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 <trace/events/sched.h>
25 static DEFINE_SPINLOCK(kthread_create_lock
);
26 static LIST_HEAD(kthread_create_list
);
27 struct task_struct
*kthreadd_task
;
29 struct kthread_create_info
31 /* Information passed to kthread() from kthreadd. */
32 int (*threadfn
)(void *data
);
36 /* Result passed back to kthread_create() from kthreadd. */
37 struct task_struct
*result
;
38 struct completion
*done
;
40 struct list_head list
;
47 struct completion parked
;
48 struct completion exited
;
49 #ifdef CONFIG_BLK_CGROUP
50 struct cgroup_subsys_state
*blkcg_css
;
55 KTHREAD_IS_PER_CPU
= 0,
60 static inline void set_kthread_struct(void *kthread
)
63 * We abuse ->set_child_tid to avoid the new member and because it
64 * can't be wrongly copied by copy_process(). We also rely on fact
65 * that the caller can't exec, so PF_KTHREAD can't be cleared.
67 current
->set_child_tid
= (__force
void __user
*)kthread
;
70 static inline struct kthread
*to_kthread(struct task_struct
*k
)
72 WARN_ON(!(k
->flags
& PF_KTHREAD
));
73 return (__force
void *)k
->set_child_tid
;
76 void free_kthread_struct(struct task_struct
*k
)
78 struct kthread
*kthread
;
81 * Can be NULL if this kthread was created by kernel_thread()
82 * or if kmalloc() in kthread() failed.
84 kthread
= to_kthread(k
);
85 #ifdef CONFIG_BLK_CGROUP
86 WARN_ON_ONCE(kthread
&& kthread
->blkcg_css
);
92 * kthread_should_stop - should this kthread return now?
94 * When someone calls kthread_stop() on your kthread, it will be woken
95 * and this will return true. You should then return, and your return
96 * value will be passed through to kthread_stop().
98 bool kthread_should_stop(void)
100 return test_bit(KTHREAD_SHOULD_STOP
, &to_kthread(current
)->flags
);
102 EXPORT_SYMBOL(kthread_should_stop
);
105 * kthread_should_park - should this kthread park now?
107 * When someone calls kthread_park() on your kthread, it will be woken
108 * and this will return true. You should then do the necessary
109 * cleanup and call kthread_parkme()
111 * Similar to kthread_should_stop(), but this keeps the thread alive
112 * and in a park position. kthread_unpark() "restarts" the thread and
113 * calls the thread function again.
115 bool kthread_should_park(void)
117 return test_bit(KTHREAD_SHOULD_PARK
, &to_kthread(current
)->flags
);
119 EXPORT_SYMBOL_GPL(kthread_should_park
);
122 * kthread_freezable_should_stop - should this freezable kthread return now?
123 * @was_frozen: optional out parameter, indicates whether %current was frozen
125 * kthread_should_stop() for freezable kthreads, which will enter
126 * refrigerator if necessary. This function is safe from kthread_stop() /
127 * freezer deadlock and freezable kthreads should use this function instead
128 * of calling try_to_freeze() directly.
130 bool kthread_freezable_should_stop(bool *was_frozen
)
136 if (unlikely(freezing(current
)))
137 frozen
= __refrigerator(true);
140 *was_frozen
= frozen
;
142 return kthread_should_stop();
144 EXPORT_SYMBOL_GPL(kthread_freezable_should_stop
);
147 * kthread_data - return data value specified on kthread creation
148 * @task: kthread task in question
150 * Return the data value specified when kthread @task was created.
151 * The caller is responsible for ensuring the validity of @task when
152 * calling this function.
154 void *kthread_data(struct task_struct
*task
)
156 return to_kthread(task
)->data
;
160 * kthread_probe_data - speculative version of kthread_data()
161 * @task: possible kthread task in question
163 * @task could be a kthread task. Return the data value specified when it
164 * was created if accessible. If @task isn't a kthread task or its data is
165 * inaccessible for any reason, %NULL is returned. This function requires
166 * that @task itself is safe to dereference.
