Rather then open-code the disabling/enabling of KCSAN across the guts of
{READ,WRITE}_ONCE(), defer to the data_race() macro instead.Cc: Marco Elver <[email protected]> Signed-off-by: Will Deacon <[email protected]> --- include/linux/compiler.h | 53 ++++++++++++++++++---------------------- 1 file changed, 24 insertions(+), 29 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index f2a64195ee8e..d21a823e73c6 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -199,6 +199,26 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, #include <linux/kasan-checks.h> #include <linux/kcsan-checks.h> +/** + * data_race - mark an expression as containing intentional data races + * + * This data_race() macro is useful for situations in which data races + * should be forgiven. One example is diagnostic code that accesses + * shared variables but is not a part of the core synchronization design. + * + * This macro *does not* affect normal code generation, but is a hint + * to tooling that data races here are to be ignored. + */ +#define data_race(expr) \ +({ \ + __kcsan_disable_current(); \ + ({ \ + __unqual_scalar_typeof(({ expr; })) __v = ({ expr; }); \ + __kcsan_enable_current(); \ + __v; \ + }); \ +}) + /* * Use __READ_ONCE() instead of READ_ONCE() if you do not require any * atomicity or dependency ordering guarantees. Note that this may result @@ -209,14 +229,10 @@ 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)); \ - __kcsan_disable_current(); \ - ({ \ - __unqual_scalar_typeof(x) __x = __READ_ONCE(*__xp); \ - __kcsan_enable_current(); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ - }); \ + smp_read_barrier_depends(); \ + (typeof(x))__x; \ }) #define READ_ONCE(x) \ @@ -234,9 +250,7 @@ do { \ do { \ typeof(x) *__xp = &(x); \ kcsan_check_atomic_write(__xp, sizeof(*__xp)); \ - __kcsan_disable_current(); \ - __WRITE_ONCE(*__xp, val); \ - __kcsan_enable_current(); \ + data_race(({ __WRITE_ONCE(*__xp, val); 0; })); \ } while (0) #define WRITE_ONCE(x, val) \ @@ -304,25 +318,6 @@ unsigned long read_word_at_a_time(const void *addr) return *(unsigned long *)addr; } -/** - * data_race - mark an expression as containing intentional data races - * - * This data_race() macro is useful for situations in which data races - * should be forgiven. One example is diagnostic code that accesses - * shared variables but is not a part of the core synchronization design. - * - * This macro *does not* affect normal code generation, but is a hint - * to tooling that data races here are to be ignored. - */ -#define data_race(expr) \ -({ \ - __kcsan_disable_current(); \ - ({ \ - __unqual_scalar_typeof(({ expr; })) __v = ({ expr; }); \ - __kcsan_enable_current(); \ - __v; \ - }); \ -}) #else #endif /* __KERNEL__ */ -- 2.26.2.645.ge9eca65c58-goog
