On Mon, 2006-05-29 at 18:33 -0700, Andrew Morton wrote:
> On Mon, 29 May 2006 23:23:28 +0200
> Ingo Molnar <[email protected]> wrote:
>
> > add WARN_ON_ONCE(cond) to print once-per-bootup messages.
> >
> > Signed-off-by: Ingo Molnar <[email protected]>
> > Signed-off-by: Arjan van de Ven <[email protected]>
> > ---
> > include/asm-generic/bug.h | 13 +++++++++++++
> > 1 file changed, 13 insertions(+)
> >
> > Index: linux/include/asm-generic/bug.h
> > ===================================================================
> > --- linux.orig/include/asm-generic/bug.h
> > +++ linux/include/asm-generic/bug.h
> > @@ -44,4 +44,17 @@
> > # define WARN_ON_SMP(x) do { } while (0)
> > #endif
> >
> > +#define WARN_ON_ONCE(condition) \
> > +({ \
> > + static int __warn_once = 1; \
> > + int __ret = 0; \
> > + \
> > + if (unlikely(__warn_once && (condition))) { \
Since __warn_once is likely to be true, and the condition is likely to
be false, wouldn't it be better to switch this around to:
if (unlikely((condition) && __warn_once)) {
So the && will fall out before having to check a global variable.
Only after the unlikely condition would the __warn_once be false.
-- Steve
> > + __warn_once = 0; \
> > + WARN_ON(1); \
> > + __ret = 1; \
> > + } \
> > + __ret; \
> > +})
> > +
> > #endif
>
> I'll queue this for mainline inclusion.
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