Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / workqueue.c
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 <andrewm@uow.edu.au>
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
37 /*
38 * The per-CPU workqueue (if single thread, we always use the first
39 * possible cpu).
40 */
41 struct cpu_workqueue_struct {
42
43 spinlock_t lock;
44
45 struct list_head worklist;
46 wait_queue_head_t more_work;
47 struct work_struct *current_work;
48
49 struct workqueue_struct *wq;
50 struct task_struct *thread;
51
52 int run_depth; /* Detect run_workqueue() recursion depth */
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 #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 cpumask_t 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_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_single_threaded(struct workqueue_struct *wq)
87 {
88 return wq->singlethread;
89 }
90
91 static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
92 {
93 return is_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_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 static void insert_work(struct cpu_workqueue_struct *cwq,
128 struct work_struct *work, int tail)
129 {
130 set_wq_data(work, cwq);
131 /*
132 * Ensure that we get the right work->data if we see the
133 * result of list_add() below, see try_to_grab_pending().
134 */
135 smp_wmb();
136 if (tail)
137 list_add_tail(&work->entry, &cwq->worklist);
138 else
139 list_add(&work->entry, &cwq->worklist);
140 wake_up(&cwq->more_work);
141 }
142
143 static void __queue_work(struct cpu_workqueue_struct *cwq,
144 struct work_struct *work)
145 {
146 unsigned long flags;
147
148 spin_lock_irqsave(&cwq->lock, flags);
149 insert_work(cwq, work, 1);
150 spin_unlock_irqrestore(&cwq->lock, flags);
151 }
152
153 /**
154 * queue_work - queue work on a workqueue
155 * @wq: workqueue to use
156 * @work: work to queue
157 *
158 * Returns 0 if @work was already on a queue, non-zero otherwise.
159 *
160 * We queue the work to the CPU on which it was submitted, but if the CPU dies
161 * it can be processed by another CPU.
162 */
163 int queue_work(struct workqueue_struct *wq, struct work_struct *work)
164 {
165 int ret = 0;
166
167 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
168 BUG_ON(!list_empty(&work->entry));
169 __queue_work(wq_per_cpu(wq, get_cpu()), work);
170 put_cpu();
171 ret = 1;
172 }
173 return ret;
174 }
175 EXPORT_SYMBOL_GPL(queue_work);
176
177 /**
178 * queue_work_on - queue work on specific cpu
179 * @cpu: CPU number to execute work on
180 * @wq: workqueue to use
181 * @work: work to queue
182 *
183 * Returns 0 if @work was already on a queue, non-zero otherwise.
184 *
185 * We queue the work to a specific CPU, the caller must ensure it
186 * can't go away.
187 */
188 int
189 queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
190 {
191 int ret = 0;
192
193 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
194 BUG_ON(!list_empty(&work->entry));
195 __queue_work(wq_per_cpu(wq, cpu), work);
196 ret = 1;
197 }
198 return ret;
199 }
200 EXPORT_SYMBOL_GPL(queue_work_on);
201
202 static void delayed_work_timer_fn(unsigned long __data)
203 {
204 struct delayed_work *dwork = (struct delayed_work *)__data;
205 struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
206 struct workqueue_struct *wq = cwq->wq;
207
208 __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
209 }
210
211 /**
212 * queue_delayed_work - queue work on a workqueue after delay
213 * @wq: workqueue to use
214 * @dwork: delayable work to queue
215 * @delay: number of jiffies to wait before queueing
216 *
217 * Returns 0 if @work was already on a queue, non-zero otherwise.
218 */
219 int queue_delayed_work(struct workqueue_struct *wq,
220 struct delayed_work *dwork, unsigned long delay)
221 {
222 if (delay == 0)
223 return queue_work(wq, &dwork->work);
224
225 return queue_delayed_work_on(-1, wq, dwork, delay);
226 }
227 EXPORT_SYMBOL_GPL(queue_delayed_work);
228
229 /**
230 * queue_delayed_work_on - queue work on specific CPU after delay
231 * @cpu: CPU number to execute work on
232 * @wq: workqueue to use
233 * @dwork: work to queue
234 * @delay: number of jiffies to wait before queueing
235 *
236 * Returns 0 if @work was already on a queue, non-zero otherwise.
