MIPS: New macro smp_mb__before_llsc.

Replace some instances of smp_llsc_mb() with a new macro
smp_mb__before_llsc().  It is used before ll/sc sequences that are
documented as needing write barrier semantics.

The default implementation of smp_mb__before_llsc() is just smp_llsc_mb(),
so there are no changes in semantics.

Also simplify definition of smp_mb(), smp_rmb(), and smp_wmb() to be just
barrier() in the non-SMP case.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/851/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h
index 815a438a268..ed9aaaaf074 100644
--- a/arch/mips/include/asm/cmpxchg.h
+++ b/arch/mips/include/asm/cmpxchg.h
@@ -72,14 +72,14 @@
  */
 extern void __cmpxchg_called_with_bad_pointer(void);
 
-#define __cmpxchg(ptr, old, new, barrier)                               \
+#define __cmpxchg(ptr, old, new, pre_barrier, post_barrier)             \
 ({                                                                      \
         __typeof__(ptr) __ptr = (ptr);                                  \
         __typeof__(*(ptr)) __old = (old);                               \
         __typeof__(*(ptr)) __new = (new);                               \
         __typeof__(*(ptr)) __res = 0;                                   \
                                                                         \
-        barrier;                                                        \
+        pre_barrier;                                                    \
                                                                         \
         switch (sizeof(*(__ptr))) {                                     \
         case 4:                                                         \
@@ -96,13 +96,13 @@ extern void __cmpxchg_called_with_bad_pointer(void);
                 break;                                                  \
         }                                                               \
                                                                         \
-        barrier;                                                        \
+        post_barrier;                                                   \
                                                                         \
         __res;                                                          \
 })
 
-#define cmpxchg(ptr, old, new)          __cmpxchg(ptr, old, new, smp_llsc_mb())
-#define cmpxchg_local(ptr, old, new)    __cmpxchg(ptr, old, new, )
+#define cmpxchg(ptr, old, new)          __cmpxchg(ptr, old, new, smp_mb__before_llsc(), smp_llsc_mb())
+#define cmpxchg_local(ptr, old, new)    __cmpxchg(ptr, old, new, , )
 
 #define cmpxchg64(ptr, o, n)                                            \
   ({                                                                    \