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 };
334 char name
[TASK_COMM_LEN
];
337 * task is already visible to other tasks, so updating
338 * COMM must be protected.
340 vsnprintf(name
, sizeof(name
), namefmt
, args
);
341 set_task_comm(task
, name
);
343 * root may have changed our (kthreadd's) priority or CPU mask.
344 * The kernel thread should not inherit these properties.
346 sched_setscheduler_nocheck(task
, SCHED_NORMAL
, ¶m
);
347 set_cpus_allowed_ptr(task
, cpu_all_mask
);
354 * kthread_create_on_node - create a kthread.
355 * @threadfn: the function to run until signal_pending(current).
356 * @data: data ptr for @threadfn.
357 * @node: task and thread structures for the thread are allocated on this node
358 * @namefmt: printf-style name for the thread.
360 * Description: This helper function creates and names a kernel
361 * thread. The thread will be stopped: use wake_up_process() to start
362 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
363 * is affine to all CPUs.
365 * If thread is going to be bound on a particular cpu, give its node
366 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
367 * When woken, the thread will run @threadfn() with @data as its
368 * argument. @threadfn() can either call do_exit() directly if it is a
369 * standalone thread for which no one will call kthread_stop(), or
370 * return when 'kthread_should_stop()' is true (which means
371 * kthread_stop() has been called). The return value should be zero
372 * or a negative error number; it will be passed to kthread_stop().
374 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
376 struct task_struct
*kthread_create_on_node(int (*threadfn
)(void *data
),
377 void *data
, int node
,
378 const char namefmt
[],
381 struct task_struct
*task
;
384 va_start(args
, namefmt
);
385 task
= __kthread_create_on_node(threadfn
, data
, node
, namefmt
, args
);
390 EXPORT_SYMBOL(kthread_create_on_node
);
392 static void __kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
, long state
)
396 if (!wait_task_inactive(p
, state
)) {
401 /* It's safe because the task is inactive. */
402 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
403 do_set_cpus_allowed(p
, mask
);
404 p
->flags
|= PF_NO_SETAFFINITY
;
405 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
408 static void __kthread_bind(struct task_struct
*p
, unsigned int cpu
, long state
)
410 __kthread_bind_mask(p
, cpumask_of(cpu
), state
);
413 void kthread_bind_mask(struct task_struct
*p
, const struct cpumask
*mask
)
415 __kthread_bind_mask(p
, mask
, TASK_UNINTERRUPTIBLE
);
419 * kthread_bind - bind a just-created kthread to a cpu.
420 * @p: thread created by kthread_create().
421 * @cpu: cpu (might not be online, must be possible) for @k to run on.
423 * Description: This function is equivalent to set_cpus_allowed(),
424 * except that @cpu doesn't need to be online, and the thread must be
425 * stopped (i.e., just returned from kthread_create()).
427 void kthread_bind(struct task_struct
*p
, unsigned int cpu
)
429 __kthread_bind(p
, cpu
, TASK_UNINTERRUPTIBLE
);
431 EXPORT_SYMBOL(kthread_bind
);
434 * kthread_create_on_cpu - Create a cpu bound kthread
435 * @threadfn: the function to run until signal_pending(current).
436 * @data: data ptr for @threadfn.
437 * @cpu: The cpu on which the thread should be bound,
438 * @namefmt: printf-style name for the thread. Format is restricted
439 * to "name.*%u". Code fills in cpu number.
441 * Description: This helper function creates and names a kernel thread
442 * The thread will be woken and put into park mode.
444 struct task_struct
*kthread_create_on_cpu(int (*threadfn
)(void *data
),
445 void *data
, unsigned int cpu
,
448 struct task_struct
*p
;
450 p
= kthread_create_on_node(threadfn
, data
, cpu_to_node(cpu
), namefmt
,
454 kthread_bind(p
, cpu
);
455 /* CPU hotplug need to bind once again when unparking the thread. */
456 set_bit(KTHREAD_IS_PER_CPU
, &to_kthread(p
)->flags
);
457 to_kthread(p
)->cpu
= cpu
;
462 * kthread_unpark - unpark a thread created by kthread_create().
463 * @k: thread created by kthread_create().
465 * Sets kthread_should_park() for @k to return false, wakes it, and
466 * waits for it to return. If the thread is marked percpu then its
467 * bound to the cpu again.