237 */
238 int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
239 struct delayed_work *dwork, unsigned long delay)
240 {
241 int ret = 0;
242 struct timer_list *timer = &dwork->timer;
243 struct work_struct *work = &dwork->work;
244
245 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
246 BUG_ON(timer_pending(timer));
247 BUG_ON(!list_empty(&work->entry));
248
249 timer_stats_timer_set_start_info(&dwork->timer);
250
251 /* This stores cwq for the moment, for the timer_fn */
252 set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id()));
253 timer->expires = jiffies + delay;
254 timer->data = (unsigned long)dwork;
255 timer->function = delayed_work_timer_fn;
256
257 if (unlikely(cpu >= 0))
258 add_timer_on(timer, cpu);
259 else
260 add_timer(timer);
261 ret = 1;
262 }
263 return ret;
264 }
265 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
266
267 static void run_workqueue(struct cpu_workqueue_struct *cwq)
268 {
269 spin_lock_irq(&cwq->lock);
270 cwq->run_depth++;
271 if (cwq->run_depth > 3) {
272 /* morton gets to eat his hat */
273 printk("%s: recursion depth exceeded: %d\n",
274 __func__, cwq->run_depth);
275 dump_stack();
276 }
277 while (!list_empty(&cwq->worklist)) {
278 struct work_struct *work = list_entry(cwq->worklist.next,
279 struct work_struct, entry);
280 work_func_t f = work->func;
281 #ifdef CONFIG_LOCKDEP
282 /*
283 * It is permissible to free the struct work_struct
284 * from inside the function that is called from it,
285 * this we need to take into account for lockdep too.
286 * To avoid bogus "held lock freed" warnings as well
287 * as problems when looking into work->lockdep_map,
288 * make a copy and use that here.
289 */
290 struct lockdep_map lockdep_map = work->lockdep_map;
291 #endif
292
293 cwq->current_work = work;
294 list_del_init(cwq->worklist.next);
295 spin_unlock_irq(&cwq->lock);
296
297 BUG_ON(get_wq_data(work) != cwq);
298 work_clear_pending(work);
299 lock_acquire(&cwq->wq->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
300 lock_acquire(&lockdep_map, 0, 0, 0, 2, _THIS_IP_);
301 f(work);
302 lock_release(&lockdep_map, 1, _THIS_IP_);
303 lock_release(&cwq->wq->lockdep_map, 1, _THIS_IP_);
304
305 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
306 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
307 "%s/0x%08x/%d\n",
308 current->comm, preempt_count(),
309 task_pid_nr(current));
310 printk(KERN_ERR " last function: ");
311 print_symbol("%s\n", (unsigned long)f);
312 debug_show_held_locks(current);
313 dump_stack();
314 }
315
316 spin_lock_irq(&cwq->lock);
317 cwq->current_work = NULL;
318 }
319 cwq->run_depth--;
320 spin_unlock_irq(&cwq->lock);
321 }
322
323 static int worker_thread(void *__cwq)
324 {
325 struct cpu_workqueue_struct *cwq = __cwq;
326 DEFINE_WAIT(wait);
327
328 if (cwq->wq->freezeable)
329 set_freezable();
330
331 set_user_nice(current, -5);
332
333 for (;;) {
334 prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
335 if (!freezing(current) &&
336 !kthread_should_stop() &&
337 list_empty(&cwq->worklist))
338 schedule();
339 finish_wait(&cwq->more_work, &wait);
340
341 try_to_freeze();
342
343 if (kthread_should_stop())
344 break;
345
346 run_workqueue(cwq);
347 }
348
349 return 0;
350 }
351
352 struct wq_barrier {
353 struct work_struct work;
354 struct completion done;
355 };
356
357 static void wq_barrier_func(struct work_struct *work)
358 {
359 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
360 complete(&barr->done);
361 }
362
363 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
364 struct wq_barrier *barr, int tail)
365 {
366 INIT_WORK(&barr->work, wq_barrier_func);
367 __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
368
369 init_completion(&barr->done);
370
371 insert_work(cwq, &barr->work, tail);
372 }
373
374 static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
375 {
376 int active;
377
378 if (cwq->thread == current) {
379 /*
380 * Probably keventd trying to flush its own queue. So simply run
381 * it by hand rather than deadlocking.
382 */
383 run_workqueue(cwq);
384 active = 1;
385 } else {
386 struct wq_barrier barr;
387
388 active = 0;
389 spin_lock_irq(&cwq->lock);
390 if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
391 insert_wq_barrier(cwq, &barr, 1);
392 active = 1;
393 }
394 spin_unlock_irq(&cwq->lock);
395
396 if (active)
397 wait_for_completion(&barr.done);
398 }
399
400 return active;
401 }
402
403 /**
404 * flush_workqueue - ensure that any scheduled work has run to completion.
405 * @wq: workqueue to flush
406 *
407 * Forces execution of the workqueue and blocks until its completion.
408 * This is typically used in driver shutdown handlers.
409 *
410 * We sleep until all works which were queued on entry have been handled,
411 * but we are not livelocked by new incoming ones.
412 *
413 * This function used to run the workqueues itself. Now we just wait for the
414 * helper threads to do it.
415 */
416 void flush_workqueue(struct workqueue_struct *wq)
417 {
418 const cpumask_t *cpu_map = wq_cpu_map(wq);
419 int cpu;
420
421 might_sleep();
422 lock_acquire(&wq->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
423 lock_release(&wq->lockdep_map, 1, _THIS_IP_);
424 for_each_cpu_mask_nr(cpu, *cpu_map)
425 flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
426 }
427 EXPORT_SYMBOL_GPL(flush_workqueue);
428
429 /*
430 * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
431 * so this work can't be re-armed in any way.
432 */
433 static int try_to_grab_pending(struct work_struct *work)
434 {
435 struct cpu_workqueue_struct *cwq;
436 int ret = -1;
437
438 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
439 return 0;
440
441 /*
442 * The queueing is in progress, or it is already queued. Try to
443 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
444 */
445
446 cwq = get_wq_data(work);
447 if (!cwq)
448 return ret;
449
450 spin_lock_irq(&cwq->lock);
451 if (!list_empty(&work->entry)) {
452 /*
453 * This work is queued, but perhaps we locked the wrong cwq.
454 * In that case we must see the new value after rmb(), see
455 * insert_work()->wmb().
456 */
457 smp_rmb();
458 if (cwq == get_wq_data(work)) {
459 list_del_init(&work->entry);
460 ret = 1;
461 }
462 }
463 spin_unlock_irq(&cwq->lock);
464
465 return ret;
466 }
467
468 static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
469 struct work_struct *work)
470 {
471 struct wq_barrier barr;
472 int running = 0;
473
474 spin_lock_irq(&cwq->lock);
475 if (unlikely(cwq->current_work == work)) {
476 insert_wq_barrier(cwq, &barr, 0);
477 running = 1;
478 }
479 spin_unlock_irq(&cwq->lock);
480
481 if (unlikely(running))
482 wait_for_completion(&barr.done);
483 }
484
485 static void wait_on_work(struct work_struct *work)
486 {
487 struct cpu_workqueue_struct *cwq;
488 struct workqueue_struct *wq;
489 const cpumask_t *cpu_map;
490 int cpu;
491
492 might_sleep();
493
494 lock_acquire(&work->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
495 lock_release(&work->lockdep_map, 1, _THIS_IP_);
496
497 cwq = get_wq_data(work);
498 if (!cwq)
499 return;
500
501 wq = cwq->wq;
502 cpu_map = wq_cpu_map(wq);
503
504 for_each_cpu_mask_nr(cpu, *cpu_map)
505 wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
506 }
507
508 static int __cancel_work_timer(struct work_struct *work,
509 struct timer_list* timer)
510 {
511 int ret;
512
513 do {
514 ret = (timer && likely(del_timer(timer)));
515 if (!ret)
516 ret = try_to_grab_pending(work);
517 wait_on_work(work);
518 } while (unlikely(ret < 0));
519
520 work_clear_pending(work);
521 return ret;
522 }
523
524 /**
525 * cancel_work_sync - block until a work_struct's callback has terminated
526 * @work: the work which is to be flushed
527 *
528 * Returns true if @work was pending.
