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(&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
))) {
309 * I got SIGKILL, but wait for 10 more seconds for completion
310 * unless chosen by the OOM killer. This delay is there as a
311 * workaround for boot failure caused by SIGKILL upon device
312 * driver initialization timeout.
314 while (i
++ < 10 && !test_tsk_thread_flag(current
, TIF_MEMDIE
))
315 if (wait_for_completion_timeout(&done
, HZ
))
318 * If I was SIGKILLed before kthreadd (or new kernel thread)
319 * calls complete(), leave the cleanup of this structure to
322 if (xchg(&create
->done
, NULL
))
323 return ERR_PTR(-EINTR
);
325 * kthreadd (or new kernel thread) will call complete()
328 wait_for_completion(&done
);
331 task
= create
->result
;
333 static const struct sched_param param
= { .sched_priority
= 0 };
335 vsnprintf(task
->comm
, sizeof(task
->comm
), namefmt
, args
);
337 * root may have changed our (kthreadd's) priority or CPU mask.
338 * The kernel thread should not inherit these properties.
340 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
341 set_cpus_allowed_ptr(task
, cpu_all_mask
);
348 * kthread_create_on_node - create a kthread.
349 * @threadfn: the function to run until signal_pending(current).
350 * @data: data ptr for @threadfn.
351 * @node: task and thread structures for the thread are allocated on this node
352 * @namefmt: printf-style name for the thread.
354 * Description: This helper function creates and names a kernel
355 * thread. The thread will be stopped: use wake_up_process() to start
356 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
357 * is affine to all CPUs.
359 * If thread is going to be bound on a particular cpu, give its node
360 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
361 * When woken, the thread will run @threadfn() with @data as its
362 * argument. @threadfn() can either call do_exit() directly if it is a
363 * standalone thread for which no one will call kthread_stop(), or
364 * return when 'kthread_should_stop()' is true (which means
365 * kthread_stop() has been called). The return value should be zero
366 * or a negative error number; it will be passed to kthread_stop().
368 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
370 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
371 void *data
, int node
,
372 const char namefmt
[],
375 struct task_struct
*task
;
378 va_start(args
, namefmt
);
379 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
384 EXPORT_SYMBOL(kthread_create_on_node
);
386 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
390 if (!wait_task_inactive(p
, state
)) {
395 /* It's safe because the task is inactive. */
396 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
397 do_set_cpus_allowed(p
, mask
);
398 p
->flags
|= PF_NO_SETAFFINITY
;
399 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
402 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
404 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
407 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
409 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
413 * kthread_bind - bind a just-created kthread to a cpu.
414 * @p: thread created by kthread_create().
415 * @cpu: cpu (might not be online, must be possible) for @k to run on.
417 * Description: This function is equivalent to set_cpus_allowed(),
418 * except that @cpu doesn't need to be online, and the thread must be
419 * stopped (i.e., just returned from kthread_create()).
421 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
423 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
425 EXPORT_SYMBOL(kthread_bind
);
428 * kthread_create_on_cpu - Create a cpu bound kthread
429 * @threadfn: the function to run until signal_pending(current).
430 * @data: data ptr for @threadfn.
431 * @cpu: The cpu on which the thread should be bound,
432 * @namefmt: printf-style name for the thread. Format is restricted
433 * to "name.*%u". Code fills in cpu number.
435 * Description: This helper function creates and names a kernel thread
436 * The thread will be woken and put into park mode.
438 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
439 void *data
, unsigned int cpu
,
442 struct task_struct
*p
;
444 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
448 kthread_bind(p
, cpu
);
449 /* CPU hotplug need to bind once again when unparking the thread. */
450 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
451 to_kthread(p
)->cpu
= cpu
;
456 * kthread_unpark - unpark a thread created by kthread_create().
457 * @k: thread created by kthread_create().
459 * Sets kthread_should_park() for @k to return false, wakes it, and
460 * waits for it to return. If the thread is marked percpu then its
461 * bound to the cpu again.
463 void kthread_unpark(struct task_struct
*k
)
465 struct kthread
*kthread
= to_kthread(k
);
468 * Newly created kthread was parked when the CPU was offline.
469 * The binding was lost and we need to set it again.
471 if (test_bit(KTHREAD_IS_PER_CPU
, &kthread
->flags
))
472 __kthread_bind(k
, kthread
->cpu
, TASK_PARKED
);
474 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
475 wake_up_state(k
, TASK_PARKED
);
477 EXPORT_SYMBOL_GPL(kthread_unpark
);
480 * kthread_park - park a thread created by kthread_create().
481 * @k: thread created by kthread_create().
