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>
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.
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>
39 * The per-CPU workqueue (if single thread, we always use the first
42 struct cpu_workqueue_struct {
46 struct list_head worklist;
47 wait_queue_head_t more_work;
48 struct work_struct *current_work;
50 struct workqueue_struct *wq;
51 struct task_struct *thread;
52 } ____cacheline_aligned;
55 * The externally visible workqueue abstraction is an array of
58 struct workqueue_struct {
59 struct cpu_workqueue_struct *cpu_wq;
60 struct list_head list;
63 int freezeable; /* Freeze threads during suspend */
66 struct lockdep_map lockdep_map;
70 /* Serializes the accesses to the list of workqueues. */
71 static DEFINE_SPINLOCK(workqueue_lock);
72 static LIST_HEAD(workqueues);
74 static int singlethread_cpu __read_mostly;
75 static const struct cpumask *cpu_singlethread_map __read_mostly;
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
83 static cpumask_var_t cpu_populated_map __read_mostly;
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)
88 return wq->singlethread;
91 static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq)
93 return is_wq_single_threaded(wq)
94 ? cpu_singlethread_map : cpu_populated_map;
98 struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
100 if (unlikely(is_wq_single_threaded(wq)))
101 cpu = singlethread_cpu;
102 return per_cpu_ptr(wq->cpu_wq, cpu);
106 * Set the workqueue on which a work item is to be run
107 * - Must *only* be called if the pending flag is set
109 static inline void set_wq_data(struct work_struct *work,
110 struct cpu_workqueue_struct *cwq)
114 BUG_ON(!work_pending(work));
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);
122 struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
124 return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
127 DEFINE_TRACE(workqueue_insertion);
129 static void insert_work(struct cpu_workqueue_struct *cwq,
130 struct work_struct *work, struct list_head *head)
132 trace_workqueue_insertion(cwq->thread, work);
134 set_wq_data(work, cwq);
136 * Ensure that we get the right work->data if we see the
137 * result of list_add() below, see try_to_grab_pending().
140 list_add_tail(&work->entry, head);
141 wake_up(&cwq->more_work);
144 static void __queue_work(struct cpu_workqueue_struct *cwq,
145 struct work_struct *work)
149 spin_lock_irqsave(&cwq->lock, flags);
150 insert_work(cwq, work, &cwq->worklist);
151 spin_unlock_irqrestore(&cwq->lock, flags);
155 * queue_work - queue work on a workqueue
156 * @wq: workqueue to use
157 * @work: work to queue
159 * Returns 0 if @work was already on a queue, non-zero otherwise.
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.
164 int queue_work(struct workqueue_struct *wq, struct work_struct *work)
168 ret = queue_work_on(get_cpu(), wq, work);
173 EXPORT_SYMBOL_GPL(queue_work);
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
181 * Returns 0 if @work was already on a queue, non-zero otherwise.
183 * We queue the work to a specific CPU, the caller must ensure it
187 queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
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);
198 EXPORT_SYMBOL_GPL(queue_work_on);
200 static void delayed_work_timer_fn(unsigned long __data)
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;
206 __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
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
215 * Returns 0 if @work was already on a queue, non-zero otherwise.
217 int queue_delayed_work(struct workqueue_struct *wq,
218 struct delayed_work *dwork, unsigned long delay)
221 return queue_work(wq, &dwork->work);
223 return queue_delayed_work_on(-1, wq, dwork, delay);
225 EXPORT_SYMBOL_GPL(queue_delayed_work);
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
234 * Returns 0 if @work was already on a queue, non-zero otherwise.
236 int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
237 struct delayed_work *dwork, unsigned long delay)
240 struct timer_list *timer = &dwork->timer;
241 struct work_struct *work = &dwork->work;
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));
247 timer_stats_timer_set_start_info(&dwork->timer);
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;
255 if (unlikely(cpu >= 0))
256 add_timer_on(timer, cpu);
263 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
265 DEFINE_TRACE(workqueue_execution);
267 static void run_workqueue(struct cpu_workqueue_struct *cwq)
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
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.
