From: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
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 08:51:18 -0700 [thread overview]
Message-ID: <db9a4d35-891e-4b66-aa70-25c1f65012fd@BN1BFFO11FD021.protection.gbl> (raw)
In-Reply-To: <20140728100538.GA16237@amd.pavel.ucw.cz>
On Mon, 2014-07-28 at 12:05PM +0200, Pavel Machek wrote:
> On Fri 2014-07-25 14:06:48, 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>
>
> Did you test the hibernation?
No, I don't have a system to test hibernation. Suspend seems to work
fine though.
Sören
WARNING: multiple messages have this Message-ID (diff)
From: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
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 08:51:18 -0700 [thread overview]
Message-ID: <db9a4d35-891e-4b66-aa70-25c1f65012fd@BN1BFFO11FD021.protection.gbl> (raw)
In-Reply-To: <20140728100538.GA16237@amd.pavel.ucw.cz>
On Mon, 2014-07-28 at 12:05PM +0200, Pavel Machek wrote:
> On Fri 2014-07-25 14:06:48, 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>
>
> Did you test the hibernation?
No, I don't have a system to test hibernation. Suspend seems to work
fine though.
Sören
next prev parent reply other threads:[~2014-07-28 15:51 UTC|newest]
Thread overview: 18+ 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
2014-07-24 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 [this message]
2014-07-28 15:51 ` Sören Brinkmann
2014-07-28 19:19 ` Stephen Boyd
2014-07-28 19:24 ` John Stultz
2014-07-28 19:38 ` Stephen Boyd
2014-07-28 20:02 ` Sören Brinkmann
2014-07-28 20:02 ` Sören Brinkmann
2014-07-29 23:05 ` Stephen Boyd
2014-07-29 23:22 ` Sören Brinkmann
2014-07-29 23:22 ` Sören Brinkmann
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