From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753332AbaHTUzf (ORCPT ); Wed, 20 Aug 2014 16:55:35 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:54763 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752816AbaHTUzc (ORCPT ); Wed, 20 Aug 2014 16:55:32 -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 , Stephen Boyd , Soren Brinkmann Subject: [PATCH] PM / sleep: Fix racing timers Date: Wed, 20 Aug 2014 13:55:09 -0700 Message-Id: <1408568109-30297-1-git-send-email-soren.brinkmann@xilinx.com> X-Mailer: git-send-email 2.0.1.1.gfbfc394 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, there was a little of an dicussion on the RFC for this patch, but that eventually ended (https://lkml.org/lkml/2014/7/21/493). In the meantime I found one small flaw that is fixed in this patch (changelog below). This resolves the issues I see on my Zynq (ARM) platform and I also patched my Laptop's (x86_64) kernel with this where it looks good as well. Though, in both cases only suspend is used. Any testing - especially of hibernation - would be much appreciated. Thanks, Sören Changes since RFC: - remove resume notification from syscore_resume path. --- kernel/power/hibernate.c | 9 +++++++++ kernel/power/suspend.c | 5 +++++ kernel/time/timekeeping.c | 3 --- 3 files changed, 14 insertions(+), 3 deletions(-) diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index a9dfa79b6bab..76f15644aec8 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: @@ -438,6 +441,8 @@ 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(); @@ -472,6 +477,7 @@ static int resume_target_kernel(bool platform_mode) syscore_resume(); Enable_irqs: + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); Enable_cpus: @@ -550,6 +556,8 @@ 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()) { @@ -563,6 +571,7 @@ 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 6dadb25cb0d8..6bba2f907bcb 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -294,6 +295,8 @@ 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()); @@ -311,6 +314,8 @@ 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 fb4a9c2cf8d9..f13332185b07 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1188,8 +1188,6 @@ static void timekeeping_resume(void) touch_softlockup_watchdog(); - clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); - /* Resume hrtimers */ hrtimers_resume(); } @@ -1242,7 +1240,6 @@ static int timekeeping_suspend(void) write_seqcount_end(&tk_core.seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); clocksource_suspend(); clockevents_suspend(); -- 2.0.1.1.gfbfc394