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,
61 static inline void set_kthread_struct(void *kthread
)
64 * We abuse ->set_child_tid to avoid the new member and because it
65 * can't be wrongly copied by copy_process(). We also rely on fact
66 * that the caller can't exec, so PF_KTHREAD can't be cleared.
68 current
->set_child_tid
= (__force
void __user
*)kthread
;
71 static inline struct kthread
*to_kthread(struct task_struct
*k
)
73 WARN_ON(!(k
->flags
& PF_KTHREAD
));
74 return (__force
void *)k
->set_child_tid
;
77 void free_kthread_struct(struct task_struct
*k
)
79 struct kthread
*kthread
;
82 * Can be NULL if this kthread was created by kernel_thread()
83 * or if kmalloc() in kthread() failed.
85 kthread
= to_kthread(k
);
86 #ifdef CONFIG_BLK_CGROUP
87 WARN_ON_ONCE(kthread
&& kthread
->blkcg_css
);
93 * kthread_should_stop - should this kthread return now?
95 * When someone calls kthread_stop() on your kthread, it will be woken
96 * and this will return true. You should then return, and your return
97 * value will be passed through to kthread_stop().
99 bool kthread_should_stop(void)
101 return test_bit(KTHREAD_SHOULD_STOP
, &to_kthread(current
)->flags
);
103 EXPORT_SYMBOL(kthread_should_stop
);
106 * kthread_should_park - should this kthread park now?
108 * When someone calls kthread_park() on your kthread, it will be woken
109 * and this will return true. You should then do the necessary
110 * cleanup and call kthread_parkme()
112 * Similar to kthread_should_stop(), but this keeps the thread alive
113 * and in a park position. kthread_unpark() "restarts" the thread and
114 * calls the thread function again.
116 bool kthread_should_park(void)
118 return test_bit(KTHREAD_SHOULD_PARK
, &to_kthread(current
)->flags
);
120 EXPORT_SYMBOL_GPL(kthread_should_park
);
123 * kthread_freezable_should_stop - should this freezable kthread return now?
124 * @was_frozen: optional out parameter, indicates whether %current was frozen
126 * kthread_should_stop() for freezable kthreads, which will enter
127 * refrigerator if necessary. This function is safe from kthread_stop() /
128 * freezer deadlock and freezable kthreads should use this function instead
129 * of calling try_to_freeze() directly.
131 bool kthread_freezable_should_stop(bool *was_frozen
)
137 if (unlikely(freezing(current
)))
138 frozen
= __refrigerator(true);
141 *was_frozen
= frozen
;
143 return kthread_should_stop();
145 EXPORT_SYMBOL_GPL(kthread_freezable_should_stop
);
148 * kthread_data - return data value specified on kthread creation
149 * @task: kthread task in question
151 * Return the data value specified when kthread @task was created.
152 * The caller is responsible for ensuring the validity of @task when
153 * calling this function.
155 void *kthread_data(struct task_struct
*task
)
157 return to_kthread(task
)->data
;
161 * kthread_probe_data - speculative version of kthread_data()
162 * @task: possible kthread task in question
164 * @task could be a kthread task. Return the data value specified when it
165 * was created if accessible. If @task isn't a kthread task or its data is
166 * inaccessible for any reason, %NULL is returned. This function requires
167 * that @task itself is safe to dereference.
