Commit 1d6a0d19 authored Feb 21, 2013 by Daniel Santos Committed by Linus Torvalds Feb 21, 2013

bug.h: prevent double evaulation of `condition' in BUILD_BUG_ON



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.

[akpm@linux-foundation.org: tweak code layout]
Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Joe Perches <joe@perches.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ca623c91

include/linux/bug.h

+4 −3

Original line number	Diff line number	Diff line
		@@ -59,8 +59,9 @@ 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])); \
		if (__cond) __build_bug_on_failed = 1; \
		} while (0)
		#endif

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