x86: consolidate xchg and xadd macros

They both have a basic "put new value in location, return old value"
pattern, so they can use the same macro easily.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>

diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index 49eade1..5488e10 100644 (file)
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -33,60 +33,47 @@ extern void __add_wrong_size(void)
 #define        __X86_CASE_Q    -1              /* sizeof will never return -1 */
 #endif
 
+/* 
+ * An exchange-type operation, which takes a value and a pointer, and
+ * returns a the old value.
+ */
+#define __xchg_op(ptr, arg, op, lock)                                  \
+       ({                                                              \
+               __typeof__ (*(ptr)) __ret = (arg);                      \
+               switch (sizeof(*(ptr))) {                               \
+               case __X86_CASE_B:                                      \
+                       asm volatile (lock #op "b %b0, %1\n"            \
+                                     : "+r" (__ret), "+m" (*(ptr))     \
+                                     : : "memory", "cc");              \
+                       break;                                          \
+               case __X86_CASE_W:                                      \
+                       asm volatile (lock #op "w %w0, %1\n"            \
+                                     : "+r" (__ret), "+m" (*(ptr))     \
+                                     : : "memory", "cc");              \
+                       break;                                          \
+               case __X86_CASE_L:                                      \
+                       asm volatile (lock #op "l %0, %1\n"             \
+                                     : "+r" (__ret), "+m" (*(ptr))     \
+                                     : : "memory", "cc");              \
+                       break;                                          \
+               case __X86_CASE_Q:                                      \
+                       asm volatile (lock #op "q %q0, %1\n"            \
+                                     : "+r" (__ret), "+m" (*(ptr))     \
+                                     : : "memory", "cc");              \
+                       break;                                          \
+               default:                                                \
+                       __ ## op ## _wrong_size();                      \
+               }                                                       \
+               __ret;                                                  \
+       })
+
 /*
  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway.
  * Since this is generally used to protect other memory information, we
  * use "asm volatile" and "memory" clobbers to prevent gcc from moving
  * information around.
  */
-#define __xchg(x, ptr, size)                                           \
-({                                                                     \
-       __typeof(*(ptr)) __x = (x);                                     \
-       switch (size) {                                                 \
-       case __X86_CASE_B:                                              \
-       {                                                               \
-               volatile u8 *__ptr = (volatile u8 *)(ptr);              \
-               asm volatile("xchgb %0,%1"                              \
-                            : "=q" (__x), "+m" (*__ptr)                \
-                            : "0" (__x)                                \
-                            : "memory");                               \
-               break;                                                  \
-       }                                                               \
-       case __X86_CASE_W:                                              \
-       {                                                               \
-               volatile u16 *__ptr = (volatile u16 *)(ptr);            \
-               asm volatile("xchgw %0,%1"                              \
-                            : "=r" (__x), "+m" (*__ptr)                \
-                            : "0" (__x)                                \
-                            : "memory");                               \
-               break;                                                  \
-       }                                                               \
-       case __X86_CASE_L:                                              \
-       {                                                               \
-               volatile u32 *__ptr = (volatile u32 *)(ptr);            \
-               asm volatile("xchgl %0,%1"                              \
-                            : "=r" (__x), "+m" (*__ptr)                \
-                            : "0" (__x)                                \
-                            : "memory");                               \
-               break;                                                  \
-       }                                                               \
-       case __X86_CASE_Q:                                              \
-       {                                                               \
-               volatile u64 *__ptr = (volatile u64 *)(ptr);            \
-               asm volatile("xchgq %0,%1"                              \
-                            : "=r" (__x), "+m" (*__ptr)                \
-                            : "0" (__x)                                \
-                            : "memory");                               \
-               break;                                                  \
-       }                                                               \
-       default:                                                        \
-               __xchg_wrong_size();                                    \
-       }                                                               \
-       __x;                                                            \
-})
-
-#define xchg(ptr, v)                                                   \
-       __xchg((v), (ptr), sizeof(*ptr))
+#define xchg(ptr, v)   __xchg_op((ptr), (v), xchg, "")
 
 /*
  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
@@ -167,36 +154,6 @@ extern void __add_wrong_size(void)
        __cmpxchg_local((ptr), (old), (new), sizeof(*ptr))
 #endif
 
-#define __xadd(ptr, inc, lock)                                         \
-       ({                                                              \
-               __typeof__ (*(ptr)) __ret = (inc);                      \
-               switch (sizeof(*(ptr))) {                               \
-               case __X86_CASE_B:                                      \
-                       asm volatile (lock "xaddb %b0, %1\n"            \
-                                     : "+r" (__ret), "+m" (*(ptr))     \
-                                     : : "memory", "cc");              \
-                       break;                                          \
-               case __X86_CASE_W:                                      \
-                       asm volatile (lock "xaddw %w0, %1\n"            \
-                                     : "+r" (__ret), "+m" (*(ptr))     \
-                                     : : "memory", "cc");              \
-                       break;                                          \
-               case __X86_CASE_L:                                      \
-                       asm volatile (lock "xaddl %0, %1\n"             \
-                                     : "+r" (__ret), "+m" (*(ptr))     \
-                                     : : "memory", "cc");              \
-                       break;                                          \
-               case __X86_CASE_Q:                                      \
-                       asm volatile (lock "xaddq %q0, %1\n"            \
-                                     : "+r" (__ret), "+m" (*(ptr))     \
-                                     : : "memory", "cc");              \
-                       break;                                          \
-               default:                                                \
-                       __xadd_wrong_size();                            \
-               }                                                       \
-               __ret;                                                  \
-       })
-
 /*
  * xadd() adds "inc" to "*ptr" and atomically returns the previous
  * value of "*ptr".
@@ -205,6 +162,7 @@ extern void __add_wrong_size(void)
  * xadd_sync() is always locked
  * xadd_local() is never locked
  */
+#define __xadd(ptr, inc, lock) __xchg_op((ptr), (inc), xadd, lock)
 #define xadd(ptr, inc)         __xadd((ptr), (inc), LOCK_PREFIX)
 #define xadd_sync(ptr, inc)    __xadd((ptr), (inc), "lock; ")
 #define xadd_local(ptr, inc)   __xadd((ptr), (inc), "")