From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09A87C10F0E for ; Mon, 15 Apr 2019 05:44:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF48920833 for ; Mon, 15 Apr 2019 05:44:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726200AbfDOFow (ORCPT ); Mon, 15 Apr 2019 01:44:52 -0400 Received: from mailgw01.mediatek.com ([210.61.82.183]:19077 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725816AbfDOFow (ORCPT ); Mon, 15 Apr 2019 01:44:52 -0400 X-UUID: abe40107d18848b5afdce674cbe32720-20190415 X-UUID: abe40107d18848b5afdce674cbe32720-20190415 Received: from mtkexhb01.mediatek.inc [(172.21.101.102)] by mailgw01.mediatek.com (envelope-from ) (mhqrelay.mediatek.com ESMTP with TLS) with ESMTP id 1448580266; Mon, 15 Apr 2019 13:44:42 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs01n1.mediatek.inc (172.21.101.68) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Mon, 15 Apr 2019 13:44:41 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Mon, 15 Apr 2019 13:44:41 +0800 Message-ID: <1555307081.12121.2.camel@mtkswgap22> Subject: Re: [PATCH v2] sched/clock: Prevent generic sched_clock wrap caused by tick_freeze() From: Chang-An Chen To: Frederic Weisbecker , Matthias Brugger , Ingo Molnar , Thomas Gleixner CC: John Stultz , Kees Cook , Corey Minyard , "linux-kernel@vger.kernel.org" , "linux-mediatek@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" , Stanley Chu =?UTF-8?Q?=28=E6=9C=B1=E5=8E=9F=E9=99=9E=29?= , Kuohong Wang =?UTF-8?Q?=28=E7=8E=8B=E5=9C=8B=E9=B4=BB=29?= , Freddy Hsin =?UTF-8?Q?=28=E8=BE=9B=E6=81=92=E8=B1=90=29?= Date: Mon, 15 Apr 2019 13:44:41 +0800 In-Reply-To: <1553828349-8914-1-git-send-email-chang-an.chen@mediatek.com> References: <1553828349-8914-1-git-send-email-chang-an.chen@mediatek.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, This is just a gentle ping for this patch. On Fri, 2019-03-29 at 10:59 +0800, Chang-An Chen wrote: > tick_freeze() introduced by suspend-to-idle in commit 124cf9117c5f > ("PM / sleep: Make it possible to quiesce timers during suspend-to-idle") > will use timekeeping_suspend() instead of syscore_suspend() during > suspend-to-idle. It means that generic sched_clock will keep going because > sched_clock_suspend() and sched_clock_resume() are not taken during > suspend-to-idle. This will lead to generic sched_clock wrap. > > For example: > In my arm system with suspend-to-idle enabled, sched_clock is registered > as "56 bits at 13MHz, resolution 76ns, wraps every 4398046511101ns", which > means the real wrapping duration is 8796093022202ns. > > [ 134.551779] suspend-to-idle suspend (timekeeping_suspend()) > [ 1204.912239] suspend-to-idle resume (timekeeping_resume()) > ...... > [ 1206.912239] suspend-to-idle suspend (timekeeping_suspend()) > [ 5880.502807] suspend-to-idle resume (timekeeping_resume()) > ...... > [ 6000.403724] suspend-to-idle suspend (timekeeping_suspend()) > [ 8035.753167] suspend-to-idle resume (timekeeping_resume()) > ...... > [ 8795.786684] (2)[321:charger_thread]...... > [ 8795.788387] (2)[321:charger_thread]...... > [ 0.057226] (0)[0:swapper/0]...... > [ 0.061447] (2)[0:swapper/2]...... > > Sched_clock was not stopped during suspend-to-idle, and sched_clock_poll > hrtimer was not expired because timekeeping_suspend() is taken during > suspend-to-idle. It makes sched_clock wrap at kernel time 8796s. > > To fix this issue, we add sched_clock_suspend() and sched_clock_resume() in > tick_freeze() together with timekeeping_suspend() and timekeeping_resume() > to make sure generic sched_clock wrapping will not happen. > > Signed-off-by: Chang-An Chen > Fixes: 124cf9117c5f (PM / sleep: Make it possible to quiesce timers during suspend-to-idle) > --- > kernel/time/sched_clock.c | 4 ++-- > kernel/time/tick-common.c | 2 ++ > kernel/time/timekeeping.h | 7 +++++++ > 3 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c > index 094b82c..930113b 100644 > --- a/kernel/time/sched_clock.c > +++ b/kernel/time/sched_clock.c > @@ -272,7 +272,7 @@ static u64 notrace suspended_sched_clock_read(void) > return cd.read_data[seq & 1].epoch_cyc; > } > > -static int sched_clock_suspend(void) > +int sched_clock_suspend(void) > { > struct clock_read_data *rd = &cd.read_data[0]; > > @@ -283,7 +283,7 @@ static int sched_clock_suspend(void) > return 0; > } > > -static void sched_clock_resume(void) > +void sched_clock_resume(void) > { > struct clock_read_data *rd = &cd.read_data[0]; > > diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c > index 529143b..df40146 100644 > --- a/kernel/time/tick-common.c > +++ b/kernel/time/tick-common.c > @@ -487,6 +487,7 @@ void tick_freeze(void) > trace_suspend_resume(TPS("timekeeping_freeze"), > smp_processor_id(), true); > system_state = SYSTEM_SUSPEND; > + sched_clock_suspend(); > timekeeping_suspend(); > } else { > tick_suspend_local(); > @@ -510,6 +511,7 @@ void tick_unfreeze(void) > > if (tick_freeze_depth == num_online_cpus()) { > timekeeping_resume(); > + sched_clock_resume(); > system_state = SYSTEM_RUNNING; > trace_suspend_resume(TPS("timekeeping_freeze"), > smp_processor_id(), false); > diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h > index 7a9b4eb..141ab3a 100644 > --- a/kernel/time/timekeeping.h > +++ b/kernel/time/timekeeping.h > @@ -14,6 +14,13 @@ extern ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, > extern void timekeeping_warp_clock(void); > extern int timekeeping_suspend(void); > extern void timekeeping_resume(void); > +#ifdef CONFIG_GENERIC_SCHED_CLOCK > +extern int sched_clock_suspend(void); > +extern void sched_clock_resume(void); > +#else > +static inline int sched_clock_suspend(void) { return 0; } > +static inline void sched_clock_resume(void) { } > +#endif > > extern void do_timer(unsigned long ticks); > extern void update_wall_time(void);