From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757298AbZBFAG7 (ORCPT ); Thu, 5 Feb 2009 19:06:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756410AbZBFAGp (ORCPT ); Thu, 5 Feb 2009 19:06:45 -0500 Received: from gateway-1237.mvista.com ([63.81.120.158]:49391 "EHLO gateway-1237.mvista.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756223AbZBFAGo (ORCPT ); Thu, 5 Feb 2009 19:06:44 -0500 Message-ID: <498B7F13.7040104@ct.jp.nec.com> Date: Thu, 05 Feb 2009 16:06:43 -0800 From: Hiroshi Shimamoto User-Agent: Thunderbird 2.0.0.19 (Windows/20081209) MIME-Version: 1.0 To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] sched_rt: protect rt_rq->rt_time by rt_runtime_lock References: <498B77F6.4020702@ct.jp.nec.com> <498B7862.2040004@ct.jp.nec.com> <1233878343.4620.44.camel@laptop> In-Reply-To: <1233878343.4620.44.camel@laptop> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra wrote: > On Thu, 2009-02-05 at 15:38 -0800, Hiroshi Shimamoto wrote: >> From: Hiroshi Shimamoto >> >> Impact: fix possible race condition >> >> rt_rq->rt_time should be protected. > > Don't think so, all we do is check the value for non-zero outside the > lock, that should be ok. > > If there's still a race, your changelog utterly fails to mention the > race scenario. OK. I just noticed rt_time is accessed with rt_runtime_lock held except this point. Will look at this again. Thanks, Hiroshi > >> Signed-off-by: Hiroshi Shimamoto >> --- >> kernel/sched_rt.c | 4 ++-- >> 1 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c >> index 299d012..d7654a3 100644 >> --- a/kernel/sched_rt.c >> +++ b/kernel/sched_rt.c >> @@ -496,10 +496,10 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) >> struct rq *rq = rq_of_rt_rq(rt_rq); >> >> spin_lock(&rq->lock); >> + spin_lock(&rt_rq->rt_runtime_lock); >> if (rt_rq->rt_time) { >> u64 runtime; >> >> - spin_lock(&rt_rq->rt_runtime_lock); >> if (rt_rq->rt_throttled) >> balance_runtime(rt_rq); >> runtime = rt_rq->rt_runtime; >> @@ -510,9 +510,9 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) >> } >> if (rt_rq->rt_time || rt_rq->rt_nr_running) >> idle = 0; >> - spin_unlock(&rt_rq->rt_runtime_lock); >> } else if (rt_rq->rt_nr_running) >> idle = 0; >> + spin_unlock(&rt_rq->rt_runtime_lock); >> >> if (enqueue) >> sched_rt_rq_enqueue(rt_rq); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >