From 1d6a0d19c85587581a364850b77f30446810a560 Mon Sep 17 00:00:00 2001
From: Daniel Santos <daniel.santos@pobox.com>
Date: Thu, 21 Feb 2013 16:41:45 -0800
Subject: [PATCH] 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>
---
include/linux/bug.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/include/linux/bug.h b/include/linux/bug.h
index 27d404f91b3e..89fb91d0c929 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -59,9 +59,10 @@ 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; \
- } while(0)
+ bool __cond = !!(condition); \
+ ((void)sizeof(char[1 - 2 * __cond])); \
+ if (__cond) __build_bug_on_failed = 1; \
+ } while (0)
#endif
/**
--
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