1 /* Kernel thread helper functions.
2 * Copyright (C) 2004 IBM Corporation, Rusty Russell.
4 * Creation is done via kthreadd, so that we get a clean environment
5 * even if we're invoked from userspace (think modprobe, hotplug cpu,
8 #include <linux/sched.h>
9 #include <linux/kthread.h>
10 #include <linux/completion.h>
11 #include <linux/err.h>
12 #include <linux/cpuset.h>
13 #include <linux/unistd.h>
14 #include <linux/file.h>
15 #include <linux/export.h>
16 #include <linux/mutex.h>
17 #include <linux/slab.h>
18 #include <linux/freezer.h>
19 #include <linux/ptrace.h>
20 #include <linux/uaccess.h>
21 #include <trace/events/sched.h>
23 static DEFINE_SPINLOCK(kthread_create_lock
);
24 static LIST_HEAD(kthread_create_list
);
25 struct task_struct
*kthreadd_task
;
27 struct kthread_create_info
29 /* Information passed to kthread() from kthreadd. */
30 int (*threadfn
)(void *data
);
34 /* Result passed back to kthread_create() from kthreadd. */
35 struct task_struct
*result
;
36 struct completion
*done
;
38 struct list_head list
;
45 struct completion parked
;
46 struct completion exited
;
50 KTHREAD_IS_PER_CPU
= 0,
56 static inline void set_kthread_struct(void *kthread
)
59 * We abuse ->set_child_tid to avoid the new member and because it
60 * can't be wrongly copied by copy_process(). We also rely on fact
61 * that the caller can't exec, so PF_KTHREAD can't be cleared.
63 current
->set_child_tid
= (__force
void __user
*)kthread
;
66 static inline struct kthread
*to_kthread(struct task_struct
*k
)
68 WARN_ON(!(k
->flags
& PF_KTHREAD
));
69 return (__force
void *)k
->set_child_tid
;
72 void free_kthread_struct(struct task_struct
*k
)
75 * Can be NULL if this kthread was created by kernel_thread()
76 * or if kmalloc() in kthread() failed.
82 * kthread_should_stop - should this kthread return now?
84 * When someone calls kthread_stop() on your kthread, it will be woken
85 * and this will return true. You should then return, and your return
86 * value will be passed through to kthread_stop().
88 bool kthread_should_stop(void)
90 return test_bit(KTHREAD_SHOULD_STOP
, &to_kthread(current
)->flags
);
92 EXPORT_SYMBOL(kthread_should_stop
);
95 * kthread_should_park - should this kthread park now?
97 * When someone calls kthread_park() on your kthread, it will be woken
98 * and this will return true. You should then do the necessary
99 * cleanup and call kthread_parkme()
101 * Similar to kthread_should_stop(), but this keeps the thread alive
102 * and in a park position. kthread_unpark() "restarts" the thread and
103 * calls the thread function again.
105 bool kthread_should_park(void)
107 return test_bit(KTHREAD_SHOULD_PARK
, &to_kthread(current
)->flags
);
109 EXPORT_SYMBOL_GPL(kthread_should_park
);
112 * kthread_freezable_should_stop - should this freezable kthread return now?
113 * @was_frozen: optional out parameter, indicates whether %current was frozen
115 * kthread_should_stop() for freezable kthreads, which will enter
116 * refrigerator if necessary. This function is safe from kthread_stop() /
117 * freezer deadlock and freezable kthreads should use this function instead
118 * of calling try_to_freeze() directly.
120 bool kthread_freezable_should_stop(bool *was_frozen
)
126 if (unlikely(freezing(current
)))
127 frozen
= __refrigerator(true);
130 *was_frozen
= frozen
;
132 return kthread_should_stop();
134 EXPORT_SYMBOL_GPL(kthread_freezable_should_stop
);
137 * kthread_data - return data value specified on kthread creation
138 * @task: kthread task in question
140 * Return the data value specified when kthread @task was created.
141 * The caller is responsible for ensuring the validity of @task when
142 * calling this function.
144 void *kthread_data(struct task_struct
*task
)
146 return to_kthread(task
)->data
;
150 * kthread_probe_data - speculative version of kthread_data()
151 * @task: possible kthread task in question
153 * @task could be a kthread task. Return the data value specified when it
154 * was created if accessible. If @task isn't a kthread task or its data is
155 * inaccessible for any reason, %NULL is returned. This function requires
156 * that @task itself is safe to dereference.