469 void kthread_unpark(struct task_struct
*k
)
471 struct kthread
*kthread
= to_kthread(k
);
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
);
480 clear_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
481 wake_up_state(k
, TASK_PARKED
);
483 EXPORT_SYMBOL_GPL(kthread_unpark
);
486 * kthread_park - park a thread created by kthread_create().
487 * @k: thread created by kthread_create().
489 * Sets kthread_should_park() for @k to return true, wakes it, and
490 * waits for it to return. This can also be called after kthread_create()
491 * instead of calling wake_up_process(): the thread will park without
492 * calling threadfn().
494 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
495 * If called by the kthread itself just the park bit is set.
497 int kthread_park(struct task_struct
*k
)
499 struct kthread
*kthread
= to_kthread(k
);
501 if (WARN_ON(k
->flags
& PF_EXITING
))
504 if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
)))
507 set_bit(KTHREAD_SHOULD_PARK
, &kthread
->flags
);
510 wait_for_completion(&kthread
->parked
);
515 EXPORT_SYMBOL_GPL(kthread_park
);
518 * kthread_stop - stop a thread created by kthread_create().
519 * @k: thread created by kthread_create().
521 * Sets kthread_should_stop() for @k to return true, wakes it, and
522 * waits for it to exit. This can also be called after kthread_create()
523 * instead of calling wake_up_process(): the thread will exit without
524 * calling threadfn().
526 * If threadfn() may call do_exit() itself, the caller must ensure
527 * task_struct can't go away.
529 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
532 int kthread_stop(struct task_struct
*k
)
534 struct kthread
*kthread
;
537 trace_sched_kthread_stop(k
);
540 kthread
= to_kthread(k
);
541 set_bit(KTHREAD_SHOULD_STOP
, &kthread
->flags
);
544 wait_for_completion(&kthread
->exited
);
548 trace_sched_kthread_stop_ret(ret
);
551 EXPORT_SYMBOL(kthread_stop
);
553 int kthreadd(void *unused
)
555 struct task_struct
*tsk
= current
;
557 /* Setup a clean context for our children to inherit. */
558 set_task_comm(tsk
, "kthreadd");
560 set_cpus_allowed_ptr(tsk
, cpu_all_mask
);
561 set_mems_allowed(node_states
[N_MEMORY
]);
563 current
->flags
|= PF_NOFREEZE
;
564 cgroup_init_kthreadd();
567 set_current_state(TASK_INTERRUPTIBLE
);
568 if (list_empty(&kthread_create_list
))
570 __set_current_state(TASK_RUNNING
);
572 spin_lock(&kthread_create_lock
);
573 while (!list_empty(&kthread_create_list
)) {
574 struct kthread_create_info
*create
;
576 create
= list_entry(kthread_create_list
.next
,
577 struct kthread_create_info
, list
);
578 list_del_init(&create
->list
);
579 spin_unlock(&kthread_create_lock
);
581 create_kthread(create
);
583 spin_lock(&kthread_create_lock
);
585 spin_unlock(&kthread_create_lock
);
591 void __kthread_init_worker(struct kthread_worker
*worker
,
593 struct lock_class_key
*key
)
595 memset(worker
, 0, sizeof(struct kthread_worker
));
596 spin_lock_init(&worker
->lock
);
597 lockdep_set_class_and_name(&worker
->lock
, key
, name
);
598 INIT_LIST_HEAD(&worker
->work_list
);
599 INIT_LIST_HEAD(&worker
->delayed_work_list
);
601 EXPORT_SYMBOL_GPL(__kthread_init_worker
);
604 * kthread_worker_fn - kthread function to process kthread_worker
605 * @worker_ptr: pointer to initialized kthread_worker
607 * This function implements the main cycle of kthread worker. It processes
608 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
611 * The works are not allowed to keep any locks, disable preemption or interrupts
612 * when they finish. There is defined a safe point for freezing when one work
613 * finishes and before a new one is started.
615 * Also the works must not be handled by more than one worker at the same time,
616 * see also kthread_queue_work().
618 int kthread_worker_fn(void *worker_ptr
)
620 struct kthread_worker
*worker
= worker_ptr
;
621 struct kthread_work
*work
;
624 * FIXME: Update the check and remove the assignment when all kthread
625 * worker users are created using kthread_create_worker*() functions.
