[IPV6]: Deprecate all-on-link assumption

If we don't have IPv6 default routes, we assume all ipv6 destinations 
are on-link as specified in RFC2461. It, however, is considered harmful now;
it is problematic with IPv6-capable nodes that do not have off-link
IPv6 connectivity (eg no default routers) and such nodes will take
a few seconds until they fall back to use IPv4.

See <draft-ietf-v6ops-onlinkassumption-02.txt> for details.

From: KUNITAKE Koichi <kunitake@anchor.jp>
Signed-off-by: KUNITAKE Koichi <kunitake@anchor.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -2108,21 +2108,13 @@ static void addrconf_rs_timer(unsigned long data)
 
 		ndisc_send_rs(ifp->idev->dev, &ifp->addr, &all_routers);
 	} else {
-		struct in6_rtmsg rtmsg;
-
 		spin_unlock(&ifp->lock);
-
+		/*
+		 * Note: we do not support deprecated "all on-link"
+		 * assumption any longer.
+		 */
 		printk(KERN_DEBUG "%s: no IPv6 routers present\n",
 		       ifp->idev->dev->name);
-
-		memset(&rtmsg, 0, sizeof(struct in6_rtmsg));
-		rtmsg.rtmsg_type = RTMSG_NEWROUTE;
-		rtmsg.rtmsg_metric = IP6_RT_PRIO_ADDRCONF;
-		rtmsg.rtmsg_flags = (RTF_ALLONLINK | RTF_DEFAULT | RTF_UP);
-
-		rtmsg.rtmsg_ifindex = ifp->idev->dev->ifindex;
-
-		ip6_route_add(&rtmsg, NULL, NULL);
 	}
 
 out: