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 <uapi/linux/sched/types.h>
9 #include <linux/sched.h>
10 #include <linux/sched/task.h>
11 #include <linux/kthread.h>
12 #include <linux/completion.h>
13 #include <linux/err.h>
14 #include <linux/cpuset.h>
15 #include <linux/unistd.h>
16 #include <linux/file.h>
17 #include <linux/export.h>
18 #include <linux/mutex.h>
19 #include <linux/slab.h>
20 #include <linux/freezer.h>
21 #include <linux/ptrace.h>
22 #include <linux/uaccess.h>
23 #include <linux/cgroup.h>
24 #include <trace/events/sched.h>
26 static DEFINE_SPINLOCK(kthread_create_lock
);
27 static LIST_HEAD(kthread_create_list
);
28 struct task_struct
*kthreadd_task
;
30 struct kthread_create_info
32 /* Information passed to kthread() from kthreadd. */
33 int (*threadfn
)(void *data
);
37 /* Result passed back to kthread_create() from kthreadd. */
38 struct task_struct
*result
;
39 struct completion
*done
;
41 struct list_head list
;
48 struct completion parked
;
49 struct completion exited
;
53 KTHREAD_IS_PER_CPU
= 0,
59 static inline void set_kthread_struct(void *kthread
)
62 * We abuse ->set_child_tid to avoid the new member and because it
63 * can't be wrongly copied by copy_process(). We also rely on fact
64 * that the caller can't exec, so PF_KTHREAD can't be cleared.
66 current
->set_child_tid
= (__force
void __user
*)kthread
;
69 static inline struct kthread
*to_kthread(struct task_struct
*k
)
71 WARN_ON(!(k
->flags
& PF_KTHREAD
));
72 return (__force
void *)k
->set_child_tid
;
75 void free_kthread_struct(struct task_struct
*k
)
78 * Can be NULL if this kthread was created by kernel_thread()
79 * or if kmalloc() in kthread() failed.
85 * kthread_should_stop - should this kthread return now?
87 * When someone calls kthread_stop() on your kthread, it will be woken
88 * and this will return true. You should then return, and your return
89 * value will be passed through to kthread_stop().
91 bool kthread_should_stop(void)
93 return test_bit(KTHREAD_SHOULD_STOP
, &to_kthread(current
)->flags
);
95 EXPORT_SYMBOL(kthread_should_stop
);
98 * kthread_should_park - should this kthread park now?
100 * When someone calls kthread_park() on your kthread, it will be woken
101 * and this will return true. You should then do the necessary
102 * cleanup and call kthread_parkme()
104 * Similar to kthread_should_stop(), but this keeps the thread alive
105 * and in a park position. kthread_unpark() "restarts" the thread and
106 * calls the thread function again.
108 bool kthread_should_park(void)
110 return test_bit(KTHREAD_SHOULD_PARK
, &to_kthread(current
)->flags
);
112 EXPORT_SYMBOL_GPL(kthread_should_park
);
115 * kthread_freezable_should_stop - should this freezable kthread return now?
116 * @was_frozen: optional out parameter, indicates whether %current was frozen
118 * kthread_should_stop() for freezable kthreads, which will enter
119 * refrigerator if necessary. This function is safe from kthread_stop() /
120 * freezer deadlock and freezable kthreads should use this function instead
121 * of calling try_to_freeze() directly.
123 bool kthread_freezable_should_stop(bool *was_frozen
)
129 if (unlikely(freezing(current
)))
130 frozen
= __refrigerator(true);
133 *was_frozen
= frozen
;
135 return kthread_should_stop();
137 EXPORT_SYMBOL_GPL(kthread_freezable_should_stop
);
140 * kthread_data - return data value specified on kthread creation
141 * @task: kthread task in question
143 * Return the data value specified when kthread @task was created.
144 * The caller is responsible for ensuring the validity of @task when
145 * calling this function.
147 void *kthread_data(struct task_struct
*task
)
149 return to_kthread(task
)->data
;
153 * kthread_probe_data - speculative version of kthread_data()
154 * @task: possible kthread task in question
156 * @task could be a kthread task. Return the data value specified when it
157 * was created if accessible. If @task isn't a kthread task or its data is
158 * inaccessible for any reason, %NULL is returned. This function requires
159 * that @task itself is safe to dereference.
