346 | struct completion done; | |
347 | }; | |
348 | ||
349 | static void wq_barrier_func(struct work_struct *work) | |
350 | { | |
351 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
352 | complete(&barr->done); | |
353 | } | |
354 | ||
355 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, | |
356 | struct wq_barrier *barr, struct list_head *head) | |
357 | { | |
358 | INIT_WORK(&barr->work, wq_barrier_func); | |
359 | __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work)); | |
360 | ||
361 | init_completion(&barr->done); | |
362 | ||
363 | insert_work(cwq, &barr->work, head); | |
364 | } | |
365 | ||
366 | static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) | |
367 | { | |
368 | int active = 0; | |
369 | struct wq_barrier barr; | |
370 | ||
371 | WARN_ON(cwq->thread == current); | |
372 | ||
373 | spin_lock_irq(&cwq->lock); | |
374 | if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { | |
375 | insert_wq_barrier(cwq, &barr, &cwq->worklist); | |
376 | active = 1; | |
377 | } | |
378 | spin_unlock_irq(&cwq->lock); | |
379 | ||
380 | if (active) | |
381 | wait_for_completion(&barr.done); | |
382 | ||
383 | return active; | |
384 | } | |
385 | ||
386 | /** | |
387 | * flush_workqueue - ensure that any scheduled work has run to completion. | |
388 | * @wq: workqueue to flush | |
389 | * | |
390 | * Forces execution of the workqueue and blocks until its completion. | |
391 | * This is typically used in driver shutdown handlers. | |
392 | * | |
393 | * We sleep until all works which were queued on entry have been handled, | |
394 | * but we are not livelocked by new incoming ones. | |
395 | * | |
396 | * This function used to run the workqueues itself. Now we just wait for the | |
397 | * helper threads to do it. | |
398 | */ | |
399 | void flush_workqueue(struct workqueue_struct *wq) | |
400 | { | |
401 | const struct cpumask *cpu_map = wq_cpu_map(wq); | |
402 | int cpu; | |
403 | ||
404 | might_sleep(); | |
405 | lock_map_acquire(&wq->lockdep_map); | |
406 | lock_map_release(&wq->lockdep_map); | |
407 | for_each_cpu(cpu, cpu_map) | |
408 | flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu)); | |
409 | } | |
410 | EXPORT_SYMBOL_GPL(flush_workqueue); | |
411 | ||
412 | /** | |
413 | * flush_work - block until a work_struct's callback has terminated | |
414 | * @work: the work which is to be flushed | |
415 | * | |
416 | * Returns false if @work has already terminated. | |
417 | * | |
418 | * It is expected that, prior to calling flush_work(), the caller has | |
419 | * arranged for the work to not be requeued, otherwise it doesn't make | |
420 | * sense to use this function. | |
421 | */ | |
422 | int flush_work(struct work_struct *work) | |
423 | { | |
424 | struct cpu_workqueue_struct *cwq; | |
425 | struct list_head *prev; | |
426 | struct wq_barrier barr; | |
427 | ||
428 | might_sleep(); | |
429 | cwq = get_wq_data(work); | |
430 | if (!cwq) | |
431 | return 0; | |
432 | ||
433 | lock_map_acquire(&cwq->wq->lockdep_map); | |
434 | lock_map_release(&cwq->wq->lockdep_map); | |
435 | ||
436 | prev = NULL; | |
437 | spin_lock_irq(&cwq->lock); | |
438 | if (!list_empty(&work->entry)) { | |
439 | /* | |
440 | * See the comment near try_to_grab_pending()->smp_rmb(). | |
441 | * If it was re-queued under us we are not going to wait. | |
442 | */ | |
443 | smp_rmb(); | |
444 | if (unlikely(cwq != get_wq_data(work))) | |
445 | goto out; | |
446 | prev = &work->entry; | |
447 | } else { | |
448 | if (cwq->current_work != work) | |
449 | goto out; | |
450 | prev = &cwq->worklist; | |
451 | } | |
452 | insert_wq_barrier(cwq, &barr, prev->next); | |
453 | out: | |
454 | spin_unlock_irq(&cwq->lock); | |
455 | if (!prev) | |
456 | return 0; | |
457 | ||
458 | wait_for_completion(&barr.done); | |
459 | return 1; | |
460 | } | |
461 | EXPORT_SYMBOL_GPL(flush_work); | |
462 | ||
463 | /* | |
464 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, | |
465 | * so this work can't be re-armed in any way. | |
466 | */ | |
467 | static int try_to_grab_pending(struct work_struct *work) | |
468 | { | |
469 | struct cpu_workqueue_struct *cwq; | |
470 | int ret = -1; | |
471 | ||
472 | if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) | |
473 | return 0; | |
474 | ||
475 | /* | |
476 | * The queueing is in progress, or it is already queued. Try to | |
477 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
478 | */ | |
479 | ||
480 | cwq = get_wq_data(work); | |
481 | if (!cwq) | |
482 | return ret; | |
483 | ||
484 | spin_lock_irq(&cwq->lock); | |
485 | if (!list_empty(&work->entry)) { | |
486 | /* | |
487 | * This work is queued, but perhaps we locked the wrong cwq. | |
488 | * In that case we must see the new value after rmb(), see | |
489 | * insert_work()->wmb(). | |
490 | */ | |
491 | smp_rmb(); | |
492 | if (cwq == get_wq_data(work)) { | |
493 | list_del_init(&work->entry); | |
494 | ret = 1; | |
495 | } | |
496 | } | |
497 | spin_unlock_irq(&cwq->lock); | |
498 | ||
499 | return ret; | |
500 | } | |
501 | ||
502 | static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, | |
503 | struct work_struct *work) | |
504 | { | |
505 | struct wq_barrier barr; | |
506 | int running = 0; | |
507 | ||
508 | spin_lock_irq(&cwq->lock); | |
509 | if (unlikely(cwq->current_work == work)) { | |
510 | insert_wq_barrier(cwq, &barr, cwq->worklist.next); | |
511 | running = 1; | |
512 | } | |
513 | spin_unlock_irq(&cwq->lock); | |
514 | ||
515 | if (unlikely(running)) | |
516 | wait_for_completion(&barr.done); | |
517 | } | |
518 | ||
519 | static void wait_on_work(struct work_struct *work) | |
520 | { | |
521 | struct cpu_workqueue_struct *cwq; | |
522 | struct workqueue_struct *wq; | |
523 | const struct cpumask *cpu_map; | |
524 | int cpu; | |
525 | ||
526 | might_sleep(); | |
527 | ||
528 | lock_map_acquire(&work->lockdep_map); | |
529 | lock_map_release(&work->lockdep_map); | |
530 | ||
531 | cwq = get_wq_data(work); | |
532 | if (!cwq) | |
533 | return; | |
534 | ||
535 | wq = cwq->wq; | |
536 | cpu_map = wq_cpu_map(wq); | |
537 | ||
538 | for_each_cpu(cpu, cpu_map) | |
539 | wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work); | |
540 | } | |
541 | ||
542 | static int __cancel_work_timer(struct work_struct *work, | |
543 | struct timer_list* timer) | |
544 | { | |
545 | int ret; | |
546 | ||
547 | do { | |
548 | ret = (timer && likely(del_timer(timer))); | |
549 | if (!ret) | |
550 | ret = try_to_grab_pending(work); | |
551 | wait_on_work(work); | |
552 | } while (unlikely(ret < 0)); | |
553 | ||
554 | work_clear_pending(work); | |
555 | return ret; | |
556 | } | |
557 | ||
558 | /** | |
559 | * cancel_work_sync - block until a work_struct's callback has terminated | |
560 | * @work: the work which is to be flushed | |
561 | * | |
562 | * Returns true if @work was pending. | |
563 | * | |
564 | * cancel_work_sync() will cancel the work if it is queued. If the work's | |
565 | * callback appears to be running, cancel_work_sync() will block until it | |
566 | * has completed. | |
567 | * | |
568 | * It is possible to use this function if the work re-queues itself. It can | |
569 | * cancel the work even if it migrates to another workqueue, however in that | |
570 | * case it only guarantees that work->func() has completed on the last queued | |
571 | * workqueue. | |
572 | * | |
573 | * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not | |