169 void *kthread_probe_data(struct task_struct
*task
)
171 struct kthread
*kthread
= to_kthread(task
);
174 probe_kernel_read(&data
, &kthread
->data
, sizeof(data
));
178 static void __kthread_parkme(struct kthread
*self
)
180 __set_current_state(TASK_PARKED
);
181 while (test_bit(KTHREAD_SHOULD_PARK
, &self
->flags
)) {
182 if (!test_and_set_bit(KTHREAD_IS_PARKED
, &self
->flags
))
183 complete(&self
->parked
);
185 __set_current_state(TASK_PARKED
);
187 clear_bit(KTHREAD_IS_PARKED
, &self
->flags
);
188 __set_current_state(TASK_RUNNING
);
191 void kthread_parkme(void)
193 __kthread_parkme(to_kthread(current
));
195 EXPORT_SYMBOL_GPL(kthread_parkme
);
197 static int kthread(void *_create
)
199 /* Copy data: it's on kthread's stack */
200 struct kthread_create_info
*create
= _create
;
201 int (*threadfn
)(void *data
) = create
->threadfn
;
202 void *data
= create
->data
;
203 struct completion
*done
;
204 struct kthread
*self
;
207 self
= kzalloc(sizeof(*self
), GFP_KERNEL
);
208 set_kthread_struct(self
);
210 /* If user was SIGKILLed, I release the structure. */
211 done
= xchg(&create
->done
, NULL
);
218 create
->result
= ERR_PTR(-ENOMEM
);
224 init_completion(&self
->exited
);
225 init_completion(&self
->parked
);
226 current
->vfork_done
= &self
->exited
;
228 /* OK, tell user we're spawned, wait for stop or wakeup */
229 __set_current_state(TASK_UNINTERRUPTIBLE
);
230 create
->result
= current
;
235 if (!test_bit(KTHREAD_SHOULD_STOP
, &self
->flags
)) {
236 cgroup_kthread_ready();
237 __kthread_parkme(self
);
238 ret
= threadfn(data
);
243 /* called from do_fork() to get node information for about to be created task */
244 int tsk_fork_get_node(struct task_struct
*tsk
)
247 if (tsk
== kthreadd_task
)
248 return tsk
->pref_node_fork
;
253 static void create_kthread(struct kthread_create_info
*create
)
258 current
->pref_node_fork
= create
->node
;
260 /* We want our own signal handler (we take no signals by default). */
261 pid
= kernel_thread(kthread
, create
, CLONE_FS
| CLONE_FILES
| SIGCHLD
);
263 /* If user was SIGKILLed, I release the structure. */
264 struct completion
*done
= xchg(&create
->done
, NULL
);
270 create
->result
= ERR_PTR(pid
);
275 static __printf(4, 0)
276 struct task_struct
*__kthread_create_on_node(int (*threadfn
)(void *data
),
277 void *data
, int node
,
278 const char namefmt
[],
281 DECLARE_COMPLETION_ONSTACK(done
);
282 struct task_struct
*task
;
283 struct kthread_create_info
*create
= kmalloc(sizeof(*create
),
287 return ERR_PTR(-ENOMEM
);
288 create
->threadfn
= threadfn
;
291 create
->done
= &done
;
293 spin_lock(&kthread_create_lock
);
294 list_add_tail(&create
->list
, &kthread_create_list
);
295 spin_unlock(&kthread_create_lock
);
297 wake_up_process(kthreadd_task
);
299 * Wait for completion in killable state, for I might be chosen by
300 * the OOM killer while kthreadd is trying to allocate memory for
303 if (unlikely(wait_for_completion_killable(&done
))) {
307 * I got SIGKILL, but wait for 10 more seconds for completion
308 * unless chosen by the OOM killer. This delay is there as a
309 * workaround for boot failure caused by SIGKILL upon device
310 * driver initialization timeout.
312 while (i
++ < 10 && !test_tsk_thread_flag(current
, TIF_MEMDIE
))
313 if (wait_for_completion_timeout(&done
, HZ
))
316 * If I was SIGKILLed before kthreadd (or new kernel thread)
317 * calls complete(), leave the cleanup of this structure to
320 if (xchg(&create
->done
, NULL
))
321 return ERR_PTR(-EINTR
);
323 * kthreadd (or new kernel thread) will call complete()
326 wait_for_completion(&done
);
329 task
= create
->result
;
331 static const struct sched_param param
= { .sched_priority
= 0 };
333 vsnprintf(task
->comm
, sizeof(task
->comm
), namefmt
, args
);
335 * root may have changed our (kthreadd's) priority or CPU mask.
336 * The kernel thread should not inherit these properties.
338 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
339 set_cpus_allowed_ptr(task
, cpu_all_mask
);
346 * kthread_create_on_node - create a kthread.
347 * @threadfn: the function to run until signal_pending(current).
348 * @data: data ptr for @threadfn.
349 * @node: task and thread structures for the thread are allocated on this node
350 * @namefmt: printf-style name for the thread.
352 * Description: This helper function creates and names a kernel
353 * thread. The thread will be stopped: use wake_up_process() to start
354 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
355 * is affine to all CPUs.