161 void *kthread_probe_data(struct task_struct
*task
)
163 struct kthread
*kthread
= to_kthread(task
);
166 probe_kernel_read(&data
, &kthread
->data
, sizeof(data
));
170 static void __kthread_parkme(struct kthread
*self
)
172 __set_current_state(TASK_PARKED
);
173 while (test_bit(KTHREAD_SHOULD_PARK
, &self
->flags
)) {
174 if (!test_and_set_bit(KTHREAD_IS_PARKED
, &self
->flags
))
175 complete(&self
->parked
);
177 __set_current_state(TASK_PARKED
);
179 clear_bit(KTHREAD_IS_PARKED
, &self
->flags
);
180 __set_current_state(TASK_RUNNING
);
183 void kthread_parkme(void)
185 __kthread_parkme(to_kthread(current
));
187 EXPORT_SYMBOL_GPL(kthread_parkme
);
189 static int kthread(void *_create
)
191 /* Copy data: it's on kthread's stack */
192 struct kthread_create_info
*create
= _create
;
193 int (*threadfn
)(void *data
) = create
->threadfn
;
194 void *data
= create
->data
;
195 struct completion
*done
;
196 struct kthread
*self
;
199 self
= kmalloc(sizeof(*self
), GFP_KERNEL
);
200 set_kthread_struct(self
);
202 /* If user was SIGKILLed, I release the structure. */
203 done
= xchg(&create
->done
, NULL
);
210 create
->result
= ERR_PTR(-ENOMEM
);
217 init_completion(&self
->exited
);
218 init_completion(&self
->parked
);
219 current
->vfork_done
= &self
->exited
;
221 /* OK, tell user we're spawned, wait for stop or wakeup */
222 __set_current_state(TASK_UNINTERRUPTIBLE
);
223 create
->result
= current
;
228 if (!test_bit(KTHREAD_SHOULD_STOP
, &self
->flags
)) {
229 cgroup_kthread_ready();
230 __kthread_parkme(self
);
231 ret
= threadfn(data
);
236 /* called from do_fork() to get node information for about to be created task */
237 int tsk_fork_get_node(struct task_struct
*tsk
)
240 if (tsk
== kthreadd_task
)
241 return tsk
->pref_node_fork
;
246 static void create_kthread(struct kthread_create_info
*create
)
251 current
->pref_node_fork
= create
->node
;
253 /* We want our own signal handler (we take no signals by default). */
254 pid
= kernel_thread(kthread
, create
, CLONE_FS
| CLONE_FILES
| SIGCHLD
);
256 /* If user was SIGKILLed, I release the structure. */
257 struct completion
*done
= xchg(&create
->done
, NULL
);
263 create
->result
= ERR_PTR(pid
);
268 static __printf(4, 0)
269 struct task_struct
*__kthread_create_on_node(int (*threadfn
)(void *data
),
270 void *data
, int node
,
271 const char namefmt
[],
274 DECLARE_COMPLETION_ONSTACK(done
);
275 struct task_struct
*task
;
276 struct kthread_create_info
*create
= kmalloc(sizeof(*create
),
280 return ERR_PTR(-ENOMEM
);
281 create
->threadfn
= threadfn
;
284 create
->done
= &done
;
286 spin_lock(&kthread_create_lock
);
287 list_add_tail(&create
->list
, &kthread_create_list
);
288 spin_unlock(&kthread_create_lock
);
290 wake_up_process(kthreadd_task
);
292 * Wait for completion in killable state, for I might be chosen by
293 * the OOM killer while kthreadd is trying to allocate memory for
296 if (unlikely(wait_for_completion_killable(&done
))) {
300 * I got SIGKILL, but wait for 10 more seconds for completion
301 * unless chosen by the OOM killer. This delay is there as a
302 * workaround for boot failure caused by SIGKILL upon device
303 * driver initialization timeout.
305 while (i
++ < 10 && !test_tsk_thread_flag(current
, TIF_MEMDIE
))
306 if (wait_for_completion_timeout(&done
, HZ
))
309 * If I was SIGKILLed before kthreadd (or new kernel thread)
310 * calls complete(), leave the cleanup of this structure to
313 if (xchg(&create
->done
, NULL
))
314 return ERR_PTR(-EINTR
);
316 * kthreadd (or new kernel thread) will call complete()
319 wait_for_completion(&done
);
322 task
= create
->result
;
324 static const struct sched_param param
= { .sched_priority
= 0 };
326 vsnprintf(task
->comm
, sizeof(task
->comm
), namefmt
, args
);
328 * root may have changed our (kthreadd's) priority or CPU mask.
