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>
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h
index 815a438..ed9aaaaf 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 @@
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) \
({ \