MIPS: cmpxchg: Implement __cmpxchg() as a function

Replace the macro definition of __cmpxchg() with an inline function,
which is easier to read & modify. The cmpxchg() & cmpxchg_local() macros
are adjusted to call the new __cmpxchg() function.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16353/
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 e9c1e97bc29da63ff50099b08e021dcd6c30c04f..516cb66f066b2f06828bf6fd45964b8d23e1ebf4 100644 (file)
--- a/arch/mips/include/asm/cmpxchg.h
+++ b/arch/mips/include/asm/cmpxchg.h
@@ -34,7 +34,7 @@
  *
  * - Get an error at link-time due to the call to the missing function.
  */
-extern void __cmpxchg_called_with_bad_pointer(void)
+extern unsigned long __cmpxchg_called_with_bad_pointer(void)
        __compiletime_error("Bad argument size for cmpxchg");
 extern unsigned long __xchg_called_with_bad_pointer(void)
        __compiletime_error("Bad argument size for xchg");
@@ -137,38 +137,43 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
        __ret;                                                          \
 })
 
-#define __cmpxchg(ptr, old, new, pre_barrier, post_barrier)            \
+static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+                                     unsigned long new, unsigned int size)
+{
+       switch (size) {
+       case 4:
+               return __cmpxchg_asm("ll", "sc", (volatile u32 *)ptr, old, new);
+
+       case 8:
+               /* lld/scd are only available for MIPS64 */
+               if (!IS_ENABLED(CONFIG_64BIT))
+                       return __cmpxchg_called_with_bad_pointer();
+
+               return __cmpxchg_asm("lld", "scd", (volatile u64 *)ptr, old, new);
+
+       default:
+               return __cmpxchg_called_with_bad_pointer();
+       }
+}
+
+#define cmpxchg_local(ptr, old, new)                                   \
+       ((__typeof__(*(ptr)))                                           \
+               __cmpxchg((ptr),                                        \
+                         (unsigned long)(__typeof__(*(ptr)))(old),     \
+                         (unsigned long)(__typeof__(*(ptr)))(new),     \
+                         sizeof(*(ptr))))
+
+#define cmpxchg(ptr, old, new)                                         \
 ({                                                                     \
-       __typeof__(ptr) __ptr = (ptr);                                  \
-       __typeof__(*(ptr)) __old = (old);                               \
-       __typeof__(*(ptr)) __new = (new);                               \
-       __typeof__(*(ptr)) __res = 0;                                   \
-                                                                       \
-       pre_barrier;                                                    \
-                                                                       \
-       switch (sizeof(*(__ptr))) {                                     \
-       case 4:                                                         \
-               __res = __cmpxchg_asm("ll", "sc", __ptr, __old, __new); \
-               break;                                                  \
-       case 8:                                                         \
-               if (sizeof(long) == 8) {                                \
-                       __res = __cmpxchg_asm("lld", "scd", __ptr,      \
-                                          __old, __new);               \
-                       break;                                          \
-               }                                                       \
-       default:                                                        \
-               __cmpxchg_called_with_bad_pointer();                    \
-               break;                                                  \
-       }                                                               \
+       __typeof__(*(ptr)) __res;                                       \
                                                                        \
-       post_barrier;                                                   \
+       smp_mb__before_llsc();                                          \
+       __res = cmpxchg_local((ptr), (old), (new));                     \
+       smp_llsc_mb();                                                  \
                                                                        \
        __res;                                                          \
 })
 
-#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, , )
-
 #ifdef CONFIG_64BIT
 #define cmpxchg64_local(ptr, o, n)                                     \
   ({                                                                   \