Re: [PATCH 16/20] sched/idle: Use explicit broadcast oneshot control function

[Sudeep Holla]

On 28/04/15 11:34, Daniel Lezcano wrote:
> On 04/28/2015 12:11 PM, Linus Walleij wrote:
> > On Thu, Apr 2, 2015 at 12:22 AM, Rafael J. Wysocki
> > <rjw@xxxxxxxxxxxxx> wrote:
> >
> > > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > >
> > > Replace the clockevents_notify() call with an explicit function
> > > call.
> > >
> > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > For some reason this makes my Ux500 system arbitrarily hang,
> > especially during boot. Bisected down to this commit. Since the
> > entire changeset is removing the notifications altogether I can't
> > just revert it.
> >
> > Disabling CONFIG_CPU_IDLE removes the problem.
> >
> > Tried registering a stub driver (I just #if 0 all the code in
> > drivers/cpuidle/cpuidle-ux500.c) it still crashes.
> >
> > That makes me think something inside the cpuidle subsystem is
> > locking up after this, but my other idea is that the timer may be
> > involved in some way, like this is stressing the timer in some new
> > yet untested way.
> >
> > Has anyone else seen problems with this or is it only ux500?
> >
> > I'm looking closer at it but feel a bit clueless...
>
> If you keep the #if 0 and remove the CPUIDLE_FLAG_TIMER_STOP flag,
> does it still crash ?

At-least I observed issue only when I am using hardware broadcast timer.
It doesn't hang when I am using hrtimer as broadcast timer in which case
one of the cpu will be not enter deeper idle states that lose timer.
I will rerun on v4.1-rc1 and post the complete log.

Regards,
Sudeep
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