329 * The kernel thread should not inherit these properties.
331 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
332 set_cpus_allowed_ptr(task
, cpu_all_mask
);
339 * kthread_create_on_node - create a kthread.
340 * @threadfn: the function to run until signal_pending(current).
341 * @data: data ptr for @threadfn.
342 * @node: task and thread structures for the thread are allocated on this node
343 * @namefmt: printf-style name for the thread.
345 * Description: This helper function creates and names a kernel
346 * thread. The thread will be stopped: use wake_up_process() to start
347 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
348 * is affine to all CPUs.
350 * If thread is going to be bound on a particular cpu, give its node
351 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
352 * When woken, the thread will run @threadfn() with @data as its
353 * argument. @threadfn() can either call do_exit() directly if it is a
354 * standalone thread for which no one will call kthread_stop(), or
355 * return when 'kthread_should_stop()' is true (which means
356 * kthread_stop() has been called). The return value should be zero
357 * or a negative error number; it will be passed to kthread_stop().
359 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
361 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
362 void *data
, int node
,
363 const char namefmt
[],
366 struct task_struct
*task
;
369 va_start(args
, namefmt
);
370 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
375 EXPORT_SYMBOL(kthread_create_on_node
);
377 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
381 if (!wait_task_inactive(p
, state
)) {
386 /* It's safe because the task is inactive. */
387 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
388 do_set_cpus_allowed(p
, mask
);
389 p
->flags
|= PF_NO_SETAFFINITY
;
390 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
393 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
395 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
398 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
400 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
404 * kthread_bind - bind a just-created kthread to a cpu.
405 * @p: thread created by kthread_create().
406 * @cpu: cpu (might not be online, must be possible) for @k to run on.
408 * Description: This function is equivalent to set_cpus_allowed(),
409 * except that @cpu doesn't need to be online, and the thread must be
410 * stopped (i.e., just returned from kthread_create()).
412 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
414 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
416 EXPORT_SYMBOL(kthread_bind
);
419 * kthread_create_on_cpu - Create a cpu bound kthread
420 * @threadfn: the function to run until signal_pending(current).
421 * @data: data ptr for @threadfn.
422 * @cpu: The cpu on which the thread should be bound,
423 * @namefmt: printf-style name for the thread. Format is restricted
424 * to "name.*%u". Code fills in cpu number.
426 * Description: This helper function creates and names a kernel thread
427 * The thread will be woken and put into park mode.
429 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
430 void *data
, unsigned int cpu
,
433 struct task_struct
*p
;
435 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
439 kthread_bind(p
, cpu
);
440 /* CPU hotplug need to bind once again when unparking the thread. */
441 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
442 to_kthread(p
)->cpu
= cpu
;
447 * kthread_unpark - unpark a thread created by kthread_create().
448 * @k: thread created by kthread_create().
450 * Sets kthread_should_park() for @k to return false, wakes it, and
451 * waits for it to return. If the thread is marked percpu then its
452 * bound to the cpu again.
454 void kthread_unpark(struct task_struct
*k
)
456 struct kthread
*kthread
= to_kthread(k
);
458 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
460 * We clear the IS_PARKED bit here as we don't wait
461 * until the task has left the park code. So if we'd
462 * park before that happens we'd see the IS_PARKED bit
463 * which might be about to be cleared.
465 if (test_and_clear_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
467 * Newly created kthread was parked when the CPU was offline.
468 * The binding was lost and we need to set it again.
470 if (test_bit(KTHREAD_IS_PER_CPU
, &kthread
->flags
))
471 __kthread_bind(k
, kthread
->cpu
, TASK_PARKED
);
472 wake_up_state(k
, TASK_PARKED
);
475 EXPORT_SYMBOL_GPL(kthread_unpark
);
478 * kthread_park - park a thread created by kthread_create().
479 * @k: thread created by kthread_create().
