diff options
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index c00cc6c0878a..2594553bb30b 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -194,16 +194,22 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * 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. + * For example, if accesses to a given variable are protected by a lock, + * except for diagnostic code, then the accesses under the lock should + * be plain C-language accesses and those in the diagnostic code should + * use data_race(). This way, KCSAN will complain if buggy lockless + * accesses to that variable are introduced, even if the buggy accesses + * are protected by READ_ONCE() or WRITE_ONCE(). * * This macro *does not* affect normal code generation, but is a hint - * to tooling that data races here are to be ignored. + * to tooling that data races here are to be ignored. If the access must + * be atomic *and* KCSAN should ignore the access, use both data_race() + * and READ_ONCE(), for example, data_race(READ_ONCE(x)). */ #define data_race(expr) \ ({ \ - __unqual_scalar_typeof(({ expr; })) __v = ({ \ - __kcsan_disable_current(); \ - expr; \ - }); \ + __kcsan_disable_current(); \ + __auto_type __v = (expr); \ __kcsan_enable_current(); \ __v; \ }) @@ -268,7 +274,7 @@ static inline void *offset_to_ptr(const int *off) * - When one operand is a null pointer constant (i.e. when x is an integer * constant expression) and the other is an object pointer (i.e. our * third operand), the conditional operator returns the type of the - * object pointer operand (i.e. "int *). Here, within the sizeof(), we + * object pointer operand (i.e. "int *"). Here, within the sizeof(), we * would then get: * sizeof(*((int *)(...)) == sizeof(int) == 4 * - When one operand is a void pointer (i.e. when x is not an integer |