Messages in this thread | | | Subject | Re: [patch 05/61] lock validator: introduce WARN_ON_ONCE(cond) | From | Steven Rostedt <> | Date | Tue, 30 May 2006 13:38:17 -0400 |
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On Mon, 2006-05-29 at 18:33 -0700, Andrew Morton wrote: > On Mon, 29 May 2006 23:23:28 +0200 > Ingo Molnar <mingo@elte.hu> wrote: > > > add WARN_ON_ONCE(cond) to print once-per-bootup messages. > > > > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> > > --- > > 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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