ipv6: don't count addrconf generated routes against gc limit

[ Upstream commit a3300ef4 ]

Brett Ciphery reported that new ipv6 addresses failed to get installed
because the addrconf generated dsts where counted against the dst gc
limit. We don't need to count those routes like we currently don't count
administratively added routes.

Because the max_addresses check enforces a limit on unbounded address
generation first in case someone plays with router advertisments, we
are still safe here.
Reported-by: Brett Ciphery <brett.ciphery@windriver.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/ipv6/route.c

@@ -2058,15 +2058,11 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
 {
 	struct net *net = dev_net(idev->dev);
 	struct rt6_info *rt = ip6_dst_alloc(&net->ipv6.ip6_dst_ops,
-					    net->loopback_dev, 0);
+					    net->loopback_dev, DST_NOCOUNT);
 	struct neighbour *neigh;
 
-	if (rt == NULL) {
-		if (net_ratelimit())
-			pr_warning("IPv6:  Maximum number of routes reached,"
-				   " consider increasing route/max_size.\n");
+	if (rt == NULL)
 		return ERR_PTR(-ENOMEM);
-	}
 
 	in6_dev_hold(idev);