158 void *kthread_probe_data(struct task_struct
*task
)
160 struct kthread
*kthread
= to_kthread(task
);
163 probe_kernel_read(&data
, &kthread
->data
, sizeof(data
));
167 static void __kthread_parkme(struct kthread
*self
)
169 __set_current_state(TASK_PARKED
);
170 while (test_bit(KTHREAD_SHOULD_PARK
, &self
->flags
)) {
171 if (!test_and_set_bit(KTHREAD_IS_PARKED
, &self
->flags
))
172 complete(&self
->parked
);
174 __set_current_state(TASK_PARKED
);
176 clear_bit(KTHREAD_IS_PARKED
, &self
->flags
);
177 __set_current_state(TASK_RUNNING
);
180 void kthread_parkme(void)
182 __kthread_parkme(to_kthread(current
));
184 EXPORT_SYMBOL_GPL(kthread_parkme
);
186 static int kthread(void *_create
)
188 /* Copy data: it's on kthread's stack */
189 struct kthread_create_info
*create
= _create
;
190 int (*threadfn
)(void *data
) = create
->threadfn
;
191 void *data
= create
->data
;
192 struct completion
*done
;
193 struct kthread
*self
;
196 self
= kmalloc(sizeof(*self
), GFP_KERNEL
);
197 set_kthread_struct(self
);
199 /* If user was SIGKILLed, I release the structure. */
200 done
= xchg(&create
->done
, NULL
);
207 create
->result
= ERR_PTR(-ENOMEM
);
214 init_completion(&self
->exited
);
215 init_completion(&self
->parked
);
216 current
->vfork_done
= &self
->exited
;
218 /* OK, tell user we're spawned, wait for stop or wakeup */
219 __set_current_state(TASK_UNINTERRUPTIBLE
);
220 create
->result
= current
;
225 if (!test_bit(KTHREAD_SHOULD_STOP
, &self
->flags
)) {
226 __kthread_parkme(self
);
227 ret
= threadfn(data
);
232 /* called from do_fork() to get node information for about to be created task */
233 int tsk_fork_get_node(struct task_struct
*tsk
)
236 if (tsk
== kthreadd_task
)
237 return tsk
->pref_node_fork
;
242 static void create_kthread(struct kthread_create_info
*create
)
247 current
->pref_node_fork
= create
->node
;
249 /* We want our own signal handler (we take no signals by default). */
250 pid
= kernel_thread(kthread
, create
, CLONE_FS
| CLONE_FILES
| SIGCHLD
);
252 /* If user was SIGKILLed, I release the structure. */
253 struct completion
*done
= xchg(&create
->done
, NULL
);
259 create
->result
= ERR_PTR(pid
);
264 static struct task_struct
*__kthread_create_on_node(int (*threadfn
)(void *data
),
265 void *data
, int node
,
266 const char namefmt
[],
269 DECLARE_COMPLETION_ONSTACK(done
);
270 struct task_struct
*task
;
271 struct kthread_create_info
*create
= kmalloc(sizeof(*create
),
275 return ERR_PTR(-ENOMEM
);
276 create
->threadfn
= threadfn
;
279 create
->done
= &done
;
281 spin_lock(&kthread_create_lock
);
282 list_add_tail(&create
->list
, &kthread_create_list
);
283 spin_unlock(&kthread_create_lock
);
285 wake_up_process(kthreadd_task
);
287 * Wait for completion in killable state, for I might be chosen by
288 * the OOM killer while kthreadd is trying to allocate memory for
291 if (unlikely(wait_for_completion_killable(&done
))) {
293 * If I was SIGKILLed before kthreadd (or new kernel thread)
294 * calls complete(), leave the cleanup of this structure to
297 if (xchg(&create
->done
, NULL
))
298 return ERR_PTR(-EINTR
);
300 * kthreadd (or new kernel thread) will call complete()
303 wait_for_completion(&done
);
305 task
= create
->result
;
307 static const struct sched_param param
= { .sched_priority
= 0 };
309 vsnprintf(task
->comm
, sizeof(task
->comm
), namefmt
, args
);
311 * root may have changed our (kthreadd's) priority or CPU mask.
