2 * linux/kernel/workqueue.c
4 * Generic mechanism for defining kernel helper threads for running
5 * arbitrary tasks in process context.
7 * Started by Ingo Molnar, Copyright (C) 2002
9 * Derived from the taskqueue/keventd code by:
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>
16 * Made to use alloc_percpu by Christoph Lameter <clameter@sgi.com>.
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>
37 * The per-CPU workqueue (if single thread, we always use the first
40 struct cpu_workqueue_struct
{
44 struct list_head worklist
;
45 wait_queue_head_t more_work
;
46 struct work_struct
*current_work
;
48 struct workqueue_struct
*wq
;
49 struct task_struct
*thread
;
52 int run_depth
; /* Detect run_workqueue() recursion depth */
53 } ____cacheline_aligned
;
56 * The externally visible workqueue abstraction is an array of
59 struct workqueue_struct
{
60 struct cpu_workqueue_struct
*cpu_wq
;
61 struct list_head list
;
64 int freezeable
; /* Freeze threads during suspend */
67 /* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
68 threads to each one as cpus come/go. */
69 static DEFINE_MUTEX(workqueue_mutex
);
70 static LIST_HEAD(workqueues
);
72 static int singlethread_cpu __read_mostly
;
73 static cpumask_t cpu_singlethread_map __read_mostly
;
74 /* optimization, we could use cpu_possible_map */
75 static cpumask_t cpu_populated_map __read_mostly
;
77 /* If it's single threaded, it isn't in the list of workqueues. */
78 static inline int is_single_threaded(struct workqueue_struct
*wq
)
80 return wq
->singlethread
;
83 static const cpumask_t
*wq_cpu_map(struct workqueue_struct
*wq
)
85 return is_single_threaded(wq
)
86 ? &cpu_singlethread_map
: &cpu_populated_map
;
90 * Set the workqueue on which a work item is to be run
91 * - Must *only* be called if the pending flag is set
93 static inline void set_wq_data(struct work_struct
*work
, void *wq
)
97 BUG_ON(!work_pending(work
));
99 new = (unsigned long) wq
| (1UL << WORK_STRUCT_PENDING
);
100 new |= WORK_STRUCT_FLAG_MASK
& *work_data_bits(work
);
101 atomic_long_set(&work
->data
, new);
104 static inline void *get_wq_data(struct work_struct
*work
)
106 return (void *) (atomic_long_read(&work
->data
) & WORK_STRUCT_WQ_DATA_MASK
);
109 static void insert_work(struct cpu_workqueue_struct
*cwq
,
110 struct work_struct
*work
, int tail
)
112 set_wq_data(work
, cwq
);
114 list_add_tail(&work
->entry
, &cwq
->worklist
);
116 list_add(&work
->entry
, &cwq
->worklist
);
117 wake_up(&cwq
->more_work
);
120 /* Preempt must be disabled. */
121 static void __queue_work(struct cpu_workqueue_struct
*cwq
,
122 struct work_struct
*work
)
126 spin_lock_irqsave(&cwq
->lock
, flags
);
127 insert_work(cwq
, work
, 1);
128 spin_unlock_irqrestore(&cwq
->lock
, flags
);
132 * queue_work - queue work on a workqueue
133 * @wq: workqueue to use
134 * @work: work to queue
136 * Returns 0 if @work was already on a queue, non-zero otherwise.
138 * We queue the work to the CPU it was submitted, but there is no
139 * guarantee that it will be processed by that CPU.
