FRV: Don't make smp_{r, w, }mb() interpolate MEMBAR when CONFIG_SMP=n [try #2]

Don't make smp_{r,w,}mb() interpolate a MEMBAR instruction when CONFIG_SMP=n as
SMP memory barries on UP systems should interpolate a compiler barrier only.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 6 deletions

diff --git a/include/asm-frv/system.h b/include/asm-frv/system.h
index 2c57f4734746..30a67a9da11a 100644
--- a/include/asm-frv/system.h
+++ b/include/asm-frv/system.h
@@ -179,14 +179,23 @@ do {							\
 #define mb()                    asm volatile ("membar" : : :"memory")
 #define rmb()                   asm volatile ("membar" : : :"memory")
 #define wmb()                   asm volatile ("membar" : : :"memory")
-#define set_mb(var, value)      do { var = value; mb(); } while (0)
+#define read_barrier_depends()  barrier()
 
-#define smp_mb()                mb()
-#define smp_rmb()               rmb()
-#define smp_wmb()               wmb()
-
-#define read_barrier_depends()          do {} while(0)
+#ifdef CONFIG_SMP
+#define smp_mb()                        mb()
+#define smp_rmb()                       rmb()
+#define smp_wmb()                       wmb()
 #define smp_read_barrier_depends()      read_barrier_depends()
+#define set_mb(var, value) \
+        do { xchg(&var, (value)); } while (0)
+#else
+#define smp_mb()                        barrier()
+#define smp_rmb()                       barrier()
+#define smp_wmb()                       barrier()
+#define smp_read_barrier_depends()      do {} while(0)
+#define set_mb(var, value) \
+        do { var = (value); barrier(); } while (0)
+#endif
 
 #define HARD_RESET_NOW()                        \
 do {                                            \