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Date: Wed, 5 Jul 2006 16:50:26 -0700
From: "Randy.Dunlap" <rdunlap@xenotime.net>
To: Andrew Morton <akpm@osdl.org>
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Subject: Re: [PATCH] genirq: ARM dyntick cleanup
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On Wed, 5 Jul 2006 16:35:30 -0700 Andrew Morton wrote:

> On Wed, 5 Jul 2006 16:24:25 -0700
> "Randy.Dunlap" <rdunlap@xenotime.net> wrote:
> 
> > On Mon, 03 Jul 2006 19:27:07 +0200 Arjan van de Ven wrote:
> > 
> > > On Mon, 2006-07-03 at 10:13 -0700, Linus Torvalds wrote:
> > > >         #ifndef xyzzy
> > > >         #define zyzzy() /* empty */
> > > >         #endif
> > > > 
> > > 
> > > now if you write it as
> > > 
> > > #define zyzzy() do { ; } while (0)
> > > 
> > > it even works in a
> > > 
> > > if (foo())
> > > 	zyzzy();
> > > bar();
> > > 
> > > scenario 
> > > 
> > > (I know you know that, just pointing that out before people copy your
> > > example :-)
> > 
> > OK, I'll bite.  What part of Linus's macro doesn't work.
> > I compiled your foo/zyzzy/bar example with both his "empty"
> > macro and the do-while macro.  Same code produced both ways,
> > no compile warnings/errors.
> > 
> 
> 	if (foo())
> 		;
> 
> will generate `warning: empty body in an if-statement' when compiled with -W.
> 
> We go round this loop regularly.  Maybe someone should write it up.  Meanwhile,
> use do{}while(0) and be happy and secure.

Thanks, I was missing the -W.

or I should read the kernelnewbies FAQ  :)

http://kernelnewbies.org/FAQ/DoWhile0

---
~Randy