529 *
530 * cancel_work_sync() will cancel the work if it is queued. If the work's
531 * callback appears to be running, cancel_work_sync() will block until it
532 * has completed.
533 *
534 * It is possible to use this function if the work re-queues itself. It can
535 * cancel the work even if it migrates to another workqueue, however in that
536 * case it only guarantees that work->func() has completed on the last queued
537 * workqueue.
538 *
539 * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not
540 * pending, otherwise it goes into a busy-wait loop until the timer expires.
541 *
542 * The caller must ensure that workqueue_struct on which this work was last
543 * queued can't be destroyed before this function returns.
544 */
545 int cancel_work_sync(struct work_struct *work)
546 {
547 return __cancel_work_timer(work, NULL);
548 }
549 EXPORT_SYMBOL_GPL(cancel_work_sync);
550
551 /**
552 * cancel_delayed_work_sync - reliably kill off a delayed work.
553 * @dwork: the delayed work struct
554 *
555 * Returns true if @dwork was pending.
556 *
557 * It is possible to use this function if @dwork rearms itself via queue_work()
558 * or queue_delayed_work(). See also the comment for cancel_work_sync().
559 */
560 int cancel_delayed_work_sync(struct delayed_work *dwork)
561 {
562 return __cancel_work_timer(&dwork->work, &dwork->timer);
563 }
564 EXPORT_SYMBOL(cancel_delayed_work_sync);
565
566 static struct workqueue_struct *keventd_wq __read_mostly;
567
568 /**
569 * schedule_work - put work task in global workqueue
570 * @work: job to be done
571 *
572 * This puts a job in the kernel-global workqueue.
573 */
574 int schedule_work(struct work_struct *work)
575 {
576 return queue_work(keventd_wq, work);
577 }
578 EXPORT_SYMBOL(schedule_work);
579
580 /*
581 * schedule_work_on - put work task on a specific cpu
582 * @cpu: cpu to put the work task on
583 * @work: job to be done
584 *
585 * This puts a job on a specific cpu
586 */
587 int schedule_work_on(int cpu, struct work_struct *work)
588 {
589 return queue_work_on(cpu, keventd_wq, work);
590 }
591 EXPORT_SYMBOL(schedule_work_on);
592
593 /**
594 * schedule_delayed_work - put work task in global workqueue after delay
595 * @dwork: job to be done
596 * @delay: number of jiffies to wait or 0 for immediate execution
597 *
598 * After waiting for a given time this puts a job in the kernel-global
599 * workqueue.
600 */
601 int schedule_delayed_work(struct delayed_work *dwork,
602 unsigned long delay)
603 {
604 return queue_delayed_work(keventd_wq, dwork, delay);
605 }
606 EXPORT_SYMBOL(schedule_delayed_work);
607
608 /**
609 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
610 * @cpu: cpu to use
611 * @dwork: job to be done
612 * @delay: number of jiffies to wait
613 *
614 * After waiting for a given time this puts a job in the kernel-global
615 * workqueue on the specified CPU.
616 */
617 int schedule_delayed_work_on(int cpu,
618 struct delayed_work *dwork, unsigned long delay)
619 {
620 return queue_delayed_work_on(cpu, keventd_wq, dwork, delay);
621 }
622 EXPORT_SYMBOL(schedule_delayed_work_on);
623
624 /**
625 * schedule_on_each_cpu - call a function on each online CPU from keventd
626 * @func: the function to call
627 *
628 * Returns zero on success.
629 * Returns -ve errno on failure.
630 *
631 * schedule_on_each_cpu() is very slow.
