Index: alpha/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/alpha/include/atomic.h,v
retrieving revision 1.23
diff -u -r1.23 atomic.h
--- alpha/include/atomic.h	15 Sep 2005 19:31:22 -0000	1.23
+++ alpha/include/atomic.h	26 Sep 2005 21:05:43 -0000
@@ -365,6 +365,27 @@
 	return (atomic_cmpset_64(p, cmpval, newval));
 }
 
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ */
+static __inline u_int
+atomic_fetchadd_32(volatile u_int32_t *p, u_int32_t v)
+{
+	u_int32_t value, temp;
+
+#ifdef __GNUCLIKE_ASM
+	__asm __volatile (
+		"1:\tldl_l %0, %1\n\t"		/* load old value */
+		"addl %0, %3, %2\n\t"		/* calculate new value */
+		"stl_c %2, %1\n\t"		/* attempt to store */
+		"beq %2, 1b\n"			/* spin if failed */
+		: "=&r" (value), "=m" (*p), "=r" (temp)
+		: "r" (v), "m" (*p));
+#endif
+	return (value);
+}
+
 /* Operations on chars. */
 #define	atomic_set_char		atomic_set_8
 #define	atomic_set_acq_char	atomic_set_acq_8
@@ -412,6 +433,7 @@
 #define	atomic_load_acq_int	atomic_load_acq_32
 #define	atomic_store_rel_int	atomic_store_rel_32
 #define	atomic_readandclear_int	atomic_readandclear_32
+#define	atomic_fetchadd_int	atomic_fetchadd_32
 
 /* Operations on longs. */
 #define	atomic_set_long		atomic_set_64
Index: amd64/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/amd64/include/atomic.h,v
retrieving revision 1.38
diff -u -r1.38 atomic.h
--- amd64/include/atomic.h	15 Sep 2005 19:31:22 -0000	1.38
+++ amd64/include/atomic.h	26 Sep 2005 21:05:43 -0000
@@ -73,6 +73,7 @@
 
 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);
 
 #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)			\
 u_##TYPE	atomic_load_acq_##TYPE(volatile u_##TYPE *p);	\
@@ -154,6 +155,25 @@
 	return (res);
 }
 
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ */
+static __inline u_int
+atomic_fetchadd_int(volatile u_int *p, u_int v)
+{
+
+	__asm __volatile (
+	"	" __XSTRING(MPLOCKED) "	"
+	"	xaddl	%0, %1 ;	"
+	"# atomic_fetchadd_int"
+	: "+r" (v),			/* 0 (result) */
+	  "=m" (*p)			/* 1 */
+	: "m" (*p));			/* 2 */
+
+	return (v);
+}
+
 #if defined(_KERNEL) && !defined(SMP)
 
 /*
@@ -375,6 +395,7 @@
 #define	atomic_cmpset_acq_32	atomic_cmpset_acq_int
 #define	atomic_cmpset_rel_32	atomic_cmpset_rel_int
 #define	atomic_readandclear_32	atomic_readandclear_int
+#define	atomic_fetchadd_32	atomic_fetchadd_int
 
 /* Operations on 64-bit quad words. */
 #define	atomic_set_64		atomic_set_long
Index: arm/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/arm/include/atomic.h,v
retrieving revision 1.10
diff -u -r1.10 atomic.h
--- arm/include/atomic.h	27 Jul 2005 20:01:44 -0000	1.10
+++ arm/include/atomic.h	26 Sep 2005 20:58:58 -0000
@@ -262,6 +262,17 @@
 	return (__swp(0, p));
 }
 
+static __inline uint32_t
+atomic_fetchadd_32(volatile uint32_t *p, uint32_t v)
+{
+	uint32_t value;
+
+	do {
+		value = *p;
+	} while (!atomic_cmpset_32(p, value, value + v));
+	return (value);
+}
+
 #undef __with_interrupts_disabled
 
 #endif /* _LOCORE */
@@ -291,5 +302,6 @@
 #define	atomic_store_ptr		atomic_store_32
 #define	atomic_cmpset_ptr		atomic_cmpset_32
 #define	atomic_set_ptr			atomic_set_32
+#define	atomic_fetchadd_int		atomic_fetchadd_32
 