283 struct lockdep_map lockdep_map = work->lockdep_map;
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);
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);
295 lock_map_release(&lockdep_map);
296 lock_map_release(&cwq->wq->lockdep_map);
298 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
299 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
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);
309 spin_lock_irq(&cwq->lock);
310 cwq->current_work = NULL;
312 spin_unlock_irq(&cwq->lock);
315 static int worker_thread(void *__cwq)
317 struct cpu_workqueue_struct *cwq = __cwq;
320 if (cwq->wq->freezeable)
323 set_user_nice(current, -5);
326 prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
327 if (!freezing(current) &&
328 !kthread_should_stop() &&
329 list_empty(&cwq->worklist))
331 finish_wait(&cwq->more_work, &wait);
335 if (kthread_should_stop())
345 struct work_struct work;
346 struct completion done;
349 static void wq_barrier_func(struct work_struct *work)
351 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
352 complete(&barr->done);
355 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
356 struct wq_barrier *barr, struct list_head *head)
358 INIT_WORK(&barr->work, wq_barrier_func);
359 __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
361 init_completion(&barr->done);
363 insert_work(cwq, &barr->work, head);
366 static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
369 struct wq_barrier barr;
371 WARN_ON(cwq->thread == current);
373 spin_lock_irq(&cwq->lock);
374 if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
375 insert_wq_barrier(cwq, &barr, &cwq->worklist);
378 spin_unlock_irq(&cwq->lock);
381 wait_for_completion(&barr.done);
387 * flush_workqueue - ensure that any scheduled work has run to completion.
388 * @wq: workqueue to flush
390 * Forces execution of the workqueue and blocks until its completion.
391 * This is typically used in driver shutdown handlers.
393 * We sleep until all works which were queued on entry have been handled,
394 * but we are not livelocked by new incoming ones.
396 * This function used to run the workqueues itself. Now we just wait for the
397 * helper threads to do it.
399 void flush_workqueue(struct workqueue_struct *wq)
401 const struct cpumask *cpu_map = wq_cpu_map(wq);
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));
410 EXPORT_SYMBOL_GPL(flush_workqueue);
413 * flush_work - block until a work_struct's callback has terminated
414 * @work: the work which is to be flushed
416 * Returns false if @work has already terminated.
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.
422 int flush_work(struct work_struct *work)
424 struct cpu_workqueue_struct *cwq;
425 struct list_head *prev;
426 struct wq_barrier barr;
429 cwq = get_wq_data(work);
433 lock_map_acquire(&cwq->wq->lockdep_map);
434 lock_map_release(&cwq->wq->lockdep_map);
437 spin_lock_irq(&cwq->lock);
438 if (!list_empty(&work->entry)) {
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.
444 if (unlikely(cwq != get_wq_data(work)))
448 if (cwq->current_work != work)
450 prev = &cwq->worklist;
452 insert_wq_barrier(cwq, &barr, prev->next);
454 spin_unlock_irq(&cwq->lock);
458 wait_for_completion(&barr.done);
461 EXPORT_SYMBOL_GPL(flush_work);
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.
467 static int try_to_grab_pending(struct work_struct *work)
469 struct cpu_workqueue_struct *cwq;
472 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
476 * The queueing is in progress, or it is already queued. Try to
477 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
480 cwq = get_wq_data(work);
484 spin_lock_irq(&cwq->lock);
485 if (!list_empty(&work->entry)) {
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().
492 if (cwq == get_wq_data(work)) {
493 list_del_init(&work->entry);
497 spin_unlock_irq(&cwq->lock);
502 static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
503 struct work_struct *work)
505 struct wq_barrier barr;
508 spin_lock_irq(&cwq->lock);
509 if (unlikely(cwq->current_work == work)) {
510 insert_wq_barrier(cwq, &barr, cwq->worklist.next);
513 spin_unlock_irq(&cwq->lock);
515 if (unlikely(running))
516 wait_for_completion(&barr.done);
519 static void wait_on_work(struct work_struct *work)
521 struct cpu_workqueue_struct *cwq;
522 struct workqueue_struct *wq;
523 const struct cpumask *cpu_map;
528 lock_map_acquire(&work->lockdep_map);
529 lock_map_release(&work->lockdep_map);
531 cwq = get_wq_data(work);
536 cpu_map = wq_cpu_map(wq);
538 for_each_cpu(cpu, cpu_map)
539 wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
542 static int __cancel_work_timer(struct work_struct *work,
543 struct timer_list* timer)
548 ret = (timer && likely(del_timer(timer)));
550 ret = try_to_grab_pending(work);
552 } while (unlikely(ret < 0));
554 work_clear_pending(work);
559 * cancel_work_sync - block until a work_struct's callback has terminated
560 * @work: the work which is to be flushed
562 * Returns true if @work was pending.
