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authorMarco Elver <elver@google.com>2020-05-21 17:20:44 +0300
committerThomas Gleixner <tglx@linutronix.de>2020-06-11 21:04:03 +0300
commit44b97dccb2291a56454549827adc5e99d94811f3 (patch)
tree51af718dd6e23737c8ee29bab352f52c71a995e6 /include
parent0bb9ab3a6fa7ca9f627d85f6f683fae51598e8c8 (diff)
downloadlinux-44b97dccb2291a56454549827adc5e99d94811f3.tar.xz
compiler.h: Remove data_race() and unnecessary checks from {READ,WRITE}_ONCE()
The volatile accesses no longer need to be wrapped in data_race() because compilers that emit instrumentation distinguishing volatile accesses are required for KCSAN. Consequently, the explicit kcsan_check_atomic*() are no longer required either since the compiler emits instrumentation distinguishing the volatile accesses. Finally, simplify __READ_ONCE_SCALAR() and remove __WRITE_ONCE_SCALAR(). [ bp: Convert commit message to passive voice. ] Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lkml.kernel.org/r/20200521142047.169334-9-elver@google.com
Diffstat (limited to 'include')
-rw-r--r--include/linux/compiler.h13
1 files changed, 2 insertions, 11 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 6d307c0aa4b4..7b090d263fec 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -281,9 +281,7 @@ 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)); \
- kcsan_check_atomic_read(__xp, sizeof(*__xp)); \
+ __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \
smp_read_barrier_depends(); \
(typeof(x))__x; \
})
@@ -299,17 +297,10 @@ do { \
*(volatile typeof(x) *)&(x) = (val); \
} while (0)
-#define __WRITE_ONCE_SCALAR(x, val) \
-do { \
- typeof(x) *__xp = &(x); \
- kcsan_check_atomic_write(__xp, sizeof(*__xp)); \
- data_race(({ __WRITE_ONCE(*__xp, val); 0; })); \
-} while (0)
-
#define WRITE_ONCE(x, val) \
do { \
compiletime_assert_rwonce_type(x); \
- __WRITE_ONCE_SCALAR(x, val); \
+ __WRITE_ONCE(x, val); \
} while (0)
#ifdef CONFIG_KASAN