linux-kernel - Re: [PATCH v2] cpuidle: coupled: abort idle if pokes are pending

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Message-ID: <7272744.lhUaaLc3cm@vostro.rjw.lan>
Date:	Thu, 29 Aug 2013 22:28:28 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Colin Cross <ccross@...roid.com>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Neil Zhang <zhangwm@...vell.com>,
	Joseph Lo <josephl@...dia.com>, linux-tegra@...r.kernel.org,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Jon Medhurst <tixy@...aro.org>,
	Sivaram Nair <sivaramn@...dia.com>
Subject: Re: [PATCH v2] cpuidle: coupled: abort idle if pokes are pending

On Wednesday, August 28, 2013 06:41:47 PM Colin Cross wrote:
> Joseph Lo <josephl@...dia.com> reported a lockup on Tegra20 caused
> by a race condition in coupled cpuidle.  When two or more cpus
> enter idle at the same time, the first cpus to arrive may go to the
> ready loop without processing pending pokes from the last cpu to
> arrive.
> 
> This patch adds a check for pending pokes once all cpus have been
> synchronized in the ready loop and resets the coupled state and
> retries if any cpus failed to handle their pending poke.
> 
> Retrying on all cpus may trigger the same issue again, so this patch
> also adds a check to ensure that each cpu has received at least one
> poke between when it enters the waiting loop and when it moves on to
> the ready loop.
> 
> Reported-by: Joseph Lo <josephl@...dia.com>
> Tested-by: Stephen Warren <swarren@...dia.com>
> Tested-by: Joseph Lo <josephl@...dia.com>
> Signed-off-by: Colin Cross <ccross@...roid.com>

Still stable material I suppose?

Queued up for 3.12, thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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