Implement atomic_fetchadd_long() for all architectures and document it.

Reviewed by:	attilio, jhb, jeff, kris (as a part of the uidinfo_waitfree.patch)

1 files changed, 20 insertions, 0 deletions

diff --git a/sys/amd64/include/atomic.h b/sys/amd64/include/atomic.h
index dc12d4d..0edbfff 100644
--- a/sys/amd64/include/atomic.h
+++ b/sys/amd64/include/atomic.h
@@ -74,6 +74,7 @@ void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
 int	atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src);
 int	atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src);
 u_int	atomic_fetchadd_int(volatile u_int *p, u_int v);
+u_long	atomic_fetchadd_long(volatile u_long *p, u_long v);
 
 #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)			\
 u_##TYPE	atomic_load_acq_##TYPE(volatile u_##TYPE *p);	\
@@ -174,6 +175,25 @@ atomic_fetchadd_int(volatile u_int *p, u_int v)
 	return (v);
 }
 
+/*
+ * Atomically add the value of v to the long integer pointed to by p and return
+ * the previous value of *p.
+ */
+static __inline u_long
+atomic_fetchadd_long(volatile u_long *p, u_long v)
+{
+
+	__asm __volatile(
+	"	" MPLOCKED "		"
+	"	xaddq	%0, %1 ;	"
+	"# atomic_fetchadd_long"
+	: "+r" (v),			/* 0 (result) */
+	  "=m" (*p)			/* 1 */
+	: "m" (*p));			/* 2 */
+
+	return (v);
+}
+
 #if defined(_KERNEL) && !defined(SMP)
 
 /*