Messages in this thread Patch in this message | | | Subject | Re: [bisected] Clocksource tsc unstable git | From | Peter Zijlstra <> | Date | Tue, 09 Nov 2010 14:45:33 +0100 |
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On Tue, 2010-11-09 at 14:21 +0100, Markus Trippelsdorf wrote: > > You've missed the fact that Peter already has a patch that fixes the > problem, but he never bothered to post it in this thread. > Right, forgot about that, sorry.
Still Heiko has a good point, I've queued the below after I realized that PREEMPT_ACTIVE would still require two tests and the on_rq bit is actually sufficient.
--- Subject: sched: Fix runnable condition for stoptask From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Tue Nov 09 14:36:52 CET 2010
Heiko reported that the TASK_RUNNING check is not sufficient for CONFIG_PREEMPT=y since we can get preempted with !TASK_RUNNING.
He suggested adding a ->se.on_rq test to the existing TASK_RUNNING one, however TASK_RUNNING will always have ->se.on_rq, so we might as well reduce that to a single test.
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> --- kernel/sched_stoptask.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6/kernel/sched_stoptask.c =================================================================== --- linux-2.6.orig/kernel/sched_stoptask.c +++ linux-2.6/kernel/sched_stoptask.c @@ -26,7 +26,7 @@ static struct task_struct *pick_next_tas { struct task_struct *stop = rq->stop; - if (stop && stop->state == TASK_RUNNING) + if (stop && stop->se.on_rq) return stop; return NULL;
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