The following commit has been merged into the locking/kcsan branch of tip: Commit-ID: 777f73c4e79106d45b304f6af0d31917864dbdf1 Gitweb: https://git.kernel.org/tip/777f73c4e79106d45b304f6af0d31917864dbdf1 Author: Marco Elver <elver@xxxxxxxxxx> AuthorDate: Thu, 21 May 2020 16:20:44 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Fri, 22 May 2020 15:19:53 +02:00 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@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Will Deacon <will@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20200521142047.169334-9-elver@xxxxxxxxxx --- 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 17c98b2..7444f02 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
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