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

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Message-ID: <CACRpkdZ2kueU5-kZx2-eTBg9B=nUpU1Anx8u+M3XckRUYWWwnQ@mail.gmail.com>
Date:	Tue, 28 Apr 2015 14:37:10 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Sudeep Holla <sudeep.holla@....com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH 16/20] sched/idle: Use explicit broadcast oneshot control function

On Tue, Apr 28, 2015 at 2:19 PM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> Sudeep:
>> 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.
>
> So the bug here is that cpuidle_enter() enables interrupts, so the
> assumption about them being not enabled made by
> tick_broadcast_oneshot_control() is actually not valid.
>
> It looks like we need to acquire the clockevents_lock at least in this
> particular case.  Let me see where to put it and I'll send a patch for
> testing.

Aha that looks very much like it. Put me on the patch and I'll
take it for a spin.

Yours,
Linus Walleij
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