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 __printf(4, 0)
265 struct task_struct
*__kthread_create_on_node(int (*threadfn
)(void *data
),
266 void *data
, int node
,
267 const char namefmt
[],
270 DECLARE_COMPLETION_ONSTACK(done
);
271 struct task_struct
*task
;
272 struct kthread_create_info
*create
= kmalloc(sizeof(*create
),
276 return ERR_PTR(-ENOMEM
);
277 create
->threadfn
= threadfn
;
280 create
->done
= &done
;
282 spin_lock(&kthread_create_lock
);
283 list_add_tail(&create
->list
, &kthread_create_list
);
284 spin_unlock(&kthread_create_lock
);
286 wake_up_process(kthreadd_task
);
288 * Wait for completion in killable state, for I might be chosen by
289 * the OOM killer while kthreadd is trying to allocate memory for
292 if (unlikely(wait_for_completion_killable(&done
))) {
296 * I got SIGKILL, but wait for 10 more seconds for completion
297 * unless chosen by the OOM killer. This delay is there as a
298 * workaround for boot failure caused by SIGKILL upon device
299 * driver initialization timeout.
301 while (i
++ < 10 && !test_tsk_thread_flag(current
, TIF_MEMDIE
))
302 if (wait_for_completion_timeout(&done
, HZ
))
305 * If I was SIGKILLed before kthreadd (or new kernel thread)
306 * calls complete(), leave the cleanup of this structure to
309 if (xchg(&create
->done
, NULL
))
310 return ERR_PTR(-EINTR
);
312 * kthreadd (or new kernel thread) will call complete()
315 wait_for_completion(&done
);
318 task
= create
->result
;
320 static const struct sched_param param
= { .sched_priority
= 0 };
322 vsnprintf(task
->comm
, sizeof(task
->comm
), namefmt
, args
);
324 * root may have changed our (kthreadd's) priority or CPU mask.
325 * The kernel thread should not inherit these properties.
327 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
328 set_cpus_allowed_ptr(task
, cpu_all_mask
);
335 * kthread_create_on_node - create a kthread.
336 * @threadfn: the function to run until signal_pending(current).
337 * @data: data ptr for @threadfn.
338 * @node: task and thread structures for the thread are allocated on this node
339 * @namefmt: printf-style name for the thread.
341 * Description: This helper function creates and names a kernel
342 * thread. The thread will be stopped: use wake_up_process() to start
343 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
344 * is affine to all CPUs.
346 * If thread is going to be bound on a particular cpu, give its node
347 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
348 * When woken, the thread will run @threadfn() with @data as its
349 * argument. @threadfn() can either call do_exit() directly if it is a
350 * standalone thread for which no one will call kthread_stop(), or
351 * return when 'kthread_should_stop()' is true (which means
352 * kthread_stop() has been called). The return value should be zero
353 * or a negative error number; it will be passed to kthread_stop().
355 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
357 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
358 void *data
, int node
,
359 const char namefmt
[],
362 struct task_struct
*task
;
365 va_start(args
, namefmt
);
366 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
371 EXPORT_SYMBOL(kthread_create_on_node
);
373 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
377 if (!wait_task_inactive(p
, state
)) {
382 /* It's safe because the task is inactive. */
383 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
384 do_set_cpus_allowed(p
, mask
);
385 p
->flags
|= PF_NO_SETAFFINITY
;
386 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
389 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
391 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
394 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
396 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
400 * kthread_bind - bind a just-created kthread to a cpu.
401 * @p: thread created by kthread_create().
402 * @cpu: cpu (might not be online, must be possible) for @k to run on.
404 * Description: This function is equivalent to set_cpus_allowed(),
405 * except that @cpu doesn't need to be online, and the thread must be
406 * stopped (i.e., just returned from kthread_create()).
408 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
410 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
412 EXPORT_SYMBOL(kthread_bind
);
415 * kthread_create_on_cpu - Create a cpu bound kthread
416 * @threadfn: the function to run until signal_pending(current).
417 * @data: data ptr for @threadfn.
418 * @cpu: The cpu on which the thread should be bound,
419 * @namefmt: printf-style name for the thread. Format is restricted
420 * to "name.*%u". Code fills in cpu number.
422 * Description: This helper function creates and names a kernel thread
423 * The thread will be woken and put into park mode.
425 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
426 void *data
, unsigned int cpu
,
429 struct task_struct
*p
;
431 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
435 kthread_bind(p
, cpu
);
436 /* CPU hotplug need to bind once again when unparking the thread. */
437 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
438 to_kthread(p
)->cpu
= cpu
;
443 * kthread_unpark - unpark a thread created by kthread_create().
