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Subject: Re: [PATCH] Disable branch profiling macros when sparsed.
From: Harvey Harrison <harvey.harrison@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: alexey.zaytsev@gmail.com, linux-kernel@vger.kernel.org, mingo@elte.hu,
       rostedt@goodmis.org
In-Reply-To: <20090109.221348.166902734.davem@davemloft.net>
References: <20090110052727.5471.3654.stgit@zaytsev.su>
	 <20090109.221348.166902734.davem@davemloft.net>
Content-Type: text/plain
Date: Fri, 09 Jan 2009 23:18:26 -0800
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On Fri, 2009-01-09 at 22:13 -0800, David Miller wrote:
> From: Alexey Zaytsev <alexey.zaytsev@gmail.com>
> Date: Sat, 10 Jan 2009 08:57:28 +0300
> 
> > The macros produce lots of unneeded warnings when
> > recursive if(({ .. if() {..} ..})) {..} and such
> > are substituted. And there is no point in sparsing
> > them anyway. This is useful if someone decides to
> > sparse an allyesconfig kernel.
> > 
> > Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
> 
> If even sparse can't handle these things, it's no surprise
> how many gcc bogus warning problems we've run into because
> of this hairy if() macro.

It's not that sparse can't handle it, the warning is valid,
_____r and ______f are shadowed when these get nested.  It
gets even worse when interacting with likely/unlikely tracing
as that chose the same identifiers too.  So there the noise
could be drastically reduced changing the different identifiers
for the if () and __branch_check macros, but nesting will always
warn.

I've just been setting this to no in my allyesconfig sparse
runs....just wait until kmemtrace gets to mainline, then it
gets really bad :(

Cheers,

Harvey

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