linux-kernel - Re: [PATCH] WARN_ONCE(): use bool for condition

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Date:	Tue, 29 Sep 2009 13:59:47 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Cesar Eduardo Barros <cesarb@...arb.net>
Cc:	linux-kernel@...r.kernel.org, rolandd@...co.com, cesarb@...arb.net,
	dwalker@...o99.com
Subject: Re: [PATCH] WARN_ONCE(): use bool for condition

On Sun, 27 Sep 2009 15:25:12 -0300
Cesar Eduardo Barros <cesarb@...arb.net> wrote:

> Use the type bool for __ret_warn_once and __ret_warn_on, instead of int
> with a double negation. This matches the intent of the code better and
> should allow the compiler to generate better code, like in commit
> 70867453092297be9afb2249e712a1f960ec0a09. However, some versions of gcc
> seems to pessimize the code instead when the condition is not trivial.
> 
> Cc: Daniel Walker <dwalker@...o99.com>
> Signed-off-by: Cesar Eduardo Barros <cesarb@...arb.net>
> ---
>  arch/avr32/include/asm/bug.h    |    2 +-
>  arch/blackfin/include/asm/bug.h |    2 +-
>  arch/parisc/include/asm/bug.h   |    2 +-
>  arch/powerpc/include/asm/bug.h  |    2 +-
>  arch/s390/include/asm/bug.h     |    2 +-
>  arch/sh/include/asm/bug.h       |    4 ++--
>  include/asm-generic/bug.h       |   12 ++++++------

There's a small reject in include/asm-generic/bug.h against current
mainline, easily fixed.

It would be nice if we had some accurate numbers on the kernel size
reductions from this, please.  I assume that the patch is still of
benefit in 2.6.32-rc1(2?), but it's always good to confirm.


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