312 * The kernel thread should not inherit these properties.
314 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
315 set_cpus_allowed_ptr(task
, cpu_all_mask
);
322 * kthread_create_on_node - create a kthread.
323 * @threadfn: the function to run until signal_pending(current).
324 * @data: data ptr for @threadfn.
325 * @node: task and thread structures for the thread are allocated on this node
326 * @namefmt: printf-style name for the thread.
328 * Description: This helper function creates and names a kernel
329 * thread. The thread will be stopped: use wake_up_process() to start
330 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
331 * is affine to all CPUs.
333 * If thread is going to be bound on a particular cpu, give its node
334 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
335 * When woken, the thread will run @threadfn() with @data as its
336 * argument. @threadfn() can either call do_exit() directly if it is a
337 * standalone thread for which no one will call kthread_stop(), or
338 * return when 'kthread_should_stop()' is true (which means
339 * kthread_stop() has been called). The return value should be zero
340 * or a negative error number; it will be passed to kthread_stop().
342 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
344 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
345 void *data
, int node
,
346 const char namefmt
[],
349 struct task_struct
*task
;
352 va_start(args
, namefmt
);
353 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
358 EXPORT_SYMBOL(kthread_create_on_node
);
360 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
364 if (!wait_task_inactive(p
, state
)) {
369 /* It's safe because the task is inactive. */
370 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
371 do_set_cpus_allowed(p
, mask
);
372 p
->flags
|= PF_NO_SETAFFINITY
;
373 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
376 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
378 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
381 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
383 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
387 * kthread_bind - bind a just-created kthread to a cpu.
388 * @p: thread created by kthread_create().
389 * @cpu: cpu (might not be online, must be possible) for @k to run on.
391 * Description: This function is equivalent to set_cpus_allowed(),
392 * except that @cpu doesn't need to be online, and the thread must be
393 * stopped (i.e., just returned from kthread_create()).
395 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
397 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
399 EXPORT_SYMBOL(kthread_bind
);
402 * kthread_create_on_cpu - Create a cpu bound kthread
403 * @threadfn: the function to run until signal_pending(current).
404 * @data: data ptr for @threadfn.
405 * @cpu: The cpu on which the thread should be bound,
406 * @namefmt: printf-style name for the thread. Format is restricted
407 * to "name.*%u". Code fills in cpu number.
409 * Description: This helper function creates and names a kernel thread
410 * The thread will be woken and put into park mode.
412 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
413 void *data
, unsigned int cpu
,
416 struct task_struct
*p
;
418 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
422 kthread_bind(p
, cpu
);
423 /* CPU hotplug need to bind once again when unparking the thread. */
424 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
425 to_kthread(p
)->cpu
= cpu
;
430 * kthread_unpark - unpark a thread created by kthread_create().
431 * @k: thread created by kthread_create().
433 * Sets kthread_should_park() for @k to return false, wakes it, and
434 * waits for it to return. If the thread is marked percpu then its
435 * bound to the cpu again.
437 void kthread_unpark(struct task_struct
*k
)
439 struct kthread
*kthread
= to_kthread(k
);
441 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
443 * We clear the IS_PARKED bit here as we don't wait
444 * until the task has left the park code. So if we'd
445 * park before that happens we'd see the IS_PARKED bit
446 * which might be about to be cleared.
448 if (test_and_clear_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
450 * Newly created kthread was parked when the CPU was offline.
451 * The binding was lost and we need to set it again.
453 if (test_bit(KTHREAD_IS_PER_CPU
, &kthread
->flags
))
454 __kthread_bind(k
, kthread
->cpu
, TASK_PARKED
);
455 wake_up_state(k
, TASK_PARKED
);
458 EXPORT_SYMBOL_GPL(kthread_unpark
);
461 * kthread_park - park a thread created by kthread_create().
462 * @k: thread created by kthread_create().
464 * Sets kthread_should_park() for @k to return true, wakes it, and
465 * waits for it to return. This can also be called after kthread_create()
466 * instead of calling wake_up_process(): the thread will park without
467 * calling threadfn().
469 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
470 * If called by the kthread itself just the park bit is set.
