diff options
| -rw-r--r-- | include/qemu/atomic.h | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index 98e05ca875..bd2c075343 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -99,7 +99,13 @@ #ifndef smp_wmb #ifdef __ATOMIC_RELEASE -#define smp_wmb() __atomic_thread_fence(__ATOMIC_RELEASE) +/* __atomic_thread_fence does not include a compiler barrier; instead, + * the barrier is part of __atomic_load/__atomic_store's "volatile-like" + * semantics. If smp_wmb() is a no-op, absence of the barrier means that + * the compiler is free to reorder stores on each side of the barrier. + * Add one here, and similarly in smp_rmb() and smp_read_barrier_depends(). + */ +#define smp_wmb() ({ barrier(); __atomic_thread_fence(__ATOMIC_RELEASE); barrier(); }) #else #define smp_wmb() __sync_synchronize() #endif @@ -107,7 +113,7 @@ #ifndef smp_rmb #ifdef __ATOMIC_ACQUIRE -#define smp_rmb() __atomic_thread_fence(__ATOMIC_ACQUIRE) +#define smp_rmb() ({ barrier(); __atomic_thread_fence(__ATOMIC_ACQUIRE); barrier(); }) #else #define smp_rmb() __sync_synchronize() #endif @@ -115,7 +121,7 @@ #ifndef smp_read_barrier_depends #ifdef __ATOMIC_CONSUME -#define smp_read_barrier_depends() __atomic_thread_fence(__ATOMIC_CONSUME) +#define smp_read_barrier_depends() ({ barrier(); __atomic_thread_fence(__ATOMIC_CONSUME); barrier(); }) #else #define smp_read_barrier_depends() barrier() #endif |