linux-kernel - Re: [PATCH UPDATED#3 04/16] x86: setup_local_APIC() must always be called with preemption disabled

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Message-ID: <alpine.LFD.2.00.1012101209580.2653@localhost6.localdomain6>
Date:	Fri, 10 Dec 2010 12:10:24 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Tejun Heo <tj@...nel.org>
cc:	linux-kernel@...r.kernel.org, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, eric.dumazet@...il.com, yinghai@...nel.org,
	brgerst@...il.com, gorcunov@...il.com, penberg@...nel.org
Subject: Re: [PATCH UPDATED#3 04/16] x86: setup_local_APIC() must always be
 called with preemption disabled

On Fri, 10 Dec 2010, Tejun Heo wrote:

> On 12/09/2010 10:56 PM, Thomas Gleixner wrote:
> > On Thu, 9 Dec 2010, Tejun Heo wrote:
> > 
> >> setup_local_APIC() is used to setup local APIC early during CPU
> >> initialization and already assumes that preemption is disabled on
> >> entry.  However, The function unnecessarily disables and enables
> >> preemption and uses smp_processor_id() multiple times in and out of
> >> the nested preemption disabled section.  This gives the wrong
> >> impression that the function might be able to handle being called with
> >> preemption enabled and/or migrated to another processor in the middle.
> >>
> >> Make it clear that the function is always called with preemption
> >> disabled, drop the confusing preemption disable block and call
> >> smp_processor_id() once at the beginning of the function.
> > 
> > AFAICT, this one is completely unrelated to that NUMA cleanup, right ?
> > 
> > So this can be applied independent and should never have been part of
> > that NUMA series in the first place.
> 
> Originally, it was a trivial prep patch.  Anyways, I'll push it
> to the top of the series so that it can be taken separately.

I pick it up from mail.

Thanks,

	tglx
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