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Date: Tue, 7 Apr 2009 18:42:17 -0400
Message-ID: <f73f7ab80904071542r1d3e5e1au21c8c4ded9d36f7d@mail.gmail.com>
Subject: Re: [PATCH] intel-iommu: fix build with CONFIG_BRANCH_TRACER=y
From: Kyle Moffett <kyle@moffetthome.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Woodhouse <dwmw2@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
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Whoops, resent the original HTML email as plain text, sorry...

On Tue, Apr 7, 2009 at 10:59 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Tue, 7 Apr 2009, Linus Torvalds wrote:
> >
> > Can we please do it something like the following instead:
> >
> >       #define if(a, ...) \
> >               __trace_if( (a, ## __VA_ARGS__) )
> >
> > so that you don't need to do that ", ## __VA_ARGS__" thing three times?
>
> IOW, does this (TOTALLY UNTESTED) patch work?
>
>                Linus
>
> -#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) :         \
> +#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
> +#define __trace_if(cond) \
> +       if (__builtin_constant_p((cond)) ? !!(cond) :                   \

Umm, why not just use the much nicer pre-C99 GCC syntax?  It
automatically makes "cond" expand into the full comma-separated
argument list.  No other changes should be necessary.  IOW, something
like this:

-#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) :         \
+#define if(cond...) if (__builtin_constant_p((cond)) ? !!(cond) :         \

Cheers,
Kyle Moffett