481 * Sets kthread_should_park() for @k to return true, wakes it, and
482 * waits for it to return. This can also be called after kthread_create()
483 * instead of calling wake_up_process(): the thread will park without
484 * calling threadfn().
486 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
487 * If called by the kthread itself just the park bit is set.
489 int kthread_park(struct task_struct
*k
)
491 struct kthread
*kthread
= to_kthread(k
);
493 if (WARN_ON(k
->flags
& PF_EXITING
))
496 if (!test_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
497 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
500 wait_for_completion(&kthread
->parked
);
506 EXPORT_SYMBOL_GPL(kthread_park
);
509 * kthread_stop - stop a thread created by kthread_create().
510 * @k: thread created by kthread_create().
512 * Sets kthread_should_stop() for @k to return true, wakes it, and
513 * waits for it to exit. This can also be called after kthread_create()
514 * instead of calling wake_up_process(): the thread will exit without
515 * calling threadfn().
517 * If threadfn() may call do_exit() itself, the caller must ensure
518 * task_struct can't go away.
520 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
523 int kthread_stop(struct task_struct
*k
)
525 struct kthread
*kthread
;
528 trace_sched_kthread_stop(k
);
531 kthread
= to_kthread(k
);
532 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
535 wait_for_completion(&kthread
->exited
);
539 trace_sched_kthread_stop_ret(ret
);
542 EXPORT_SYMBOL(kthread_stop
);
544 int kthreadd(void *unused
)
546 struct task_struct
*tsk
= current
;
548 /* Setup a clean context for our children to inherit. */
549 set_task_comm(tsk
, "kthreadd");
551 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
552 set_mems_allowed(node_states
[N_MEMORY
]);
554 current
->flags
|= PF_NOFREEZE
;
555 cgroup_init_kthreadd();
558 set_current_state(TASK_INTERRUPTIBLE
);
559 if (list_empty(&kthread_create_list
))
561 __set_current_state(TASK_RUNNING
);
563 spin_lock(&kthread_create_lock
);
564 while (!list_empty(&kthread_create_list
)) {
565 struct kthread_create_info
*create
;
567 create
= list_entry(kthread_create_list
.next
,
568 struct kthread_create_info
, list
);
569 list_del_init(&create
->list
);
570 spin_unlock(&kthread_create_lock
);
572 create_kthread(create
);
574 spin_lock(&kthread_create_lock
);
576 spin_unlock(&kthread_create_lock
);
582 void __kthread_init_worker(struct kthread_worker
*worker
,
584 struct lock_class_key
*key
)
586 memset(worker
, 0, sizeof(struct kthread_worker
));
587 spin_lock_init(&worker
->lock
);
588 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
589 INIT_LIST_HEAD(&worker
->work_list
);
590 INIT_LIST_HEAD(&worker
->delayed_work_list
);
592 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
595 * kthread_worker_fn - kthread function to process kthread_worker
596 * @worker_ptr: pointer to initialized kthread_worker
598 * This function implements the main cycle of kthread worker. It processes
599 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
602 * The works are not allowed to keep any locks, disable preemption or interrupts
603 * when they finish. There is defined a safe point for freezing when one work
604 * finishes and before a new one is started.
606 * Also the works must not be handled by more than one worker at the same time,
607 * see also kthread_queue_work().
609 int kthread_worker_fn(void *worker_ptr
)
611 struct kthread_worker
*worker
= worker_ptr
;
612 struct kthread_work
*work
;
615 * FIXME: Update the check and remove the assignment when all kthread
616 * worker users are created using kthread_create_worker*() functions.