632 */
633 int schedule_on_each_cpu(work_func_t func)
634 {
635 int cpu;
636 struct work_struct *works;
637
638 works = alloc_percpu(struct work_struct);
639 if (!works)
640 return -ENOMEM;
641
642 get_online_cpus();
643 for_each_online_cpu(cpu) {
644 struct work_struct *work = per_cpu_ptr(works, cpu);
645
646 INIT_WORK(work, func);
647 set_bit(WORK_STRUCT_PENDING, work_data_bits(work));
648 __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), work);
649 }
650 flush_workqueue(keventd_wq);
651 put_online_cpus();
652 free_percpu(works);
653 return 0;
654 }
655
656 void flush_scheduled_work(void)
657 {
658 flush_workqueue(keventd_wq);
659 }
660 EXPORT_SYMBOL(flush_scheduled_work);
661
662 /**
663 * execute_in_process_context - reliably execute the routine with user context
664 * @fn: the function to execute
665 * @ew: guaranteed storage for the execute work structure (must
666 * be available when the work executes)
667 *
668 * Executes the function immediately if process context is available,
669 * otherwise schedules the function for delayed execution.
670 *
671 * Returns: 0 - function was executed
672 * 1 - function was scheduled for execution
673 */
674 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
675 {
676 if (!in_interrupt()) {
677 fn(&ew->work);
678 return 0;
679 }
680
681 INIT_WORK(&ew->work, fn);
682 schedule_work(&ew->work);
683
684 return 1;
685 }
686 EXPORT_SYMBOL_GPL(execute_in_process_context);
687
688 int keventd_up(void)
689 {
690 return keventd_wq != NULL;
691 }
692
693 int current_is_keventd(void)
694 {
695 struct cpu_workqueue_struct *cwq;
696 int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */
697 int ret = 0;
698
699 BUG_ON(!keventd_wq);
700
701 cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu);
702 if (current == cwq->thread)
703 ret = 1;
704
705 return ret;
706
707 }
708
709 static struct cpu_workqueue_struct *
710 init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
711 {
712 struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
713
714 cwq->wq = wq;
715 spin_lock_init(&cwq->lock);
716 INIT_LIST_HEAD(&cwq->worklist);
717 init_waitqueue_head(&cwq->more_work);
718
719 return cwq;
720 }
721
722 static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
723 {
724 struct workqueue_struct *wq = cwq->wq;
725 const char *fmt = is_single_threaded(wq) ? "%s" : "%s/%d";
726 struct task_struct *p;
727
728 p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
729 /*
730 * Nobody can add the work_struct to this cwq,
731 * if (caller is __create_workqueue)
732 * nobody should see this wq
733 * else // caller is CPU_UP_PREPARE
734 * cpu is not on cpu_online_map
735 * so we can abort safely.
736 */
737 if (IS_ERR(p))
738 return PTR_ERR(p);
739
740 cwq->thread = p;
741
742 return 0;
743 }
744
745 static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
746 {
747 struct task_struct *p = cwq->thread;
748
749 if (p != NULL) {
750 if (cpu >= 0)
751 kthread_bind(p, cpu);
752 wake_up_process(p);
753 }
754 }
755
756 struct workqueue_struct *__create_workqueue_key(const char *name,
757 int singlethread,
758 int freezeable,
759 struct lock_class_key *key,
760 const char *lock_name)
761 {
762 struct workqueue_struct *wq;
763 struct cpu_workqueue_struct *cwq;
764 int err = 0, cpu;
765
766 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
767 if (!wq)
768 return NULL;
769
770 wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
771 if (!wq->cpu_wq) {
772 kfree(wq);
773 return NULL;
774 }
775
776 wq->name = name;
777 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
778 wq->singlethread = singlethread;
779 wq->freezeable = freezeable;
780 INIT_LIST_HEAD(&wq->list);
781
782 if (singlethread) {
783 cwq = init_cpu_workqueue(wq, singlethread_cpu);
784 err = create_workqueue_thread(cwq, singlethread_cpu);
785 start_workqueue_thread(cwq, -1);
786 } else {
787 get_online_cpus();
788 spin_lock(&workqueue_lock);
789 list_add(&wq->list, &workqueues);
790 spin_unlock(&workqueue_lock);
791
792 for_each_possible_cpu(cpu) {
793 cwq = init_cpu_workqueue(wq, cpu);
794 if (err || !cpu_online(cpu))
795 continue;
796 err = create_workqueue_thread(cwq, cpu);
797 start_workqueue_thread(cwq, cpu);
798 }
799 put_online_cpus();
800 }
801
802 if (err) {
803 destroy_workqueue(wq);
804 wq = NULL;
805 }
806 return wq;
807 }
808 EXPORT_SYMBOL_GPL(__create_workqueue_key);
809
810 static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
811 {
812 /*
813 * Our caller is either destroy_workqueue() or CPU_DEAD,
814 * get_online_cpus() protects cwq->thread.
