From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760461AbaGYVG7 (ORCPT ); Fri, 25 Jul 2014 17:06:59 -0400 Received: from mail-yh0-f52.google.com ([209.85.213.52]:61727 "EHLO mail-yh0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759874AbaGYVG6 (ORCPT ); Fri, 25 Jul 2014 17:06:58 -0400 From: Soren Brinkmann To: John Stultz , Thomas Gleixner , "Rafael J. Wysocki" , Pavel Machek , Len Brown Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Daniel Lezcano , Soren Brinkmann Subject: [PATCH RFC v2] PM / sleep: Fix racing timers Date: Fri, 25 Jul 2014 14:06:48 -0700 Message-Id: <1406322408-15408-1-git-send-email-soren.brinkmann@xilinx.com> X-Mailer: git-send-email 2.0.1.1.gfbfc394 In-Reply-To: <53D083C5.2000501@linaro.org> References: <53D083C5.2000501@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On platforms that do not power off during suspend, successfully entering suspend races with timers. The race happening in a couple of location is: 1. disable IRQs (e.g. arch_suspend_disable_irqs()) ... 2. syscore_suspend() -> timekeeping_suspend() -> clockevents_notify(SUSPEND) -> tick_suspend() (timers are turned off here) ... 3. wfi (wait for wake-IRQ here) Between steps 1 and 2 the timers can still generate interrupts that are not handled and stay pending until step 3. That pending IRQ causes an immediate - spurious - wake. The solution is to move the clockevents suspend/resume notification out of the syscore_suspend step and explictly call them at the appropriate time in the suspend/hibernation paths. I.e. timers are suspend _before_ IRQs get disabled. And accordingly in the resume path. Signed-off-by: Soren Brinkmann --- Hi, This is my second shot at this. I followed John's suggestion to keep the timekeeping suspend where it is and just move the shutdown of the clockevent devices around. Thanks, Sören kernel/power/hibernate.c | 9 +++++++++ kernel/power/suspend.c | 5 +++++ kernel/time/timekeeping.c | 1 - 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index fcc2611d3f14..ab9f807e2ccb 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -285,6 +285,8 @@ static int create_image(int platform_mode) if (error || hibernation_test(TEST_CPUS)) goto Enable_cpus; + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + local_irq_disable(); error = syscore_suspend(); @@ -316,6 +318,7 @@ static int create_image(int platform_mode) syscore_resume(); Enable_irqs: + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); Enable_cpus: @@ -440,6 +443,8 @@ static int resume_target_kernel(bool platform_mode) if (error) goto Enable_cpus; + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + local_irq_disable(); error = syscore_suspend(); @@ -474,6 +479,7 @@ static int resume_target_kernel(bool platform_mode) syscore_resume(); Enable_irqs: + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); Enable_cpus: @@ -555,6 +561,8 @@ int hibernation_platform_enter(void) if (error) goto Platform_finish; + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + local_irq_disable(); syscore_suspend(); if (pm_wakeup_pending()) { @@ -568,6 +576,7 @@ int hibernation_platform_enter(void) Power_up: syscore_resume(); + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); enable_nonboot_cpus(); diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index ed35a4790afe..ca6c56a87ea3 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -253,6 +254,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup) if (error || suspend_test(TEST_CPUS)) goto Enable_cpus; + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + arch_suspend_disable_irqs(); BUG_ON(!irqs_disabled()); @@ -270,6 +273,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup) syscore_resume(); } + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); + arch_suspend_enable_irqs(); BUG_ON(irqs_disabled()); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 32d8d6aaedb8..d2f21cbe2bfd 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1032,7 +1032,6 @@ static int timekeeping_suspend(void) write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); clocksource_suspend(); clockevents_suspend(); -- 2.0.1.1.gfbfc394