[2/5] atomic_inc_return-linux-2.6.9-rc1.x86_64.patch
This patch implements atomic_inc_return() and so on for x86_64.
It is same as I posted to LKML and Andi Kleen at '04/09/01.
Signed-off-by: KaiGai, Kohei <[email protected]>
--------
Kai Gai <[email protected]>
diff -rNU4 linux-2.6.9-rc1/include/asm-x86_64/atomic.h linux-2.6.9-rc1.atomic_inc_return/include/asm-x86_64/atomic.h
--- linux-2.6.9-rc1/include/asm-x86_64/atomic.h 2004-08-24 16:03:38.000000000 +0900
+++ linux-2.6.9-rc1.atomic_inc_return/include/asm-x86_64/atomic.h 2004-09-10 10:15:18.000000000 +0900
@@ -177,8 +177,33 @@
:"ir" (i), "m" (v->counter) : "memory");
return c;
}
+/**
+ * atomic_add_return - add and return
+ * @v: pointer of type atomic_t
+ * @i: integer value to add
+ *
+ * Atomically adds @i to @v and returns @i + @v
+ */
+static __inline__ int atomic_add_return(int i, atomic_t *v)
+{
+ int __i = i;
+ __asm__ __volatile__(
+ LOCK "xaddl %0, %1;"
+ :"=r"(i)
+ :"m"(v->counter), "0"(i));
+ return i + __i;
+}
+
+static __inline__ int atomic_sub_return(int i, atomic_t *v)
+{
+ return atomic_add_return(-i,v);
+}
+
+#define atomic_inc_return(v) (atomic_add_return(1,v))
+#define atomic_dec_return(v) (atomic_sub_return(1,v))
+
/* These are x86-specific, used by some header files */
#define atomic_clear_mask(mask, addr) \
__asm__ __volatile__(LOCK "andl %0,%1" \
: : "r" (~(mask)),"m" (*addr) : "memory")