815 */
816 if (cwq->thread == NULL)
817 return;
818
819 lock_acquire(&cwq->wq->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
820 lock_release(&cwq->wq->lockdep_map, 1, _THIS_IP_);
821
822 flush_cpu_workqueue(cwq);
823 /*
824 * If the caller is CPU_DEAD and cwq->worklist was not empty,
825 * a concurrent flush_workqueue() can insert a barrier after us.
826 * However, in that case run_workqueue() won't return and check
827 * kthread_should_stop() until it flushes all work_struct's.
828 * When ->worklist becomes empty it is safe to exit because no
829 * more work_structs can be queued on this cwq: flush_workqueue
830 * checks list_empty(), and a "normal" queue_work() can't use
831 * a dead CPU.
832 */
833 kthread_stop(cwq->thread);
834 cwq->thread = NULL;
835 }
836
837 /**
838 * destroy_workqueue - safely terminate a workqueue
839 * @wq: target workqueue
840 *
841 * Safely destroy a workqueue. All work currently pending will be done first.
842 */
843 void destroy_workqueue(struct workqueue_struct *wq)
844 {
845 const cpumask_t *cpu_map = wq_cpu_map(wq);
846 int cpu;
847
848 get_online_cpus();
849 spin_lock(&workqueue_lock);
850 list_del(&wq->list);
851 spin_unlock(&workqueue_lock);
852
853 for_each_cpu_mask_nr(cpu, *cpu_map)
854 cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu));
855 put_online_cpus();
856
857 free_percpu(wq->cpu_wq);
858 kfree(wq);
859 }
860 EXPORT_SYMBOL_GPL(destroy_workqueue);
861
862 static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
863 unsigned long action,
864 void *hcpu)
865 {
866 unsigned int cpu = (unsigned long)hcpu;
867 struct cpu_workqueue_struct *cwq;
868 struct workqueue_struct *wq;
869
870 action &= ~CPU_TASKS_FROZEN;
871
872 switch (action) {
873 case CPU_UP_PREPARE:
874 cpu_set(cpu, cpu_populated_map);
875 }
876
877 list_for_each_entry(wq, &workqueues, list) {
878 cwq = per_cpu_ptr(wq->cpu_wq, cpu);
879
880 switch (action) {
881 case CPU_UP_PREPARE:
882 if (!create_workqueue_thread(cwq, cpu))
883 break;
884 printk(KERN_ERR "workqueue [%s] for %i failed\n",
885 wq->name, cpu);
886 return NOTIFY_BAD;
887
888 case CPU_ONLINE:
889 start_workqueue_thread(cwq, cpu);
890 break;
891
892 case CPU_UP_CANCELED:
893 start_workqueue_thread(cwq, -1);
894 case CPU_DEAD:
895 cleanup_workqueue_thread(cwq);
896 break;
897 }
898 }
899
900 switch (action) {
901 case CPU_UP_CANCELED:
902 case CPU_DEAD:
903 cpu_clear(cpu, cpu_populated_map);
904 }
905
906 return NOTIFY_OK;
907 }
908
909 void __init init_workqueues(void)
910 {
911 cpu_populated_map = cpu_online_map;
912 singlethread_cpu = first_cpu(cpu_possible_map);
913 cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu);
914 hotcpu_notifier(workqueue_cpu_callback, 0);
915 keventd_wq = create_workqueue("events");
916 BUG_ON(!keventd_wq);
917 }