141 int fastcall
queue_work(struct workqueue_struct
*wq
, struct work_struct
*work
)
143 int ret
= 0, cpu
= get_cpu();
145 if (!test_and_set_bit(WORK_STRUCT_PENDING
, work_data_bits(work
))) {
146 if (unlikely(is_single_threaded(wq
)))
147 cpu
= singlethread_cpu
;
148 BUG_ON(!list_empty(&work
->entry
));
149 __queue_work(per_cpu_ptr(wq
->cpu_wq
, cpu
), work
);
155 EXPORT_SYMBOL_GPL(queue_work
);
157 void delayed_work_timer_fn(unsigned long __data
)
159 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
160 struct workqueue_struct
*wq
= get_wq_data(&dwork
->work
);
161 int cpu
= smp_processor_id();
163 if (unlikely(is_single_threaded(wq
)))
164 cpu
= singlethread_cpu
;
166 __queue_work(per_cpu_ptr(wq
->cpu_wq
, cpu
), &dwork
->work
);
170 * queue_delayed_work - queue work on a workqueue after delay
171 * @wq: workqueue to use
172 * @dwork: delayable work to queue
173 * @delay: number of jiffies to wait before queueing
175 * Returns 0 if @work was already on a queue, non-zero otherwise.
177 int fastcall
queue_delayed_work(struct workqueue_struct
*wq
,
178 struct delayed_work
*dwork
, unsigned long delay
)
181 struct timer_list
*timer
= &dwork
->timer
;
182 struct work_struct
*work
= &dwork
->work
;
184 timer_stats_timer_set_start_info(timer
);
186 return queue_work(wq
, work
);
188 if (!test_and_set_bit(WORK_STRUCT_PENDING
, work_data_bits(work
))) {
189 BUG_ON(timer_pending(timer
));
190 BUG_ON(!list_empty(&work
->entry
));
192 /* This stores wq for the moment, for the timer_fn */
193 set_wq_data(work
, wq
);
194 timer
->expires
= jiffies
+ delay
;
195 timer
->data
= (unsigned long)dwork
;
196 timer
->function
= delayed_work_timer_fn
;
202 EXPORT_SYMBOL_GPL(queue_delayed_work
);
205 * queue_delayed_work_on - queue work on specific CPU after delay
206 * @cpu: CPU number to execute work on
207 * @wq: workqueue to use
208 * @dwork: work to queue
209 * @delay: number of jiffies to wait before queueing
211 * Returns 0 if @work was already on a queue, non-zero otherwise.
213 int queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
214 struct delayed_work
*dwork
, unsigned long delay
)
217 struct timer_list
*timer
= &dwork
->timer
;
218 struct work_struct
*work
= &dwork
->work
;
220 if (!test_and_set_bit(WORK_STRUCT_PENDING
, work_data_bits(work
))) {
221 BUG_ON(timer_pending(timer
));
222 BUG_ON(!list_empty(&work
->entry
));
224 /* This stores wq for the moment, for the timer_fn */
225 set_wq_data(work
, wq
);
226 timer
->expires
= jiffies
+ delay
;
227 timer
->data
= (unsigned long)dwork
;
228 timer
->function
= delayed_work_timer_fn
;
229 add_timer_on(timer
, cpu
);
234 EXPORT_SYMBOL_GPL(queue_delayed_work_on
);
236 static void run_workqueue(struct cpu_workqueue_struct
*cwq
)
238 spin_lock_irq(&cwq
->lock
);
240 if (cwq
->run_depth
> 3) {
241 /* morton gets to eat his hat */
242 printk("%s: recursion depth exceeded: %d\n",
243 __FUNCTION__
, cwq
->run_depth
);
246 while (!list_empty(&cwq
->worklist
)) {
247 struct work_struct
*work
= list_entry(cwq
->worklist
.next
,
248 struct work_struct
, entry
);
249 work_func_t f
= work
->func
;
251 cwq
->current_work
= work
;
252 list_del_init(cwq
->worklist
.next
);
253 spin_unlock_irq(&cwq
->lock
);
255 BUG_ON(get_wq_data(work