574 | * pending, otherwise it goes into a busy-wait loop until the timer expires. | |
575 | * | |
576 | * The caller must ensure that workqueue_struct on which this work was last | |
577 | * queued can't be destroyed before this function returns. | |
578 | */ | |
579 | int cancel_work_sync(struct work_struct *work) | |
580 | { | |
581 | return __cancel_work_timer(work, NULL); | |
582 | } | |
583 | EXPORT_SYMBOL_GPL(cancel_work_sync); | |
584 | ||
585 | /** | |
586 | * cancel_delayed_work_sync - reliably kill off a delayed work. | |
587 | * @dwork: the delayed work struct | |
588 | * | |
589 | * Returns true if @dwork was pending. | |
590 | * | |
591 | * It is possible to use this function if @dwork rearms itself via queue_work() | |
592 | * or queue_delayed_work(). See also the comment for cancel_work_sync(). | |
593 | */ | |
594 | int cancel_delayed_work_sync(struct delayed_work *dwork) | |
595 | { | |
596 | return __cancel_work_timer(&dwork->work, &dwork->timer); | |
597 | } | |
598 | EXPORT_SYMBOL(cancel_delayed_work_sync); | |
599 | ||
600 | static struct workqueue_struct *keventd_wq __read_mostly; | |
601 | ||
602 | /** | |
603 | * schedule_work - put work task in global workqueue | |
604 | * @work: job to be done | |
605 | * | |
606 | * This puts a job in the kernel-global workqueue. | |
607 | */ | |
608 | int schedule_work(struct work_struct *work) | |
609 | { | |
610 | return queue_work(keventd_wq, work); | |
611 | } | |
612 | EXPORT_SYMBOL(schedule_work); | |
613 | ||
614 | /* | |
615 | * schedule_work_on - put work task on a specific cpu | |
616 | * @cpu: cpu to put the work task on | |
617 | * @work: job to be done | |
618 | * | |
619 | * This puts a job on a specific cpu | |
620 | */ | |
621 | int schedule_work_on(int cpu, struct work_struct *work) | |
622 | { | |
623 | return queue_work_on(cpu, keventd_wq, work); | |
624 | } | |
625 | EXPORT_SYMBOL(schedule_work_on); | |
626 | ||
627 | /** | |
628 | * schedule_delayed_work - put work task in global workqueue after delay | |
629 | * @dwork: job to be done | |
630 | * @delay: number of jiffies to wait or 0 for immediate execution | |
631 | * | |
632 | * After waiting for a given time this puts a job in the kernel-global | |
633 | * workqueue. | |
634 | */ | |
635 | int schedule_delayed_work(struct delayed_work *dwork, | |
636 | unsigned long delay) | |
637 | { | |
638 | return queue_delayed_work(keventd_wq, dwork, delay); | |
639 | } | |
640 | EXPORT_SYMBOL(schedule_delayed_work); | |
641 | ||
642 | /** | |
643 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay | |
644 | * @cpu: cpu to use | |
645 | * @dwork: job to be done | |
646 | * @delay: number of jiffies to wait | |
647 | * | |
648 | * After waiting for a given time this puts a job in the kernel-global | |
649 | * workqueue on the specified CPU. | |
650 | */ | |
651 | int schedule_delayed_work_on(int cpu, | |
652 | struct delayed_work *dwork, unsigned long delay) | |
653 | { | |
654 | return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); | |
655 | } | |
656 | EXPORT_SYMBOL(schedule_delayed_work_on); | |
657 | ||
658 | /** | |
659 | * schedule_on_each_cpu - call a function on each online CPU from keventd | |
660 | * @func: the function to call | |
661 | * | |
662 | * Returns zero on success. | |
663 | * Returns -ve errno on failure. | |
664 | * | |
665 | * schedule_on_each_cpu() is very slow. | |
666 | */ | |
667 | int schedule_on_each_cpu(work_func_t func) | |
668 | { | |
669 | int cpu; | |
670 | struct work_struct *works; | |
671 | ||
672 | works = alloc_percpu(struct work_struct); | |
673 | if (!works) | |
674 | return -ENOMEM; | |
675 | ||
676 | get_online_cpus(); | |
677 | for_each_online_cpu(cpu) { | |
678 | struct work_struct *work = per_cpu_ptr(works, cpu); | |
