// 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);
|
|
void swake_up_all_locked(struct swait_queue_head *q)
|
{
|
struct swait_queue *curr;
|
int wakes = 0;
|
|
while (!list_empty(&q->task_list)) {
|
|
curr = list_first_entry(&q->task_list, typeof(*curr),
|
task_list);
|
wake_up_process(curr->task);
|
list_del_init(&curr->task_list);
|
wakes++;
|
}
|
if (pm_in_action)
|
return;
|
WARN(wakes > 2, "complete_all() with %d waiters\n", wakes);
|
}
|
EXPORT_SYMBOL(swake_up_all_locked);
|
|
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);
|
|
WARN_ON(irqs_disabled());
|
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 (unlikely(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);
|
