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Message-Id: <20200422095050.661714139@linuxfoundation.org>
Date: Wed, 22 Apr 2020 11:57:08 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Vegard Nossum <vegard.nossum@...cle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Daniel Santos <daniel.santos@...ox.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Ian Abbott <abbotti@....co.uk>, Joe Perches <joe@...ches.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 111/125] compiler.h: fix error in BUILD_BUG_ON() reporting
From: Vegard Nossum <vegard.nossum@...cle.com>
[ Upstream commit af9c5d2e3b355854ff0e4acfbfbfadcd5198a349 ]
compiletime_assert() uses __LINE__ to create a unique function name. This
means that if you have more than one BUILD_BUG_ON() in the same source
line (which can happen if they appear e.g. in a macro), then the error
message from the compiler might output the wrong condition.
For this source file:
#include <linux/build_bug.h>
#define macro() \
BUILD_BUG_ON(1); \
BUILD_BUG_ON(0);
void foo()
{
macro();
}
gcc would output:
./include/linux/compiler.h:350:38: error: call to `__compiletime_assert_9' declared with attribute error: BUILD_BUG_ON failed: 0
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
However, it was not the BUILD_BUG_ON(0) that failed, so it should say 1
instead of 0. With this patch, we use __COUNTER__ instead of __LINE__, so
each BUILD_BUG_ON() gets a different function name and the correct
condition is printed:
./include/linux/compiler.h:350:38: error: call to `__compiletime_assert_0' declared with attribute error: BUILD_BUG_ON failed: 1
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
Signed-off-by: Vegard Nossum <vegard.nossum@...cle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
Reviewed-by: Daniel Santos <daniel.santos@...ox.com>
Cc: Rasmus Villemoes <linux@...musvillemoes.dk>
Cc: Ian Abbott <abbotti@....co.uk>
Cc: Joe Perches <joe@...ches.com>
Link: http://lkml.kernel.org/r/20200331112637.25047-1-vegard.nossum@oracle.com
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
include/linux/compiler.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 0020ee1cab37a..7837afabbd78e 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -546,7 +546,7 @@ unsigned long read_word_at_a_time(const void *addr)
* compiler has support to do so.
*/
#define compiletime_assert(condition, msg) \
- _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
+ _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
#define compiletime_assert_atomic_type(t) \
compiletime_assert(__native_word(t), \
--
2.20.1
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