679 | ||
680 | INIT_WORK(work, func); | |
681 | schedule_work_on(cpu, work); | |
682 | } | |
683 | for_each_online_cpu(cpu) | |
684 | flush_work(per_cpu_ptr(works, cpu)); | |
685 | put_online_cpus(); | |
686 | free_percpu(works); | |
687 | return 0; | |
688 | } | |
689 | ||
690 | void flush_scheduled_work(void) | |
691 | { | |
692 | flush_workqueue(keventd_wq); | |
693 | } | |
694 | EXPORT_SYMBOL(flush_scheduled_work); | |
695 | ||
696 | /** | |
697 | * execute_in_process_context - reliably execute the routine with user context | |
698 | * @fn: the function to execute | |
699 | * @ew: guaranteed storage for the execute work structure (must | |
700 | * be available when the work executes) | |
701 | * | |
702 | * Executes the function immediately if process context is available, | |
703 | * otherwise schedules the function for delayed execution. | |
704 | * | |
705 | * Returns: 0 - function was executed | |
706 | * 1 - function was scheduled for execution | |
707 | */ | |
708 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) | |
709 | { | |
710 | if (!in_interrupt()) { | |
711 | fn(&ew->work); | |
712 | return 0; | |
713 | } | |
714 | ||
715 | INIT_WORK(&ew->work, fn); | |
716 | schedule_work(&ew->work); | |
717 | ||
718 | return 1; | |
719 | } | |
720 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
721 | ||
722 | int keventd_up(void) | |
723 | { | |
724 | return keventd_wq != NULL; | |
725 | } | |
726 | ||
727 | int current_is_keventd(void) | |
728 | { | |
729 | struct cpu_workqueue_struct *cwq; | |
730 | int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ | |
731 | int ret = 0; | |
732 | ||
733 | BUG_ON(!keventd_wq); | |
734 | ||
735 | cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu); | |
736 | if (current == cwq->thread) | |
737 | ret = 1; | |
738 | ||
739 | return ret; | |
740 | ||
741 | } | |
742 | ||
743 | static struct cpu_workqueue_struct * | |
744 | init_cpu_workqueue(struct workqueue_struct *wq, int cpu) | |
745 | { | |
746 | struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); | |
747 | ||
748 | cwq->wq = wq; | |
749 | spin_lock_init(&cwq->lock); | |
750 | INIT_LIST_HEAD(&cwq->worklist); | |
751 | init_waitqueue_head(&cwq->more_work); | |
752 | ||
753 | return cwq; | |
754 | } | |
755 | ||
756 | DEFINE_TRACE(workqueue_creation); | |
757 | ||
758 | static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) | |
759 | { | |
760 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
761 | struct workqueue_struct *wq = cwq->wq; | |
762 | const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d"; | |
763 | struct task_struct *p; | |
764 | ||
765 | p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu); | |
766 | /* | |
767 | * Nobody can add the work_struct to this cwq, | |
768 | * if (caller is __create_workqueue) | |
769 | * nobody should see this wq | |
770 | * else // caller is CPU_UP_PREPARE | |
771 | * cpu is not on cpu_online_map | |
772 | * so we can abort safely. | |
773 | */ | |
774 | if (IS_ERR(p)) | |
775 | return PTR_ERR(p); | |
776 | if (cwq->wq->rt) | |
777 | sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); | |
778 | cwq->thread = p; | |
779 | ||
780 | trace_workqueue_creation(cwq->thread, cpu); | |
781 | ||
782 | return 0; | |
783 | } | |
784 | ||
785 | static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) | |
786 | { | |
787 | struct task_struct *p = cwq->thread; | |
788 | ||
789 | if (p != NULL) { | |
790 | if (cpu >= 0) | |
791 | kthread_bind(p, cpu); | |
792 | wake_up_process(p); | |
793 | } | |
794 | } | |
795 | ||
796 | struct workqueue_struct *__create_workqueue_key(const char *name, | |
797 | int singlethread, | |
798 | int freezeable, | |