444 * @k: thread created by kthread_create().
446 * Sets kthread_should_park() for @k to return false, wakes it, and
447 * waits for it to return. If the thread is marked percpu then its
448 * bound to the cpu again.
450 void kthread_unpark(struct task_struct
*k
)
452 struct kthread
*kthread
= to_kthread(k
);
454 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
456 * We clear the IS_PARKED bit here as we don't wait
457 * until the task has left the park code. So if we'd
458 * park before that happens we'd see the IS_PARKED bit
459 * which might be about to be cleared.
461 if (test_and_clear_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
463 * Newly created kthread was parked when the CPU was offline.
464 * The binding was lost and we need to set it again.
466 if (test_bit(KTHREAD_IS_PER_CPU
, &kthread
->flags
))
467 __kthread_bind(k
, kthread
->cpu
, TASK_PARKED
);
468 wake_up_state(k
, TASK_PARKED
);
471 EXPORT_SYMBOL_GPL(kthread_unpark
);
474 * kthread_park - park a thread created by kthread_create().
475 * @k: thread created by kthread_create().
477 * Sets kthread_should_park() for @k to return true, wakes it, and
478 * waits for it to return. This can also be called after kthread_create()
479 * instead of calling wake_up_process(): the thread will park without
480 * calling threadfn().
482 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
483 * If called by the kthread itself just the park bit is set.
485 int kthread_park(struct task_struct
*k
)
487 struct kthread
*kthread
= to_kthread(k
);
489 if (WARN_ON(k
->flags
& PF_EXITING
))
492 if (!test_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
493 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
496 wait_for_completion(&kthread
->parked
);
502 EXPORT_SYMBOL_GPL(kthread_park
);
505 * kthread_stop - stop a thread created by kthread_create().
506 * @k: thread created by kthread_create().
508 * Sets kthread_should_stop() for @k to return true, wakes it, and
509 * waits for it to exit. This can also be called after kthread_create()
510 * instead of calling wake_up_process(): the thread will exit without
511 * calling threadfn().
513 * If threadfn() may call do_exit() itself, the caller must ensure
514 * task_struct can't go away.
516 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
519 int kthread_stop(struct task_struct
*k
)
521 struct kthread
*kthread
;
524 trace_sched_kthread_stop(k
);
527 kthread
= to_kthread(k
);
528 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
531 wait_for_completion(&kthread
->exited
);
535 trace_sched_kthread_stop_ret(ret
);
538 EXPORT_SYMBOL(kthread_stop
);
540 int kthreadd(void *unused
)
542 struct task_struct
*tsk
= current
;
544 /* Setup a clean context for our children to inherit. */
545 set_task_comm(tsk
, "kthreadd");
547 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
548 set_mems_allowed(node_states
[N_MEMORY
]);
550 current
->flags
|= PF_NOFREEZE
;
553 set_current_state(TASK_INTERRUPTIBLE
);
554 if (list_empty(&kthread_create_list
))
556 __set_current_state(TASK_RUNNING
);
558 spin_lock(&kthread_create_lock
);
559 while (!list_empty(&kthread_create_list
)) {
560 struct kthread_create_info
*create
;
562 create
= list_entry(kthread_create_list
.next
,
563 struct kthread_create_info
, list
);
564 list_del_init(&create
->list
);
565 spin_unlock(&kthread_create_lock
);
567 create_kthread(create
);
569 spin_lock(&kthread_create_lock
);
571 spin_unlock(&kthread_create_lock
);
577 void __kthread_init_worker(struct kthread_worker
*worker
,
579 struct lock_class_key
*key
)
581 memset(worker
, 0, sizeof(struct kthread_worker
));
582 spin_lock_init(&worker
->lock
);
583 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
584 INIT_LIST_HEAD(&worker
->work_list
);
585 INIT_LIST_HEAD(&worker
->delayed_work_list
);
587 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
590 * kthread_worker_fn - kthread function to process kthread_worker
591 * @worker_ptr: pointer to initialized kthread_worker
593 * This function implements the main cycle of kthread worker. It processes
594 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
597 * The works are not allowed to keep any locks, disable preemption or interrupts
598 * when they finish. There is defined a safe point for freezing when one work
599 * finishes and before a new one is started.
601 * Also the works must not be handled by more than one worker at the same time,
602 * see also kthread_queue_work().
604 int kthread_worker_fn(void *worker_ptr
)
606 struct kthread_worker
*worker
= worker_ptr
;
607 struct kthread_work
*work
;
610 * FIXME: Update the check and remove the assignment when all kthread
611 * worker users are created using kthread_create_worker*() functions.
