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-rw-r--r--kernel/sched/swait.c32
1 files changed, 22 insertions, 10 deletions
diff --git a/kernel/sched/swait.c b/kernel/sched/swait.c
index b6fb2c3b3ff7..66b59ac77c22 100644
--- a/kernel/sched/swait.c
+++ b/kernel/sched/swait.c
@@ -32,7 +32,7 @@ void swake_up_locked(struct swait_queue_head *q)
}
EXPORT_SYMBOL(swake_up_locked);
-void swake_up(struct swait_queue_head *q)
+void swake_up_one(struct swait_queue_head *q)
{
unsigned long flags;
@@ -40,7 +40,7 @@ void swake_up(struct swait_queue_head *q)
swake_up_locked(q);
raw_spin_unlock_irqrestore(&q->lock, flags);
}
-EXPORT_SYMBOL(swake_up);
+EXPORT_SYMBOL(swake_up_one);
/*
* Does not allow usage from IRQ disabled, since we must be able to
@@ -69,14 +69,14 @@ void swake_up_all(struct swait_queue_head *q)
}
EXPORT_SYMBOL(swake_up_all);
-void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
+static void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
{
wait->task = current;
if (list_empty(&wait->task_list))
- list_add(&wait->task_list, &q->task_list);
+ list_add_tail(&wait->task_list, &q->task_list);
}
-void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int state)
+void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state)
{
unsigned long flags;
@@ -85,16 +85,28 @@ void prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait, int
set_current_state(state);
raw_spin_unlock_irqrestore(&q->lock, flags);
}
-EXPORT_SYMBOL(prepare_to_swait);
+EXPORT_SYMBOL(prepare_to_swait_exclusive);
long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state)
{
- if (signal_pending_state(state, current))
- return -ERESTARTSYS;
+ unsigned long flags;
+ long ret = 0;
- prepare_to_swait(q, wait, state);
+ 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 0;
+ return ret;
}
EXPORT_SYMBOL(prepare_to_swait_event);