x86: fix IO write barrier
wmb() on x86 must always include a barrier, because stores can go out of
order in many cases when dealing with devices (eg. WC memory).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-x86/system_64.h b/include/asm-x86/system_64.h
index 02175aa..eff730b 100644
--- a/include/asm-x86/system_64.h
+++ b/include/asm-x86/system_64.h
@@ -159,12 +159,8 @@
*/
#define mb() asm volatile("mfence":::"memory")
#define rmb() asm volatile("lfence":::"memory")
-
-#ifdef CONFIG_UNORDERED_IO
#define wmb() asm volatile("sfence" ::: "memory")
-#else
-#define wmb() asm volatile("" ::: "memory")
-#endif
+
#define read_barrier_depends() do {} while(0)
#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)