From: Stephen Boyd <sboyd@codeaurora.org>
To: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: Re: [PATCH RFC v2] PM / sleep: Fix racing timers
Date: Mon, 28 Jul 2014 12:19:22 -0700 [thread overview]
Message-ID: <53D6A23A.6010904@codeaurora.org> (raw)
In-Reply-To: <1406322408-15408-1-git-send-email-soren.brinkmann@xilinx.com>
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 <soren.brinkmann@xilinx.com>
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
next prev parent reply other threads:[~2014-07-28 19:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-21 17:35 [PATCH RFC] suspend/hibernation: Fix racing timers Soren Brinkmann
2014-07-24 3:55 ` John Stultz
2014-07-24 15:59 ` Sören Brinkmann
2014-07-25 21:06 ` [PATCH RFC v2] PM / sleep: " Soren Brinkmann
2014-07-27 23:18 ` Rafael J. Wysocki
2014-07-28 19:26 ` John Stultz
2014-07-28 10:05 ` Pavel Machek
2014-07-28 15:51 ` Sören Brinkmann
2014-07-28 19:19 ` Stephen Boyd [this message]
2014-07-28 19:24 ` John Stultz
2014-07-28 19:38 ` Stephen Boyd
2014-07-28 20:02 ` Sören Brinkmann
2014-07-29 23:05 ` Stephen Boyd
2014-07-29 23:22 ` Sören Brinkmann
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