Index: head/share/man/man9/EVENTHANDLER.9
===================================================================
--- head/share/man/man9/EVENTHANDLER.9
+++ head/share/man/man9/EVENTHANDLER.9
@@ -23,7 +23,7 @@
 .\" SUCH DAMAGE.
 .\" $FreeBSD$
 .\"
-.Dd September 6, 2018
+.Dd October 21, 2018
 .Dt EVENTHANDLER 9
 .Os
 .Sh NAME
@@ -298,6 +298,8 @@
 Callback invoked when an interfance has been removed from an interface group.
 .It Vt ifaddr_event
 Callbacks invoked when an address is set up on a network interface.
+.It Vt ifaddr_event_ext
+Callback invoked when an address has been added or removed from an interface. 
 .It Vt if_clone_event
 Callbacks invoked when an interface is cloned.
 .It Vt iflladdr_event
Index: head/sys/net/if.c
===================================================================
--- head/sys/net/if.c
+++ head/sys/net/if.c
@@ -328,6 +328,18 @@
 MALLOC_DEFINE(M_IFADDR, "ifaddr", "interface address");
 MALLOC_DEFINE(M_IFMADDR, "ether_multi", "link-level multicast address");
 
+/*
+ * Support for old ifaddr_event.
+ */
+static void
+ifaddr_event_compat(void *arg __unused, struct ifnet *ifp,
+    struct ifaddr *ifa __unused, int event __unused)
+{
+
+	EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+}
+EVENTHANDLER_DEFINE(ifaddr_event_ext, ifaddr_event_compat, NULL, 0);
+
 struct ifnet *
 ifnet_byindex_locked(u_short idx)
 {
Index: head/sys/net/if_var.h
===================================================================
--- head/sys/net/if_var.h
+++ head/sys/net/if_var.h
@@ -432,6 +432,11 @@
 /* interface address change event */
 typedef void (*ifaddr_event_handler_t)(void *, struct ifnet *);
 EVENTHANDLER_DECLARE(ifaddr_event, ifaddr_event_handler_t);
+typedef void (*ifaddr_event_ext_handler_t)(void *, struct ifnet *,
+    struct ifaddr *, int);
+EVENTHANDLER_DECLARE(ifaddr_event_ext, ifaddr_event_ext_handler_t);
+#define	IFADDR_EVENT_ADD	0
+#define	IFADDR_EVENT_DEL	1
 /* new interface arrival event */
 typedef void (*ifnet_arrival_event_handler_t)(void *, struct ifnet *);
 EVENTHANDLER_DECLARE(ifnet_arrival_event, ifnet_arrival_event_handler_t);
Index: head/sys/netinet/in.c
===================================================================
--- head/sys/netinet/in.c
+++ head/sys/netinet/in.c
@@ -520,7 +520,12 @@
 			&ii->ii_allhosts);
 	}
 
-	EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+	/*
+	 * Note: we don't need extra reference for ifa, since we called
+	 * with sx lock held, and ifaddr can not be deleted in concurrent
+	 * thread.
+	 */
+	EVENTHANDLER_INVOKE(ifaddr_event_ext, ifp, ifa, IFADDR_EVENT_ADD);
 
 	return (error);
 
@@ -643,7 +648,8 @@
 	}
 	IF_ADDR_WUNLOCK(ifp);
 
-	EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+	EVENTHANDLER_INVOKE(ifaddr_event_ext, ifp, &ia->ia_ifa,
+	    IFADDR_EVENT_DEL);
 	ifa_free(&ia->ia_ifa);		/* in_ifaddrhead */
 
 	return (0);
Index: head/sys/netinet6/in6.c
===================================================================
--- head/sys/netinet6/in6.c
+++ head/sys/netinet6/in6.c
@@ -712,7 +712,8 @@
 			ND6_WUNLOCK();
 			nd6_prefix_del(pr);
 		}
-		EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+		EVENTHANDLER_INVOKE(ifaddr_event_ext, ifp, &ia->ia_ifa,
+		    IFADDR_EVENT_DEL);
 		break;
 	}
 
@@ -1456,7 +1457,10 @@
 	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 	    "Invoking IPv6 network device address event may sleep");
 
-	EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+	ifa_ref(&ia->ia_ifa);
+	EVENTHANDLER_INVOKE(ifaddr_event_ext, ifp, &ia->ia_ifa,
+	    IFADDR_EVENT_ADD);
+	ifa_free(&ia->ia_ifa);
 
 	return (error);
 }