linux-kernel - Re: [169/197] modules: fix incorrect percpu usage

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Message-ID: <20100428174600.GA4205@Krystal>
Date:	Wed, 28 Apr 2010 13:46:00 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Greg KH <gregkh@...e.de>, Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Greg KH <greg@...ah.com>, stable-review@...nel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Randy Dunlap <randy.dunlap@...cle.com>,
	Eric Dumazet <dada1@...mosbay.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [169/197] modules: fix incorrect percpu usage

* Greg KH (gregkh@...e.de) wrote:
> 2.6.32-stable review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> 
> From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> 
> Mainline does not need this fix, as commit
> 259354deaaf03d49a02dbb9975d6ec2a54675672 fixed the problem by refactoring.
> 
> Should use per_cpu_ptr() to obfuscate the per cpu pointers (RELOC_HIDE is needed
> for per cpu pointers).
> 
> Introduced by commit:
> 
> module.c: commit 6b588c18f8dacfa6d7957c33c5ff832096e752d3
> 
> This patch should be queued for the stable branch, for kernels 2.6.29.x to
> 2.6.33.x.  (tested on 2.6.33.1 x86_64)

Tejun, should this patch be applied to 2.6.32.x, or will it cause problems on
ia64 ?

Thanks,

Mathieu

> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> CC: Randy Dunlap <randy.dunlap@...cle.com>
> CC: Eric Dumazet <dada1@...mosbay.com>
> CC: Rusty Russell <rusty@...tcorp.com.au>
> CC: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> CC: Tejun Heo <tj@...nel.org>
> CC: Ingo Molnar <mingo@...e.hu>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: Linus Torvalds <torvalds@...ux-foundation.org>
> CC: Greg Kroah-Hartman <gregkh@...e.de>
> CC: Steven Rostedt <rostedt@...dmis.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  kernel/module.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -555,7 +555,7 @@ static void percpu_modcopy(void *pcpudes
>  	int cpu;
>  
>  	for_each_possible_cpu(cpu)
> -		memcpy(pcpudest + per_cpu_offset(cpu), from, size);
> +		memcpy(per_cpu_ptr(pcpudest, cpu), from, size);
>  }
>  
>  #else /* ... !CONFIG_SMP */
> 
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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