linux-kernel - Re: [PATCH UPDATED 04/16] x86: Use local variable to cache smp_processor_id() in setup_local

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Date:	Tue, 30 Nov 2010 20:32:54 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
	hpa@...or.com, x86@...nel.org, eric.dumazet@...il.com,
	yinghai@...nel.org, brgerst@...il.com, penberg@...nel.org
Subject: Re: [PATCH UPDATED 04/16] x86: Use local variable to cache
	smp_processor_id() in setup_local_APIC()

On Tue, Nov 30, 2010 at 05:17:19PM +0100, Tejun Heo wrote:
> Subject: x86: Use local variable to cache smp_processor_id() in setup_local_APIC()
> 
> This is a trivial clean up.
> 
> * Move initialization of @cpu inside preemption disabled region as
>   suggested by Cyrill Gorcunov.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: Yinghai Lu <yinghai@...nel.org>
> Cc: Cyrill Gorcunov <gorcunov@...il.com>
> ---
> Updated as suggested.  Git tree updated too.
> 
> Thanks.
> 

Thanks Tejun, but please don't modify the snippet below
(ie leave it with smp_processor_id). It happens when preempt
gets enabled again but cpu cached with preempt disabled.
So we should not mess this I believe. ok?

Other than that
Acked-by: Cyrill Gorcunov <gorcunov@...il.com>

Thanks!

> @@ -1368,7 +1367,7 @@ void __cpuinit setup_local_APIC(void)
> 
>  #ifdef CONFIG_X86_MCE_INTEL
>  	/* Recheck CMCI information after local APIC is up on CPU #0 */
> -	if (smp_processor_id() == 0)
> +	if (cpu == 0)
>  		cmci_recheck();
>  #endif
>  }
> 
  Cyrill
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