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Commit 8cd162ce authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: only update rq->clock while holding rq->lock 



Vatsa noticed rq->clock going funny and tracked it down to an update_rq_clock()
outside a rq->lock section.

This is a problem because things like double_rq_lock() update the rq->clock
value for both rqs. Therefore disabling interrupts isn't strong enough.

Reported-by: default avatarSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5b16a221

kernel/sched.c

+1 −5
Original line number Diff line number Diff line
@@ -4441,12 +4441,8 @@ need_resched_nonpreemptible: 
	if (sched_feat(HRTICK))

		hrtick_clear(rq);



	/*

	 * Do the rq-clock update outside the rq lock:

	 */

	local_irq_disable();

	spin_lock_irq(&rq->lock);

	update_rq_clock(rq);

	spin_lock(&rq->lock);

	clear_tsk_need_resched(prev);



	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {