1 // SPDX-License-Identifier: GPL-2.0
3 * <linux/swait.h> (simple wait queues ) implementation:
7 void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
8 struct lock_class_key *key)
10 raw_spin_lock_init(&q->lock);
11 lockdep_set_class_and_name(&q->lock, key, name);
12 INIT_LIST_HEAD(&q->task_list);
14 EXPORT_SYMBOL(__init_swait_queue_head);
17 * The thing about the wake_up_state() return value; I think we can ignore it.
19 * If for some reason it would return 0, that means the previously waiting
20 * task is already running, so it will observe condition true (or has already).
22 void swake_up_locked(struct swait_queue_head *q)
24 struct swait_queue *curr;
26 if (list_empty(&q->task_list))
29 curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
30 wake_up_process(curr->task);
31 list_del_init(&curr->task_list);
33 EXPORT_SYMBOL(swake_up_locked);
36 * Wake up all waiters. This is an interface which is solely exposed for
37 * completions and not for general usage.
39 * It is intentionally different from swake_up_all() to allow usage from
40 * hard interrupt context and interrupt disabled regions.
42 void swake_up_all_locked(struct swait_queue_head *q)
44 while (!list_empty(&q->task_list))
48 void swake_up_one(struct swait_queue_head *q)
52 raw_spin_lock_irqsave(&q->lock, flags);
54 raw_spin_unlock_irqrestore(&q->lock, flags);
56 EXPORT_SYMBOL(swake_up_one);
59 * Does not allow usage from IRQ disabled, since we must be able to
60 * release IRQs to guarantee bounded hold time.
62 void swake_up_all(struct swait_queue_head *q)
64 struct swait_queue *curr;
67 raw_spin_lock_irq(&q->lock);
68 list_splice_init(&q->task_list, &tmp);
69 while (!list_empty(&tmp)) {
70 curr = list_first_entry(&tmp, typeof(*curr), task_list);
72 wake_up_state(curr->task, TASK_NORMAL);
73 list_del_init(&curr->task_list);
78 raw_spin_unlock_irq(&q->lock);
79 raw_spin_lock_irq(&q->lock);
81 raw_spin_unlock_irq(&q->lock);
83 EXPORT_SYMBOL(swake_up_all);
85 void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
88 if (list_empty(&wait->task_list))
89 list_add_tail(&wait->task_list, &q->task_list);
92 void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state)
96 raw_spin_lock_irqsave(&q->lock, flags);
97 __prepare_to_swait(q, wait);
98 set_current_state(state);
99 raw_spin_unlock_irqrestore(&q->lock, flags);
101 EXPORT_SYMBOL(prepare_to_swait_exclusive);
103 long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state)
108 raw_spin_lock_irqsave(&q->lock, flags);
109 if (signal_pending_state(state, current)) {
111 * See prepare_to_wait_event(). TL;DR, subsequent swake_up_one()
114 list_del_init(&wait->task_list);
117 __prepare_to_swait(q, wait);
118 set_current_state(state);
120 raw_spin_unlock_irqrestore(&q->lock, flags);
124 EXPORT_SYMBOL(prepare_to_swait_event);
126 void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
128 __set_current_state(TASK_RUNNING);
129 if (!list_empty(&wait->task_list))
130 list_del_init(&wait->task_list);
133 void finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
137 __set_current_state(TASK_RUNNING);
139 if (!list_empty_careful(&wait->task_list)) {
140 raw_spin_lock_irqsave(&q->lock, flags);
141 list_del_init(&wait->task_list);
142 raw_spin_unlock_irqrestore(&q->lock, flags);
145 EXPORT_SYMBOL(finish_swait);