168 void *kthread_probe_data(struct task_struct
*task
)
170 struct kthread
*kthread
= to_kthread(task
);
173 probe_kernel_read(&data
, &kthread
->data
, sizeof(data
));
177 static void __kthread_parkme(struct kthread
*self
)
180 set_current_state(TASK_PARKED
);
181 if (!test_bit(KTHREAD_SHOULD_PARK
, &self
->flags
))
185 __set_current_state(TASK_RUNNING
);
188 void kthread_parkme(void)
190 __kthread_parkme(to_kthread(current
));
192 EXPORT_SYMBOL_GPL(kthread_parkme
);
194 void kthread_park_complete(struct task_struct
*k
)
196 complete_all(&to_kthread(k
)->parked
);
199 static int kthread(void *_create
)
201 /* Copy data: it's on kthread's stack */
202 struct kthread_create_info
*create
= _create
;
203 int (*threadfn
)(void *data
) = create
->threadfn
;
204 void *data
= create
->data
;
205 struct completion
*done
;
206 struct kthread
*self
;
209 self
= kzalloc(sizeof(*self
), GFP_KERNEL
);
210 set_kthread_struct(self
);
212 /* If user was SIGKILLed, I release the structure. */
213 done
= xchg(&create
->done
, NULL
);
220 create
->result
= ERR_PTR(-ENOMEM
);
226 init_completion(&self
->exited
);
227 init_completion(&self
->parked
);
228 current
->vfork_done
= &self
->exited
;
230 /* OK, tell user we're spawned, wait for stop or wakeup */
231 __set_current_state(TASK_UNINTERRUPTIBLE
);
232 create
->result
= current
;
237 if (!test_bit(KTHREAD_SHOULD_STOP
, &self
->flags
)) {
238 cgroup_kthread_ready();
239 __kthread_parkme(self
);
240 ret
= threadfn(data
);
245 /* called from do_fork() to get node information for about to be created task */
246 int tsk_fork_get_node(struct task_struct
*tsk
)
249 if (tsk
== kthreadd_task
)
250 return tsk
->pref_node_fork
;
255 static void create_kthread(struct kthread_create_info
*create
)
260 current
->pref_node_fork
= create
->node
;
262 /* We want our own signal handler (we take no signals by default). */
263 pid
= kernel_thread(kthread
, create
, CLONE_FS
| CLONE_FILES
| SIGCHLD
);
265 /* If user was SIGKILLed, I release the structure. */
266 struct completion
*done
= xchg(&create
->done
, NULL
);
272 create
->result
= ERR_PTR(pid
);
277 static __printf(4, 0)
278 struct task_struct
*__kthread_create_on_node(int (*threadfn
)(void *data
),
279 void *data
, int node
,
280 const char namefmt
[],
283 DECLARE_COMPLETION_ONSTACK(done
);
284 struct task_struct
*task
;
285 struct kthread_create_info
*create
= kmalloc(sizeof(*create
),
289 return ERR_PTR(-ENOMEM
);
290 create
->threadfn
= threadfn
;
293 create
->done
= &done
;
295 spin_lock(&kthread_create_lock
);
296 list_add_tail(&create
->list
, &kthread_create_list
);
297 spin_unlock(&kthread_create_lock
);
299 wake_up_process(kthreadd_task
);
301 * Wait for completion in killable state, for I might be chosen by
302 * the OOM killer while kthreadd is trying to allocate memory for
305 if (unlikely(wait_for_completion_killable(&done
))) {
307 * If I was SIGKILLed before kthreadd (or new kernel thread)
308 * calls complete(), leave the cleanup of this structure to
311 if (xchg(&create
->done
, NULL
))
312 return ERR_PTR(-EINTR
);
314 * kthreadd (or new kernel thread) will call complete()
317 wait_for_completion(&done
);
319 task
= create
->result
;
321 static const struct sched_param param
= { .sched_priority
= 0 };
323 vsnprintf(task
->comm
, sizeof(task
->comm
), namefmt
, args
);
325 * root may have changed our (kthreadd's) priority or CPU mask.
326 * The kernel thread should not inherit these properties.
328 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
329 set_cpus_allowed_ptr(task
, cpu_all_mask
);
336 * kthread_create_on_node - create a kthread.
337 * @threadfn: the function to run until signal_pending(current).
338 * @data: data ptr for @threadfn.
339 * @node: task and thread structures for the thread are allocated on this node
340 * @namefmt: printf-style name for the thread.
342 * Description: This helper function creates and names a kernel
343 * thread. The thread will be stopped: use wake_up_process() to start
344 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
345 * is affine to all CPUs.
