atomic.h: add atomic64 cmpxchg, xchg and add_unless to alpha

This series mainly adds support for missing 64 bits cmpxchg and 64 bits atomic
add unless.  Therefore, principally 64 bits architectures are targeted by
these patches.  It also adds the complete list of atomic operations on the
atomic_long type.

This patch:

atomic.h: add atomic64 cmpxchg, xchg and add_unless to alpha
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/asm-alpha/atomic.h

@@ -175,19 +175,62 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t * v)
 	return result;
 }
 
-#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
+#define atomic64_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), old, new))
+#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
+
+#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), old, new))
 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
 
+/**
+ * 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.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
 #define atomic_add_unless(v, a, u)				\
 ({								\
-	int c, old;						\
+	__typeof__((v)->counter) c, old;			\
 	c = atomic_read(v);					\
-	while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+	for (;;) {						\
+		if (unlikely(c == (u)))				\
+			break;					\
+		old = atomic_cmpxchg((v), c, c + (a));		\
+		if (likely(old == c))				\
+			break;					\
 		c = old;					\
+	}							\
 	c != (u);						\
 })
 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
 
+/**
+ * atomic64_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic64_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic64_add_unless(v, a, u)				\
+({								\
+	__typeof__((v)->counter) c, old;			\
+	c = atomic64_read(v);					\
+	for (;;) {						\
+		if (unlikely(c == (u)))				\
+			break;					\
+		old = atomic64_cmpxchg((v), c, c + (a));	\
+		if (likely(old == c))				\
+			break;					\
+		c = old;					\
+	}							\
+	c != (u);						\
+})
+#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
+
 #define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
 #define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)