613 WARN_ON(worker
->task
&& worker
->task
!= current
);
614 worker
->task
= current
;
616 if (worker
->flags
& KTW_FREEZABLE
)
620 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
622 if (kthread_should_stop()) {
623 __set_current_state(TASK_RUNNING
);
624 spin_lock_irq(&worker
->lock
);
626 spin_unlock_irq(&worker
->lock
);
631 spin_lock_irq(&worker
->lock
);
632 if (!list_empty(&worker
->work_list
)) {
633 work
= list_first_entry(&worker
->work_list
,
634 struct kthread_work
, node
);
635 list_del_init(&work
->node
);
637 worker
->current_work
= work
;
638 spin_unlock_irq(&worker
->lock
);
641 __set_current_state(TASK_RUNNING
);
643 } else if (!freezing(current
))
649 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
651 static __printf(3, 0) struct kthread_worker
*
652 __kthread_create_worker(int cpu
, unsigned int flags
,
653 const char namefmt
[], va_list args
)
655 struct kthread_worker
*worker
;
656 struct task_struct
*task
;
659 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
661 return ERR_PTR(-ENOMEM
);
663 kthread_init_worker(worker
);
666 node
= cpu_to_node(cpu
);
668 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
669 node
, namefmt
, args
);
674 kthread_bind(task
, cpu
);
676 worker
->flags
= flags
;
678 wake_up_process(task
);
683 return ERR_CAST(task
);
687 * kthread_create_worker - create a kthread worker
688 * @flags: flags modifying the default behavior of the worker
689 * @namefmt: printf-style name for the kthread worker (task).
691 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
692 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
693 * when the worker was SIGKILLed.
695 struct kthread_worker
*
696 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
698 struct kthread_worker
*worker
;
701 va_start(args
, namefmt
);
702 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
707 EXPORT_SYMBOL(kthread_create_worker
);
710 * kthread_create_worker_on_cpu - create a kthread worker and bind it
711 * it to a given CPU and the associated NUMA node.
713 * @flags: flags modifying the default behavior of the worker
714 * @namefmt: printf-style name for the kthread worker (task).
716 * Use a valid CPU number if you want to bind the kthread worker
717 * to the given CPU and the associated NUMA node.
719 * A good practice is to add the cpu number also into the worker name.
720 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
722 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
723 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
724 * when the worker was SIGKILLed.
726 struct kthread_worker
*
727 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
728 const char namefmt
[], ...)
730 struct kthread_worker
*worker
;
733 va_start(args
, namefmt
);
734 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
739 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
742 * Returns true when the work could not be queued at the moment.
743 * It happens when it is already pending in a worker list
744 * or when it is being cancelled.
746 static inline bool queuing_blocked(struct kthread_worker
*worker
,
747 struct kthread_work
*work
)
749 lockdep_assert_held(&worker
->lock
);
751 return !list_empty(&work
->node
) || work
->canceling
;
754 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
755 struct kthread_work
*work
)
757 lockdep_assert_held(&worker
->lock
);
758 WARN_ON_ONCE(!list_empty(&work
->node
));
759 /* Do not use a work with >1 worker, see kthread_queue_work() */
760 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
763 /* insert @work before @pos in @worker */
764 static void kthread_insert_work(struct kthread_worker
*worker
,
765 struct kthread_work
*work
,
766 struct list_head
*pos
)
768 kthread_insert_work_sanity_check(worker
, work
);
770 list_add_tail(&work
->node
, pos
);
771 work
->worker
= worker
;
772 if (!worker
->current_work
&& likely(worker
->task
))
773 wake_up_process(worker
->task
);
777 * kthread_queue_work - queue a kthread_work
778 * @worker: target kthread_worker
779 * @work: kthread_work to queue
781 * Queue @work to work processor @task for async execution. @task
782 * must have been created with kthread_worker_create(). Returns %true
783 * if @work was successfully queued, %false if it was already pending.
785 * Reinitialize the work if it needs to be used by another worker.
786 * For example, when the worker was stopped and started again.
788 bool kthread_queue_work(struct kthread_worker
*worker
,
789 struct kthread_work
*work
)
794 spin_lock_irqsave(&worker
->lock
, flags
);
795 if (!queuing_blocked(worker
, work
)) {
796 kthread_insert_work(worker
, work
, &worker
->work_list
);
799 spin_unlock_irqrestore(&worker
->lock
, flags
);
802 EXPORT_SYMBOL_GPL(kthread_queue_work
);
805 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
806 * delayed work when the timer expires.