 #endif /* _MACHINE_ATOMIC_H_ */
Index: i386/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/i386/include/atomic.h,v
retrieving revision 1.40
diff -u -r1.40 atomic.h
--- i386/include/atomic.h	15 Sep 2005 19:31:22 -0000	1.40
+++ i386/include/atomic.h	26 Sep 2005 21:05:43 -0000
@@ -72,6 +72,7 @@
 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);
+u_int atomic_fetchadd_int(volatile u_int *p, u_int v);
 
 #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)			\
 u_##TYPE	atomic_load_acq_##TYPE(volatile u_##TYPE *p);	\
@@ -163,6 +164,25 @@
 
 #endif /* defined(CPU_DISABLE_CMPXCHG) */
 
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ */
+static __inline u_int
+atomic_fetchadd_int(volatile u_int *p, u_int v)
+{
+
+	__asm __volatile (
+	"	" __XSTRING(MPLOCKED) "	"
+	"	xaddl	%0, %1 ;	"
+	"# atomic_fetchadd_int"
+	: "+r" (v),			/* 0 (result) */
+	  "=m" (*p)			/* 1 */
+	: "m" (*p));			/* 2 */
+
+	return (v);
+}
+
 #if defined(_KERNEL) && !defined(SMP)
 
 /*
@@ -392,6 +412,7 @@
 #define	atomic_cmpset_acq_32	atomic_cmpset_acq_int
 #define	atomic_cmpset_rel_32	atomic_cmpset_rel_int
 #define	atomic_readandclear_32	atomic_readandclear_int
+#define	atomic_fetchadd_32	atomic_fetchadd_int
 
 /* Operations on pointers. */
 #define	atomic_set_ptr		atomic_set_int
Index: ia64/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/ia64/include/atomic.h,v
retrieving revision 1.9
diff -u -r1.9 atomic.h
--- ia64/include/atomic.h	15 Jul 2005 18:17:58 -0000	1.9
+++ ia64/include/atomic.h	26 Sep 2005 21:05:43 -0000
@@ -342,4 +342,23 @@
 #define	atomic_readandclear_int		atomic_readandclear_32
 #define	atomic_readandclear_long	atomic_readandclear_64
 
+/*
+ * Atomically add the value of v to the integer pointed to by p and return
+ * the previous value of *p.
+ *
+ * XXX: Should we use the fetchadd instruction here?
+ */
+static __inline uint32_t
+atomic_fetchadd_32(volatile uint32_t *p, uint32_t v)
+{
+	uint32_t value;
+
+	do {
+		value = *p;
+	} while (!atomic_cmpset_32(p, value, value + v));
+	return (value);
+}
+
+#define	atomic_fetchadd_int		atomic_fetchadd_32
+
 #endif /* ! _MACHINE_ATOMIC_H_ */
Index: powerpc/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/powerpc/include/atomic.h,v
retrieving revision 1.13
diff -u -r1.13 atomic.h
--- powerpc/include/atomic.h	15 Sep 2005 19:31:22 -0000	1.13
+++ powerpc/include/atomic.h	26 Sep 2005 20:58:58 -0000
@@ -444,4 +444,17 @@
 #define	atomic_cmpset_acq_ptr	atomic_cmpset_acq_32
 #define	atomic_cmpset_rel_ptr	atomic_cmpset_rel_32
 
+static __inline uint32_t
+atomic_fetchadd_32(volatile uint32_t *p, uint32_t v)
+{
+	uint32_t value;
+
+	do {
+		value = *p;
+	} while (!atomic_cmpset_32(p, value, value + v));
+	return (value);
+}
+
+#define	atomic_fetchadd_int	atomic_fetchadd_32
+
 #endif /* ! _MACHINE_ATOMIC_H_ */
Index: sparc64/include/atomic.h
===================================================================
RCS file: /usr/cvs/src/sys/sparc64/include/atomic.h,v
retrieving revision 1.9
diff -u -r1.9 atomic.h
--- sparc64/include/atomic.h	15 Jul 2005 18:17:58 -0000	1.9
+++ sparc64/include/atomic.h	26 Sep 2005 20:58:58 -0000
@@ -277,6 +277,9 @@
 
 ATOMIC_GEN(ptr, uintptr_t *, uintptr_t, uintptr_t, 64);
 
+#define	atomic_fetchadd_int	atomic_add_int
+#define	atomic_fetchadd_32	atomic_add_32
+
 #undef ATOMIC_GEN
 #undef atomic_cas
 #undef atomic_cas_acq