Re: [PATCH] genirq: ARM dyntick cleanup

[Andrew Morton]

On Wed, 5 Jul 2006 16:24:25 -0700
"Randy.Dunlap" <rdunlap@xxxxxxxxxxxx> 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.
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