807 * @__data: pointer to the data associated with the timer
809 * The format of the function is defined by struct timer_list.
810 * It should have been called from irqsafe timer with irq already off.
812 void kthread_delayed_work_timer_fn(unsigned long __data
)
814 struct kthread_delayed_work
*dwork
=
815 (struct kthread_delayed_work
*)__data
;
816 struct kthread_work
*work
= &dwork
->work
;
817 struct kthread_worker
*worker
= work
->worker
;
820 * This might happen when a pending work is reinitialized.
821 * It means that it is used a wrong way.
823 if (WARN_ON_ONCE(!worker
))
826 spin_lock(&worker
->lock
);
827 /* Work must not be used with >1 worker, see kthread_queue_work(). */
828 WARN_ON_ONCE(work
->worker
!= worker
);
830 /* Move the work from worker->delayed_work_list. */
831 WARN_ON_ONCE(list_empty(&work
->node
));
832 list_del_init(&work
->node
);
833 kthread_insert_work(worker
, work
, &worker
->work_list
);
835 spin_unlock(&worker
->lock
);
837 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
839 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
840 struct kthread_delayed_work
*dwork
,
843 struct timer_list
*timer
= &dwork
->timer
;
844 struct kthread_work
*work
= &dwork
->work
;
846 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
||
847 timer
->data
!= (unsigned long)dwork
);
850 * If @delay is 0, queue @dwork->work immediately. This is for
851 * both optimization and correctness. The earliest @timer can
852 * expire is on the closest next tick and delayed_work users depend
853 * on that there's no such delay when @delay is 0.
856 kthread_insert_work(worker
, work
, &worker
->work_list
);
860 /* Be paranoid and try to detect possible races already now. */
861 kthread_insert_work_sanity_check(worker
, work
);
863 list_add(&work
->node
, &worker
->delayed_work_list
);
864 work
->worker
= worker
;
865 timer_stats_timer_set_start_info(&dwork
->timer
);
866 timer
->expires
= jiffies
+ delay
;
871 * kthread_queue_delayed_work - queue the associated kthread work
873 * @worker: target kthread_worker
874 * @dwork: kthread_delayed_work to queue
875 * @delay: number of jiffies to wait before queuing
877 * If the work has not been pending it starts a timer that will queue
878 * the work after the given @delay. If @delay is zero, it queues the
881 * Return: %false if the @work has already been pending. It means that
882 * either the timer was running or the work was queued. It returns %true
885 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
886 struct kthread_delayed_work
*dwork
,
889 struct kthread_work
*work
= &dwork
->work
;
893 spin_lock_irqsave(&worker
->lock
, flags
);
895 if (!queuing_blocked(worker
, work
)) {
896 __kthread_queue_delayed_work(worker
, dwork
, delay
);
900 spin_unlock_irqrestore(&worker
->lock
, flags
);
903 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
905 struct kthread_flush_work
{
906 struct kthread_work work
;
907 struct completion done
;
910 static void kthread_flush_work_fn(struct kthread_work
*work
)
912 struct kthread_flush_work
*fwork
=
913 container_of(work
, struct kthread_flush_work
, work
);
914 complete(&fwork
->done
);
918 * kthread_flush_work - flush a kthread_work
919 * @work: work to flush
921 * If @work is queued or executing, wait for it to finish execution.
923 void kthread_flush_work(struct kthread_work
*work
)
925 struct kthread_flush_work fwork
= {
926 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
927 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
929 struct kthread_worker
*worker
;
932 worker
= work
->worker
;
936 spin_lock_irq(&worker
->lock
);
937 /* Work must not be used with >1 worker, see kthread_queue_work(). */
938 WARN_ON_ONCE(work
->worker
!= worker
);
940 if (!list_empty(&work
->node
))
941 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
942 else if (worker
->current_work
== work
)
943 kthread_insert_work(worker
, &fwork
.work
,
944 worker
->work_list
.next
);
948 spin_unlock_irq(&worker
->lock
);
951 wait_for_completion(&fwork
.done
);
953 EXPORT_SYMBOL_GPL(kthread_flush_work
);
956 * This function removes the work from the worker queue. Also it makes sure
957 * that it won't get queued later via the delayed work's timer.
959 * The work might still be in use when this function finishes. See the
960 * current_work proceed by the worker.
