linux-kernel - Re: [PATCH] Fix race between attach_task and cpuset

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Message-Id: <20070325125403.3749b45c.pj@sgi.com>
Date:	Sun, 25 Mar 2007 12:54:03 -0700
From:	Paul Jackson <pj@....com>
To:	balbir@...ibm.com
Cc:	vatsa@...ibm.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix race between attach_task and cpuset_exit

> How about using a local variable like ref_count and using
> 
> ref_count = atomic_dec_and_test(&cs->count); This will avoid the two
> atomic operations, atomic_dec() and atomic_read() below.

This would also seem to address the race I just noticed in my previous
reply.

Though I would suggest that we use the same code pattern in both
cpuset_exit and attach_task -- either both use cpuset_to_be_released,
or both use ref_count.

I tend to prefer the cpuset_to_be_released form - seems a bit more
explicitly clear to me.  But vatsa's doing the patch - he gets the
last vote.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@....com> 1.925.600.0401
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