357 * If thread is going to be bound on a particular cpu, give its node
358 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
359 * When woken, the thread will run @threadfn() with @data as its
360 * argument. @threadfn() can either call do_exit() directly if it is a
361 * standalone thread for which no one will call kthread_stop(), or
362 * return when 'kthread_should_stop()' is true (which means
363 * kthread_stop() has been called). The return value should be zero
364 * or a negative error number; it will be passed to kthread_stop().
366 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
368 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
369 void *data
, int node
,
370 const char namefmt
[],
373 struct task_struct
*task
;
376 va_start(args
, namefmt
);
377 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
382 EXPORT_SYMBOL(kthread_create_on_node
);
384 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
388 if (!wait_task_inactive(p
, state
)) {
393 /* It's safe because the task is inactive. */
394 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
395 do_set_cpus_allowed(p
, mask
);
396 p
->flags
|= PF_NO_SETAFFINITY
;
397 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
400 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
402 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
405 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
407 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
411 * kthread_bind - bind a just-created kthread to a cpu.
412 * @p: thread created by kthread_create().
413 * @cpu: cpu (might not be online, must be possible) for @k to run on.
415 * Description: This function is equivalent to set_cpus_allowed(),
416 * except that @cpu doesn't need to be online, and the thread must be
417 * stopped (i.e., just returned from kthread_create()).
419 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
421 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
423 EXPORT_SYMBOL(kthread_bind
);
426 * kthread_create_on_cpu - Create a cpu bound kthread
427 * @threadfn: the function to run until signal_pending(current).
428 * @data: data ptr for @threadfn.
429 * @cpu: The cpu on which the thread should be bound,
430 * @namefmt: printf-style name for the thread. Format is restricted
431 * to "name.*%u". Code fills in cpu number.
433 * Description: This helper function creates and names a kernel thread
434 * The thread will be woken and put into park mode.
436 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
437 void *data
, unsigned int cpu
,
440 struct task_struct
*p
;
442 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
446 kthread_bind(p
, cpu
);
447 /* CPU hotplug need to bind once again when unparking the thread. */
448 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
449 to_kthread(p
)->cpu
= cpu
;
454 * kthread_unpark - unpark a thread created by kthread_create().
455 * @k: thread created by kthread_create().
457 * Sets kthread_should_park() for @k to return false, wakes it, and
458 * waits for it to return. If the thread is marked percpu then its
459 * bound to the cpu again.
461 void kthread_unpark(struct task_struct
*k
)
463 struct kthread
*kthread
= to_kthread(k
);
465 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
467 * We clear the IS_PARKED bit here as we don't wait
468 * until the task has left the park code. So if we'd
469 * park before that happens we'd see the IS_PARKED bit
470 * which might be about to be cleared.
472 if (test_and_clear_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
474 * Newly created kthread was parked when the CPU was offline.
475 * The binding was lost and we need to set it again.
477 if (test_bit(KTHREAD_IS_PER_CPU
, &kthread
->flags
))
478 __kthread_bind(k
, kthread
->cpu
, TASK_PARKED
);
479 wake_up_state(k
, TASK_PARKED
);
482 EXPORT_SYMBOL_GPL(kthread_unpark
);
485 * kthread_park - park a thread created by kthread_create().
486 * @k: thread created by kthread_create().
488 * Sets kthread_should_park() for @k to return true, wakes it, and
489 * waits for it to return. This can also be called after kthread_create()
490 * instead of calling wake_up_process(): the thread will park without
491 * calling threadfn().
493 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
494 * If called by the kthread itself just the park bit is set.
496 int kthread_park(struct task_struct
*k
)
498 struct kthread
*kthread
= to_kthread(k
);
500 if (WARN_ON(k
->flags
& PF_EXITING
))
503 if (!test_bit(KTHREAD_IS_PARKED
, &kthread
->flags
)) {
504 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
507 wait_for_completion(&kthread
->parked
);
513 EXPORT_SYMBOL_GPL(kthread_park
);
516 * kthread_stop - stop a thread created by kthread_create().
517 * @k: thread created by kthread_create().
519 * Sets kthread_should_stop() for @k to return true, wakes it, and
520 * waits for it to exit. This can also be called after kthread_create()
521 * instead of calling wake_up_process(): the thread will exit without
522 * calling threadfn().
524 * If threadfn() may call do_exit() itself, the caller must ensure
525 * task_struct can't go away.
