Rework the data_race() macro so that it:
- Accepts expressions which evaluate to a 'const' type
- Attempts to discard volatile qualifiers from scalar types, avoiding
pointless stack spills
- Uses __kcsan_{disable,enable}_current(), allowing its use from code
that is built independently from the kernel, such as the vDSO
This will allow for its use by {READ,WRITE}_ONCE() in a subsequent patch.
At the same time, fix-up some weird whitespace issues.
Cc: Marco Elver <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
---
include/linux/compiler.h | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 0caced170a8a..f2a64195ee8e 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -314,14 +314,15 @@ unsigned long read_word_at_a_time(const void *addr)
* This macro *does not* affect normal code generation, but is a hint
* to tooling that data races here are to be ignored.
*/
-#define data_race(expr)
\
- ({ \
- typeof(({ expr; })) __val; \
- kcsan_disable_current(); \
- __val = ({ expr; }); \
- kcsan_enable_current(); \
- __val; \
- })
+#define data_race(expr)
\
+({ \
+ __kcsan_disable_current(); \
+ ({ \
+ __unqual_scalar_typeof(({ expr; })) __v = ({ expr; }); \
+ __kcsan_enable_current(); \
+ __v; \
+ }); \
+})
#else
#endif /* __KERNEL__ */
--
2.26.2.645.ge9eca65c58-goog
