1 // SPDX-License-Identifier: GPL-2.0-only
11 	spin_lock_init(&wq_head->lock);  in __init_waitqueue_head()
12 	lockdep_set_class_and_name(&wq_head->lock, key, name);  in __init_waitqueue_head()
13 	INIT_LIST_HEAD(&wq_head->head);  in __init_waitqueue_head()
22 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;  in add_wait_queue()
23 	spin_lock_irqsave(&wq_head->lock, flags);  in add_wait_queue()
25 	spin_unlock_irqrestore(&wq_head->lock, flags);  in add_wait_queue()
33 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;  in add_wait_queue_exclusive()
34 	spin_lock_irqsave(&wq_head->lock, flags);  in add_wait_queue_exclusive()
36 	spin_unlock_irqrestore(&wq_head->lock, flags);  in add_wait_queue_exclusive()
44 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE | WQ_FLAG_PRIORITY;  in add_wait_queue_priority()
45 	spin_lock_irqsave(&wq_head->lock, flags);  in add_wait_queue_priority()
47 	spin_unlock_irqrestore(&wq_head->lock, flags);  in add_wait_queue_priority()
55 	spin_lock_irqsave(&wq_head->lock, flags);  in remove_wait_queue()
57 	spin_unlock_irqrestore(&wq_head->lock, flags);  in remove_wait_queue()
69  * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
70  * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
71  * number) then we wake that number of exclusive tasks, and potentially all
72  * the non-exclusive tasks. Normally, exclusive tasks will be at the end of
73  * the list and any non-exclusive tasks will be woken first. A priority task
77  * There are circumstances in which we can try to wake a task which has already
88 	lockdep_assert_held(&wq_head->lock);  in __wake_up_common()
90 	if (bookmark && (bookmark->flags & WQ_FLAG_BOOKMARK)) {  in __wake_up_common()
93 		list_del(&bookmark->entry);  in __wake_up_common()
94 		bookmark->flags = 0;  in __wake_up_common()
96 		curr = list_first_entry(&wq_head->head, wait_queue_entry_t, entry);  in __wake_up_common()
98 	if (&curr->entry == &wq_head->head)  in __wake_up_common()
101 	list_for_each_entry_safe_from(curr, next, &wq_head->head, entry) {  in __wake_up_common()
102 		unsigned flags = curr->flags;  in __wake_up_common()
108 		ret = curr->func(curr, mode, wake_flags, key);  in __wake_up_common()
111 		if (ret && (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)  in __wake_up_common()
115 				(&next->entry != &wq_head->head)) {  in __wake_up_common()
116 			bookmark->flags = WQ_FLAG_BOOKMARK;  in __wake_up_common()
117 			list_add_tail(&bookmark->entry, &next->entry);  in __wake_up_common()
137 		spin_lock_irqsave(&wq_head->lock, flags);  in __wake_up_common_lock()
140 		spin_unlock_irqrestore(&wq_head->lock, flags);  in __wake_up_common_lock()
145  * __wake_up - wake up threads blocked on a waitqueue.
148  * @nr_exclusive: how many wake-one or wake-many threads to wake up
151  * If this function wakes up a task, it executes a full memory barrier before
184  * __wake_up_sync_key - wake up threads blocked on a waitqueue.
190  * away soon, so while the target thread will be woken up, it will not
191  * be migrated to another CPU - ie. the two threads are 'synchronized'
194  * On UP it can prevent extra preemption.
196  * If this function wakes up a task, it executes a full memory barrier before
210  * __wake_up_locked_sync_key - wake up a thread blocked on a locked waitqueue.
216  * away soon, so while the target thread will be woken up, it will not
217  * be migrated to another CPU - ie. the two threads are 'synchronized'
220  * On UP it can prevent extra preemption.