962 * Return: %true if @work was pending and successfully canceled,
963 * %false if @work was not pending
965 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
966 unsigned long *flags
)
968 /* Try to cancel the timer if exists. */
970 struct kthread_delayed_work
*dwork
=
971 container_of(work
, struct kthread_delayed_work
, work
);
972 struct kthread_worker
*worker
= work
->worker
;
975 * del_timer_sync() must be called to make sure that the timer
976 * callback is not running. The lock must be temporary released
977 * to avoid a deadlock with the callback. In the meantime,
978 * any queuing is blocked by setting the canceling counter.
981 spin_unlock_irqrestore(&worker
->lock
, *flags
);
982 del_timer_sync(&dwork
->timer
);
983 spin_lock_irqsave(&worker
->lock
, *flags
);
988 * Try to remove the work from a worker list. It might either
989 * be from worker->work_list or from worker->delayed_work_list.
991 if (!list_empty(&work
->node
)) {
992 list_del_init(&work
->node
);
1000 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1001 * @worker: kthread worker to use
1002 * @dwork: kthread delayed work to queue
1003 * @delay: number of jiffies to wait before queuing
1005 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1006 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1007 * @work is guaranteed to be queued immediately.
1009 * Return: %true if @dwork was pending and its timer was modified,
1012 * A special case is when the work is being canceled in parallel.
1013 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1014 * or yet another kthread_mod_delayed_work() call. We let the other command
1015 * win and return %false here. The caller is supposed to synchronize these
1016 * operations a reasonable way.
1018 * This function is safe to call from any context including IRQ handler.
1019 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1022 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1023 struct kthread_delayed_work
*dwork
,
1024 unsigned long delay
)
1026 struct kthread_work
*work
= &dwork
->work
;
1027 unsigned long flags
;
1030 spin_lock_irqsave(&worker
->lock
, flags
);
1032 /* Do not bother with canceling when never queued. */
1036 /* Work must not be used with >1 worker, see kthread_queue_work() */
1037 WARN_ON_ONCE(work
->worker
!= worker
);
1039 /* Do not fight with another command that is canceling this work. */
1040 if (work
->canceling
)
1043 ret
= __kthread_cancel_work(work
, true, &flags
);
1045 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1047 spin_unlock_irqrestore(&worker
->lock
, flags
);
1050 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1052 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1054 struct kthread_worker
*worker
= work
->worker
;
1055 unsigned long flags
;
1061 spin_lock_irqsave(&worker
->lock
, flags
);
1062 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1063 WARN_ON_ONCE(work
->worker
!= worker
);
1065 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1067 if (worker
->current_work
!= work
)
1071 * The work is in progress and we need to wait with the lock released.
1072 * In the meantime, block any queuing by setting the canceling counter.
1075 spin_unlock_irqrestore(&worker
->lock
, flags
);
1076 kthread_flush_work(work
);
1077 spin_lock_irqsave(&worker
->lock
, flags
);
1081 spin_unlock_irqrestore(&worker
->lock
, flags
);
1087 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1088 * @work: the kthread work to cancel
1090 * Cancel @work and wait for its execution to finish. This function
1091 * can be used even if the work re-queues itself. On return from this
1092 * function, @work is guaranteed to be not pending or executing on any CPU.
1094 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1095 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1097 * The caller must ensure that the worker on which @work was last
1098 * queued can't be destroyed before this function returns.
1100 * Return: %true if @work was pending, %false otherwise.
1102 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1104 return __kthread_cancel_work_sync(work
, false);
1106 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1109 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1110 * wait for it to finish.
1111 * @dwork: the kthread delayed work to cancel
1113 * This is kthread_cancel_work_sync() for delayed works.
1115 * Return: %true if @dwork was pending, %false otherwise.
1117 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1119 return __kthread_cancel_work_sync(&dwork
->work
, true);
1121 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1124 * kthread_flush_worker - flush all current works on a kthread_worker
1125 * @worker: worker to flush
1127 * Wait until all currently executing or pending works on @worker are
1130 void kthread_flush_worker(struct kthread_worker
*worker
)
1132 struct kthread_flush_work fwork
= {
1133 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1134 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1137 kthread_queue_work(worker
, &fwork
.work
);
1138 wait_for_completion(&fwork
.done
);
1140 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1143 * kthread_destroy_worker - destroy a kthread worker
1144 * @worker: worker to be destroyed
1146 * Flush and destroy @worker. The simple flush is enough because the kthread
1147 * worker API is used only in trivial scenarios. There are no multi-step state
1150 void kthread_destroy_worker(struct kthread_worker
*worker
)
1152 struct task_struct
*task
;
1154 task
= worker
->task
;
1158 kthread_flush_worker(worker
);
1160 WARN_ON(!list_empty(&worker
->work_list
));
1163 EXPORT_SYMBOL(kthread_destroy_worker
);