627 WARN_ON(worker
->task
&& worker
->task
!= current
);
628 worker
->task
= current
;
630 if (worker
->flags
& KTW_FREEZABLE
)
634 set_current_state(TASK_INTERRUPTIBLE
); /* mb paired w/ kthread_stop */
636 if (kthread_should_stop()) {
637 __set_current_state(TASK_RUNNING
);
638 spin_lock_irq(&worker
->lock
);
640 spin_unlock_irq(&worker
->lock
);
645 spin_lock_irq(&worker
->lock
);
646 if (!list_empty(&worker
->work_list
)) {
647 work
= list_first_entry(&worker
->work_list
,
648 struct kthread_work
, node
);
649 list_del_init(&work
->node
);
651 worker
->current_work
= work
;
652 spin_unlock_irq(&worker
->lock
);
655 __set_current_state(TASK_RUNNING
);
657 } else if (!freezing(current
))
664 EXPORT_SYMBOL_GPL(kthread_worker_fn
);
666 static __printf(3, 0) struct kthread_worker
*
667 __kthread_create_worker(int cpu
, unsigned int flags
,
668 const char namefmt
[], va_list args
)
670 struct kthread_worker
*worker
;
671 struct task_struct
*task
;
674 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
676 return ERR_PTR(-ENOMEM
);
678 kthread_init_worker(worker
);
681 node
= cpu_to_node(cpu
);
683 task
= __kthread_create_on_node(kthread_worker_fn
, worker
,
684 node
, namefmt
, args
);
689 kthread_bind(task
, cpu
);
691 worker
->flags
= flags
;
693 wake_up_process(task
);
698 return ERR_CAST(task
);
702 * kthread_create_worker - create a kthread worker
703 * @flags: flags modifying the default behavior of the worker
704 * @namefmt: printf-style name for the kthread worker (task).
706 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
707 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
708 * when the worker was SIGKILLed.
710 struct kthread_worker
*
711 kthread_create_worker(unsigned int flags
, const char namefmt
[], ...)
713 struct kthread_worker
*worker
;
716 va_start(args
, namefmt
);
717 worker
= __kthread_create_worker(-1, flags
, namefmt
, args
);
722 EXPORT_SYMBOL(kthread_create_worker
);
725 * kthread_create_worker_on_cpu - create a kthread worker and bind it
726 * it to a given CPU and the associated NUMA node.
728 * @flags: flags modifying the default behavior of the worker
729 * @namefmt: printf-style name for the kthread worker (task).
731 * Use a valid CPU number if you want to bind the kthread worker
732 * to the given CPU and the associated NUMA node.
734 * A good practice is to add the cpu number also into the worker name.
735 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
737 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
738 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
739 * when the worker was SIGKILLed.
741 struct kthread_worker
*
742 kthread_create_worker_on_cpu(int cpu
, unsigned int flags
,
743 const char namefmt
[], ...)
745 struct kthread_worker
*worker
;
748 va_start(args
, namefmt
);
749 worker
= __kthread_create_worker(cpu
, flags
, namefmt
, args
);
754 EXPORT_SYMBOL(kthread_create_worker_on_cpu
);
757 * Returns true when the work could not be queued at the moment.
758 * It happens when it is already pending in a worker list
759 * or when it is being cancelled.
761 static inline bool queuing_blocked(struct kthread_worker
*worker
,
762 struct kthread_work
*work
)
764 lockdep_assert_held(&worker
->lock
);
766 return !list_empty(&work
->node
) || work
->canceling
;
769 static void kthread_insert_work_sanity_check(struct kthread_worker
*worker
,
770 struct kthread_work
*work
)
772 lockdep_assert_held(&worker
->lock
);
773 WARN_ON_ONCE(!list_empty(&work
->node
));
774 /* Do not use a work with >1 worker, see kthread_queue_work() */
775 WARN_ON_ONCE(work
->worker
&& work
->worker
!= worker
);
778 /* insert @work before @pos in @worker */
779 static void kthread_insert_work(struct kthread_worker
*worker
,
780 struct kthread_work
*work
,
781 struct list_head
*pos
)
783 kthread_insert_work_sanity_check(worker
, work
);
785 list_add_tail(&work
->node
, pos
);
786 work
->worker
= worker
;
787 if (!worker
->current_work
&& likely(worker
->task
))
788 wake_up_process(worker
->task
);
792 * kthread_queue_work - queue a kthread_work
793 * @worker: target kthread_worker
794 * @work: kthread_work to queue
796 * Queue @work to work processor @task for async execution. @task
797 * must have been created with kthread_worker_create(). Returns %true
798 * if @work was successfully queued, %false if it was already pending.