527 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
530 int kthread_stop(struct task_struct
*k
)
532 struct kthread
*kthread
;
535 trace_sched_kthread_stop(k
);
538 kthread
= to_kthread(k
);
539 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
542 wait_for_completion(&kthread
->exited
);
546 trace_sched_kthread_stop_ret(ret
);
549 EXPORT_SYMBOL(kthread_stop
);
551 int kthreadd(void *unused
)
553 struct task_struct
*tsk
= current
;
555 /* Setup a clean context for our children to inherit. */
556 set_task_comm(tsk
, "kthreadd");
558 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
559 set_mems_allowed(node_states
[N_MEMORY
]);
561 current
->flags
|= PF_NOFREEZE
;
562 cgroup_init_kthreadd();
565 set_current_state(TASK_INTERRUPTIBLE
);
566 if (list_empty(&kthread_create_list
))
568 __set_current_state(TASK_RUNNING
);
570 spin_lock(&kthread_create_lock
);
571 while (!list_empty(&kthread_create_list
)) {
572 struct kthread_create_info
*create
;
574 create
= list_entry(kthread_create_list
.next
,
575 struct kthread_create_info
, list
);
576 list_del_init(&create
->list
);
577 spin_unlock(&kthread_create_lock
);
579 create_kthread(create
);
581 spin_lock(&kthread_create_lock
);
583 spin_unlock(&kthread_create_lock
);
589 void __kthread_init_worker(struct kthread_worker
*worker
,
591 struct lock_class_key
*key
)
593 memset(worker
, 0, sizeof(struct kthread_worker
));
594 spin_lock_init(&worker
->lock
);
595 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
596 INIT_LIST_HEAD(&worker
->work_list
);
597 INIT_LIST_HEAD(&worker
->delayed_work_list
);
599 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
602 * kthread_worker_fn - kthread function to process kthread_worker
603 * @worker_ptr: pointer to initialized kthread_worker
605 * This function implements the main cycle of kthread worker. It processes
606 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
609 * The works are not allowed to keep any locks, disable preemption or interrupts
610 * when they finish. There is defined a safe point for freezing when one work
611 * finishes and before a new one is started.
613 * Also the works must not be handled by more than one worker at the same time,
614 * see also kthread_queue_work().
616 int kthread_worker_fn(void *worker_ptr
)
618 struct kthread_worker
*worker
= worker_ptr
;
619 struct kthread_work
*work
;
622 * FIXME: Update the check and remove the assignment when all kthread
623 * worker users are created using kthread_create_worker*() functions.
625 WARN_ON(worker
->task
&& worker
->task
!= current
);
626 worker
->task
= current
;
628 if (worker
->flags
& KTW_FREEZABLE
)
632 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
634 if (kthread_should_stop()) {
635 __set_current_state(TASK_RUNNING
);
636 spin_lock_irq(&worker
->lock
);
638 spin_unlock_irq(&worker
->lock
);
643 spin_lock_irq(&worker
->lock
);
644 if (!list_empty(&worker
->work_list
)) {
645 work
= list_first_entry(&worker
->work_list
,
646 struct kthread_work
, node
);
647 list_del_init(&work
->node
);
649 worker
->current_work
= work
;
650 spin_unlock_irq(&worker
->lock
);
653 __set_current_state(TASK_RUNNING
);
655 } else if (!freezing(current
))
662 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
664 static __printf(3, 0) struct kthread_worker
*
665 __kthread_create_worker(int cpu
, unsigned int flags
,
666 const char namefmt
[], va_list args
)
668 struct kthread_worker
*worker
;
669 struct task_struct
*task
;
672 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
674 return ERR_PTR(-ENOMEM
);
676 kthread_init_worker(worker
);
679 node
= cpu_to_node(cpu
);
681 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
682 node
, namefmt
, args
);
687 kthread_bind(task
, cpu
);
689 worker
->flags
= flags
;
691 wake_up_process(task
);
696 return ERR_CAST(task
);
700 * kthread_create_worker - create a kthread worker
701 * @flags: flags modifying the default behavior of the worker
702 * @namefmt: printf-style name for the kthread worker (task).
704 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
705 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
706 * when the worker was SIGKILLed.
708 struct kthread_worker
*
709 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
711 struct kthread_worker
*worker
;
714 va_start(args
, namefmt
);
715 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
720 EXPORT_SYMBOL(kthread_create_worker
);
723 * kthread_create_worker_on_cpu - create a kthread worker and bind it
724 * it to a given CPU and the associated NUMA node.
