Re: [PATCH RFC v2] PM / sleep: Fix racing timers

[SÃren Brinkmann]

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@xxxxxxxxxx>
> 
> Did you test the hibernation?
No, I don't have a system to test hibernation. Suspend seems to work
fine though.

	SÃren
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