222  * If this function wakes up a task, it executes a full memory barrier before
233  * __wake_up_sync - see __wake_up_sync_key()
242  * Note: we use "set_current_state()" _after_ the wait-queue add,
244  * wake-function that tests for the wait-queue being active
248  * The spin_unlock() itself is semi-permeable and only protects
250  * stops them from bleeding out - it would still allow subsequent
258 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;  in prepare_to_wait()
259 	spin_lock_irqsave(&wq_head->lock, flags);  in prepare_to_wait()
260 	if (list_empty(&wq_entry->entry))  in prepare_to_wait()
263 	spin_unlock_irqrestore(&wq_head->lock, flags);  in prepare_to_wait()
274 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;  in prepare_to_wait_exclusive()
275 	spin_lock_irqsave(&wq_head->lock, flags);  in prepare_to_wait_exclusive()
276 	if (list_empty(&wq_entry->entry)) {  in prepare_to_wait_exclusive()
277 		was_empty = list_empty(&wq_head->head);  in prepare_to_wait_exclusive()
281 	spin_unlock_irqrestore(&wq_head->lock, flags);  in prepare_to_wait_exclusive()
288 	wq_entry->flags = flags;  in init_wait_entry()
289 	wq_entry->private = current;  in init_wait_entry()
290 	wq_entry->func = autoremove_wake_function;  in init_wait_entry()
291 	INIT_LIST_HEAD(&wq_entry->entry);  in init_wait_entry()
300 	spin_lock_irqsave(&wq_head->lock, flags);  in prepare_to_wait_event()
307 		 * we were already woken up, we can not miss the event because  in prepare_to_wait_event()
308 		 * wakeup locks/unlocks the same wq_head->lock.  in prepare_to_wait_event()
310 		 * But we need to ensure that set-condition + wakeup after that  in prepare_to_wait_event()
311 		 * can't see us, it should wake up another exclusive waiter if  in prepare_to_wait_event()
314 		list_del_init(&wq_entry->entry);  in prepare_to_wait_event()
315 		ret = -ERESTARTSYS;  in prepare_to_wait_event()
317 		if (list_empty(&wq_entry->entry)) {  in prepare_to_wait_event()
318 			if (wq_entry->flags & WQ_FLAG_EXCLUSIVE)  in prepare_to_wait_event()
325 	spin_unlock_irqrestore(&wq_head->lock, flags);  in prepare_to_wait_event()
333  * wait-queue lock held (and interrupts off in the _irq
336  * entry to the wake queue.
340 	if (likely(list_empty(&wait->entry)))  in do_wait_intr()
345 		return -ERESTARTSYS;  in do_wait_intr()
347 	spin_unlock(&wq->lock);  in do_wait_intr()
349 	spin_lock(&wq->lock);  in do_wait_intr()
357 	if (likely(list_empty(&wait->entry)))  in do_wait_intr_irq()
362 		return -ERESTARTSYS;  in do_wait_intr_irq()
364 	spin_unlock_irq(&wq->lock);  in do_wait_intr_irq()
366 	spin_lock_irq(&wq->lock);  in do_wait_intr_irq()
373  * finish_wait - clean up after waiting in a queue
389 	 *  - we use the "careful" check that verifies both  in finish_wait()
391 	 *    be any half-pending updates in progress on other  in finish_wait()
395 	 *  - all other users take the lock (ie we can only  in finish_wait()
399 	if (!list_empty_careful(&wq_entry->entry)) {  in finish_wait()
400 		spin_lock_irqsave(&wq_head->lock, flags);  in finish_wait()
401 		list_del_init(&wq_entry->entry);  in finish_wait()
402 		spin_unlock_irqrestore(&wq_head->lock, flags);  in finish_wait()
412 		list_del_init_careful(&wq_entry->entry);  in autoremove_wake_function()
420 	return (current->flags & PF_KTHREAD) && kthread_should_stop();  in is_kthread_should_stop()
433  *     p->state = mode;				wq_entry->flags |= WQ_FLAG_WOKEN;
435  *     if (!(wq_entry->flags & WQ_FLAG_WOKEN))	   <full barrier>
436  *         schedule()				   if (p->state & mode)
437  *     p->state = TASK_RUNNING;			      p->state = TASK_RUNNING;
438  *     wq_entry->flags &= ~WQ_FLAG_WOKEN;	~~~~~~~~~~~~~~~~~~
441  * remove_wait_queue(&wq_head, &wait);		wq_entry->flags |= WQ_FLAG_WOKEN;
448 	 * either we see the store to wq_entry->flags in woken_wake_function()  in wait_woken()
449 	 * or woken_wake_function() sees our store to current->state.  in wait_woken()
452 	if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())  in wait_woken()
459 	 * being true or the store to wq_entry->flags in woken_wake_function()  in wait_woken()
462 	smp_store_mb(wq_entry->flags, wq_entry->flags & ~WQ_FLAG_WOKEN); /* B */  in wait_woken()
472 	wq_entry->flags |= WQ_FLAG_WOKEN;  in woken_wake_function()