472 int kthread_park(struct task_struct
*k
)
474 struct kthread
*kthread
= to_kthread(k
);
476 if (WARN_ON(k
->flags
& PF_EXITING
))
479 if (!test_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
480 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
483 wait_for_completion(&kthread
->parked
);
489 EXPORT_SYMBOL_GPL(kthread_park
);
492 * kthread_stop - stop a thread created by kthread_create().
493 * @k: thread created by kthread_create().
495 * Sets kthread_should_stop() for @k to return true, wakes it, and
496 * waits for it to exit. This can also be called after kthread_create()
497 * instead of calling wake_up_process(): the thread will exit without
498 * calling threadfn().
500 * If threadfn() may call do_exit() itself, the caller must ensure
501 * task_struct can't go away.
503 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
506 int kthread_stop(struct task_struct
*k
)
508 struct kthread
*kthread
;
511 trace_sched_kthread_stop(k
);
514 kthread
= to_kthread(k
);
515 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
518 wait_for_completion(&kthread
->exited
);
522 trace_sched_kthread_stop_ret(ret
);
525 EXPORT_SYMBOL(kthread_stop
);
527 int kthreadd(void *unused
)
529 struct task_struct
*tsk
= current
;
531 /* Setup a clean context for our children to inherit. */
532 set_task_comm(tsk
, "kthreadd");
534 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
535 set_mems_allowed(node_states
[N_MEMORY
]);
537 current
->flags
|= PF_NOFREEZE
;
540 set_current_state(TASK_INTERRUPTIBLE
);
541 if (list_empty(&kthread_create_list
))
543 __set_current_state(TASK_RUNNING
);
545 spin_lock(&kthread_create_lock
);
546 while (!list_empty(&kthread_create_list
)) {
547 struct kthread_create_info
*create
;
549 create
= list_entry(kthread_create_list
.next
,
550 struct kthread_create_info
, list
);
551 list_del_init(&create
->list
);
552 spin_unlock(&kthread_create_lock
);
554 create_kthread(create
);
556 spin_lock(&kthread_create_lock
);
558 spin_unlock(&kthread_create_lock
);
564 void __kthread_init_worker(struct kthread_worker
*worker
,
566 struct lock_class_key
*key
)
568 memset(worker
, 0, sizeof(struct kthread_worker
));
569 spin_lock_init(&worker
->lock
);
570 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
571 INIT_LIST_HEAD(&worker
->work_list
);
572 INIT_LIST_HEAD(&worker
->delayed_work_list
);
574 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
577 * kthread_worker_fn - kthread function to process kthread_worker
578 * @worker_ptr: pointer to initialized kthread_worker
580 * This function implements the main cycle of kthread worker. It processes
581 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
584 * The works are not allowed to keep any locks, disable preemption or interrupts
585 * when they finish. There is defined a safe point for freezing when one work
586 * finishes and before a new one is started.
588 * Also the works must not be handled by more than one worker at the same time,
589 * see also kthread_queue_work().
591 int kthread_worker_fn(void *worker_ptr
)
593 struct kthread_worker
*worker
= worker_ptr
;
594 struct kthread_work
*work
;
597 * FIXME: Update the check and remove the assignment when all kthread
598 * worker users are created using kthread_create_worker*() functions.
600 WARN_ON(worker
->task
&& worker
->task
!= current
);
601 worker
->task
= current
;
603 if (worker
->flags
& KTW_FREEZABLE
)
607 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
609 if (kthread_should_stop()) {
610 __set_current_state(TASK_RUNNING
);
611 spin_lock_irq(&worker
->lock
);
613 spin_unlock_irq(&worker
->lock
);
618 spin_lock_irq(&worker
->lock
);
619 if (!list_empty(&worker
->work_list
)) {
620 work
= list_first_entry(&worker
->work_list
,
621 struct kthread_work
, node
);
622 list_del_init(&work
->node
);
624 worker
->current_work
= work
;
625 spin_unlock_irq(&worker
->lock
);
628 __set_current_state(TASK_RUNNING
);
630 } else if (!freezing(current
))
636 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
638 static struct kthread_worker
*
639 __kthread_create_worker(int cpu
, unsigned int flags
,
640 const char namefmt
[], va_list args
)
642 struct kthread_worker
*worker
;
643 struct task_struct
*task
;
646 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
648 return ERR_PTR(-ENOMEM
);
650 kthread_init_worker(worker
);
653 node
= cpu_to_node(cpu
);
655 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
656 node
, namefmt
, args
);
661 kthread_bind(task
, cpu
);
663 worker
->flags
= flags
;
665 wake_up_process(task
);
670 return ERR_CAST(task
);
674 * kthread_create_worker - create a kthread worker
675 * @flags: flags modifying the default behavior of the worker
676 * @namefmt: printf-style name for the kthread worker (task).
