1 // SPDX-License-Identifier: GPL-2.0-only
10 	spin_lock_init(&wq_head->lock);  in __init_waitqueue_head()
11 	lockdep_set_class_and_name(&wq_head->lock, key, name);  in __init_waitqueue_head()
12 	INIT_LIST_HEAD(&wq_head->head);  in __init_waitqueue_head()
21 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;  in add_wait_queue()
22 	spin_lock_irqsave(&wq_head->lock, flags);  in add_wait_queue()
24 	spin_unlock_irqrestore(&wq_head->lock, flags);  in add_wait_queue()
32 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;  in add_wait_queue_exclusive()
33 	spin_lock_irqsave(&wq_head->lock, flags);  in add_wait_queue_exclusive()
35 	spin_unlock_irqrestore(&wq_head->lock, flags);  in add_wait_queue_exclusive()
43 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE | WQ_FLAG_PRIORITY;  in add_wait_queue_priority()
44 	spin_lock_irqsave(&wq_head->lock, flags);  in add_wait_queue_priority()
46 	spin_unlock_irqrestore(&wq_head->lock, flags);  in add_wait_queue_priority()
54 	spin_lock_irqsave(&wq_head->lock, flags);  in remove_wait_queue()
56 	spin_unlock_irqrestore(&wq_head->lock, flags);  in remove_wait_queue()
61  * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
62  * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
63  * number) then we wake that number of exclusive tasks, and potentially all
64  * the non-exclusive tasks. Normally, exclusive tasks will be at the end of
65  * the list and any non-exclusive tasks will be woken first. A priority task
69  * There are circumstances in which we can try to wake a task which has already
78 	lockdep_assert_held(&wq_head->lock);  in __wake_up_common()
80 	curr = list_first_entry(&wq_head->head, wait_queue_entry_t, entry);  in __wake_up_common()
82 	if (&curr->entry == &wq_head->head)  in __wake_up_common()
85 	list_for_each_entry_safe_from(curr, next, &wq_head->head, entry) {  in __wake_up_common()
86 		unsigned flags = curr->flags;  in __wake_up_common()
89 		ret = curr->func(curr, mode, wake_flags, key);  in __wake_up_common()
92 		if (ret && (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)  in __wake_up_common()
105 	spin_lock_irqsave(&wq_head->lock, flags);  in __wake_up_common_lock()
108 	spin_unlock_irqrestore(&wq_head->lock, flags);  in __wake_up_common_lock()
110 	return nr_exclusive - remaining;  in __wake_up_common_lock()
114  * __wake_up - wake up threads blocked on a waitqueue.
117  * @nr_exclusive: how many wake-one or wake-many threads to wake up
120  * If this function wakes up a task, it executes a full memory barrier
152  * __wake_up_sync_key - wake up threads blocked on a waitqueue.
158  * away soon, so while the target thread will be woken up, it will not
159  * be migrated to another CPU - ie. the two threads are 'synchronized'
162  * On UP it can prevent extra preemption.
164  * If this function wakes up a task, it executes a full memory barrier before
178  * __wake_up_locked_sync_key - wake up a thread blocked on a locked waitqueue.
184  * away soon, so while the target thread will be woken up, it will not
185  * be migrated to another CPU - ie. the two threads are 'synchronized'
188  * On UP it can prevent extra preemption.
