linux-kernel - Re: [PATCH v2] Remove uninitialized

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Message-ID: <alpine.DEB.2.00.1210291150470.10845@chino.kir.corp.google.com>
Date:	Mon, 29 Oct 2012 11:55:04 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Ingo Molnar <mingo@...nel.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Corey Minyard <cminyard@...sta.com>, minyard@....org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	OpenIPMI Developers <openipmi-developer@...ts.sourceforge.net>
Subject: Re: [PATCH v2] Remove uninitialized_var()

On Sun, 28 Oct 2012, Ingo Molnar wrote:

> I left it a bit mystic because in some cases this macro was 
> mis-used not to suppress GCC being wrong, but to hide GCC being 
> *right*: for example unused variable warnings in cases like:
> 
>    int uninitialized_var(var);
> 
>    #ifdef XYZ
>    var = ...;
>    ...
>    #endif
> 
> which (ab-)use was no doubt actively dangerous beyond being 
> ugly. One such example is in arch/x86/mm/numa.c. (These cases 
> now turn into clear (and always harmless) compiler warnings, as 
> they should.)
> 

I like initializing them to 0 or NULL because it will still emit the 
"unused variable" warnings whereas using uninitialized_var() would not 
with -Wall.  It's quite possible that uninitialized_var() is actually 
suppressing this warning for variables that aren't used.

I fixed a bug that was attributed to uninitialized var for rc1 in 
43385846968b ("fs, xattr: fix bug when removing a name not in xattr 
list"), so thanks very much for removing it entirely.
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