726 * @flags: flags modifying the default behavior of the worker
727 * @namefmt: printf-style name for the kthread worker (task).
729 * Use a valid CPU number if you want to bind the kthread worker
730 * to the given CPU and the associated NUMA node.
732 * A good practice is to add the cpu number also into the worker name.
733 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
735 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
736 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
737 * when the worker was SIGKILLed.
739 struct kthread_worker
*
740 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
741 const char namefmt
[], ...)
743 struct kthread_worker
*worker
;
746 va_start(args
, namefmt
);
747 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
752 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
755 * Returns true when the work could not be queued at the moment.
756 * It happens when it is already pending in a worker list
757 * or when it is being cancelled.
759 static inline bool queuing_blocked(struct kthread_worker
*worker
,
760 struct kthread_work
*work
)
762 lockdep_assert_held(&worker
->lock
);
764 return !list_empty(&work
->node
) || work
->canceling
;
767 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
768 struct kthread_work
*work
)
770 lockdep_assert_held(&worker
->lock
);
771 WARN_ON_ONCE(!list_empty(&work
->node
));
772 /* Do not use a work with >1 worker, see kthread_queue_work() */
773 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
776 /* insert @work before @pos in @worker */
777 static void kthread_insert_work(struct kthread_worker
*worker
,
778 struct kthread_work
*work
,
779 struct list_head
*pos
)
781 kthread_insert_work_sanity_check(worker
, work
);
783 list_add_tail(&work
->node
, pos
);
784 work
->worker
= worker
;
785 if (!worker
->current_work
&& likely(worker
->task
))
786 wake_up_process(worker
->task
);
790 * kthread_queue_work - queue a kthread_work
791 * @worker: target kthread_worker
792 * @work: kthread_work to queue
794 * Queue @work to work processor @task for async execution. @task
795 * must have been created with kthread_worker_create(). Returns %true
796 * if @work was successfully queued, %false if it was already pending.
798 * Reinitialize the work if it needs to be used by another worker.
799 * For example, when the worker was stopped and started again.
801 bool kthread_queue_work(struct kthread_worker
*worker
,
802 struct kthread_work
*work
)
807 spin_lock_irqsave(&worker
->lock
, flags
);
808 if (!queuing_blocked(worker
, work
)) {
809 kthread_insert_work(worker
, work
, &worker
->work_list
);
812 spin_unlock_irqrestore(&worker
->lock
, flags
);
815 EXPORT_SYMBOL_GPL(kthread_queue_work
);
818 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
819 * delayed work when the timer expires.
820 * @t: pointer to the expired timer
822 * The format of the function is defined by struct timer_list.
823 * It should have been called from irqsafe timer with irq already off.
825 void kthread_delayed_work_timer_fn(struct timer_list
*t
)
827 struct kthread_delayed_work
*dwork
= from_timer(dwork
, t
, timer
);
828 struct kthread_work
*work
= &dwork
->work
;
829 struct kthread_worker
*worker
= work
->worker
;
832 * This might happen when a pending work is reinitialized.
833 * It means that it is used a wrong way.
835 if (WARN_ON_ONCE(!worker
))
838 spin_lock(&worker
->lock
);
839 /* Work must not be used with >1 worker, see kthread_queue_work(). */
840 WARN_ON_ONCE(work
->worker
!= worker
);
842 /* Move the work from worker->delayed_work_list. */
843 WARN_ON_ONCE(list_empty(&work
->node
));
844 list_del_init(&work
->node
);
845 kthread_insert_work(worker
, work
, &worker
->work_list
);
847 spin_unlock(&worker
->lock
);
849 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
851 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
852 struct kthread_delayed_work
*dwork
,
855 struct timer_list
*timer
= &dwork
->timer
;
856 struct kthread_work
*work
= &dwork
->work
;
858 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
);
861 * If @delay is 0, queue @dwork->work immediately. This is for
862 * both optimization and correctness. The earliest @timer can
863 * expire is on the closest next tick and delayed_work users depend
864 * on that there's no such delay when @delay is 0.