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
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
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.
576 * The caller must ensure that workqueue_struct on which this work was last
577 * queued can't be destroyed before this function returns.
579 int cancel_work_sync(struct work_struct *work)
581 return __cancel_work_timer(work, NULL);
583 EXPORT_SYMBOL_GPL(cancel_work_sync);
586 * cancel_delayed_work_sync - reliably kill off a delayed work.
587 * @dwork: the delayed work struct
589 * Returns true if @dwork was pending.
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().
594 int cancel_delayed_work_sync(struct delayed_work *dwork)
596 return __cancel_work_timer(&dwork->work, &dwork->timer);
598 EXPORT_SYMBOL(cancel_delayed_work_sync);
600 static struct workqueue_struct *keventd_wq __read_mostly;
603 * schedule_work - put work task in global workqueue
604 * @work: job to be done
606 * This puts a job in the kernel-global workqueue.
608 int schedule_work(struct work_struct *work)
610 return queue_work(keventd_wq, work);
612 EXPORT_SYMBOL(schedule_work);
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
619 * This puts a job on a specific cpu
621 int schedule_work_on(int cpu, struct work_struct *work)
623 return queue_work_on(cpu, keventd_wq, work);
625 EXPORT_SYMBOL(schedule_work_on);
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
632 * After waiting for a given time this puts a job in the kernel-global
635 int schedule_delayed_work(struct delayed_work *dwork,
638 return queue_delayed_work(keventd_wq, dwork, delay);
640 EXPORT_SYMBOL(schedule_delayed_work);
643 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
645 * @dwork: job to be done
646 * @delay: number of jiffies to wait
648 * After waiting for a given time this puts a job in the kernel-global
649 * workqueue on the specified CPU.
651 int schedule_delayed_work_on(int cpu,
652 struct delayed_work *dwork, unsigned long delay)
654 return queue_delayed_work_on(cpu, keventd_wq, dwork, delay);
656 EXPORT_SYMBOL(schedule_delayed_work_on);
659 * schedule_on_each_cpu - call a function on each online CPU from keventd
660 * @func: the function to call
662 * Returns zero on success.
663 * Returns -ve errno on failure.
665 * schedule_on_each_cpu() is very slow.
667 int schedule_on_each_cpu(work_func_t func)
670 struct work_struct *works;
672 works = alloc_percpu(struct work_struct);
677 for_each_online_cpu(cpu) {
678 struct work_struct *work = per_cpu_ptr(works, cpu);
680 INIT_WORK(work, func);
681 schedule_work_on(cpu, work);
683 for_each_online_cpu(cpu)
684 flush_work(per_cpu_ptr(works, cpu));
690 void flush_scheduled_work(void)
692 flush_workqueue(keventd_wq);
694 EXPORT_SYMBOL(flush_scheduled_work);
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)
702 * Executes the function immediately if process context is available,
703 * otherwise schedules the function for delayed execution.
705 * Returns: 0 - function was executed
706 * 1 - function was scheduled for execution
708 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
710 if (!in_interrupt()) {
715 INIT_WORK(&ew->work, fn);
716 schedule_work(&ew->work);
720 EXPORT_SYMBOL_GPL(execute_in_process_context);
724 return keventd_wq != NULL;
727 int current_is_keventd(void)
729 struct cpu_workqueue_struct *cwq;
730 int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */
735 cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu);
736 if (current == cwq->thread)
743 static struct cpu_workqueue_struct *
744 init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
746 struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
749 spin_lock_init(&cwq->lock);
750 INIT_LIST_HEAD(&cwq->worklist);
751 init_waitqueue_head(&cwq->more_work);
756 DEFINE_TRACE(workqueue_creation);
758 static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
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;
765 p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
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.
