set_mb 90 arch/x86/include/asm/barrier.h #define set_mb(var, value) do { (void)xchg(&var, value); } while (0) set_mb 96 arch/x86/include/asm/barrier.h #define set_mb(var, value) do { var = value; barrier(); } while (0) set_mb 62 include/asm-generic/barrier.h #define set_mb(var, value) do { (var) = (value); mb(); } while (0)