From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [PATCH RFC v2] PM / sleep: Fix racing timers Date: Mon, 28 Jul 2014 12:19:22 -0700 Message-ID: <53D6A23A.6010904@codeaurora.org> References: <53D083C5.2000501@linaro.org> <1406322408-15408-1-git-send-email-soren.brinkmann@xilinx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.11.231]:49667 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998AbaG1TTX (ORCPT ); Mon, 28 Jul 2014 15:19:23 -0400 In-Reply-To: <1406322408-15408-1-git-send-email-soren.brinkmann@xilinx.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Soren Brinkmann Cc: John Stultz , Thomas Gleixner , "Rafael J. Wysocki" , Pavel Machek , Len Brown , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Daniel Lezcano On 07/25/14 14:06, Soren Brinkmann wrote: > 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 Do we know which timer_list or hrtimer wants to run while entering suspend? I'd suspect the scheduler tick but perhaps we just forgot to cancel some timer during suspend? -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation