[PATCH -tip v2 09/11] data_race: Avoid nested statement expression

Marco Elver
2020-05-21T11:10:16Z

It appears that compilers have trouble with nested statements
expressions, as such make the data_race() macro be only a single
statement expression. This will help us avoid potential problems in
future as its usage increases.

Link: https://lkml.kernel.org/r/20200520221712.GA21166@zn.tnic
Signed-off-by: Marco Elver <elver@google.com>
---
v2:
* Add patch to series in response to above linked discussion.
---
include/linux/compiler.h | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 7444f026eead..1f9bd9f35368 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -211,12 +211,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
*/
#define data_race(expr) \
({ \
+ __unqual_scalar_typeof(({ expr; })) __v; \
__kcsan_disable_current(); \
- ({ \
- __unqual_scalar_typeof(({ expr; })) __v = ({ expr; }); \
- __kcsan_enable_current(); \
- __v; \
- }); \
+ __v = ({ expr; }); \
+ __kcsan_enable_current(); \
+ __v; \
})

/*
--
2.26.2.761.g0e0b3e54be-goog