) != cwq
);
256 if (!test_bit(WORK_STRUCT_NOAUTOREL
, work_data_bits(work
)))
260 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
261 printk(KERN_ERR
"BUG: workqueue leaked lock or atomic: "
263 current
->comm
, preempt_count(),
265 printk(KERN_ERR
" last function: ");
266 print_symbol("%s\n", (unsigned long)f
);
267 debug_show_held_locks(current
);
271 spin_lock_irq(&cwq
->lock
);
272 cwq
->current_work
= NULL
;
275 spin_unlock_irq(&cwq
->lock
);
279 * NOTE: the caller must not touch *cwq if this func returns true
281 static int cwq_should_stop(struct cpu_workqueue_struct
*cwq
)
283 int should_stop
= cwq
->should_stop
;
285 if (unlikely(should_stop
)) {
286 spin_lock_irq(&cwq
->lock
);
287 should_stop
= cwq
->should_stop
&& list_empty(&cwq
->worklist
);
290 spin_unlock_irq(&cwq
->lock
);
296 static int worker_thread(void *__cwq
)
298 struct cpu_workqueue_struct
*cwq
= __cwq
;
300 struct k_sigaction sa
;
303 if (!cwq
->wq
->freezeable
)
304 current
->flags
|= PF_NOFREEZE
;
306 set_user_nice(current
, -5);
308 /* Block and flush all signals */
309 sigfillset(&blocked
);
310 sigprocmask(SIG_BLOCK
, &blocked
, NULL
);
311 flush_signals(current
);
314 * We inherited MPOL_INTERLEAVE from the booting kernel.
315 * Set MPOL_DEFAULT to insure node local allocations.
317 numa_default_policy();
319 /* SIG_IGN makes children autoreap: see do_notify_parent(). */
320 sa
.sa
.sa_handler
= SIG_IGN
;
322 siginitset(&sa
.sa
.sa_mask
, sigmask(SIGCHLD
));
323 do_sigaction(SIGCHLD
, &sa
, (struct k_sigaction
*)0);
326 if (cwq
->wq
->freezeable
)
329 prepare_to_wait(&cwq
->more_work
, &wait
, TASK_INTERRUPTIBLE
);
330 if (!cwq
->should_stop
&& list_empty(&cwq
->worklist
))
332 finish_wait(&cwq
->more_work
, &wait
);
334 if (cwq_should_stop(cwq
))
344 struct work_struct work
;
345 struct completion done
;
348 static void wq_barrier_func(struct work_struct
*work
)
350 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
351 complete(&barr
->done
);
354 static void insert_wq_barrier(struct cpu_workqueue_struct
*cwq
,
355 struct wq_barrier
*barr
, int tail
)
357 INIT_WORK(&barr
->work
, wq_barrier_func
);
358 __set_bit(WORK_STRUCT_PENDING
, work_data_bits(&barr
->work
));
360 init_completion(&barr
->done
);
362 insert_work(cwq
, &barr
->work
, tail
);
365 static void flush_cpu_workqueue(struct cpu_workqueue_struct
*cwq
)
367 if (cwq
->thread
== current
) {
369 * Probably keventd trying to flush its own queue. So simply run
370 * it by hand rather than deadlocking.
374 struct wq_barrier barr
;
377 spin_lock_irq(&cwq
->lock
);
378 if (!list_empty(&cwq
->worklist
) || cwq
->current_work
!= NULL
) {
379 insert_wq_barrier(cwq
, &barr
, 1);
382 spin_unlock_irq(&cwq
->lock
);
385 wait_for_completion(&barr
.done
);
390 * flush_workqueue - ensure that any scheduled work has run to completion.
391 * @wq: workqueue to flush
393 * Forces execution of the workqueue and blocks until its completion.
394 * This is typically used in driver shutdown handlers.
396 * We sleep until all works which were queued on entry have been handled,
397 * but we are not livelocked by new incoming ones.
399 * This function used to run the workqueues itself. Now we just wait for the
400 * helper threads to do it.
