Re: [PATCH 11/13] x86/ticketlock: only do kick after doing unlock

From: Jeremy Fitzhardinge
Date: Fri Sep 02 2011 - 15:34:22 EST


On 09/02/2011 07:49 AM, Peter Zijlstra wrote:
> On Thu, 2011-09-01 at 17:55 -0700, Jeremy Fitzhardinge wrote:
>> From: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
>>
>> We must release the lock before checking to see if the lock is in
>> slowpath or else there's a potential race where the lock enters the
>> slow path after the unlocker has checked the slowpath flag, but before
>> it has actually unlocked.
>>
>> Signed-off-by: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> Wouldn't it be much better to fold it back so that this bug never
> happens when you bisect?

Yes indeed.

J

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