linux-kernel - Re: [PATCH] mm/memory.c: remove warning from an uninitialized spinlock. was: Re: 2.6.21-rc7-mm2

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Date:	Thu, 8 Nov 2007 06:15:16 +0100
From:	Borislav Petkov <bbpetkov@...oo.de>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Whitcroft <apw@...dowen.org>,
	linux-kernel@...r.kernel.org,
	Jeremy Fitzhardinge <jeremy@...source.com>
Subject: Re: [PATCH] mm/memory.c: remove warning from an uninitialized
	spinlock. was: Re: 2.6.21-rc7-mm2

On Wed, Nov 07, 2007 at 02:20:03PM -0500, Steven Rostedt wrote:
> > 
> > Introduce a macro for suppressing gcc from generating a warning about a
> > probable uninitialized state of a variable.
> > 
> > Example:
> > 
> > -	spinlock_t *ptl;
> > +	spinlock_t *uninitialized_var(ptl);
> > 
> > Not a happy solution, but those warnings are obnoxious.
> > 
> > - Using the usual pointlessly-set-it-to-zero approach wastes several
> >   bytes of text.
> > 
> > - Using a macro means we can (hopefully) do something else if gcc changes
> >   cause the `x = x' hack to stop working
> > 
> > - Using a macro means that people who are worried about hiding true bugs
> >   can easily turn it off.
> > 
> > Signed-off-by: Borislav Petkov <bbpetkov@...oo.de>
> > Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> 
> I just stumbled across this being in the kernel. Well, I'm finally glad
> it made it in, even though it was suggested one year earlier ;-)
> 
>   http://lkml.org/lkml/2006/5/11/50

yeah, this was Andrew's idea. The version in the kernel, in
contrast to yours, doesn't have a config option so you still
have to make really sure you're not aiding any bugs with it.

-- 
Regards/Gruß,
    Boris.
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