618 WARN_ON(worker
->task
&& worker
->task
!= current
);
619 worker
->task
= current
;
621 if (worker
->flags
& KTW_FREEZABLE
)
625 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
627 if (kthread_should_stop()) {
628 __set_current_state(TASK_RUNNING
);
629 spin_lock_irq(&worker
->lock
);
631 spin_unlock_irq(&worker
->lock
);
636 spin_lock_irq(&worker
->lock
);
637 if (!list_empty(&worker
->work_list
)) {
638 work
= list_first_entry(&worker
->work_list
,
639 struct kthread_work
, node
);
640 list_del_init(&work
->node
);
642 worker
->current_work
= work
;
643 spin_unlock_irq(&worker
->lock
);
646 __set_current_state(TASK_RUNNING
);
648 } else if (!freezing(current
))
655 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
657 static __printf(3, 0) struct kthread_worker
*
658 __kthread_create_worker(int cpu
, unsigned int flags
,
659 const char namefmt
[], va_list args
)
661 struct kthread_worker
*worker
;
662 struct task_struct
*task
;
665 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
667 return ERR_PTR(-ENOMEM
);
669 kthread_init_worker(worker
);
672 node
= cpu_to_node(cpu
);
674 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
675 node
, namefmt
, args
);
680 kthread_bind(task
, cpu
);
682 worker
->flags
= flags
;
684 wake_up_process(task
);
689 return ERR_CAST(task
);
693 * kthread_create_worker - create a kthread worker
694 * @flags: flags modifying the default behavior of the worker
695 * @namefmt: printf-style name for the kthread worker (task).
697 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
698 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
699 * when the worker was SIGKILLed.
701 struct kthread_worker
*
702 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
704 struct kthread_worker
*worker
;
707 va_start(args
, namefmt
);
708 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
713 EXPORT_SYMBOL(kthread_create_worker
);
716 * kthread_create_worker_on_cpu - create a kthread worker and bind it
717 * it to a given CPU and the associated NUMA node.
719 * @flags: flags modifying the default behavior of the worker
720 * @namefmt: printf-style name for the kthread worker (task).
722 * Use a valid CPU number if you want to bind the kthread worker
723 * to the given CPU and the associated NUMA node.
725 * A good practice is to add the cpu number also into the worker name.
726 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
728 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
729 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
730 * when the worker was SIGKILLed.
732 struct kthread_worker
*
733 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
734 const char namefmt
[], ...)
736 struct kthread_worker
*worker
;
739 va_start(args
, namefmt
);
740 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
745 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
748 * Returns true when the work could not be queued at the moment.
749 * It happens when it is already pending in a worker list
750 * or when it is being cancelled.
752 static inline bool queuing_blocked(struct kthread_worker
*worker
,
753 struct kthread_work
*work
)
755 lockdep_assert_held(&worker
->lock
);
757 return !list_empty(&work
->node
) || work
->canceling
;
760 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
761 struct kthread_work
*work
)
763 lockdep_assert_held(&worker
->lock
);
764 WARN_ON_ONCE(!list_empty(&work
->node
));
765 /* Do not use a work with >1 worker, see kthread_queue_work() */
766 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
769 /* insert @work before @pos in @worker */
770 static void kthread_insert_work(struct kthread_worker
*worker
,
771 struct kthread_work
*work
,
772 struct list_head
*pos
)
774 kthread_insert_work_sanity_check(worker
, work
);
776 list_add_tail(&work
->node
, pos
);
777 work
->worker
= worker
;
778 if (!worker
->current_work
&& likely(worker
->task
))
779 wake_up_process(worker
->task
);
783 * kthread_queue_work - queue a kthread_work
784 * @worker: target kthread_worker
785 * @work: kthread_work to queue
787 * Queue @work to work processor @task for async execution. @task
788 * must have been created with kthread_worker_create(). Returns %true
789 * if @work was successfully queued, %false if it was already pending.
791 * Reinitialize the work if it needs to be used by another worker.
792 * For example, when the worker was stopped and started again.
794 bool kthread_queue_work(struct kthread_worker
*worker
,
795 struct kthread_work
*work
)
800 spin_lock_irqsave(&worker
->lock
, flags
);
801 if (!queuing_blocked(worker
, work
)) {
802 kthread_insert_work(worker
, work
, &worker
->work_list
);
805 spin_unlock_irqrestore(&worker
->lock
, flags
);
808 EXPORT_SYMBOL_GPL(kthread_queue_work
);
811 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
812 * delayed work when the timer expires.
813 * @__data: pointer to the data associated with the timer
815 * The format of the function is defined by struct timer_list.
816 * It should have been called from irqsafe timer with irq already off.
818 void kthread_delayed_work_timer_fn(unsigned long __data
)
820 struct kthread_delayed_work
*dwork
=
821 (struct kthread_delayed_work
*)__data
;
822 struct kthread_work
*work
= &dwork
->work
;
823 struct kthread_worker
*worker
= work
->worker
;
826 * This might happen when a pending work is reinitialized.
827 * It means that it is used a wrong way.
