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