linux-kernel - Re: Preemption Broken: centrino_target busted under SMP on 2.6.20.4

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Message-ID: <20070410042939.GA17179@redhat.com>
Date:	Tue, 10 Apr 2007 00:29:39 -0400
From:	Dave Jones <davej@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Jeff V. Merkey" <jmerkey@...fmountaingroup.com>,
	Linux kernel <linux-kernel@...r.kernel.org>,
	Venki Pallipadi <venkatesh.pallipadi@...el.com>
Subject: Re: Preemption Broken:  centrino_target busted under SMP on 2.6.20.4

On Mon, Apr 09, 2007 at 08:51:36PM -0700, Andrew Morton wrote:
 > On Mon, 9 Apr 2007 23:08:23 -0400 Dave Jones <davej@...hat.com> wrote:
 > 
 > >  > This whole file is going away in .22, and we have a viable alternative in
 > >  > .21 (acpi-cpufreq), so I'm not overly worried about fixing this up
 > >  > given it only shows up in debug kernels, especially at this stage in -rc.
 > >  > 
 > >  > (Yeah, it's a cop-out, but unless someone with more interest in this problem
 > >  >  steps up, I've bigger fishes to fry).
 > > 
 > > One last try...
 > > (I didn't think too long about this, so this might be equally busted,
 > >  but if so, see comment above).
 > 
 > Yes, I expect that should squish the warnings.  It looks all racy wrt cpu hotplug
 > and against async set_cpus_allowed(), but if those are our worst problems, we're
 > good.

It probably needs a couple more preempt_enable()'s sprinkled throughout the function
to take care of the break's. I also missed a goto case.
Meh, this cure is as bad as the disease.

	Dave

-- 
http://www.codemonkey.org.uk
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