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| author | Marco Elver <elver@google.com> | 2020-05-21 17:20:44 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-06-11 21:04:03 +0300 |
| commit | 44b97dccb2291a56454549827adc5e99d94811f3 (patch) | |
| tree | 51af718dd6e23737c8ee29bab352f52c71a995e6 /include | |
| parent | 0bb9ab3a6fa7ca9f627d85f6f683fae51598e8c8 (diff) | |
| download | linux-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.h | 13 |
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 |