Messages in this thread | | | Date | Thu, 15 Nov 2012 16:07:27 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v5 6/9] bug.h: Prevent double evaulation of in BUILD_BUG_ON |
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On Tue, Nov 13, 2012 at 04:13:38PM -0600, danielfsantos@att.net wrote: > When calling BUILD_BUG_ON in an optimized build using gcc 4.3 and later, > the condition will be evaulated twice, possibily with side-effects. > This patch eliminates that error. > > Signed-off-by: Daniel Santos <daniel.santos@pobox.com> > --- > include/linux/bug.h | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/linux/bug.h b/include/linux/bug.h > index 1b2465d..ccd44ce 100644 > --- a/include/linux/bug.h > +++ b/include/linux/bug.h > @@ -58,8 +58,9 @@ struct pt_regs; > extern int __build_bug_on_failed; > #define BUILD_BUG_ON(condition) \ > do { \ > - ((void)sizeof(char[1 - 2*!!(condition)])); \ > - if (condition) __build_bug_on_failed = 1; \ > + bool __cond = !!(condition); \ > + ((void)sizeof(char[1 - 2*!!(__cond)])); \
No need for the !!(__cond) here because you've done it in the line above. IOW,
bool __cond = !!(condition); ((void)sizeof(char[1 - 2 * __cond]));
which is even a bit more readable, as a matter of fact.
> + if (__cond) __build_bug_on_failed = 1; \ > } while(0) > #endif
Thanks.
-- Regards/Gruss, Boris.
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