678 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
679 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
680 * when the worker was SIGKILLed.
682 struct kthread_worker
*
683 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
685 struct kthread_worker
*worker
;
688 va_start(args
, namefmt
);
689 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
694 EXPORT_SYMBOL(kthread_create_worker
);
697 * kthread_create_worker_on_cpu - create a kthread worker and bind it
698 * it to a given CPU and the associated NUMA node.
700 * @flags: flags modifying the default behavior of the worker
701 * @namefmt: printf-style name for the kthread worker (task).
703 * Use a valid CPU number if you want to bind the kthread worker
704 * to the given CPU and the associated NUMA node.
706 * A good practice is to add the cpu number also into the worker name.
707 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
709 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
710 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
711 * when the worker was SIGKILLed.
713 struct kthread_worker
*
714 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
715 const char namefmt
[], ...)
717 struct kthread_worker
*worker
;
720 va_start(args
, namefmt
);
721 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
726 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
729 * Returns true when the work could not be queued at the moment.
730 * It happens when it is already pending in a worker list
731 * or when it is being cancelled.
733 static inline bool queuing_blocked(struct kthread_worker
*worker
,
734 struct kthread_work
*work
)
736 lockdep_assert_held(&worker
->lock
);
738 return !list_empty(&work
->node
) || work
->canceling
;
741 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
742 struct kthread_work
*work
)
744 lockdep_assert_held(&worker
->lock
);
745 WARN_ON_ONCE(!list_empty(&work
->node
));
746 /* Do not use a work with >1 worker, see kthread_queue_work() */
747 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
750 /* insert @work before @pos in @worker */
751 static void kthread_insert_work(struct kthread_worker
*worker
,
752 struct kthread_work
*work
,
753 struct list_head
*pos
)
755 kthread_insert_work_sanity_check(worker
, work
);
757 list_add_tail(&work
->node
, pos
);
758 work
->worker
= worker
;
759 if (!worker
->current_work
&& likely(worker
->task
))
760 wake_up_process(worker
->task
);
764 * kthread_queue_work - queue a kthread_work
765 * @worker: target kthread_worker
766 * @work: kthread_work to queue
768 * Queue @work to work processor @task for async execution. @task
769 * must have been created with kthread_worker_create(). Returns %true
770 * if @work was successfully queued, %false if it was already pending.
772 * Reinitialize the work if it needs to be used by another worker.
773 * For example, when the worker was stopped and started again.
775 bool kthread_queue_work(struct kthread_worker
*worker
,
776 struct kthread_work
*work
)
781 spin_lock_irqsave(&worker
->lock
, flags
);
782 if (!queuing_blocked(worker
, work
)) {
783 kthread_insert_work(worker
, work
, &worker
->work_list
);
786 spin_unlock_irqrestore(&worker
->lock
, flags
);
789 EXPORT_SYMBOL_GPL(kthread_queue_work
);
792 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
793 * delayed work when the timer expires.
794 * @__data: pointer to the data associated with the timer
796 * The format of the function is defined by struct timer_list.
797 * It should have been called from irqsafe timer with irq already off.
799 void kthread_delayed_work_timer_fn(unsigned long __data
)
801 struct kthread_delayed_work
*dwork
=
802 (struct kthread_delayed_work
*)__data
;
803 struct kthread_work
*work
= &dwork
->work
;
804 struct kthread_worker
*worker
= work
->worker
;
807 * This might happen when a pending work is reinitialized.
808 * It means that it is used a wrong way.