347 * If thread is going to be bound on a particular cpu, give its node
348 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
349 * When woken, the thread will run @threadfn() with @data as its
350 * argument. @threadfn() can either call do_exit() directly if it is a
351 * standalone thread for which no one will call kthread_stop(), or
352 * return when 'kthread_should_stop()' is true (which means
353 * kthread_stop() has been called). The return value should be zero
354 * or a negative error number; it will be passed to kthread_stop().
356 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
358 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
359 void *data
, int node
,
360 const char namefmt
[],
363 struct task_struct
*task
;
366 va_start(args
, namefmt
);
367 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
372 EXPORT_SYMBOL(kthread_create_on_node
);
374 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
378 if (!wait_task_inactive(p
, state
)) {
383 /* It's safe because the task is inactive. */
384 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
385 do_set_cpus_allowed(p
, mask
);
386 p
->flags
|= PF_NO_SETAFFINITY
;
387 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
390 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
392 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
395 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
397 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
401 * kthread_bind - bind a just-created kthread to a cpu.
402 * @p: thread created by kthread_create().
403 * @cpu: cpu (might not be online, must be possible) for @k to run on.
405 * Description: This function is equivalent to set_cpus_allowed(),
406 * except that @cpu doesn't need to be online, and the thread must be
407 * stopped (i.e., just returned from kthread_create()).
409 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
411 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
413 EXPORT_SYMBOL(kthread_bind
);
416 * kthread_create_on_cpu - Create a cpu bound kthread
417 * @threadfn: the function to run until signal_pending(current).
418 * @data: data ptr for @threadfn.
419 * @cpu: The cpu on which the thread should be bound,
420 * @namefmt: printf-style name for the thread. Format is restricted
421 * to "name.*%u". Code fills in cpu number.
423 * Description: This helper function creates and names a kernel thread
424 * The thread will be woken and put into park mode.
426 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
427 void *data
, unsigned int cpu
,
430 struct task_struct
*p
;
432 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
436 kthread_bind(p
, cpu
);
437 /* CPU hotplug need to bind once again when unparking the thread. */
438 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
439 to_kthread(p
)->cpu
= cpu
;
444 * kthread_unpark - unpark a thread created by kthread_create().
445 * @k: thread created by kthread_create().
447 * Sets kthread_should_park() for @k to return false, wakes it, and
448 * waits for it to return. If the thread is marked percpu then its
449 * bound to the cpu again.
451 void kthread_unpark(struct task_struct
*k
)
453 struct kthread
*kthread
= to_kthread(k
);
456 * Newly created kthread was parked when the CPU was offline.
457 * The binding was lost and we need to set it again.
459 if (test_bit(KTHREAD_IS_PER_CPU
, &kthread
->flags
))
460 __kthread_bind(k
, kthread
->cpu
, TASK_PARKED
);
462 reinit_completion(&kthread
->parked
);
463 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
464 wake_up_state(k
, TASK_PARKED
);
466 EXPORT_SYMBOL_GPL(kthread_unpark
);
469 * kthread_park - park a thread created by kthread_create().
470 * @k: thread created by kthread_create().
472 * Sets kthread_should_park() for @k to return true, wakes it, and
473 * waits for it to return. This can also be called after kthread_create()
474 * instead of calling wake_up_process(): the thread will park without
475 * calling threadfn().
477 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
478 * If called by the kthread itself just the park bit is set.
480 int kthread_park(struct task_struct
*k
)
482 struct kthread
*kthread
= to_kthread(k
);
484 if (WARN_ON(k
->flags
& PF_EXITING
))
487 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
490 wait_for_completion(&kthread
->parked
);
495 EXPORT_SYMBOL_GPL(kthread_park
);
498 * kthread_stop - stop a thread created by kthread_create().
499 * @k: thread created by kthread_create().
501 * Sets kthread_should_stop() for @k to return true, wakes it, and
502 * waits for it to exit. This can also be called after kthread_create()
503 * instead of calling wake_up_process(): the thread will exit without
504 * calling threadfn().
506 * If threadfn() may call do_exit() itself, the caller must ensure
507 * task_struct can't go away.
509 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
512 int kthread_stop(struct task_struct
*k
)
514 struct kthread
*kthread
;
517 trace_sched_kthread_stop(k
);
520 kthread
= to_kthread(k
);
521 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
524 wait_for_completion(&kthread
->exited
);
528 trace_sched_kthread_stop_ret(ret
);
531 EXPORT_SYMBOL(kthread_stop
);
533 int kthreadd(void *unused
)
535 struct task_struct
*tsk
= current
;
537 /* Setup a clean context for our children to inherit. */
538 set_task_comm(tsk
, "kthreadd");
540 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
541 set_mems_allowed(node_states
[N_MEMORY
]);
543 current
->flags
|= PF_NOFREEZE
;
544 cgroup_init_kthreadd();
547 set_current_state(TASK_INTERRUPTIBLE
);
548 if (list_empty(&kthread_create_list
))
550 __set_current_state(TASK_RUNNING
);
552 spin_lock(&kthread_create_lock
);
553 while (!list_empty(&kthread_create_list
)) {
554 struct kthread_create_info
*create
;
556 create
= list_entry(kthread_create_list
.next
,
557 struct kthread_create_info
, list
);
558 list_del_init(&create
->list
);
559 spin_unlock(&kthread_create_lock
);
561 create_kthread(create
);
563 spin_lock(&kthread_create_lock
);
565 spin_unlock(&kthread_create_lock
);
571 void __kthread_init_worker(struct kthread_worker
*worker
,
573 struct lock_class_key
*key
)
575 memset(worker
, 0, sizeof(struct kthread_worker
));
576 spin_lock_init(&worker
->lock
);
577 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
578 INIT_LIST_HEAD(&worker
->work_list
);
579 INIT_LIST_HEAD(&worker
->delayed_work_list
);
581 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
584 * kthread_worker_fn - kthread function to process kthread_worker
585 * @worker_ptr: pointer to initialized kthread_worker
587 * This function implements the main cycle of kthread worker. It processes
588 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
591 * The works are not allowed to keep any locks, disable preemption or interrupts
592 * when they finish. There is defined a safe point for freezing when one work
593 * finishes and before a new one is started.
595 * Also the works must not be handled by more than one worker at the same time,
596 * see also kthread_queue_work().
598 int kthread_worker_fn(void *worker_ptr
)
600 struct kthread_worker
*worker
= worker_ptr
;
601 struct kthread_work
*work
;
604 * FIXME: Update the check and remove the assignment when all kthread
605 * worker users are created using kthread_create_worker*() functions.
607 WARN_ON(worker
->task
&& worker
->task
!= current
);
608 worker
->task
= current
;
610 if (worker
->flags
& KTW_FREEZABLE
)
614 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
616 if (kthread_should_stop()) {
617 __set_current_state(TASK_RUNNING
);
618 spin_lock_irq(&worker
->lock
);
620 spin_unlock_irq(&worker
->lock
);
625 spin_lock_irq(&worker
->lock
);
626 if (!list_empty(&worker
->work_list
)) {
627 work
= list_first_entry(&worker
->work_list
,
628 struct kthread_work
, node
);
629 list_del_init(&work
->node
);
631 worker
->current_work
= work
;
632 spin_unlock_irq(&worker
->lock
);
635 __set_current_state(TASK_RUNNING
);
637 } else if (!freezing(current
))
644 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
646 static __printf(3, 0) struct kthread_worker
*
647 __kthread_create_worker(int cpu
, unsigned int flags
,
648 const char namefmt
[], va_list args
)
650 struct kthread_worker
*worker
;
651 struct task_struct
*task
;
654 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
656 return ERR_PTR(-ENOMEM
);
658 kthread_init_worker(worker
);
661 node
= cpu_to_node(cpu
);
663 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
664 node
, namefmt
, args
);
669 kthread_bind(task
, cpu
);
671 worker
->flags
= flags
;
673 wake_up_process(task
);
678 return ERR_CAST(task
);
682 * kthread_create_worker - create a kthread worker
683 * @flags: flags modifying the default behavior of the worker
684 * @namefmt: printf-style name for the kthread worker (task).
686 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
687 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
688 * when the worker was SIGKILLed.
690 struct kthread_worker
*
691 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
693 struct kthread_worker
*worker
;
696 va_start(args
, namefmt
);
697 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
702 EXPORT_SYMBOL(kthread_create_worker
);
705 * kthread_create_worker_on_cpu - create a kthread worker and bind it
706 * it to a given CPU and the associated NUMA node.