483 * Sets kthread_should_park() for @k to return true, wakes it, and
484 * waits for it to return. This can also be called after kthread_create()
485 * instead of calling wake_up_process(): the thread will park without
486 * calling threadfn().
488 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
489 * If called by the kthread itself just the park bit is set.
491 int kthread_park(struct task_struct
*k
)
493 struct kthread
*kthread
= to_kthread(k
);
495 if (WARN_ON(k
->flags
& PF_EXITING
))
498 if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
)))
501 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
504 wait_for_completion(&kthread
->parked
);
509 EXPORT_SYMBOL_GPL(kthread_park
);
512 * kthread_stop - stop a thread created by kthread_create().
513 * @k: thread created by kthread_create().
515 * Sets kthread_should_stop() for @k to return true, wakes it, and
516 * waits for it to exit. This can also be called after kthread_create()
517 * instead of calling wake_up_process(): the thread will exit without
518 * calling threadfn().
520 * If threadfn() may call do_exit() itself, the caller must ensure
521 * task_struct can't go away.
523 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
526 int kthread_stop(struct task_struct
*k
)
528 struct kthread
*kthread
;
531 trace_sched_kthread_stop(k
);
534 kthread
= to_kthread(k
);
535 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
538 wait_for_completion(&kthread
->exited
);
542 trace_sched_kthread_stop_ret(ret
);
545 EXPORT_SYMBOL(kthread_stop
);
547 int kthreadd(void *unused
)
549 struct task_struct
*tsk
= current
;
551 /* Setup a clean context for our children to inherit. */
552 set_task_comm(tsk
, "kthreadd");
554 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
555 set_mems_allowed(node_states
[N_MEMORY
]);
557 current
->flags
|= PF_NOFREEZE
;
558 cgroup_init_kthreadd();
561 set_current_state(TASK_INTERRUPTIBLE
);
562 if (list_empty(&kthread_create_list
))
564 __set_current_state(TASK_RUNNING
);
566 spin_lock(&kthread_create_lock
);
567 while (!list_empty(&kthread_create_list
)) {
568 struct kthread_create_info
*create
;
570 create
= list_entry(kthread_create_list
.next
,
571 struct kthread_create_info
, list
);
572 list_del_init(&create
->list
);
573 spin_unlock(&kthread_create_lock
);
575 create_kthread(create
);
577 spin_lock(&kthread_create_lock
);
579 spin_unlock(&kthread_create_lock
);
585 void __kthread_init_worker(struct kthread_worker
*worker
,
587 struct lock_class_key
*key
)
589 memset(worker
, 0, sizeof(struct kthread_worker
));
590 spin_lock_init(&worker
->lock
);
591 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
592 INIT_LIST_HEAD(&worker
->work_list
);
593 INIT_LIST_HEAD(&worker
->delayed_work_list
);
595 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
598 * kthread_worker_fn - kthread function to process kthread_worker
599 * @worker_ptr: pointer to initialized kthread_worker
601 * This function implements the main cycle of kthread worker. It processes
602 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
605 * The works are not allowed to keep any locks, disable preemption or interrupts
606 * when they finish. There is defined a safe point for freezing when one work
607 * finishes and before a new one is started.
609 * Also the works must not be handled by more than one worker at the same time,
610 * see also kthread_queue_work().
612 int kthread_worker_fn(void *worker_ptr
)
614 struct kthread_worker
*worker
= worker_ptr
;
615 struct kthread_work
*work
;
618 * FIXME: Update the check and remove the assignment when all kthread
619 * worker users are created using kthread_create_worker*() functions.
621 WARN_ON(worker
->task
&& worker
->task
!= current
);
622 worker
->task
= current
;
624 if (worker
->flags
& KTW_FREEZABLE
)
628 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
630 if (kthread_should_stop()) {
631 __set_current_state(TASK_RUNNING
);
632 spin_lock_irq(&worker
->lock
);
634 spin_unlock_irq(&worker
->lock
);
639 spin_lock_irq(&worker
->lock
);
640 if (!list_empty(&worker
->work_list
)) {
641 work
= list_first_entry(&worker
->work_list
,
642 struct kthread_work
, node
);
643 list_del_init(&work
->node
);
645 worker
->current_work
= work
;
646 spin_unlock_irq(&worker
->lock
);
649 __set_current_state(TASK_RUNNING
);
651 } else if (!freezing(current
))
658 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
660 static __printf(3, 0) struct kthread_worker
*
661 __kthread_create_worker(int cpu
, unsigned int flags
,
662 const char namefmt
[], va_list args
)
664 struct kthread_worker
*worker
;
665 struct task_struct
*task
;
668 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
670 return ERR_PTR(-ENOMEM
);
672 kthread_init_worker(worker
);
675 node
= cpu_to_node(cpu
);
677 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
678 node
, namefmt
, args
);
683 kthread_bind(task
, cpu
);
685 worker
->flags
= flags
;
687 wake_up_process(task
);
692 return ERR_CAST(task
);
696 * kthread_create_worker - create a kthread worker
697 * @flags: flags modifying the default behavior of the worker
698 * @namefmt: printf-style name for the kthread worker (task).
