Date: Wed, 11 May 2005 13:45:54 -0700
From: Paul Jackson <pj@sgi.com>
To: Nathan Lynch <ntl@pobox.com>
Cc: dino@in.ibm.com, Simon.Derr@bull.net, lse-tech@lists.sourceforge.net,
       akpm@osdl.org, nickpiggin@yahoo.com.au, vatsa@in.ibm.com,
       linux-kernel@vger.kernel.org
Subject: Re: [Lse-tech] [PATCH] cpusets+hotplug+preepmt broken
Message-Id: <20050511134554.3d72db59.pj@sgi.com>
In-Reply-To: <20050511202648.GF3614@otto>
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	<20050511202648.GF3614@otto>
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Nathan asked:
> Won't holding cpuset_sem while calling cpuset_cpus_allowed cause a
> deadlock?

It definitely would, which is why Dinakar's patch both added a call to
get cpuset_sem earlier in the hot unplug code, as well as removed the
call to get cpuset_sem that was inside the cpuset_cpus_allowed code (as
well as modified the other caller of cpuset_cpus_allowed, the
sched_setaffinity code, to explicitly get cpuset_sem before calling
cpuset_cpus_allowed, since that call no longer acquired cpuset_sem on
its own.


-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@engr.sgi.com> 1.650.933.1373, 1.925.600.0401
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