867 kthread_insert_work(worker
, work
, &worker
->work_list
);
871 /* Be paranoid and try to detect possible races already now. */
872 kthread_insert_work_sanity_check(worker
, work
);
874 list_add(&work
->node
, &worker
->delayed_work_list
);
875 work
->worker
= worker
;
876 timer
->expires
= jiffies
+ delay
;
881 * kthread_queue_delayed_work - queue the associated kthread work
883 * @worker: target kthread_worker
884 * @dwork: kthread_delayed_work to queue
885 * @delay: number of jiffies to wait before queuing
887 * If the work has not been pending it starts a timer that will queue
888 * the work after the given @delay. If @delay is zero, it queues the
891 * Return: %false if the @work has already been pending. It means that
892 * either the timer was running or the work was queued. It returns %true
895 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
896 struct kthread_delayed_work
*dwork
,
899 struct kthread_work
*work
= &dwork
->work
;
903 spin_lock_irqsave(&worker
->lock
, flags
);
905 if (!queuing_blocked(worker
, work
)) {
906 __kthread_queue_delayed_work(worker
, dwork
, delay
);
910 spin_unlock_irqrestore(&worker
->lock
, flags
);
913 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
915 struct kthread_flush_work
{
916 struct kthread_work work
;
917 struct completion done
;
920 static void kthread_flush_work_fn(struct kthread_work
*work
)
922 struct kthread_flush_work
*fwork
=
923 container_of(work
, struct kthread_flush_work
, work
);
924 complete(&fwork
->done
);
928 * kthread_flush_work - flush a kthread_work
929 * @work: work to flush
931 * If @work is queued or executing, wait for it to finish execution.
933 void kthread_flush_work(struct kthread_work
*work
)
935 struct kthread_flush_work fwork
= {
936 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
937 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
939 struct kthread_worker
*worker
;
942 worker
= work
->worker
;
946 spin_lock_irq(&worker
->lock
);
947 /* Work must not be used with >1 worker, see kthread_queue_work(). */
948 WARN_ON_ONCE(work
->worker
!= worker
);
950 if (!list_empty(&work
->node
))
951 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
952 else if (worker
->current_work
== work
)
953 kthread_insert_work(worker
, &fwork
.work
,
954 worker
->work_list
.next
);
958 spin_unlock_irq(&worker
->lock
);
961 wait_for_completion(&fwork
.done
);
963 EXPORT_SYMBOL_GPL(kthread_flush_work
);
966 * This function removes the work from the worker queue. Also it makes sure
967 * that it won't get queued later via the delayed work's timer.
969 * The work might still be in use when this function finishes. See the
970 * current_work proceed by the worker.
972 * Return: %true if @work was pending and successfully canceled,
973 * %false if @work was not pending
975 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
976 unsigned long *flags
)
978 /* Try to cancel the timer if exists. */
980 struct kthread_delayed_work
*dwork
=
981 container_of(work
, struct kthread_delayed_work
, work
);
982 struct kthread_worker
*worker
= work
->worker
;
985 * del_timer_sync() must be called to make sure that the timer
986 * callback is not running. The lock must be temporary released
987 * to avoid a deadlock with the callback. In the meantime,
988 * any queuing is blocked by setting the canceling counter.
991 spin_unlock_irqrestore(&worker
->lock
, *flags
);
992 del_timer_sync(&dwork
->timer
);
993 spin_lock_irqsave(&worker
->lock
, *flags
);
998 * Try to remove the work from a worker list. It might either
999 * be from worker->work_list or from worker->delayed_work_list.
1001 if (!list_empty(&work
->node
)) {
1002 list_del_init(&work
->node
);
1010 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1011 * @worker: kthread worker to use
1012 * @dwork: kthread delayed work to queue
1013 * @delay: number of jiffies to wait before queuing
1015 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1016 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1017 * @work is guaranteed to be queued immediately.
1019 * Return: %true if @dwork was pending and its timer was modified,
1022 * A special case is when the work is being canceled in parallel.
1023 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1024 * or yet another kthread_mod_delayed_work() call. We let the other command
1025 * win and return %false here. The caller is supposed to synchronize these
1026 * operations a reasonable way.
1028 * This function is safe to call from any context including IRQ handler.