800 * Reinitialize the work if it needs to be used by another worker.
801 * For example, when the worker was stopped and started again.
803 bool kthread_queue_work(struct kthread_worker
*worker
,
804 struct kthread_work
*work
)
809 spin_lock_irqsave(&worker
->lock
, flags
);
810 if (!queuing_blocked(worker
, work
)) {
811 kthread_insert_work(worker
, work
, &worker
->work_list
);
814 spin_unlock_irqrestore(&worker
->lock
, flags
);
817 EXPORT_SYMBOL_GPL(kthread_queue_work
);
820 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
821 * delayed work when the timer expires.
822 * @t: pointer to the expired timer
824 * The format of the function is defined by struct timer_list.
825 * It should have been called from irqsafe timer with irq already off.
827 void kthread_delayed_work_timer_fn(struct timer_list
*t
)
829 struct kthread_delayed_work
*dwork
= from_timer(dwork
, t
, timer
);
830 struct kthread_work
*work
= &dwork
->work
;
831 struct kthread_worker
*worker
= work
->worker
;
834 * This might happen when a pending work is reinitialized.
835 * It means that it is used a wrong way.
837 if (WARN_ON_ONCE(!worker
))
840 spin_lock(&worker
->lock
);
841 /* Work must not be used with >1 worker, see kthread_queue_work(). */
842 WARN_ON_ONCE(work
->worker
!= worker
);
844 /* Move the work from worker->delayed_work_list. */
845 WARN_ON_ONCE(list_empty(&work
->node
));
846 list_del_init(&work
->node
);
847 kthread_insert_work(worker
, work
, &worker
->work_list
);
849 spin_unlock(&worker
->lock
);
851 EXPORT_SYMBOL(kthread_delayed_work_timer_fn
);
853 void __kthread_queue_delayed_work(struct kthread_worker
*worker
,
854 struct kthread_delayed_work
*dwork
,
857 struct timer_list
*timer
= &dwork
->timer
;
858 struct kthread_work
*work
= &dwork
->work
;
860 WARN_ON_ONCE(timer
->function
!= kthread_delayed_work_timer_fn
);
863 * If @delay is 0, queue @dwork->work immediately. This is for
864 * both optimization and correctness. The earliest @timer can
865 * expire is on the closest next tick and delayed_work users depend
866 * on that there's no such delay when @delay is 0.
869 kthread_insert_work(worker
, work
, &worker
->work_list
);
873 /* Be paranoid and try to detect possible races already now. */
874 kthread_insert_work_sanity_check(worker
, work
);
876 list_add(&work
->node
, &worker
->delayed_work_list
);
877 work
->worker
= worker
;
878 timer
->expires
= jiffies
+ delay
;
883 * kthread_queue_delayed_work - queue the associated kthread work
885 * @worker: target kthread_worker
886 * @dwork: kthread_delayed_work to queue
887 * @delay: number of jiffies to wait before queuing
889 * If the work has not been pending it starts a timer that will queue
890 * the work after the given @delay. If @delay is zero, it queues the
893 * Return: %false if the @work has already been pending. It means that
894 * either the timer was running or the work was queued. It returns %true
897 bool kthread_queue_delayed_work(struct kthread_worker
*worker
,
898 struct kthread_delayed_work
*dwork
,
901 struct kthread_work
*work
= &dwork
->work
;
905 spin_lock_irqsave(&worker
->lock
, flags
);
907 if (!queuing_blocked(worker
, work
)) {
908 __kthread_queue_delayed_work(worker
, dwork
, delay
);
912 spin_unlock_irqrestore(&worker
->lock
, flags
);
915 EXPORT_SYMBOL_GPL(kthread_queue_delayed_work
);
917 struct kthread_flush_work
{
918 struct kthread_work work
;
919 struct completion done
;
922 static void kthread_flush_work_fn(struct kthread_work
*work
)
924 struct kthread_flush_work
*fwork
=
925 container_of(work
, struct kthread_flush_work
, work
);
926 complete(&fwork
->done
);
930 * kthread_flush_work - flush a kthread_work
931 * @work: work to flush
933 * If @work is queued or executing, wait for it to finish execution.
