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Commit 26ae58d2 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/core: Add WARNING for multiple update_rq_clock() calls 



Now that we have no missing calls, add a warning to find multiple
calls.

By having only a single update_rq_clock() call per rq-lock section,
the section appears 'atomic' wrt time.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3e777f99

kernel/sched/core.c

+3 −0
Original line number Diff line number Diff line
@@ -233,8 +233,11 @@ void update_rq_clock(struct rq *rq) 
		return;



#ifdef CONFIG_SCHED_DEBUG

	if (sched_feat(WARN_DOUBLE_CLOCK))

		SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);

	rq->clock_update_flags |= RQCF_UPDATED;

#endif



	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;

	if (delta < 0)

		return;

kernel/sched/features.h

+7 −0
Original line number Diff line number Diff line
@@ -56,6 +56,13 @@ SCHED_FEAT(TTWU_QUEUE, true) 
 */

SCHED_FEAT(SIS_AVG_CPU, false)



/*

 * Issue a WARN when we do multiple update_rq_clock() calls

 * in a single rq->lock section. Default disabled because the

 * annotations are not complete.

 */

SCHED_FEAT(WARN_DOUBLE_CLOCK, false)



#ifdef HAVE_RT_PUSH_IPI

/*

 * In order to avoid a thundering herd attack of CPUs that are