799 | int rt, | |
800 | struct lock_class_key *key, | |
801 | const char *lock_name) | |
802 | { | |
803 | struct workqueue_struct *wq; | |
804 | struct cpu_workqueue_struct *cwq; | |
805 | int err = 0, cpu; | |
806 | ||
807 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); | |
808 | if (!wq) | |
809 | return NULL; | |
810 | ||
811 | wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); | |
812 | if (!wq->cpu_wq) { | |
813 | kfree(wq); | |
814 | return NULL; | |
815 | } | |
816 | ||
817 | wq->name = name; | |
818 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); | |
819 | wq->singlethread = singlethread; | |
820 | wq->freezeable = freezeable; | |
821 | wq->rt = rt; | |
822 | INIT_LIST_HEAD(&wq->list); | |
823 | ||
824 | if (singlethread) { | |
825 | cwq = init_cpu_workqueue(wq, singlethread_cpu); | |
826 | err = create_workqueue_thread(cwq, singlethread_cpu); | |
827 | start_workqueue_thread(cwq, -1); | |
828 | } else { | |
829 | cpu_maps_update_begin(); | |
830 | /* | |
831 | * We must place this wq on list even if the code below fails. | |
832 | * cpu_down(cpu) can remove cpu from cpu_populated_map before | |
833 | * destroy_workqueue() takes the lock, in that case we leak | |
834 | * cwq[cpu]->thread. | |
835 | */ | |
836 | spin_lock(&workqueue_lock); | |
837 | list_add(&wq->list, &workqueues); | |
838 | spin_unlock(&workqueue_lock); | |
839 | /* | |
840 | * We must initialize cwqs for each possible cpu even if we | |
841 | * are going to call destroy_workqueue() finally. Otherwise | |
842 | * cpu_up() can hit the uninitialized cwq once we drop the | |
843 | * lock. | |
844 | */ | |
845 | for_each_possible_cpu(cpu) { | |
846 | cwq = init_cpu_workqueue(wq, cpu); | |
847 | if (err || !cpu_online(cpu)) | |
848 | continue; | |
849 | err = create_workqueue_thread(cwq, cpu); | |
850 | start_workqueue_thread(cwq, cpu); | |
851 | } | |
852 | cpu_maps_update_done(); | |
853 | } | |
854 | ||
855 | if (err) { | |
856 | destroy_workqueue(wq); | |
857 | wq = NULL; | |
858 | } | |
859 | return wq; | |
860 | } | |
861 | EXPORT_SYMBOL_GPL(__create_workqueue_key); | |
862 | ||
863 | DEFINE_TRACE(workqueue_destruction); | |
864 | ||
865 | static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) | |
866 | { | |
867 | /* | |
868 | * Our caller is either destroy_workqueue() or CPU_POST_DEAD, | |
869 | * cpu_add_remove_lock protects cwq->thread. | |
870 | */ | |
871 | if (cwq->thread == NULL) | |
872 | return; | |
873 | ||
874 | lock_map_acquire(&cwq->wq->lockdep_map); | |
875 | lock_map_release(&cwq->wq->lockdep_map); | |
876 | ||
877 | flush_cpu_workqueue(cwq); | |
878 | /* | |
879 | * If the caller is CPU_POST_DEAD and cwq->worklist was not empty, | |
880 | * a concurrent flush_workqueue() can insert a barrier after us. | |
881 | * However, in that case run_workqueue() won't return and check | |
882 | * kthread_should_stop() until it flushes all work_struct's. | |
883 | * When ->worklist becomes empty it is safe to exit because no | |
884 | * more work_structs can be queued on this cwq: flush_workqueue | |
885 | * checks list_empty(), and a "normal" queue_work() can't use | |
886 | * a dead CPU. | |
887 | */ | |
888 | trace_workqueue_destruction(cwq->thread); | |
889 | kthread_stop(cwq->thread); | |
890 | cwq->thread = NULL; | |
891 | } | |
892 | ||
893 | /** | |
894 | * destroy_workqueue - safely terminate a workqueue | |
895 | * @wq: target workqueue | |
896 | * | |
897 | * Safely destroy a workqueue. All work currently pending will be done first. | |
898 | */ | |
899 | void destroy_workqueue(struct workqueue_struct *wq) | |
900 | { | |
901 | const struct cpumask *cpu_map = wq_cpu_map(wq); | |
902 | int cpu; | |
903 | ||
904 | cpu_maps_update_begin(); | |
