linux-kernel - Re: [tip:core/urgent] WARN_ON_SMP(): Add comment to explain ({0;})

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Message-ID: <1301324940.14261.232.camel@gandalf.stny.rr.com>
Date:	Mon, 28 Mar 2011 11:09:00 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	richard -rw- weinberger <richard.weinberger@...il.com>,
	linux-kernel@...r.kernel.org, mingo@...hat.com,
	torvalds@...ux-foundation.org, srostedt@...hat.com,
	tglx@...utronix.de, adobriyan@...il.com,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:core/urgent] WARN_ON_SMP(): Add comment to explain ({0;})

On Mon, 2011-03-28 at 07:58 -0700, H. Peter Anvin wrote:
> On 03/28/2011 07:56 AM, richard -rw- weinberger wrote:
> >>
> >> What the heck is wrong with the idiomatic and non-gcc-extension-using:
> >>
> >>        ((void)0)
> >>
> >> ?
> > 
> > AFAIK you cannot use it within an if-statement.
> > 
> 
> OK, fair enough.

If people hate the ({0;}) so much, we could replace it with:

static inline int _WARN_ON_SMP(void) { return 0; }
#define WARN_ON_SMP(x) _WARN_ON_SMP()

That would pretty much do the same thing.

 o Keeps the parameters from being evaluated, as they may not be defined
   for SMP

 o Can be used as a standalone statement without gcc complaining

 o Can be used within an if condition.

Geeze, I never expected such a fuss over a simple change ;)


-- Steve


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