[PATCH] Make cpu_relax() imply barrier() on all arches

During the recent discussion of taking 'volatile' off of the spinlock, I
noticed that while most arches #define cpu_relax() such that it implies
barrier(), some arches define cpu_relax() to be empty.

This patch changes the definition of cpu_relax() for frv, h8300, m68knommu,
sh, sh64, v850 and xtensa from an empty while(0) to the compiler barrier().

Signed-off-by: Chase Venters <chase.venters@clientec.com>
Acked-by: Arjan van de Ven <arjan@Linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/asm-m68knommu/processor.h b/include/asm-m68knommu/processor.h
index 0ee158e09abb..9d3a1bf41231 100644
--- a/include/asm-m68knommu/processor.h
+++ b/include/asm-m68knommu/processor.h
@@ -13,6 +13,7 @@
  */
 #define current_text_addr() ({ __label__ _l; _l: &&_l;})
 
+#include <linux/compiler.h>
 #include <linux/threads.h>
 #include <asm/types.h>
 #include <asm/segment.h>
@@ -137,6 +138,6 @@ unsigned long get_wchan(struct task_struct *p);
         eip; })
 #define KSTK_ESP(tsk)   ((tsk) == current ? rdusp() : (tsk)->thread.usp)
 
-#define cpu_relax()    do { } while (0)
+#define cpu_relax()    barrier()
 
 #endif