The following commit has been merged into the locking/kcsan branch of tip:
Commit-ID: c48981eeb0d56e107691df590007d6699441a689
Gitweb: https://git.kernel.org/tip/c48981eeb0d56e107691df590007d6699441a689
Author: Marco Elver <elver@xxxxxxxxxx>
AuthorDate: Thu, 14 Nov 2019 19:02:55 +01:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Sat, 16 Nov 2019 07:23:13 -08:00
include/linux/compiler.h: Introduce data_race(expr) macro
This introduces the data_race(expr) macro, which can be used to annotate
expressions for purposes of (1) documenting, and (2) giving tooling such
as KCSAN information about which data races are deemed "safe".
More context:
http://lkml.kernel.org/r/CAHk-=wg5CkOEF8DTez1Qu0XTEFw_oHhxN98bDnFqbY7HL5AB2g@xxxxxxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
include/linux/compiler.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c42fa83..7d3e777 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -310,6 +310,26 @@ unsigned long read_word_at_a_time(const void *addr)
__u.__val; \
})
+#include <linux/kcsan.h>
+
+/*
+ * data_race: macro to document that accesses in an expression may conflict with
+ * other concurrent accesses resulting in data races, but the resulting
+ * behaviour is deemed safe regardless.
+ *
+ * This macro *does not* affect normal code generation, but is a hint to tooling
+ * that data races here should be ignored.
+ */
+#define data_race(expr) \
+ ({ \
+ typeof(({ expr; })) __val; \
+ kcsan_nestable_atomic_begin(); \
+ __val = ({ expr; }); \
+ kcsan_nestable_atomic_end(); \
+ __val; \
+ })
+#else
+
#endif /* __KERNEL__ */
/*
|