The volatile accesses no longer need to be wrapped in data_race(), because we require compilers that emit instrumentation distinguishing volatile accesses. Consequently, we also no longer require the explicit kcsan_check_atomic*(), since the compiler emits instrumentation distinguishing the volatile accesses. Finally, simplify __READ_ONCE_SCALAR and remove __WRITE_ONCE_SCALAR.
Signed-off-by: Marco Elver <el...@google.com> --- v2: * Remove unnecessary kcsan_check_atomic*() in *_ONCE. * Simplify __READ_ONCE_SCALAR and remove __WRITE_ONCE_SCALAR. This effectively restores Will Deacon's pre-KCSAN version: https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/tree/include/linux/compiler.h?h=rwonce/cleanup#n202 --- include/linux/compiler.h | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 17c98b215572..7444f026eead 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -228,9 +228,7 @@ 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; \ }) @@ -246,17 +244,10 @@ 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 -- 2.26.2.761.g0e0b3e54be-goog
