linux-kernel - Re: [PATCH] x86: perf: fix incorrect use of do

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Date:	Fri, 12 Jul 2013 14:08:43 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Dave Hansen <dave@...1.net>
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] x86: perf: fix incorrect use of do_div() in nmi warning


* Dave Hansen <dave@...1.net> wrote:

> 
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> This fixes a bug present in 3.10 and introduced here:
> 
> commit 2ab00456ea8a0d79acb1390659b98416111880b2
> Author: Dave Hansen <dave.hansen@...ux.intel.com>
> Date:   Fri Jun 21 08:51:35 2013 -0700
> 
>     x86: Warn when NMI handlers take large amounts of time
> 
> I completely botched understanding the calling conventions of
> do_div().  I assumed that do_div() returned the result instead
> of realizing that it modifies its argument and returns a
> remainder.  The side-effect from this would be bogus numbers
> for the "msecs" value in the warning messages:
> 
> 	INFO: NMI handler (perf_event_nmi_handler) took too long to run: 0.114 msecs
> 
> Note, there was a second fix posted by Stephane Eranian for
> a separate patch which I also botched:
> 
> 	http://lkml.kernel.org/r/20130704223010.GA30625@quad
> 
> Both of these fixes need to get pulled in to Linus's tree and
> the 3.10 stable tree.

This is a brand new v3.11 commit.

It should not be included in any -stable tree, is it?

Thanks,

	Ingo
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