402 void fastcall
flush_workqueue(struct workqueue_struct
*wq
)
404 const cpumask_t
*cpu_map
= wq_cpu_map(wq
);
408 for_each_cpu_mask(cpu
, *cpu_map
)
409 flush_cpu_workqueue(per_cpu_ptr(wq
->cpu_wq
, cpu
));
411 EXPORT_SYMBOL_GPL(flush_workqueue
);
413 static void wait_on_work(struct cpu_workqueue_struct
*cwq
,
414 struct work_struct
*work
)
416 struct wq_barrier barr
;
419 spin_lock_irq(&cwq
->lock
);
420 if (unlikely(cwq
->current_work
== work
)) {
421 insert_wq_barrier(cwq
, &barr
, 0);
424 spin_unlock_irq(&cwq
->lock
);
426 if (unlikely(running
))
427 wait_for_completion(&barr
.done
);
431 * flush_work - block until a work_struct's callback has terminated
432 * @wq: the workqueue on which the work is queued
433 * @work: the work which is to be flushed
435 * flush_work() will attempt to cancel the work if it is queued. If the work's
436 * callback appears to be running, flush_work() will block until it has
439 * flush_work() is designed to be used when the caller is tearing down data
440 * structures which the callback function operates upon. It is expected that,
441 * prior to calling flush_work(), the caller has arranged for the work to not
444 void flush_work(struct workqueue_struct
*wq
, struct work_struct
*work
)
446 const cpumask_t
*cpu_map
= wq_cpu_map(wq
);
447 struct cpu_workqueue_struct
*cwq
;
452 cwq
= get_wq_data(work
);
453 /* Was it ever queued ? */
458 * This work can't be re-queued, no need to re-check that
459 * get_wq_data() is still the same when we take cwq->lock.
461 spin_lock_irq(&cwq
->lock
);
462 list_del_init(&work
->entry
);
464 spin_unlock_irq(&cwq
->lock
);
466 for_each_cpu_mask(cpu
, *cpu_map
)
467 wait_on_work(per_cpu_ptr(wq
->cpu_wq
, cpu
), work
);
469 EXPORT_SYMBOL_GPL(flush_work
);
472 static struct workqueue_struct
*keventd_wq
;
475 * schedule_work - put work task in global workqueue
476 * @work: job to be done
478 * This puts a job in the kernel-global workqueue.
480 int fastcall
schedule_work(struct work_struct
*work
)
482 return queue_work(keventd_wq
, work
);
484 EXPORT_SYMBOL(schedule_work
);
487 * schedule_delayed_work - put work task in global workqueue after delay
488 * @dwork: job to be done
489 * @delay: number of jiffies to wait or 0 for immediate execution
491 * After waiting for a given time this puts a job in the kernel-global
494 int fastcall
schedule_delayed_work(struct delayed_work
*dwork
,
497 timer_stats_timer_set_start_info(&dwork
->timer
);
498 return queue_delayed_work(keventd_wq
, dwork
, delay
);
500 EXPORT_SYMBOL(schedule_delayed_work
);
503 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
505 * @dwork: job to be done
506 * @delay: number of jiffies to wait
508 * After waiting for a given time this puts a job in the kernel-global
509 * workqueue on the specified CPU.
511 int schedule_delayed_work_on(int cpu
,
512 struct delayed_work
*dwork
, unsigned long delay
)
514 return queue_delayed_work_on(cpu
, keventd_wq
, dwork
, delay
);
516 EXPORT_SYMBOL(schedule_delayed_work_on
);
519 * schedule_on_each_cpu - call a function on each online CPU from keventd
520 * @func: the function to call
522 * Returns zero on success.
523 * Returns -ve errno on failure.
525 * Appears to be racy against CPU hotplug.
527 * schedule_on_each_cpu() is very slow.
