linux-kernel - [PATCH -tip 08/10] READ_ONCE, WRITE_ONCE: Remove data

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Message-Id: <20200515150338.190344-9-elver@google.com>
Date:   Fri, 15 May 2020 17:03:36 +0200
From:   Marco Elver <elver@...gle.com>
To:     elver@...gle.com
Cc:     paulmck@...nel.org, dvyukov@...gle.com, glider@...gle.com,
        andreyknvl@...gle.com, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...nel.org,
        peterz@...radead.org, will@...nel.org,
        clang-built-linux@...glegroups.com
Subject: [PATCH -tip 08/10] READ_ONCE, WRITE_ONCE: Remove data_race() wrapping

The volatile access no longer needs to be wrapped in data_race(),
because we require compilers that emit instrumentation distinguishing
volatile accesses.

Signed-off-by: Marco Elver <elver@...gle.com>
---
 include/linux/compiler.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 17c98b215572..fce56402c082 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -229,7 +229,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define __READ_ONCE_SCALAR(x)						\
 ({									\
 	typeof(x) *__xp = &(x);						\
-	__unqual_scalar_typeof(x) __x = data_race(__READ_ONCE(*__xp));	\
+	__unqual_scalar_typeof(x) __x = __READ_ONCE(*__xp);		\
 	kcsan_check_atomic_read(__xp, sizeof(*__xp));			\
 	smp_read_barrier_depends();					\
 	(typeof(x))__x;							\
@@ -250,7 +250,7 @@ do {									\
 do {									\
 	typeof(x) *__xp = &(x);						\
 	kcsan_check_atomic_write(__xp, sizeof(*__xp));			\
-	data_race(({ __WRITE_ONCE(*__xp, val); 0; }));			\
+	__WRITE_ONCE(*__xp, val);					\
 } while (0)
 
 #define WRITE_ONCE(x, val)						\
-- 
2.26.2.761.g0e0b3e54be-goog