Index: in6_pcb.c
===================================================================
RCS file: /home/dcvs/src/sys/netinet6/in6_pcb.c,v
retrieving revision 1.34
diff -u -u -r1.34 in6_pcb.c
--- in6_pcb.c	5 Jan 2008 14:02:40 -0000	1.34
+++ in6_pcb.c	11 Aug 2008 10:09:58 -0000
@@ -879,6 +879,20 @@
 
  		if ((inp->inp_vflag & INP_IPV6) == 0)
 			continue;
+		/*
+		 * If the error designates a new path MTU for a destination
+		 * and the application (associated with this socket) wanted to
+		 * know the value, notify. Note that we notify for all
+		 * disconnected sockets if the corresponding application
+		 * wanted. This is because some UDP applications keep sending
+		 * sockets disconnected.
+		 * XXX: should we avoid to notify the value to TCP sockets?
+		 */
+		if (cmd == PRC_MSGSIZE && (inp->inp_flags & IN6P_MTU) != 0 &&
+		    (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) ||
+		     IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &sa6_dst->sin6_addr))) {
+			ip6_notify_pmtu(inp, (struct sockaddr_in6 *)dst, arg);
+		}
 
 		/*
 		 * Detect if we should notify the error. If no source and