1029 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1032 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1033 struct kthread_delayed_work
*dwork
,
1034 unsigned long delay
)
1036 struct kthread_work
*work
= &dwork
->work
;
1037 unsigned long flags
;
1040 spin_lock_irqsave(&worker
->lock
, flags
);
1042 /* Do not bother with canceling when never queued. */
1046 /* Work must not be used with >1 worker, see kthread_queue_work() */
1047 WARN_ON_ONCE(work
->worker
!= worker
);
1049 /* Do not fight with another command that is canceling this work. */
1050 if (work
->canceling
)
1053 ret
= __kthread_cancel_work(work
, true, &flags
);
1055 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1057 spin_unlock_irqrestore(&worker
->lock
, flags
);
1060 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1062 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1064 struct kthread_worker
*worker
= work
->worker
;
1065 unsigned long flags
;
1071 spin_lock_irqsave(&worker
->lock
, flags
);
1072 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1073 WARN_ON_ONCE(work
->worker
!= worker
);
1075 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1077 if (worker
->current_work
!= work
)
1081 * The work is in progress and we need to wait with the lock released.
1082 * In the meantime, block any queuing by setting the canceling counter.
1085 spin_unlock_irqrestore(&worker
->lock
, flags
);
1086 kthread_flush_work(work
);
1087 spin_lock_irqsave(&worker
->lock
, flags
);
1091 spin_unlock_irqrestore(&worker
->lock
, flags
);
1097 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1098 * @work: the kthread work to cancel
1100 * Cancel @work and wait for its execution to finish. This function
1101 * can be used even if the work re-queues itself. On return from this
1102 * function, @work is guaranteed to be not pending or executing on any CPU.
1104 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1105 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1107 * The caller must ensure that the worker on which @work was last
1108 * queued can't be destroyed before this function returns.
1110 * Return: %true if @work was pending, %false otherwise.
1112 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1114 return __kthread_cancel_work_sync(work
, false);
1116 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1119 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1120 * wait for it to finish.
1121 * @dwork: the kthread delayed work to cancel
1123 * This is kthread_cancel_work_sync() for delayed works.
1125 * Return: %true if @dwork was pending, %false otherwise.
1127 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1129 return __kthread_cancel_work_sync(&dwork
->work
, true);
1131 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1134 * kthread_flush_worker - flush all current works on a kthread_worker
1135 * @worker: worker to flush
1137 * Wait until all currently executing or pending works on @worker are
1140 void kthread_flush_worker(struct kthread_worker
*worker
)
1142 struct kthread_flush_work fwork
= {
1143 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1144 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1147 kthread_queue_work(worker
, &fwork
.work
);
1148 wait_for_completion(&fwork
.done
);
1150 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1153 * kthread_destroy_worker - destroy a kthread worker
1154 * @worker: worker to be destroyed
1156 * Flush and destroy @worker. The simple flush is enough because the kthread
1157 * worker API is used only in trivial scenarios. There are no multi-step state
1160 void kthread_destroy_worker(struct kthread_worker
*worker
)
1162 struct task_struct
*task
;
1164 task
= worker
->task
;
1168 kthread_flush_worker(worker
);
1170 WARN_ON(!list_empty(&worker
->work_list
));
1173 EXPORT_SYMBOL(kthread_destroy_worker
);
1175 #ifdef CONFIG_BLK_CGROUP
1177 * kthread_associate_blkcg - associate blkcg to current kthread
1178 * @css: the cgroup info
1180 * Current thread must be a kthread. The thread is running jobs on behalf of
1181 * other threads. In some cases, we expect the jobs attach cgroup info of
1182 * original threads instead of that of current thread. This function stores
1183 * original thread's cgroup info in current kthread context for later
1186 void kthread_associate_blkcg(struct cgroup_subsys_state
*css
)
1188 struct kthread
*kthread
;
1190 if (!(current
->flags
& PF_KTHREAD
))
1192 kthread
= to_kthread(current
);
1196 if (kthread
->blkcg_css
) {
1197 css_put(kthread
->blkcg_css
);
1198 kthread
->blkcg_css
= NULL
;
1202 kthread
->blkcg_css
= css
;
1205 EXPORT_SYMBOL(kthread_associate_blkcg
);
1208 * kthread_blkcg - get associated blkcg css of current kthread
1210 * Current thread must be a kthread.
1212 struct cgroup_subsys_state
*kthread_blkcg(void)
1214 struct kthread
*kthread
;
1216 if (current
->flags
& PF_KTHREAD
) {
1217 kthread
= to_kthread(current
);
1219 return kthread
->blkcg_css
;
1223 EXPORT_SYMBOL(kthread_blkcg
);