700 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
701 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
702 * when the worker was SIGKILLed.
704 struct kthread_worker
*
705 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
707 struct kthread_worker
*worker
;
710 va_start(args
, namefmt
);
711 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
716 EXPORT_SYMBOL(kthread_create_worker
);
719 * kthread_create_worker_on_cpu - create a kthread worker and bind it
720 * it to a given CPU and the associated NUMA node.
722 * @flags: flags modifying the default behavior of the worker
723 * @namefmt: printf-style name for the kthread worker (task).
725 * Use a valid CPU number if you want to bind the kthread worker
726 * to the given CPU and the associated NUMA node.
728 * A good practice is to add the cpu number also into the worker name.
729 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
731 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
732 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
733 * when the worker was SIGKILLed.
735 struct kthread_worker
*
736 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
737 const char namefmt
[], ...)
739 struct kthread_worker
*worker
;
742 va_start(args
, namefmt
);
743 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
748 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
751 * Returns true when the work could not be queued at the moment.
752 * It happens when it is already pending in a worker list
753 * or when it is being cancelled.
755 static inline bool queuing_blocked(struct kthread_worker
*worker
,
756 struct kthread_work
*work
)
758 lockdep_assert_held(&worker
->lock
);
760 return !list_empty(&work
->node
) || work
->canceling
;
763 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
764 struct kthread_work
*work
)
766 lockdep_assert_held(&worker
->lock
);
767 WARN_ON_ONCE(!list_empty(&work
->node
));
768 /* Do not use a work with >1 worker, see kthread_queue_work() */
769 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
772 /* insert @work before @pos in @worker */
773 static void kthread_insert_work(struct kthread_worker
*worker
,
774 struct kthread_work
*work
,
775 struct list_head
*pos
)
777 kthread_insert_work_sanity_check(worker
, work
);
779 list_add_tail(&work
->node
, pos
);
780 work
->worker
= worker
;
781 if (!worker
->current_work
&& likely(worker
->task
))
782 wake_up_process(worker
->task
);
786 * kthread_queue_work - queue a kthread_work
787 * @worker: target kthread_worker
788 * @work: kthread_work to queue
790 * Queue @work to work processor @task for async execution. @task
791 * must have been created with kthread_worker_create(). Returns %true
792 * if @work was successfully queued, %false if it was already pending.
794 * Reinitialize the work if it needs to be used by another worker.
795 * For example, when the worker was stopped and started again.
797 bool kthread_queue_work(struct kthread_worker
*worker
,
798 struct kthread_work
*work
)
803 spin_lock_irqsave(&worker
->lock
, flags
);
804 if (!queuing_blocked(worker
, work
)) {
805 kthread_insert_work(worker
, work
, &worker
->work_list
);
808 spin_unlock_irqrestore(&worker
->lock
, flags
);
811 EXPORT_SYMBOL_GPL(kthread_queue_work
);
814 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
815 * delayed work when the timer expires.
816 * @t: pointer to the expired timer
818 * The format of the function is defined by struct timer_list.
819 * It should have been called from irqsafe timer with irq already off.
821 void kthread_delayed_work_timer_fn(struct timer_list
*t
)
823 struct kthread_delayed_work
*dwork
= from_timer(dwork
, t
, timer
);
824 struct kthread_work
*work
= &dwork
->work
;
825 struct kthread_worker
*worker
= work
->worker
;
828 * This might happen when a pending work is reinitialized.
829 * It means that it is used a wrong way.
831 if (WARN_ON_ONCE(!worker
))
834 spin_lock(&worker
->lock
);
835 /* Work must not be used with >1 worker, see kthread_queue_work(). */
836 WARN_ON_ONCE(work
->worker
!= worker
);
838 /* Move the work from worker->delayed_work_list. */
839 WARN_ON_ONCE(list_empty(&work
->node
));
840 list_del_init(&work
->node
);
841 kthread_insert_work(worker
, work
, &worker
->work_list
);
843 spin_unlock(&worker
->lock
);
845 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
847 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
848 struct kthread_delayed_work
*dwork
,
851 struct timer_list
*timer
= &dwork
->timer
;
852 struct kthread_work
*work
= &dwork
->work
;
854 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
);
857 * If @delay is 0, queue @dwork->work immediately. This is for
858 * both optimization and correctness. The earliest @timer can
859 * expire is on the closest next tick and delayed_work users depend
860 * on that there's no such delay when @delay is 0.