529 int schedule_on_each_cpu(work_func_t func
)
532 struct work_struct
*works
;
534 works
= alloc_percpu(struct work_struct
);
538 preempt_disable(); /* CPU hotplug */
539 for_each_online_cpu(cpu
) {
540 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
542 INIT_WORK(work
, func
);
543 set_bit(WORK_STRUCT_PENDING
, work_data_bits(work
));
544 __queue_work(per_cpu_ptr(keventd_wq
->cpu_wq
, cpu
), work
);
547 flush_workqueue(keventd_wq
);
552 void flush_scheduled_work(void)
554 flush_workqueue(keventd_wq
);
556 EXPORT_SYMBOL(flush_scheduled_work
);
558 void flush_work_keventd(struct work_struct
*work
)
560 flush_work(keventd_wq
, work
);
562 EXPORT_SYMBOL(flush_work_keventd
);
565 * cancel_rearming_delayed_workqueue - reliably kill off a delayed work whose handler rearms the delayed work.
566 * @wq: the controlling workqueue structure
567 * @dwork: the delayed work struct
569 void cancel_rearming_delayed_workqueue(struct workqueue_struct
*wq
,
570 struct delayed_work
*dwork
)
572 /* Was it ever queued ? */
573 if (!get_wq_data(&dwork
->work
))
576 while (!cancel_delayed_work(dwork
))
579 EXPORT_SYMBOL(cancel_rearming_delayed_workqueue
);
582 * cancel_rearming_delayed_work - reliably kill off a delayed keventd work whose handler rearms the delayed work.
583 * @dwork: the delayed work struct
585 void cancel_rearming_delayed_work(struct delayed_work
*dwork
)
587 cancel_rearming_delayed_workqueue(keventd_wq
, dwork
);
589 EXPORT_SYMBOL(cancel_rearming_delayed_work
);
592 * execute_in_process_context - reliably execute the routine with user context
593 * @fn: the function to execute
594 * @ew: guaranteed storage for the execute work structure (must
595 * be available when the work executes)
597 * Executes the function immediately if process context is available,
598 * otherwise schedules the function for delayed execution.
600 * Returns: 0 - function was executed
601 * 1 - function was scheduled for execution
603 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
605 if (!in_interrupt()) {
610 INIT_WORK(&ew
->work
, fn
);
611 schedule_work(&ew
->work
);
615 EXPORT_SYMBOL_GPL(execute_in_process_context
);
619 return keventd_wq
!= NULL
;
622 int current_is_keventd(void)
624 struct cpu_workqueue_struct
*cwq
;
625 int cpu
= smp_processor_id(); /* preempt-safe: keventd is per-cpu */
630 cwq
= per_cpu_ptr(keventd_wq
->cpu_wq
, cpu
);
631 if (current
== cwq
->thread
)
638 static struct cpu_workqueue_struct
*
639 init_cpu_workqueue(struct workqueue_struct
*wq
, int cpu
)
641 struct cpu_workqueue_struct
*cwq
= per_cpu_ptr(wq
->cpu_wq
, cpu
);
644 spin_lock_init(&cwq
->lock
);
645 INIT_LIST_HEAD(&cwq
->worklist
);
646 init_waitqueue_head(&cwq
->more_work
);
651 static int create_workqueue_thread(struct cpu_workqueue_struct
*cwq
, int cpu
)
653 struct workqueue_struct
*wq
= cwq
->wq
;
654 const char *fmt
= is_single_threaded(wq
) ? "%s" : "%s/%d";
655 struct task_struct
*p
;
657 p
= kthread_create(worker_thread
, cwq
, fmt
, wq
->name
, cpu
);
659 * Nobody can add the work_struct to this cwq,
660 * if (caller is __create_workqueue)
661 * nobody should see this wq
662 * else // caller is CPU_UP_PREPARE
663 * cpu is not on cpu_online_map
664 * so we can abort safely.
