[PATCH v7 6/9] bug.h: Prevent double evaulation of in BUILD_BUG_ON

danielfsantos
2013-01-01T21:16:40Z

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 27d404f..0d75762 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -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

--
1.7.8.6