From 8cd162ce230b154e564a1285bb5f89fcf73f0dce Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 15 Oct 2008 20:37:23 +0200
Subject: [PATCH] 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>
---
kernel/sched.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 6f230596bd0c..c530b84c7f80 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4441,12 +4441,8 @@ asmlinkage void __sched schedule(void)
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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