708 * @flags: flags modifying the default behavior of the worker
709 * @namefmt: printf-style name for the kthread worker (task).
711 * Use a valid CPU number if you want to bind the kthread worker
712 * to the given CPU and the associated NUMA node.
714 * A good practice is to add the cpu number also into the worker name.
715 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
717 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
718 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
719 * when the worker was SIGKILLed.
721 struct kthread_worker
*
722 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
723 const char namefmt
[], ...)
725 struct kthread_worker
*worker
;
728 va_start(args
, namefmt
);
729 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
734 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
737 * Returns true when the work could not be queued at the moment.
738 * It happens when it is already pending in a worker list
739 * or when it is being cancelled.
741 static inline bool queuing_blocked(struct kthread_worker
*worker
,
742 struct kthread_work
*work
)
744 lockdep_assert_held(&worker
->lock
);
746 return !list_empty(&work
->node
) || work
->canceling
;
749 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
750 struct kthread_work
*work
)
752 lockdep_assert_held(&worker
->lock
);
753 WARN_ON_ONCE(!list_empty(&work
->node
));
754 /* Do not use a work with >1 worker, see kthread_queue_work() */
755 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
758 /* insert @work before @pos in @worker */
759 static void kthread_insert_work(struct kthread_worker
*worker
,
760 struct kthread_work
*work
,
761 struct list_head
*pos
)
763 kthread_insert_work_sanity_check(worker
, work
);
765 list_add_tail(&work
->node
, pos
);
766 work
->worker
= worker
;
767 if (!worker
->current_work
&& likely(worker
->task
))
768 wake_up_process(worker
->task
);
772 * kthread_queue_work - queue a kthread_work
773 * @worker: target kthread_worker
774 * @work: kthread_work to queue
776 * Queue @work to work processor @task for async execution. @task
777 * must have been created with kthread_worker_create(). Returns %true
778 * if @work was successfully queued, %false if it was already pending.
780 * Reinitialize the work if it needs to be used by another worker.
781 * For example, when the worker was stopped and started again.
783 bool kthread_queue_work(struct kthread_worker
*worker
,
784 struct kthread_work
*work
)
789 spin_lock_irqsave(&worker
->lock
, flags
);
790 if (!queuing_blocked(worker
, work
)) {
791 kthread_insert_work(worker
, work
, &worker
->work_list
);
794 spin_unlock_irqrestore(&worker
->lock
, flags
);
797 EXPORT_SYMBOL_GPL(kthread_queue_work
);
800 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
801 * delayed work when the timer expires.
802 * @t: pointer to the expired timer
804 * The format of the function is defined by struct timer_list.
805 * It should have been called from irqsafe timer with irq already off.
807 void kthread_delayed_work_timer_fn(struct timer_list
*t
)
809 struct kthread_delayed_work
*dwork
= from_timer(dwork
, t
, timer
);
810 struct kthread_work
*work
= &dwork
->work
;
811 struct kthread_worker
*worker
= work
->worker
;
814 * This might happen when a pending work is reinitialized.
815 * It means that it is used a wrong way.
817 if (WARN_ON_ONCE(!worker
))
820 spin_lock(&worker
->lock
);
821 /* Work must not be used with >1 worker, see kthread_queue_work(). */
822 WARN_ON_ONCE(work
->worker
!= worker
);
824 /* Move the work from worker->delayed_work_list. */
825 WARN_ON_ONCE(list_empty(&work
->node
));
826 list_del_init(&work
->node
);
827 kthread_insert_work(worker
, work
, &worker
->work_list
);
829 spin_unlock(&worker
->lock
);
831 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
833 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
834 struct kthread_delayed_work
*dwork
,
837 struct timer_list
*timer
= &dwork
->timer
;
838 struct kthread_work
*work
= &dwork
->work
;
840 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
);
843 * If @delay is 0, queue @dwork->work immediately. This is for
844 * both optimization and correctness. The earliest @timer can
845 * expire is on the closest next tick and delayed_work users depend
846 * on that there's no such delay when @delay is 0.