810 if (WARN_ON_ONCE(!worker
))
813 spin_lock(&worker
->lock
);
814 /* Work must not be used with >1 worker, see kthread_queue_work(). */
815 WARN_ON_ONCE(work
->worker
!= worker
);
817 /* Move the work from worker->delayed_work_list. */
818 WARN_ON_ONCE(list_empty(&work
->node
));
819 list_del_init(&work
->node
);
820 kthread_insert_work(worker
, work
, &worker
->work_list
);
822 spin_unlock(&worker
->lock
);
824 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
826 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
827 struct kthread_delayed_work
*dwork
,
830 struct timer_list
*timer
= &dwork
->timer
;
831 struct kthread_work
*work
= &dwork
->work
;
833 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
||
834 timer
->data
!= (unsigned long)dwork
);
837 * If @delay is 0, queue @dwork->work immediately. This is for
838 * both optimization and correctness. The earliest @timer can
839 * expire is on the closest next tick and delayed_work users depend
840 * on that there's no such delay when @delay is 0.
843 kthread_insert_work(worker
, work
, &worker
->work_list
);
847 /* Be paranoid and try to detect possible races already now. */
848 kthread_insert_work_sanity_check(worker
, work
);
850 list_add(&work
->node
, &worker
->delayed_work_list
);
851 work
->worker
= worker
;
852 timer_stats_timer_set_start_info(&dwork
->timer
);
853 timer
->expires
= jiffies
+ delay
;
858 * kthread_queue_delayed_work - queue the associated kthread work
860 * @worker: target kthread_worker
861 * @dwork: kthread_delayed_work to queue
862 * @delay: number of jiffies to wait before queuing
864 * If the work has not been pending it starts a timer that will queue
865 * the work after the given @delay. If @delay is zero, it queues the
868 * Return: %false if the @work has already been pending. It means that
869 * either the timer was running or the work was queued. It returns %true
872 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
873 struct kthread_delayed_work
*dwork
,
876 struct kthread_work
*work
= &dwork
->work
;
880 spin_lock_irqsave(&worker
->lock
, flags
);
882 if (!queuing_blocked(worker
, work
)) {
883 __kthread_queue_delayed_work(worker
, dwork
, delay
);
887 spin_unlock_irqrestore(&worker
->lock
, flags
);
890 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
892 struct kthread_flush_work
{
893 struct kthread_work work
;
894 struct completion done
;
897 static void kthread_flush_work_fn(struct kthread_work
*work
)
899 struct kthread_flush_work
*fwork
=
900 container_of(work
, struct kthread_flush_work
, work
);
901 complete(&fwork
->done
);
905 * kthread_flush_work - flush a kthread_work
906 * @work: work to flush
908 * If @work is queued or executing, wait for it to finish execution.
910 void kthread_flush_work(struct kthread_work
*work
)
912 struct kthread_flush_work fwork
= {
913 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
914 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
916 struct kthread_worker
*worker
;
919 worker
= work
->worker
;
923 spin_lock_irq(&worker
->lock
);
924 /* Work must not be used with >1 worker, see kthread_queue_work(). */
925 WARN_ON_ONCE(work
->worker
!= worker
);
927 if (!list_empty(&work
->node
))
928 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
929 else if (worker
->current_work
== work
)
930 kthread_insert_work(worker
, &fwork
.work
,
931 worker
->work_list
.next
);
935 spin_unlock_irq(&worker
->lock
);
938 wait_for_completion(&fwork
.done
);
940 EXPORT_SYMBOL_GPL(kthread_flush_work
);
943 * This function removes the work from the worker queue. Also it makes sure
944 * that it won't get queued later via the delayed work's timer.
946 * The work might still be in use when this function finishes. See the
947 * current_work proceed by the worker.
949 * Return: %true if @work was pending and successfully canceled,
950 * %false if @work was not pending
952 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
953 unsigned long *flags
)
955 /* Try to cancel the timer if exists. */
957 struct kthread_delayed_work
*dwork
=
958 container_of(work
, struct kthread_delayed_work
, work
);
959 struct kthread_worker
*worker
= work
->worker
;
962 * del_timer_sync() must be called to make sure that the timer
963 * callback is not running. The lock must be temporary released
964 * to avoid a deadlock with the callback. In the meantime,
965 * any queuing is blocked by setting the canceling counter.