935 void kthread_flush_work(struct kthread_work
*work
)
937 struct kthread_flush_work fwork
= {
938 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
939 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
941 struct kthread_worker
*worker
;
944 worker
= work
->worker
;
948 spin_lock_irq(&worker
->lock
);
949 /* Work must not be used with >1 worker, see kthread_queue_work(). */
950 WARN_ON_ONCE(work
->worker
!= worker
);
952 if (!list_empty(&work
->node
))
953 kthread_insert_work(worker
, &fwork
.work
, work
->node
.next
);
954 else if (worker
->current_work
== work
)
955 kthread_insert_work(worker
, &fwork
.work
,
956 worker
->work_list
.next
);
960 spin_unlock_irq(&worker
->lock
);
963 wait_for_completion(&fwork
.done
);
965 EXPORT_SYMBOL_GPL(kthread_flush_work
);
968 * This function removes the work from the worker queue. Also it makes sure
969 * that it won't get queued later via the delayed work's timer.
971 * The work might still be in use when this function finishes. See the
972 * current_work proceed by the worker.
974 * Return: %true if @work was pending and successfully canceled,
975 * %false if @work was not pending
977 static bool __kthread_cancel_work(struct kthread_work
*work
, bool is_dwork
,
978 unsigned long *flags
)
980 /* Try to cancel the timer if exists. */
982 struct kthread_delayed_work
*dwork
=
983 container_of(work
, struct kthread_delayed_work
, work
);
984 struct kthread_worker
*worker
= work
->worker
;
987 * del_timer_sync() must be called to make sure that the timer
988 * callback is not running. The lock must be temporary released
989 * to avoid a deadlock with the callback. In the meantime,
990 * any queuing is blocked by setting the canceling counter.
993 spin_unlock_irqrestore(&worker
->lock
, *flags
);
994 del_timer_sync(&dwork
->timer
);
995 spin_lock_irqsave(&worker
->lock
, *flags
);
1000 * Try to remove the work from a worker list. It might either
1001 * be from worker->work_list or from worker->delayed_work_list.
1003 if (!list_empty(&work
->node
)) {
1004 list_del_init(&work
->node
);
1012 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1013 * @worker: kthread worker to use
1014 * @dwork: kthread delayed work to queue
1015 * @delay: number of jiffies to wait before queuing
1017 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1018 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1019 * @work is guaranteed to be queued immediately.
1021 * Return: %true if @dwork was pending and its timer was modified,
1024 * A special case is when the work is being canceled in parallel.
1025 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1026 * or yet another kthread_mod_delayed_work() call. We let the other command
1027 * win and return %false here. The caller is supposed to synchronize these
1028 * operations a reasonable way.
1030 * This function is safe to call from any context including IRQ handler.
1031 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1034 bool kthread_mod_delayed_work(struct kthread_worker
*worker
,
1035 struct kthread_delayed_work
*dwork
,
1036 unsigned long delay
)
1038 struct kthread_work
*work
= &dwork
->work
;
1039 unsigned long flags
;
1042 spin_lock_irqsave(&worker
->lock
, flags
);
1044 /* Do not bother with canceling when never queued. */
1048 /* Work must not be used with >1 worker, see kthread_queue_work() */
1049 WARN_ON_ONCE(work
->worker
!= worker
);
1051 /* Do not fight with another command that is canceling this work. */
1052 if (work
->canceling
)
1055 ret
= __kthread_cancel_work(work
, true, &flags
);
1057 __kthread_queue_delayed_work(worker
, dwork
, delay
);
1059 spin_unlock_irqrestore(&worker
->lock
, flags
);
1062 EXPORT_SYMBOL_GPL(kthread_mod_delayed_work
);
1064 static bool __kthread_cancel_work_sync(struct kthread_work
*work
, bool is_dwork
)
1066 struct kthread_worker
*worker
= work
->worker
;
1067 unsigned long flags
;
1073 spin_lock_irqsave(&worker
->lock
, flags
);
1074 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1075 WARN_ON_ONCE(work
->worker
!= worker
);
1077 ret
= __kthread_cancel_work(work
, is_dwork
, &flags
);
1079 if (worker
->current_work
!= work
)
1083 * The work is in progress and we need to wait with the lock released.