829 if (WARN_ON_ONCE(!worker
))
832 spin_lock(&worker
->lock
);
833 /* Work must not be used with >1 worker, see kthread_queue_work(). */
834 WARN_ON_ONCE(work
->worker
!= worker
);
836 /* Move the work from worker->delayed_work_list. */
837 WARN_ON_ONCE(list_empty(&work
->node
));
838 list_del_init(&work
->node
);
839 kthread_insert_work(worker
, work
, &worker
->work_list
);
841 spin_unlock(&worker
->lock
);
843 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
845 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
846 struct kthread_delayed_work
*dwork
,
849 struct timer_list
*timer
= &dwork
->timer
;
850 struct kthread_work
*work
= &dwork
->work
;
852 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
||
853 timer
->data
!= (unsigned long)dwork
);
856 * If @delay is 0, queue @dwork->work immediately. This is for
857 * both optimization and correctness. The earliest @timer can
858 * expire is on the closest next tick and delayed_work users depend
859 * on that there's no such delay when @delay is 0.
862 kthread_insert_work(worker
, work
, &worker
->work_list
);
866 /* Be paranoid and try to detect possible races already now. */
867 kthread_insert_work_sanity_check(worker
, work
);
869 list_add(&work
->node
, &worker
->delayed_work_list
);
870 work
->worker
= worker
;
871 timer
->expires
= jiffies
+ delay
;
876 * kthread_queue_delayed_work - queue the associated kthread work
878 * @worker: target kthread_worker
879 * @dwork: kthread_delayed_work to queue
880 * @delay: number of jiffies to wait before queuing
882 * If the work has not been pending it starts a timer that will queue
883 * the work after the given @delay. If @delay is zero, it queues the
886 * Return: %false if the @work has already been pending. It means that
887 * either the timer was running or the work was queued. It returns %true
890 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
891 struct kthread_delayed_work
*dwork
,
894 struct kthread_work
*work
= &dwork
->work
;
898 spin_lock_irqsave(&worker
->lock
, flags
);
900 if (!queuing_blocked(worker
, work
)) {
901 __kthread_queue_delayed_work(worker
, dwork
, delay
);
905 spin_unlock_irqrestore(&worker
->lock
, flags
);
908 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
910 struct kthread_flush_work
{
911 struct kthread_work work
;
912 struct completion done
;
915 static void kthread_flush_work_fn(struct kthread_work
*work
)
917 struct kthread_flush_work
*fwork
=
918 container_of(work
, struct kthread_flush_work
, work
);
919 complete(&fwork
->done
);
923 * kthread_flush_work - flush a kthread_work
924 * @work: work to flush
926 * If @work is queued or executing, wait for it to finish execution.
928 void kthread_flush_work(struct kthread_work
*work
)
930 struct kthread_flush_work fwork
= {
931 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
932 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
934 struct kthread_worker
*worker
;
937 worker
= work
->worker
;
941 spin_lock_irq(&worker
->lock
);
942 /* Work must not be used with >1 worker, see kthread_queue_work(). */
943 WARN_ON_ONCE(work
->worker
!= worker
);
945 if (!list_empty(&work
->node
))
946 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
947 else if (worker
->current_work
== work
)
948 kthread_insert_work(worker
, &fwork
.work
,
949 worker
->work_list
.next
);
953 spin_unlock_irq(&worker
->lock
);
956 wait_for_completion(&fwork
.done
);
958 EXPORT_SYMBOL_GPL(kthread_flush_work
);
961 * This function removes the work from the worker queue. Also it makes sure
962 * that it won't get queued later via the delayed work's timer.
964 * The work might still be in use when this function finishes. See the
965 * current_work proceed by the worker.
967 * Return: %true if @work was pending and successfully canceled,
968 * %false if @work was not pending
970 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
971 unsigned long *flags
)
973 /* Try to cancel the timer if exists. */
975 struct kthread_delayed_work
*dwork
=
976 container_of(work
, struct kthread_delayed_work
, work
);
977 struct kthread_worker
*worker
= work
->worker
;
980 * del_timer_sync() must be called to make sure that the timer
981 * callback is not running. The lock must be temporary released
982 * to avoid a deadlock with the callback. In the meantime,
983 * any queuing is blocked by setting the canceling counter.
