Commit 8cd162ce authored Oct 15, 2008 by Peter Zijlstra Committed by Ingo Molnar Oct 15, 2008

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: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo 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)) {

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