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

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Date:	Thu, 29 Aug 2013 14:23:10 -0700
From:	Colin Cross <ccross@...roid.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Neil Zhang <zhangwm@...vell.com>,
	Joseph Lo <josephl@...dia.com>,
	linux-tegra <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 Thu, Aug 29, 2013 at 1:28 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> 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?

Yes please
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