670 cwq
->should_stop
= 0;
671 if (!is_single_threaded(wq
))
672 kthread_bind(p
, cpu
);
674 if (is_single_threaded(wq
) || cpu_online(cpu
))
680 struct workqueue_struct
*__create_workqueue(const char *name
,
681 int singlethread
, int freezeable
)
683 struct workqueue_struct
*wq
;
684 struct cpu_workqueue_struct
*cwq
;
687 wq
= kzalloc(sizeof(*wq
), GFP_KERNEL
);
691 wq
->cpu_wq
= alloc_percpu(struct cpu_workqueue_struct
);
698 wq
->singlethread
= singlethread
;
699 wq
->freezeable
= freezeable
;
700 INIT_LIST_HEAD(&wq
->list
);
703 cwq
= init_cpu_workqueue(wq
, singlethread_cpu
);
704 err
= create_workqueue_thread(cwq
, singlethread_cpu
);
706 mutex_lock(&workqueue_mutex
);
707 list_add(&wq
->list
, &workqueues
);
709 for_each_possible_cpu(cpu
) {
710 cwq
= init_cpu_workqueue(wq
, cpu
);
711 if (err
|| !cpu_online(cpu
))
713 err
= create_workqueue_thread(cwq
, cpu
);
715 mutex_unlock(&workqueue_mutex
);
719 destroy_workqueue(wq
);
724 EXPORT_SYMBOL_GPL(__create_workqueue
);
726 static void cleanup_workqueue_thread(struct cpu_workqueue_struct
*cwq
, int cpu
)
728 struct wq_barrier barr
;
731 spin_lock_irq(&cwq
->lock
);
732 if (cwq
->thread
!= NULL
) {
733 insert_wq_barrier(cwq
, &barr
, 1);
734 cwq
->should_stop
= 1;
737 spin_unlock_irq(&cwq
->lock
);
740 wait_for_completion(&barr
.done
);
742 while (unlikely(cwq
->thread
!= NULL
))
745 * Wait until cwq->thread unlocks cwq->lock,
746 * it won't touch *cwq after that.
749 spin_unlock_wait(&cwq
->lock
);
754 * destroy_workqueue - safely terminate a workqueue
755 * @wq: target workqueue
757 * Safely destroy a workqueue. All work currently pending will be done first.
759 void destroy_workqueue(struct workqueue_struct
*wq
)
761 const cpumask_t
*cpu_map
= wq_cpu_map(wq
);
762 struct cpu_workqueue_struct
*cwq
;
765 mutex_lock(&workqueue_mutex
);
767 mutex_unlock(&workqueue_mutex
);
769 for_each_cpu_mask(cpu
, *cpu_map
) {
770 cwq
= per_cpu_ptr(wq
->cpu_wq
, cpu
);
771 cleanup_workqueue_thread(cwq
, cpu
);
774 free_percpu(wq
->cpu_wq
);
777 EXPORT_SYMBOL_GPL(destroy_workqueue
);
779 static int __devinit
workqueue_cpu_callback(struct notifier_block
*nfb
,
780 unsigned long action
,
783 unsigned int cpu
= (unsigned long)hcpu
;
784 struct cpu_workqueue_struct
*cwq
;
785 struct workqueue_struct
*wq
;
788 case CPU_LOCK_ACQUIRE
:
789 mutex_lock(&workqueue_mutex
);
792 case CPU_LOCK_RELEASE
:
793 mutex_unlock(&workqueue_mutex
);
797 cpu_set(cpu
, cpu_populated_map
);
800 list_for_each_entry(wq
, &workqueues
, list
) {
801 cwq
= per_cpu_ptr(wq
->cpu_wq
, cpu
);
805 if (!create_workqueue_thread(cwq
, cpu
))
807 printk(KERN_ERR
"workqueue for %i failed\n", cpu
);
811 wake_up_process(cwq
->thread
);
814 case CPU_UP_CANCELED
:
816 wake_up_process(cwq
->thread
);
818 cleanup_workqueue_thread(cwq
, cpu
);
826 void __init
init_workqueues(void)
828 cpu_populated_map
= cpu_online_map
;
829 singlethread_cpu
= first_cpu(cpu_possible_map
);
830 cpu_singlethread_map
= cpumask_of_cpu(singlethread_cpu
);
831 hotcpu_notifier(workqueue_cpu_callback
, 0);
832 keventd_wq
= create_workqueue("events");