1#if defined(__i386__) || defined(__x86_64__) 2#define barrier() asm volatile("" ::: "memory") 3#define virt_mb() __sync_synchronize() 4#define virt_rmb() barrier() 5#define virt_wmb() barrier() 6/* Atomic store should be enough, but gcc generates worse code in that case. */ 7#define virt_store_mb(var, value) do { \ 8 typeof(var) virt_store_mb_value = (value); \ 9 __atomic_exchange(&(var), &virt_store_mb_value, &virt_store_mb_value, \ 10 __ATOMIC_SEQ_CST); \ 11 barrier(); \ 12} while (0); 13/* Weak barriers should be used. If not - it's a bug */ 14# define mb() abort() 15# define rmb() abort() 16# define wmb() abort() 17#else 18#error Please fill in barrier macros 19#endif 20 21