Home Home > GIT Browse > stable-xen
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJoe Stringer <joe@ovn.org>2017-08-31 16:15:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-08-31 16:33:15 -0700
commitc03567a8e8d5cf2aaca40e605c48f319dc2ead57 (patch)
tree9dffd4bbddc275c9e662ca510cf5e680ae3b1f7a
parentc461ad6a63b37ba74632e90c063d14823c884247 (diff)
include/linux/compiler.h: don't perform compiletime_assert with -O0
Commit c7acec713d14 ("kernel.h: handle pointers to arrays better in container_of()") made use of __compiletime_assert() from container_of() thus increasing the usage of this macro, allowing developers to notice type conflicts in usage of container_of() at compile time. However, the implementation of __compiletime_assert relies on compiler optimizations to report an error. This means that if a developer uses "-O0" with any code that performs container_of(), the compiler will always report an error regardless of whether there is an actual problem in the code. This patch disables compile_time_assert when optimizations are disabled to allow such code to compile with CFLAGS="-O0". Example compilation failure: ./include/linux/compiler.h:547:38: error: call to `__compiletime_assert_94' declared with attribute error: pointer type mismatch in container_of() _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) ^ ./include/linux/compiler.h:530:4: note: in definition of macro `__compiletime_assert' prefix ## suffix(); \ ^~~~~~ ./include/linux/compiler.h:547:2: note: in expansion of macro `_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) ^~~~~~~~~~~~~~~~~~~ ./include/linux/build_bug.h:46:37: note: in expansion of macro `compiletime_assert' #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^~~~~~~~~~~~~~~~~~ ./include/linux/kernel.h:860:2: note: in expansion of macro `BUILD_BUG_ON_MSG' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^~~~~~~~~~~~~~~~ [akpm@linux-foundation.org: use do{}while(0), per Michal] Link: http://lkml.kernel.org/r/20170829230114.11662-1-joe@ovn.org Fixes: c7acec713d14c6c ("kernel.h: handle pointers to arrays better in container_of()") Signed-off-by: Joe Stringer <joe@ovn.org> Cc: Ian Abbott <abbotti@mev.co.uk> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/compiler.h6
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index eca8ad75e28b..043b60de041e 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -517,7 +517,8 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
# define __compiletime_error_fallback(condition) do { } while (0)
#endif
-#define __compiletime_assert(condition, msg, prefix, suffix) \
+#ifdef __OPTIMIZE__
+# define __compiletime_assert(condition, msg, prefix, suffix) \
do { \
bool __cond = !(condition); \
extern void prefix ## suffix(void) __compiletime_error(msg); \
@@ -525,6 +526,9 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
prefix ## suffix(); \
__compiletime_error_fallback(__cond); \
} while (0)
+#else
+# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
+#endif
#define _compiletime_assert(condition, msg, prefix, suffix) \
__compiletime_assert(condition, msg, prefix, suffix)