777 sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m);
780 trace_workqueue_creation(cwq->thread, cpu);
785 static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
787 struct task_struct *p = cwq->thread;
791 kthread_bind(p, cpu);
796 struct workqueue_struct *__create_workqueue_key(const char *name,
800 struct lock_class_key *key,
801 const char *lock_name)
803 struct workqueue_struct *wq;
804 struct cpu_workqueue_struct *cwq;
807 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
811 wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
818 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
819 wq->singlethread = singlethread;
820 wq->freezeable = freezeable;
822 INIT_LIST_HEAD(&wq->list);
825 cwq = init_cpu_workqueue(wq, singlethread_cpu);
826 err = create_workqueue_thread(cwq, singlethread_cpu);
827 start_workqueue_thread(cwq, -1);
829 cpu_maps_update_begin();
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
836 spin_lock(&workqueue_lock);
837 list_add(&wq->list, &workqueues);
838 spin_unlock(&workqueue_lock);
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
845 for_each_possible_cpu(cpu) {
846 cwq = init_cpu_workqueue(wq, cpu);
847 if (err || !cpu_online(cpu))
849 err = create_workqueue_thread(cwq, cpu);
850 start_workqueue_thread(cwq, cpu);
852 cpu_maps_update_done();
856 destroy_workqueue(wq);
861 EXPORT_SYMBOL_GPL(__create_workqueue_key);
863 DEFINE_TRACE(workqueue_destruction);
865 static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
868 * Our caller is either destroy_workqueue() or CPU_POST_DEAD,
869 * cpu_add_remove_lock protects cwq->thread.
871 if (cwq->thread == NULL)
874 lock_map_acquire(&cwq->wq->lockdep_map);
875 lock_map_release(&cwq->wq->lockdep_map);
877 flush_cpu_workqueue(cwq);
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
888 trace_workqueue_destruction(cwq->thread);
889 kthread_stop(cwq->thread);
894 * destroy_workqueue - safely terminate a workqueue
895 * @wq: target workqueue
897 * Safely destroy a workqueue. All work currently pending will be done first.
899 void destroy_workqueue(struct workqueue_struct *wq)
901 const struct cpumask *cpu_map = wq_cpu_map(wq);
904 cpu_maps_update_begin();
905 spin_lock(&workqueue_lock);
907 spin_unlock(&workqueue_lock);
909 for_each_cpu(cpu, cpu_map)
910 cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu));
911 cpu_maps_update_done();
913 free_percpu(wq->cpu_wq);
916 EXPORT_SYMBOL_GPL(destroy_workqueue);
918 static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
919 unsigned long action,
922 unsigned int cpu = (unsigned long)hcpu;
923 struct cpu_workqueue_struct *cwq;
924 struct workqueue_struct *wq;
927 action &= ~CPU_TASKS_FROZEN;
931 cpumask_set_cpu(cpu, cpu_populated_map);
934 list_for_each_entry(wq, &workqueues, list) {
935 cwq = per_cpu_ptr(wq->cpu_wq, cpu);
939 if (!create_workqueue_thread(cwq, cpu))
941 printk(KERN_ERR "workqueue [%s] for %i failed\n",
943 action = CPU_UP_CANCELED;
948 start_workqueue_thread(cwq, cpu);
951 case CPU_UP_CANCELED:
952 start_workqueue_thread(cwq, -1);
954 cleanup_workqueue_thread(cwq);
960 case CPU_UP_CANCELED:
962 cpumask_clear_cpu(cpu, cpu_populated_map);
969 static struct workqueue_struct *work_on_cpu_wq __read_mostly;
971 struct work_for_cpu {
972 struct work_struct work;
978 static void do_work_for_cpu(struct work_struct *w)
980 struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work);
982 wfc->ret = wfc->fn(wfc->arg);
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
991 * This will return the value @fn returns.
992 * It is up to the caller to ensure that the cpu doesn't go offline.
994 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
996 struct work_for_cpu wfc;
998 INIT_WORK(&wfc.work, do_work_for_cpu);
1001 queue_work_on(cpu, work_on_cpu_wq, &wfc.work);
1002 flush_work(&wfc.work);
1006 EXPORT_SYMBOL_GPL(work_on_cpu);
1007 #endif /* CONFIG_SMP */
1009 void __init init_workqueues(void)
1011 alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL);
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);
1020 work_on_cpu_wq = create_workqueue("work_on_cpu");
1021 BUG_ON(!work_on_cpu_wq);