849 kthread_insert_work(worker
, work
, &worker
->work_list
);
853 /* Be paranoid and try to detect possible races already now. */
854 kthread_insert_work_sanity_check(worker
, work
);
856 list_add(&work
->node
, &worker
->delayed_work_list
);
857 work
->worker
= worker
;
858 timer
->expires
= jiffies
+ delay
;
863 * kthread_queue_delayed_work - queue the associated kthread work
865 * @worker: target kthread_worker
866 * @dwork: kthread_delayed_work to queue
867 * @delay: number of jiffies to wait before queuing
869 * If the work has not been pending it starts a timer that will queue
870 * the work after the given @delay. If @delay is zero, it queues the
873 * Return: %false if the @work has already been pending. It means that
874 * either the timer was running or the work was queued. It returns %true
877 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
878 struct kthread_delayed_work
*dwork
,
881 struct kthread_work
*work
= &dwork
->work
;
885 spin_lock_irqsave(&worker
->lock
, flags
);
887 if (!queuing_blocked(worker
, work
)) {
888 __kthread_queue_delayed_work(worker
, dwork
, delay
);
892 spin_unlock_irqrestore(&worker
->lock
, flags
);
895 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
897 struct kthread_flush_work
{
898 struct kthread_work work
;
899 struct completion done
;
902 static void kthread_flush_work_fn(struct kthread_work
*work
)
904 struct kthread_flush_work
*fwork
=
905 container_of(work
, struct kthread_flush_work
, work
);
906 complete(&fwork
->done
);
910 * kthread_flush_work - flush a kthread_work
911 * @work: work to flush
913 * If @work is queued or executing, wait for it to finish execution.
915 void kthread_flush_work(struct kthread_work
*work
)
917 struct kthread_flush_work fwork
= {
918 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
919 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
921 struct kthread_worker
*worker
;
924 worker
= work
->worker
;
928 spin_lock_irq(&worker
->lock
);
929 /* Work must not be used with >1 worker, see kthread_queue_work(). */
930 WARN_ON_ONCE(work
->worker
!= worker
);
932 if (!list_empty(&work
->node
))
933 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
934 else if (worker
->current_work
== work
)
935 kthread_insert_work(worker
, &fwork
.work
,
936 worker
->work_list
.next
);
940 spin_unlock_irq(&worker
->lock
);
943 wait_for_completion(&fwork
.done
);
945 EXPORT_SYMBOL_GPL(kthread_flush_work
);
948 * This function removes the work from the worker queue. Also it makes sure
949 * that it won't get queued later via the delayed work's timer.
951 * The work might still be in use when this function finishes. See the
952 * current_work proceed by the worker.
954 * Return: %true if @work was pending and successfully canceled,
955 * %false if @work was not pending
957 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
958 unsigned long *flags
)
960 /* Try to cancel the timer if exists. */
962 struct kthread_delayed_work
*dwork
=
963 container_of(work
, struct kthread_delayed_work
, work
);
964 struct kthread_worker
*worker
= work
->worker
;
967 * del_timer_sync() must be called to make sure that the timer
968 * callback is not running. The lock must be temporary released
969 * to avoid a deadlock with the callback. In the meantime,
970 * any queuing is blocked by setting the canceling counter.
973 spin_unlock_irqrestore(&worker
->lock
, *flags
);
974 del_timer_sync(&dwork
->timer
);
975 spin_lock_irqsave(&worker
->lock
, *flags
);
980 * Try to remove the work from a worker list. It might either
981 * be from worker->work_list or from worker->delayed_work_list.
983 if (!list_empty(&work
->node
)) {
984 list_del_init(&work
->node
);
992 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
993 * @worker: kthread worker to use
994 * @dwork: kthread delayed work to queue
995 * @delay: number of jiffies to wait before queuing
997 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
998 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
999 * @work is guaranteed to be queued immediately.
1001 * Return: %true if @dwork was pending and its timer was modified,
1004 * A special case is when the work is being canceled in parallel.
1005 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1006 * or yet another kthread_mod_delayed_work() call. We let the other command
1007 * win and return %false here. The caller is supposed to synchronize these
1008 * operations a reasonable way.
1010 * This function is safe to call from any context including IRQ handler.
