From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964895Ab3GLNaQ (ORCPT ); Fri, 12 Jul 2013 09:30:16 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59577 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964859Ab3GLNaO (ORCPT ); Fri, 12 Jul 2013 09:30:14 -0400 Date: Fri, 12 Jul 2013 06:29:39 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, dsahern@gmail.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, dsahern@gmail.com, tglx@linutronix.de In-Reply-To: <20130628091853.GE29209@dyad.programming.kicks-ass.net> References: <20130628091853.GE29209@dyad.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Fix HRTICK Git-Commit-ID: 971ee28cbd1ccd87b3164facd9359a534c1d2892 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Fri, 12 Jul 2013 06:29:46 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 971ee28cbd1ccd87b3164facd9359a534c1d2892 Gitweb: http://git.kernel.org/tip/971ee28cbd1ccd87b3164facd9359a534c1d2892 Author: Peter Zijlstra AuthorDate: Fri, 28 Jun 2013 11:18:53 +0200 Committer: Ingo Molnar CommitDate: Fri, 12 Jul 2013 13:52:58 +0200 sched: Fix HRTICK David reported that the HRTICK sched feature was borken; which was enough motivation for me to finally fix it ;-) We should not allow hrtimer code to do softirq wakeups while holding scheduler locks. The hrtimer code only needs this when we accidentally try to program an expired time. We don't much care about those anyway since we have the regular tick to fall back to. Reported-by: David Ahern Tested-by: David Ahern Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20130628091853.GE29209@dyad.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9b1f2e5..0d8eb45 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -370,13 +370,6 @@ static struct rq *this_rq_lock(void) #ifdef CONFIG_SCHED_HRTICK /* * Use HR-timers to deliver accurate preemption points. - * - * Its all a bit involved since we cannot program an hrt while holding the - * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a - * reschedule event. - * - * When we get rescheduled we reprogram the hrtick_timer outside of the - * rq->lock. */ static void hrtick_clear(struct rq *rq) @@ -404,6 +397,15 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer) } #ifdef CONFIG_SMP + +static int __hrtick_restart(struct rq *rq) +{ + struct hrtimer *timer = &rq->hrtick_timer; + ktime_t time = hrtimer_get_softexpires(timer); + + return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0); +} + /* * called from hardirq (IPI) context */ @@ -412,7 +414,7 @@ static void __hrtick_start(void *arg) struct rq *rq = arg; raw_spin_lock(&rq->lock); - hrtimer_restart(&rq->hrtick_timer); + __hrtick_restart(rq); rq->hrtick_csd_pending = 0; raw_spin_unlock(&rq->lock); } @@ -430,7 +432,7 @@ void hrtick_start(struct rq *rq, u64 delay) hrtimer_set_expires(timer, time); if (rq == this_rq()) { - hrtimer_restart(timer); + __hrtick_restart(rq); } else if (!rq->hrtick_csd_pending) { __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0); rq->hrtick_csd_pending = 1;