diff options
Diffstat (limited to 'tools/virtio/linux/compiler.h')
| -rw-r--r-- | tools/virtio/linux/compiler.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/tools/virtio/linux/compiler.h b/tools/virtio/linux/compiler.h index 1f3a15b954b9..204ef0e9f542 100644 --- a/tools/virtio/linux/compiler.h +++ b/tools/virtio/linux/compiler.h @@ -10,4 +10,29 @@ #define READ_ONCE(var) (*((volatile typeof(var) *)(&(var)))) #define __aligned(x) __attribute((__aligned__(x))) + +/** + * 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. + * 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. 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) \ +({ \ + __auto_type __v = (expr); \ + __v; \ +}) + #endif |