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145 lines
3.6 KiB
145 lines
3.6 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* <linux/swait.h> (simple wait queues ) implementation: |
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*/ |
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#include "sched.h" |
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void __init_swait_queue_head(struct swait_queue_head *q, const char *name, |
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struct lock_class_key *key) |
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{ |
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raw_spin_lock_init(&q->lock); |
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lockdep_set_class_and_name(&q->lock, key, name); |
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INIT_LIST_HEAD(&q->task_list); |
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} |
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EXPORT_SYMBOL(__init_swait_queue_head); |
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/* |
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* The thing about the wake_up_state() return value; I think we can ignore it. |
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* |
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* If for some reason it would return 0, that means the previously waiting |
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* task is already running, so it will observe condition true (or has already). |
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*/ |
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void swake_up_locked(struct swait_queue_head *q) |
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{ |
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struct swait_queue *curr; |
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if (list_empty(&q->task_list)) |
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return; |
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curr = list_first_entry(&q->task_list, typeof(*curr), task_list); |
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wake_up_process(curr->task); |
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list_del_init(&curr->task_list); |
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} |
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EXPORT_SYMBOL(swake_up_locked); |
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/* |
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* Wake up all waiters. This is an interface which is solely exposed for |
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* completions and not for general usage. |
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* |
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* It is intentionally different from swake_up_all() to allow usage from |
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* hard interrupt context and interrupt disabled regions. |
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*/ |
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void swake_up_all_locked(struct swait_queue_head *q) |
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{ |
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while (!list_empty(&q->task_list)) |
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swake_up_locked(q); |
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} |
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void swake_up_one(struct swait_queue_head *q) |
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{ |
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unsigned long flags; |
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raw_spin_lock_irqsave(&q->lock, flags); |
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swake_up_locked(q); |
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raw_spin_unlock_irqrestore(&q->lock, flags); |
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} |
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EXPORT_SYMBOL(swake_up_one); |
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/* |
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* Does not allow usage from IRQ disabled, since we must be able to |
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* release IRQs to guarantee bounded hold time. |
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*/ |
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void swake_up_all(struct swait_queue_head *q) |
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{ |
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struct swait_queue *curr; |
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LIST_HEAD(tmp); |
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raw_spin_lock_irq(&q->lock); |
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list_splice_init(&q->task_list, &tmp); |
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while (!list_empty(&tmp)) { |
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curr = list_first_entry(&tmp, typeof(*curr), task_list); |
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wake_up_state(curr->task, TASK_NORMAL); |
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list_del_init(&curr->task_list); |
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if (list_empty(&tmp)) |
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break; |
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raw_spin_unlock_irq(&q->lock); |
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raw_spin_lock_irq(&q->lock); |
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} |
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raw_spin_unlock_irq(&q->lock); |
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} |
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EXPORT_SYMBOL(swake_up_all); |
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void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait) |
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{ |
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wait->task = current; |
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if (list_empty(&wait->task_list)) |
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list_add_tail(&wait->task_list, &q->task_list); |
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} |
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void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state) |
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{ |
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unsigned long flags; |
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raw_spin_lock_irqsave(&q->lock, flags); |
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__prepare_to_swait(q, wait); |
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set_current_state(state); |
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raw_spin_unlock_irqrestore(&q->lock, flags); |
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} |
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EXPORT_SYMBOL(prepare_to_swait_exclusive); |
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long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state) |
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{ |
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unsigned long flags; |
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long ret = 0; |
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raw_spin_lock_irqsave(&q->lock, flags); |
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if (signal_pending_state(state, current)) { |
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/* |
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* See prepare_to_wait_event(). TL;DR, subsequent swake_up_one() |
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* must not see us. |
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*/ |
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list_del_init(&wait->task_list); |
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ret = -ERESTARTSYS; |
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} else { |
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__prepare_to_swait(q, wait); |
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set_current_state(state); |
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} |
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raw_spin_unlock_irqrestore(&q->lock, flags); |
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return ret; |
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} |
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EXPORT_SYMBOL(prepare_to_swait_event); |
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void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait) |
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{ |
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__set_current_state(TASK_RUNNING); |
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if (!list_empty(&wait->task_list)) |
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list_del_init(&wait->task_list); |
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} |
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void finish_swait(struct swait_queue_head *q, struct swait_queue *wait) |
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{ |
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unsigned long flags; |
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__set_current_state(TASK_RUNNING); |
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if (!list_empty_careful(&wait->task_list)) { |
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raw_spin_lock_irqsave(&q->lock, flags); |
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list_del_init(&wait->task_list); |
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raw_spin_unlock_irqrestore(&q->lock, flags); |
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} |
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} |
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EXPORT_SYMBOL(finish_swait);
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