190  * If this function wakes up a task, it executes a full memory barrier before
201  * __wake_up_sync - see __wake_up_sync_key()
217  * Note: we use "set_current_state()" _after_ the wait-queue add,
219  * wake-function that tests for the wait-queue being active
223  * The spin_unlock() itself is semi-permeable and only protects
225  * stops them from bleeding out - it would still allow subsequent
233 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;  in prepare_to_wait()
234 	spin_lock_irqsave(&wq_head->lock, flags);  in prepare_to_wait()
235 	if (list_empty(&wq_entry->entry))  in prepare_to_wait()
238 	spin_unlock_irqrestore(&wq_head->lock, flags);  in prepare_to_wait()
249 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;  in prepare_to_wait_exclusive()
250 	spin_lock_irqsave(&wq_head->lock, flags);  in prepare_to_wait_exclusive()
251 	if (list_empty(&wq_entry->entry)) {  in prepare_to_wait_exclusive()
252 		was_empty = list_empty(&wq_head->head);  in prepare_to_wait_exclusive()
256 	spin_unlock_irqrestore(&wq_head->lock, flags);  in prepare_to_wait_exclusive()
263 	wq_entry->flags = flags;  in init_wait_entry()
264 	wq_entry->private = current;  in init_wait_entry()
265 	wq_entry->func = autoremove_wake_function;  in init_wait_entry()
266 	INIT_LIST_HEAD(&wq_entry->entry);  in init_wait_entry()
275 	spin_lock_irqsave(&wq_head->lock, flags);  in prepare_to_wait_event()
282 		 * we were already woken up, we can not miss the event because  in prepare_to_wait_event()
283 		 * wakeup locks/unlocks the same wq_head->lock.  in prepare_to_wait_event()
285 		 * But we need to ensure that set-condition + wakeup after that  in prepare_to_wait_event()
286 		 * can't see us, it should wake up another exclusive waiter if  in prepare_to_wait_event()
289 		list_del_init(&wq_entry->entry);  in prepare_to_wait_event()
290 		ret = -ERESTARTSYS;  in prepare_to_wait_event()
292 		if (list_empty(&wq_entry->entry)) {  in prepare_to_wait_event()
293 			if (wq_entry->flags & WQ_FLAG_EXCLUSIVE)  in prepare_to_wait_event()
300 	spin_unlock_irqrestore(&wq_head->lock, flags);  in prepare_to_wait_event()
308  * wait-queue lock held (and interrupts off in the _irq
311  * entry to the wake queue.
315 	if (likely(list_empty(&wait->entry)))  in do_wait_intr()
320 		return -ERESTARTSYS;  in do_wait_intr()
322 	spin_unlock(&wq->lock);  in do_wait_intr()
324 	spin_lock(&wq->lock);  in do_wait_intr()
332 	if (likely(list_empty(&wait->entry)))  in do_wait_intr_irq()
337 		return -ERESTARTSYS;  in do_wait_intr_irq()
339 	spin_unlock_irq(&wq->lock);  in do_wait_intr_irq()
341 	spin_lock_irq(&wq->lock);  in do_wait_intr_irq()
348  * finish_wait - clean up after waiting in a queue
364 	 *  - we use the "careful" check that verifies both  in finish_wait()
366 	 *    be any half-pending updates in progress on other  in finish_wait()
370 	 *  - all other users take the lock (ie we can only  in finish_wait()
374 	if (!list_empty_careful(&wq_entry->entry)) {  in finish_wait()
375 		spin_lock_irqsave(&wq_head->lock, flags);  in finish_wait()
376 		list_del_init(&wq_entry->entry);  in finish_wait()
377 		spin_unlock_irqrestore(&wq_head->lock, flags);  in finish_wait()
387 		list_del_init_careful(&wq_entry->entry);  in autoremove_wake_function()
403  *     p->state = mode;				wq_entry->flags |= WQ_FLAG_WOKEN;
405  *     if (!(wq_entry->flags & WQ_FLAG_WOKEN))	   <full barrier>
406  *         schedule()				   if (p->state & mode)
407  *     p->state = TASK_RUNNING;			      p->state = TASK_RUNNING;
408  *     wq_entry->flags &= ~WQ_FLAG_WOKEN;	~~~~~~~~~~~~~~~~~~
411  * remove_wait_queue(&wq_head, &wait);		wq_entry->flags |= WQ_FLAG_WOKEN;
418 	 * either we see the store to wq_entry->flags in woken_wake_function()  in wait_woken()
419 	 * or woken_wake_function() sees our store to current->state.  in wait_woken()
422 	if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !kthread_should_stop_or_park())  in wait_woken()
429 	 * being true or the store to wq_entry->flags in woken_wake_function()  in wait_woken()
432 	smp_store_mb(wq_entry->flags, wq_entry->flags & ~WQ_FLAG_WOKEN); /* B */  in wait_woken()
442 	wq_entry->flags |= WQ_FLAG_WOKEN;  in woken_wake_function()