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sched/swait: Prepare usage in completions 

As a preparation to use simple wait queues for completions:

  - Provide swake_up_all_locked() to support complete_all()
  - Make __prepare_to_swait() public available

This is done to enable the usage of complete() within truly atomic contexts
on a PREEMPT_RT enabled kernel.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.228481202@linutronix.de
5.9.x+fslc
Thomas Gleixner 2020-03-21 12:25:59 +01:00 committed by Peter Zijlstra
parent e5d4d1756b
commit b3212fe2bc
2 changed files with 17 additions and 1 deletions
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3
kernel/sched/sched.h
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@ -2492,3 +2492,6 @@ static inline bool is_per_cpu_kthread(struct task_struct *p)
return true;
}
#endif
void swake_up_all_locked(struct swait_queue_head *q);
void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait);

15
kernel/sched/swait.c
View File

@ -32,6 +32,19 @@ void swake_up_locked(struct swait_queue_head *q)
}
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;
@ -69,7 +82,7 @@ void swake_up_all(struct swait_queue_head *q)
}
EXPORT_SYMBOL(swake_up_all);
static void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
{
wait->task = current;
if (list_empty(&wait->task_list))