986 spin_unlock_irqrestore(&worker
->lock
, *flags
);
987 del_timer_sync(&dwork
->timer
);
988 spin_lock_irqsave(&worker
->lock
, *flags
);
993 * Try to remove the work from a worker list. It might either
994 * be from worker->work_list or from worker->delayed_work_list.
996 if (!list_empty(&work
->node
)) {
997 list_del_init(&work
->node
);
1005 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1006 * @worker: kthread worker to use
1007 * @dwork: kthread delayed work to queue
1008 * @delay: number of jiffies to wait before queuing
1010 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1011 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1012 * @work is guaranteed to be queued immediately.
1014 * Return: %true if @dwork was pending and its timer was modified,
1017 * A special case is when the work is being canceled in parallel.
1018 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1019 * or yet another kthread_mod_delayed_work() call. We let the other command
1020 * win and return %false here. The caller is supposed to synchronize these
1021 * operations a reasonable way.
1023 * This function is safe to call from any context including IRQ handler.
1024 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1027 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1028 struct kthread_delayed_work
*dwork
,
1029 unsigned long delay
)
1031 struct kthread_work
*work
= &dwork
->work
;
1032 unsigned long flags
;
1035 spin_lock_irqsave(&worker
->lock
, flags
);
1037 /* Do not bother with canceling when never queued. */
1041 /* Work must not be used with >1 worker, see kthread_queue_work() */
1042 WARN_ON_ONCE(work
->worker
!= worker
);
1044 /* Do not fight with another command that is canceling this work. */
1045 if (work
->canceling
)
1048 ret
= __kthread_cancel_work(work
, true, &flags
);
1050 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1052 spin_unlock_irqrestore(&worker
->lock
, flags
);
1055 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1057 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1059 struct kthread_worker
*worker
= work
->worker
;
1060 unsigned long flags
;
1066 spin_lock_irqsave(&worker
->lock
, flags
);
1067 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1068 WARN_ON_ONCE(work
->worker
!= worker
);
1070 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1072 if (worker
->current_work
!= work
)
1076 * The work is in progress and we need to wait with the lock released.
1077 * In the meantime, block any queuing by setting the canceling counter.
1080 spin_unlock_irqrestore(&worker
->lock
, flags
);
1081 kthread_flush_work(work
);
1082 spin_lock_irqsave(&worker
->lock
, flags
);
1086 spin_unlock_irqrestore(&worker
->lock
, flags
);
1092 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1093 * @work: the kthread work to cancel
1095 * Cancel @work and wait for its execution to finish. This function
1096 * can be used even if the work re-queues itself. On return from this
1097 * function, @work is guaranteed to be not pending or executing on any CPU.
1099 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1100 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1102 * The caller must ensure that the worker on which @work was last
1103 * queued can't be destroyed before this function returns.
1105 * Return: %true if @work was pending, %false otherwise.
1107 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1109 return __kthread_cancel_work_sync(work
, false);
1111 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1114 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1115 * wait for it to finish.
1116 * @dwork: the kthread delayed work to cancel
1118 * This is kthread_cancel_work_sync() for delayed works.
1120 * Return: %true if @dwork was pending, %false otherwise.
1122 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1124 return __kthread_cancel_work_sync(&dwork
->work
, true);
1126 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1129 * kthread_flush_worker - flush all current works on a kthread_worker
1130 * @worker: worker to flush
1132 * Wait until all currently executing or pending works on @worker are
1135 void kthread_flush_worker(struct kthread_worker
*worker
)
1137 struct kthread_flush_work fwork
= {
1138 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1139 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1142 kthread_queue_work(worker
, &fwork
.work
);
1143 wait_for_completion(&fwork
.done
);
1145 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1148 * kthread_destroy_worker - destroy a kthread worker
1149 * @worker: worker to be destroyed
1151 * Flush and destroy @worker. The simple flush is enough because the kthread
1152 * worker API is used only in trivial scenarios. There are no multi-step state
1155 void kthread_destroy_worker(struct kthread_worker
*worker
)
1157 struct task_struct
*task
;
1159 task
= worker
->task
;
1163 kthread_flush_worker(worker
);
1165 WARN_ON(!list_empty(&worker
->work_list
));
1168 EXPORT_SYMBOL(kthread_destroy_worker
);