1011 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1014 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1015 struct kthread_delayed_work
*dwork
,
1016 unsigned long delay
)
1018 struct kthread_work
*work
= &dwork
->work
;
1019 unsigned long flags
;
1022 spin_lock_irqsave(&worker
->lock
, flags
);
1024 /* Do not bother with canceling when never queued. */
1028 /* Work must not be used with >1 worker, see kthread_queue_work() */
1029 WARN_ON_ONCE(work
->worker
!= worker
);
1031 /* Do not fight with another command that is canceling this work. */
1032 if (work
->canceling
)
1035 ret
= __kthread_cancel_work(work
, true, &flags
);
1037 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1039 spin_unlock_irqrestore(&worker
->lock
, flags
);
1042 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1044 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1046 struct kthread_worker
*worker
= work
->worker
;
1047 unsigned long flags
;
1053 spin_lock_irqsave(&worker
->lock
, flags
);
1054 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1055 WARN_ON_ONCE(work
->worker
!= worker
);
1057 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1059 if (worker
->current_work
!= work
)
1063 * The work is in progress and we need to wait with the lock released.
1064 * In the meantime, block any queuing by setting the canceling counter.
1067 spin_unlock_irqrestore(&worker
->lock
, flags
);
1068 kthread_flush_work(work
);
1069 spin_lock_irqsave(&worker
->lock
, flags
);
1073 spin_unlock_irqrestore(&worker
->lock
, flags
);
1079 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1080 * @work: the kthread work to cancel
1082 * Cancel @work and wait for its execution to finish. This function
1083 * can be used even if the work re-queues itself. On return from this
1084 * function, @work is guaranteed to be not pending or executing on any CPU.
1086 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1087 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1089 * The caller must ensure that the worker on which @work was last
1090 * queued can't be destroyed before this function returns.
1092 * Return: %true if @work was pending, %false otherwise.
1094 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1096 return __kthread_cancel_work_sync(work
, false);
1098 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1101 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1102 * wait for it to finish.
1103 * @dwork: the kthread delayed work to cancel
1105 * This is kthread_cancel_work_sync() for delayed works.
1107 * Return: %true if @dwork was pending, %false otherwise.
1109 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1111 return __kthread_cancel_work_sync(&dwork
->work
, true);
1113 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1116 * kthread_flush_worker - flush all current works on a kthread_worker
1117 * @worker: worker to flush
1119 * Wait until all currently executing or pending works on @worker are
1122 void kthread_flush_worker(struct kthread_worker
*worker
)
1124 struct kthread_flush_work fwork
= {
1125 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1126 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1129 kthread_queue_work(worker
, &fwork
.work
);
1130 wait_for_completion(&fwork
.done
);
1132 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1135 * kthread_destroy_worker - destroy a kthread worker
1136 * @worker: worker to be destroyed
1138 * Flush and destroy @worker. The simple flush is enough because the kthread
1139 * worker API is used only in trivial scenarios. There are no multi-step state
1142 void kthread_destroy_worker(struct kthread_worker
*worker
)
1144 struct task_struct
*task
;
1146 task
= worker
->task
;
1150 kthread_flush_worker(worker
);
1152 WARN_ON(!list_empty(&worker
->work_list
));
1155 EXPORT_SYMBOL(kthread_destroy_worker
);
1157 #ifdef CONFIG_BLK_CGROUP
1159 * kthread_associate_blkcg - associate blkcg to current kthread
1160 * @css: the cgroup info
1162 * Current thread must be a kthread. The thread is running jobs on behalf of
1163 * other threads. In some cases, we expect the jobs attach cgroup info of
1164 * original threads instead of that of current thread. This function stores
1165 * original thread's cgroup info in current kthread context for later
1168 void kthread_associate_blkcg(struct cgroup_subsys_state
*css
)
1170 struct kthread
*kthread
;
1172 if (!(current
->flags
& PF_KTHREAD
))
1174 kthread
= to_kthread(current
);
1178 if (kthread
->blkcg_css
) {
1179 css_put(kthread
->blkcg_css
);
1180 kthread
->blkcg_css
= NULL
;
1184 kthread
->blkcg_css
= css
;
1187 EXPORT_SYMBOL(kthread_associate_blkcg
);
1190 * kthread_blkcg - get associated blkcg css of current kthread
1192 * Current thread must be a kthread.
1194 struct cgroup_subsys_state
*kthread_blkcg(void)
1196 struct kthread
*kthread
;
1198 if (current
->flags
& PF_KTHREAD
) {
1199 kthread
= to_kthread(current
);
1201 return kthread
->blkcg_css
;
1205 EXPORT_SYMBOL(kthread_blkcg
);