968 spin_unlock_irqrestore(&worker
->lock
, *flags
);
969 del_timer_sync(&dwork
->timer
);
970 spin_lock_irqsave(&worker
->lock
, *flags
);
975 * Try to remove the work from a worker list. It might either
976 * be from worker->work_list or from worker->delayed_work_list.
978 if (!list_empty(&work
->node
)) {
979 list_del_init(&work
->node
);
987 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
988 * @worker: kthread worker to use
989 * @dwork: kthread delayed work to queue
990 * @delay: number of jiffies to wait before queuing
992 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
993 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
994 * @work is guaranteed to be queued immediately.
996 * Return: %true if @dwork was pending and its timer was modified,
999 * A special case is when the work is being canceled in parallel.
1000 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1001 * or yet another kthread_mod_delayed_work() call. We let the other command
1002 * win and return %false here. The caller is supposed to synchronize these
1003 * operations a reasonable way.
1005 * This function is safe to call from any context including IRQ handler.
1006 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1009 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1010 struct kthread_delayed_work
*dwork
,
1011 unsigned long delay
)
1013 struct kthread_work
*work
= &dwork
->work
;
1014 unsigned long flags
;
1017 spin_lock_irqsave(&worker
->lock
, flags
);
1019 /* Do not bother with canceling when never queued. */
1023 /* Work must not be used with >1 worker, see kthread_queue_work() */
1024 WARN_ON_ONCE(work
->worker
!= worker
);
1026 /* Do not fight with another command that is canceling this work. */
1027 if (work
->canceling
)
1030 ret
= __kthread_cancel_work(work
, true, &flags
);
1032 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1034 spin_unlock_irqrestore(&worker
->lock
, flags
);
1037 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1039 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1041 struct kthread_worker
*worker
= work
->worker
;
1042 unsigned long flags
;
1048 spin_lock_irqsave(&worker
->lock
, flags
);
1049 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1050 WARN_ON_ONCE(work
->worker
!= worker
);
1052 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1054 if (worker
->current_work
!= work
)
1058 * The work is in progress and we need to wait with the lock released.
1059 * In the meantime, block any queuing by setting the canceling counter.
1062 spin_unlock_irqrestore(&worker
->lock
, flags
);
1063 kthread_flush_work(work
);
1064 spin_lock_irqsave(&worker
->lock
, flags
);
1068 spin_unlock_irqrestore(&worker
->lock
, flags
);
1074 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1075 * @work: the kthread work to cancel
1077 * Cancel @work and wait for its execution to finish. This function
1078 * can be used even if the work re-queues itself. On return from this
1079 * function, @work is guaranteed to be not pending or executing on any CPU.
1081 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1082 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1084 * The caller must ensure that the worker on which @work was last
1085 * queued can't be destroyed before this function returns.
1087 * Return: %true if @work was pending, %false otherwise.
1089 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1091 return __kthread_cancel_work_sync(work
, false);
1093 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1096 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1097 * wait for it to finish.
1098 * @dwork: the kthread delayed work to cancel
1100 * This is kthread_cancel_work_sync() for delayed works.
1102 * Return: %true if @dwork was pending, %false otherwise.
1104 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1106 return __kthread_cancel_work_sync(&dwork
->work
, true);
1108 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1111 * kthread_flush_worker - flush all current works on a kthread_worker
1112 * @worker: worker to flush
1114 * Wait until all currently executing or pending works on @worker are
1117 void kthread_flush_worker(struct kthread_worker
*worker
)
1119 struct kthread_flush_work fwork
= {
1120 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1121 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1124 kthread_queue_work(worker
, &fwork
.work
);
1125 wait_for_completion(&fwork
.done
);
1127 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1130 * kthread_destroy_worker - destroy a kthread worker
1131 * @worker: worker to be destroyed
1133 * Flush and destroy @worker. The simple flush is enough because the kthread
1134 * worker API is used only in trivial scenarios. There are no multi-step state
1137 void kthread_destroy_worker(struct kthread_worker
*worker
)
1139 struct task_struct
*task
;
1141 task
= worker
->task
;
1145 kthread_flush_worker(worker
);
1147 WARN_ON(!list_empty(&worker
->work_list
));
1150 EXPORT_SYMBOL(kthread_destroy_worker
);