[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-xtensa/processor.h b/include/asm-xtensa/processor.h
index d1d72ad36f08..8b96e77c9d82 100644
--- a/include/asm-xtensa/processor.h
+++ b/include/asm-xtensa/processor.h
@@ -20,6 +20,7 @@
 #include <xtensa/config/tie.h>
 #include <xtensa/config/system.h>
 
+#include <linux/compiler.h>
 #include <asm/ptrace.h>
 #include <asm/types.h>
 #include <asm/coprocessor.h>
@@ -191,7 +192,7 @@ extern unsigned long get_wchan(struct task_struct *p);
 #define KSTK_EIP(tsk)           (task_pt_regs(tsk)->pc)
 #define KSTK_ESP(tsk)           (task_pt_regs(tsk)->areg[1])
 
-#define cpu_relax()  do { } while (0)
+#define cpu_relax()  barrier()
 
 /* Special register access. */