[S390] empty function defines.

Use do { } while (0) constructs instead of empty defines to avoid
subtle compile bugs.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/asm-s390/io.h b/include/asm-s390/io.h
index d4614b35f423..a6cc27e77007 100644
--- a/include/asm-s390/io.h
+++ b/include/asm-s390/io.h
@@ -116,7 +116,7 @@ extern void iounmap(void *addr);
 #define outb(x,addr) ((void) writeb(x,addr))
 #define outb_p(x,addr) outb(x,addr)
 
-#define mmiowb()
+#define mmiowb()        do { } while (0)
 
 /*
  * Convert a physical pointer to a virtual kernel pointer for /dev/mem