From mboxrd@z Thu Jan 1 00:00:00 1970 From: Soren Brinkmann Subject: [PATCH RESEND] PM / sleep: Fix racing timers Date: Mon, 22 Sep 2014 10:07:03 -0700 Message-ID: <1411405623-7869-1-git-send-email-soren.brinkmann@xilinx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-pd0-f175.google.com ([209.85.192.175]:58808 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753542AbaIVRHQ (ORCPT ); Mon, 22 Sep 2014 13:07:16 -0400 Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Thomas Gleixner , "Rafael J. Wysocki" Cc: John Stultz , Pavel Machek , Len Brown , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Soren Brinkmann On platforms that do not power off during suspend, successfully enterin= g 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 appropri= ate 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 not a lot of discussion on the last submission. Just one comm= ent from Rafael (https://lkml.org/lkml/2014/8/26/780), which - as I outlined in = my response, does not apply, IMHO, since the platform does not re-enable interrupts. Hence, I still believe fixing this in the core is the appro= priate way. Thanks, S=C3=B6ren 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; =20 + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + local_irq_disable(); =20 error =3D syscore_suspend(); @@ -316,6 +318,7 @@ static int create_image(int platform_mode) syscore_resume(); =20 Enable_irqs: + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); =20 Enable_cpus: @@ -438,6 +441,8 @@ static int resume_target_kernel(bool platform_mode) if (error) goto Enable_cpus; =20 + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + local_irq_disable(); =20 error =3D syscore_suspend(); @@ -472,6 +477,7 @@ static int resume_target_kernel(bool platform_mode) syscore_resume(); =20 Enable_irqs: + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); =20 Enable_cpus: @@ -550,6 +556,8 @@ int hibernation_platform_enter(void) if (error) goto Platform_finish; =20 + 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) =20 Power_up: syscore_resume(); + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); local_irq_enable(); enable_nonboot_cpus(); =20 diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 18c62195660f..ded3c7d6731f 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, boo= l *wakeup) if (error || suspend_test(TEST_CPUS)) goto Enable_cpus; =20 + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); + arch_suspend_disable_irqs(); BUG_ON(!irqs_disabled()); =20 @@ -311,6 +314,8 @@ static int suspend_enter(suspend_state_t state, boo= l *wakeup) syscore_resume(); } =20 + clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); + arch_suspend_enable_irqs(); BUG_ON(irqs_disabled()); =20 diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index ec1791fae965..5b6696772ffc 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1189,8 +1189,6 @@ static void timekeeping_resume(void) =20 touch_softlockup_watchdog(); =20 - clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); - /* Resume hrtimers */ hrtimers_resume(); } @@ -1243,7 +1241,6 @@ static int timekeeping_suspend(void) write_seqcount_end(&tk_core.seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); =20 - clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); clocksource_suspend(); clockevents_suspend(); =20 --=20 2.1.0.1.g27b9230