Re: [PATCH 7/7] printk: provide a filtering macro for printk

[Marc Andre Tanner <mat@brain-dump.org>]

On Wed, Sep 02, 2009 at 08:54:47AM -0400, Mike Frysinger wrote:
> On Wed, Sep 2, 2009 at 08:44, Marc Andre Tanner wrote:
> > On Wed, Sep 02, 2009 at 07:25:43AM -0500, Bill Gatliff wrote:
> >> Jamie Lokier wrote:
> >> >Looks good, except that I think kernel style is to use "do {...} while
> >> >(0)" rather than "({ ... })"
> >>
> >> And IIRC, there was some reason for the do{...} while(0) that made
> >> other alternatives not work.  So it might be more than just style at
> >> issue.
> >
> > Do you remember the reason? I found the oposite to be ture, I actually
> > started with the do { } while(0) construct but it failed in certain
> > situations so I wrapped it with ({ }) and then later removed
> > the now useless do { } while(0).
> >
> > By the way printk_once which is defined a few lines further down in
> > kernel.h also uses ({ }).
> >
> > Anyway the next version of my patch will no longer need it.
> 
> it depends completely on how the macro is intended to be used.  if you
> want to maintain the "this macro has a return value", then you have to
> use ({...}).  if you want the macro to return a void, then you have to
> use do{...}while(0).

Ok, thanks for the clarification. This makes sense.

Marc

-- 
 Marc Andre Tanner >< http://www.brain-dump.org/ >< GPG key: CF7D56C0