1084 * In the meantime, block any queuing by setting the canceling counter.
1087 spin_unlock_irqrestore(&worker
->lock
, flags
);
1088 kthread_flush_work(work
);
1089 spin_lock_irqsave(&worker
->lock
, flags
);
1093 spin_unlock_irqrestore(&worker
->lock
, flags
);
1099 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1100 * @work: the kthread work to cancel
1102 * Cancel @work and wait for its execution to finish. This function
1103 * can be used even if the work re-queues itself. On return from this
1104 * function, @work is guaranteed to be not pending or executing on any CPU.
1106 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1107 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1109 * The caller must ensure that the worker on which @work was last
1110 * queued can't be destroyed before this function returns.
1112 * Return: %true if @work was pending, %false otherwise.
1114 bool kthread_cancel_work_sync(struct kthread_work
*work
)
1116 return __kthread_cancel_work_sync(work
, false);
1118 EXPORT_SYMBOL_GPL(kthread_cancel_work_sync
);
1121 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1122 * wait for it to finish.
1123 * @dwork: the kthread delayed work to cancel
1125 * This is kthread_cancel_work_sync() for delayed works.
1127 * Return: %true if @dwork was pending, %false otherwise.
1129 bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work
*dwork
)
1131 return __kthread_cancel_work_sync(&dwork
->work
, true);
1133 EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync
);
1136 * kthread_flush_worker - flush all current works on a kthread_worker
1137 * @worker: worker to flush
1139 * Wait until all currently executing or pending works on @worker are
1142 void kthread_flush_worker(struct kthread_worker
*worker
)
1144 struct kthread_flush_work fwork
= {
1145 KTHREAD_WORK_INIT(fwork
.work
, kthread_flush_work_fn
),
1146 COMPLETION_INITIALIZER_ONSTACK(fwork
.done
),
1149 kthread_queue_work(worker
, &fwork
.work
);
1150 wait_for_completion(&fwork
.done
);
1152 EXPORT_SYMBOL_GPL(kthread_flush_worker
);
1155 * kthread_destroy_worker - destroy a kthread worker
1156 * @worker: worker to be destroyed
1158 * Flush and destroy @worker. The simple flush is enough because the kthread
1159 * worker API is used only in trivial scenarios. There are no multi-step state
1162 void kthread_destroy_worker(struct kthread_worker
*worker
)
1164 struct task_struct
*task
;
1166 task
= worker
->task
;
1170 kthread_flush_worker(worker
);
1172 WARN_ON(!list_empty(&worker
->work_list
));
1175 EXPORT_SYMBOL(kthread_destroy_worker
);
1177 #ifdef CONFIG_BLK_CGROUP
1179 * kthread_associate_blkcg - associate blkcg to current kthread
1180 * @css: the cgroup info
1182 * Current thread must be a kthread. The thread is running jobs on behalf of
1183 * other threads. In some cases, we expect the jobs attach cgroup info of
1184 * original threads instead of that of current thread. This function stores
1185 * original thread's cgroup info in current kthread context for later
1188 void kthread_associate_blkcg(struct cgroup_subsys_state
*css
)
1190 struct kthread
*kthread
;
1192 if (!(current
->flags
& PF_KTHREAD
))
1194 kthread
= to_kthread(current
);
1198 if (kthread
->blkcg_css
) {
1199 css_put(kthread
->blkcg_css
);
1200 kthread
->blkcg_css
= NULL
;
1204 kthread
->blkcg_css
= css
;
1207 EXPORT_SYMBOL(kthread_associate_blkcg
);
1210 * kthread_blkcg - get associated blkcg css of current kthread
1212 * Current thread must be a kthread.
1214 struct cgroup_subsys_state
*kthread_blkcg(void)
1216 struct kthread
*kthread
;
1218 if (current
->flags
& PF_KTHREAD
) {
1219 kthread
= to_kthread(current
);
1221 return kthread
->blkcg_css
;
1225 EXPORT_SYMBOL(kthread_blkcg
);