863 kthread_insert_work(worker
, work
, &worker
->work_list
);
867 /* Be paranoid and try to detect possible races already now. */
868 kthread_insert_work_sanity_check(worker
, work
);
870 list_add(&work
->node
, &worker
->delayed_work_list
);
871 work
->worker
= worker
;
872 timer
->expires
= jiffies
+ delay
;
877 * kthread_queue_delayed_work - queue the associated kthread work
879 * @worker: target kthread_worker
880 * @dwork: kthread_delayed_work to queue
881 * @delay: number of jiffies to wait before queuing
883 * If the work has not been pending it starts a timer that will queue
884 * the work after the given @delay. If @delay is zero, it queues the
887 * Return: %false if the @work has already been pending. It means that
888 * either the timer was running or the work was queued. It returns %true
891 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
892 struct kthread_delayed_work
*dwork
,
895 struct kthread_work
*work
= &dwork
->work
;
899 spin_lock_irqsave(&worker
->lock
, flags
);
901 if (!queuing_blocked(worker
, work
)) {
902 __kthread_queue_delayed_work(worker
, dwork
, delay
);
906 spin_unlock_irqrestore(&worker
->lock
, flags
);
909 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
911 struct kthread_flush_work
{
912 struct kthread_work work
;
913 struct completion done
;
916 static void kthread_flush_work_fn(struct kthread_work
*work
)
918 struct kthread_flush_work
*fwork
=
919 container_of(work
, struct kthread_flush_work
, work
);
920 complete(&fwork
->done
);
924 * kthread_flush_work - flush a kthread_work
925 * @work: work to flush
927 * If @work is queued or executing, wait for it to finish execution.
929 void kthread_flush_work(struct kthread_work
*work
)
931 struct kthread_flush_work fwork
= {
932 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
933 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
935 struct kthread_worker
*worker
;
938 worker
= work
->worker
;
942 spin_lock_irq(&worker
->lock
);
943 /* Work must not be used with >1 worker, see kthread_queue_work(). */
944 WARN_ON_ONCE(work
->worker
!= worker
);
946 if (!list_empty(&work
->node
))
947 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
948 else if (worker
->current_work
== work
)
949 kthread_insert_work(worker
, &fwork
.work
,
950 worker
->work_list
.next
);
954 spin_unlock_irq(&worker
->lock
);
957 wait_for_completion(&fwork
.done
);
959 EXPORT_SYMBOL_GPL(kthread_flush_work
);
962 * This function removes the work from the worker queue. Also it makes sure
963 * that it won't get queued later via the delayed work's timer.
965 * The work might still be in use when this function finishes. See the
966 * current_work proceed by the worker.
968 * Return: %true if @work was pending and successfully canceled,
969 * %false if @work was not pending
971 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
972 unsigned long *flags
)
974 /* Try to cancel the timer if exists. */
976 struct kthread_delayed_work
*dwork
=
977 container_of(work
, struct kthread_delayed_work
, work
);
978 struct kthread_worker
*worker
= work
->worker
;
981 * del_timer_sync() must be called to make sure that the timer
982 * callback is not running. The lock must be temporary released
983 * to avoid a deadlock with the callback. In the meantime,
984 * any queuing is blocked by setting the canceling counter.
987 spin_unlock_irqrestore(&worker
->lock
, *flags
);
988 del_timer_sync(&dwork
->timer
);
989 spin_lock_irqsave(&worker
->lock
, *flags
);
994 * Try to remove the work from a worker list. It might either
995 * be from worker->work_list or from worker->delayed_work_list.
997 if (!list_empty(&work
->node
)) {
998 list_del_init(&work
->node
);
1006 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1007 * @worker: kthread worker to use
1008 * @dwork: kthread delayed work to queue
1009 * @delay: number of jiffies to wait before queuing
1011 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1012 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1013 * @work is guaranteed to be queued immediately.
1015 * Return: %true if @dwork was pending and its timer was modified,
1018 * A special case is when the work is being canceled in parallel.
1019 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1020 * or yet another kthread_mod_delayed_work() call. We let the other command
1021 * win and return %false here. The caller is supposed to synchronize these
1022 * operations a reasonable way.
1024 * This function is safe to call from any context including IRQ handler.
1025 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1028 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1029 struct kthread_delayed_work
*dwork
,
1030 unsigned long delay
)
1032 struct kthread_work
*work
= &dwork
->work
;
1033 unsigned long flags
;
1036 spin_lock_irqsave(&worker
->lock
, flags
);
1038 /* Do not bother with canceling when never queued. */
1042 /* Work must not be used with >1 worker, see kthread_queue_work() */
1043 WARN_ON_ONCE(work
->worker
!= worker
);
1045 /* Do not fight with another command that is canceling this work. */
1046 if (work
->canceling
)
1049 ret
= __kthread_cancel_work(work
, true, &flags
);
1051 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1053 spin_unlock_irqrestore(&worker
->lock
, flags
);
1056 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1058 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1060 struct kthread_worker
*worker
= work
->worker
;
1061 unsigned long flags
;
1067 spin_lock_irqsave(&worker
->lock
, flags
);
1068 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1069 WARN_ON_ONCE(work
->worker
!= worker
);
1071 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1073 if (worker
->current_work
!= work
)
1077 * The work is in progress and we need to wait with the lock released.
1078 * In the meantime, block any queuing by setting the canceling counter.
1081 spin_unlock_irqrestore(&worker
->lock
, flags
);
1082 kthread_flush_work(work
);
1083 spin_lock_irqsave(&worker
->lock
, flags
);
1087 spin_unlock_irqrestore(&worker
->lock
, flags
);
1093 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1094 * @work: the kthread work to cancel
1096 * Cancel @work and wait for its execution to finish. This function
1097 * can be used even if the work re-queues itself. On return from this
1098 * function, @work is guaranteed to be not pending or executing on any CPU.
1100 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1101 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1103 * The caller must ensure that the worker on which @work was last
1104 * queued can't be destroyed before this function returns.
1106 * Return: %true if @work was pending, %false otherwise.
1108 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1110 return __kthread_cancel_work_sync(work
, false);
1112 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1115 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1116 * wait for it to finish.
1117 * @dwork: the kthread delayed work to cancel
1119 * This is kthread_cancel_work_sync() for delayed works.
1121 * Return: %true if @dwork was pending, %false otherwise.
1123 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1125 return __kthread_cancel_work_sync(&dwork
->work
, true);
1127 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1130 * kthread_flush_worker - flush all current works on a kthread_worker
1131 * @worker: worker to flush
1133 * Wait until all currently executing or pending works on @worker are
1136 void kthread_flush_worker(struct kthread_worker
*worker
)
1138 struct kthread_flush_work fwork
= {
1139 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1140 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1143 kthread_queue_work(worker
, &fwork
.work
);
1144 wait_for_completion(&fwork
.done
);
1146 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1149 * kthread_destroy_worker - destroy a kthread worker
1150 * @worker: worker to be destroyed
1152 * Flush and destroy @worker. The simple flush is enough because the kthread
1153 * worker API is used only in trivial scenarios. There are no multi-step state
1156 void kthread_destroy_worker(struct kthread_worker
*worker
)
1158 struct task_struct
*task
;
1160 task
= worker
->task
;
1164 kthread_flush_worker(worker
);
1166 WARN_ON(!list_empty(&worker
->work_list
));
1169 EXPORT_SYMBOL(kthread_destroy_worker
);
1171 #ifdef CONFIG_BLK_CGROUP
1173 * kthread_associate_blkcg - associate blkcg to current kthread
1174 * @css: the cgroup info
1176 * Current thread must be a kthread. The thread is running jobs on behalf of
1177 * other threads. In some cases, we expect the jobs attach cgroup info of
1178 * original threads instead of that of current thread. This function stores
1179 * original thread's cgroup info in current kthread context for later
1182 void kthread_associate_blkcg(struct cgroup_subsys_state
*css
)
1184 struct kthread
*kthread
;
1186 if (!(current
->flags
& PF_KTHREAD
))
1188 kthread
= to_kthread(current
);
1192 if (kthread
->blkcg_css
) {
1193 css_put(kthread
->blkcg_css
);
1194 kthread
->blkcg_css
= NULL
;
1198 kthread
->blkcg_css
= css
;
1201 EXPORT_SYMBOL(kthread_associate_blkcg
);
1204 * kthread_blkcg - get associated blkcg css of current kthread
1206 * Current thread must be a kthread.
1208 struct cgroup_subsys_state
*kthread_blkcg(void)
1210 struct kthread
*kthread
;
1212 if (current
->flags
& PF_KTHREAD
) {
1213 kthread
= to_kthread(current
);
1215 return kthread
->blkcg_css
;
1219 EXPORT_SYMBOL(kthread_blkcg
);