atomic: move atomic_add_unless to generic code

This is in preparation for more generic atomic primitives based on
__atomic_add_unless.

Signed-off-by: Arun Sharma <asharma@fb.com>
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 25 insertions, 32 deletions

diff --git a/arch/avr32/include/asm/atomic.h b/arch/avr32/include/asm/atomic.h
index f229c3849f03..dc6c3a41a2d7 100644
--- a/arch/avr32/include/asm/atomic.h
+++ b/arch/avr32/include/asm/atomic.h
@@ -78,70 +78,63 @@ static inline int atomic_add_return(int i, atomic_t *v)
 /*
  * atomic_sub_unless - sub unless the number is a given value
  * @v: pointer of type atomic_t
- * @a: the amount to add to v...
+ * @a: the amount to subtract from v...
  * @u: ...unless v is equal to u.
  *
- * If the atomic value v is not equal to u, this function subtracts a
- * from v, and returns non zero. If v is equal to u then it returns
- * zero. This is done as an atomic operation.
+ * Atomically subtract @a from @v, so long as it was not @u.
+ * Returns the old value of @v.
 */
-static inline int atomic_sub_unless(atomic_t *v, int a, int u)
+static inline void atomic_sub_unless(atomic_t *v, int a, int u)
 {
-        int tmp, result = 0;
+        int tmp;
 
         asm volatile(
                 "/* atomic_sub_unless */\n"
                 "1:     ssrf    5\n"
-                "       ld.w    %0, %3\n"
-                "       cp.w    %0, %5\n"
+                "       ld.w    %0, %2\n"
+                "       cp.w    %0, %4\n"
                 "       breq    1f\n"
-                "       sub     %0, %4\n"
-                "       stcond  %2, %0\n"
+                "       sub     %0, %3\n"
+                "       stcond  %1, %0\n"
                 "       brne    1b\n"
-                "       mov     %1, 1\n"
                 "1:"
-                : "=&r"(tmp), "=&r"(result), "=o"(v->counter)
-                : "m"(v->counter), "rKs21"(a), "rKs21"(u), "1"(result)
+                : "=&r"(tmp), "=o"(v->counter)
+                : "m"(v->counter), "rKs21"(a), "rKs21"(u)
                 : "cc", "memory");
-
-        return result;
 }
 
 /*
- * atomic_add_unless - add unless the number is a given value
+ * __atomic_add_unless - add unless the number is a given value
  * @v: pointer of type atomic_t
  * @a: the amount to add to v...
  * @u: ...unless v is equal to u.
  *
- * If the atomic value v is not equal to u, this function adds a to v,
- * and returns non zero. If v is equal to u then it returns zero. This
- * is done as an atomic operation.
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns the old value of @v.
 */
-static inline int atomic_add_unless(atomic_t *v, int a, int u)
+static inline int __atomic_add_unless(atomic_t *v, int a, int u)
 {
-        int tmp, result;
+        int tmp, old = atomic_read(v);
 
         if (__builtin_constant_p(a) && (a >= -1048575) && (a <= 1048576))
-                result = atomic_sub_unless(v, -a, u);
+                atomic_sub_unless(v, -a, u);
         else {
-                result = 0;
                 asm volatile(
-                        "/* atomic_add_unless */\n"
+                        "/* __atomic_add_unless */\n"
                         "1:     ssrf    5\n"
-                        "       ld.w    %0, %3\n"
-                        "       cp.w    %0, %5\n"
+                        "       ld.w    %0, %2\n"
+                        "       cp.w    %0, %4\n"
                         "       breq    1f\n"
-                        "       add     %0, %4\n"
-                        "       stcond  %2, %0\n"
+                        "       add     %0, %3\n"
+                        "       stcond  %1, %0\n"
                         "       brne    1b\n"
-                        "       mov     %1, 1\n"
                         "1:"
-                        : "=&r"(tmp), "=&r"(result), "=o"(v->counter)
-                        : "m"(v->counter), "r"(a), "ir"(u), "1"(result)
+                        : "=&r"(tmp), "=o"(v->counter)
+                        : "m"(v->counter), "r"(a), "ir"(u)
                         : "cc", "memory");
         }
 
-        return result;
+        return old;
 }
 
 /*