905 | spin_lock(&workqueue_lock); | |
906 | list_del(&wq->list); | |
907 | spin_unlock(&workqueue_lock); | |
908 | ||
909 | for_each_cpu(cpu, cpu_map) | |
910 | cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); | |
911 | cpu_maps_update_done(); | |
912 | ||
913 | free_percpu(wq->cpu_wq); | |
914 | kfree(wq); | |
915 | } | |
916 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
917 | ||
918 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, | |
919 | unsigned long action, | |
920 | void *hcpu) | |
921 | { | |
922 | unsigned int cpu = (unsigned long)hcpu; | |
923 | struct cpu_workqueue_struct *cwq; | |
924 | struct workqueue_struct *wq; | |
925 | int ret = NOTIFY_OK; | |
926 | ||
927 | action &= ~CPU_TASKS_FROZEN; | |
928 | ||
929 | switch (action) { | |
930 | case CPU_UP_PREPARE: | |
931 | cpumask_set_cpu(cpu, cpu_populated_map); | |
932 | } | |
933 | undo: | |
934 | list_for_each_entry(wq, &workqueues, list) { | |
935 | cwq = per_cpu_ptr(wq->cpu_wq, cpu); | |
936 | ||
937 | switch (action) { | |
938 | case CPU_UP_PREPARE: | |
939 | if (!create_workqueue_thread(cwq, cpu)) | |
940 | break; | |
941 | printk(KERN_ERR "workqueue [%s] for %i failed\n", | |
942 | wq->name, cpu); | |
943 | action = CPU_UP_CANCELED; | |
944 | ret = NOTIFY_BAD; | |
945 | goto undo; | |
946 | ||
947 | case CPU_ONLINE: | |
948 | start_workqueue_thread(cwq, cpu); | |
949 | break; | |
950 | ||
951 | case CPU_UP_CANCELED: | |
952 | start_workqueue_thread(cwq, -1); | |
953 | case CPU_POST_DEAD: | |
954 | cleanup_workqueue_thread(cwq); | |
955 | break; | |
956 | } | |
957 | } | |
958 | ||
959 | switch (action) { | |
960 | case CPU_UP_CANCELED: | |
961 | case CPU_POST_DEAD: | |
962 | cpumask_clear_cpu(cpu, cpu_populated_map); | |
963 | } | |
964 | ||
965 | return ret; | |
966 | } | |
967 | ||
968 | #ifdef CONFIG_SMP | |
969 | static struct workqueue_struct *work_on_cpu_wq __read_mostly; | |
970 | ||
971 | struct work_for_cpu { | |
972 | struct work_struct work; | |
973 | long (*fn)(void *); | |
974 | void *arg; | |
975 | long ret; | |
976 | }; | |
977 | ||
978 | static void do_work_for_cpu(struct work_struct *w) | |
979 | { | |
980 | struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work); | |
981 | ||
982 | wfc->ret = wfc->fn(wfc->arg); | |
983 | } | |
984 | ||
985 | /** | |
986 | * work_on_cpu - run a function in user context on a particular cpu | |
987 | * @cpu: the cpu to run on | |
988 | * @fn: the function to run | |
989 | * @arg: the function arg | |
990 | * | |
991 | * This will return the value @fn returns. | |
992 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
993 | */ | |
994 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) | |
995 | { | |
996 | struct work_for_cpu wfc; | |
997 | ||
998 | INIT_WORK(&wfc.work, do_work_for_cpu); | |
999 | wfc.fn = fn; | |
1000 | wfc.arg = arg; | |
1001 | queue_work_on(cpu, work_on_cpu_wq, &wfc.work); | |
1002 | flush_work(&wfc.work); | |
1003 | ||
1004 | return wfc.ret; | |
1005 | } | |
1006 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
1007 | #endif /* CONFIG_SMP */ | |
1008 | ||
1009 | void __init init_workqueues(void) | |
1010 | { | |
1011 | alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL); | |
1012 | ||
1013 | cpumask_copy(cpu_populated_map, cpu_online_mask); | |
1014 | singlethread_cpu = cpumask_first(cpu_possible_mask); | |
1015 | cpu_singlethread_map = cpumask_of(singlethread_cpu); | |
1016 | hotcpu_notifier(workqueue_cpu_callback, 0); | |
1017 | keventd_wq = create_workqueue("events"); | |
1018 | BUG_ON(!keventd_wq); | |
1019 | #ifdef CONFIG_SMP | |
1020 | work_on_cpu_wq = create_workqueue("work_on_cpu"); | |
1021 | BUG_ON(!work_on_cpu_wq); | |
1022 | #endif | |
1023 | } |