vti6: Remove dst_entry caching

Unlike ip6_tunnel, vti6 can lookup multiple different dst entries,
dependent of the configured xfrm states. Therefore it does not make
sense to cache a dst_entry.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv6/ip6_vti.c

@@ -278,7 +278,6 @@ static void vti6_dev_uninit(struct net_device *dev)
 		RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
 	else
 		vti6_tnl_unlink(ip6n, t);
-	ip6_tnl_dst_reset(t);
 	dev_put(dev);
 }
 
@@ -356,11 +355,10 @@ vti6_addr_conflict(const struct ip6_tnl *t, const struct ipv6hdr *hdr)
  **/
 static int vti6_xmit(struct sk_buff *skb, struct net_device *dev)
 {
-	struct net *net = dev_net(dev);
 	struct ip6_tnl *t = netdev_priv(dev);
 	struct net_device_stats *stats = &t->dev->stats;
-	struct dst_entry *dst = NULL, *ndst = NULL;
-	struct flowi6 fl6;
+	struct dst_entry *dst = skb_dst(skb);
+	struct flowi fl;
 	struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 	struct net_device *tdev;
 	int err = -1;
@@ -369,22 +367,20 @@ static int vti6_xmit(struct sk_buff *skb, struct net_device *dev)
 	    !ip6_tnl_xmit_ctl(t) || vti6_addr_conflict(t, ipv6h))
 		return err;
 
-	dst = ip6_tnl_dst_check(t);
-	if (!dst) {
-		memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
+	memset(&fl, 0, sizeof(fl));
+	skb->mark = be32_to_cpu(t->parms.o_key);
+	xfrm_decode_session(skb, &fl, AF_INET6);
 
-		ndst = ip6_route_output(net, NULL, &fl6);
-
-		if (ndst->error)
+	if (!dst)
 		goto tx_err_link_failure;
-		ndst = xfrm_lookup(net, ndst, flowi6_to_flowi(&fl6), NULL, 0);
-		if (IS_ERR(ndst)) {
-			err = PTR_ERR(ndst);
-			ndst = NULL;
+
+	dst_hold(dst);
+	dst = xfrm_lookup(t->net, dst, &fl, NULL, 0);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		dst = NULL;
 		goto tx_err_link_failure;
 	}
-		dst = ndst;
-	}
 
 	if (!dst->xfrm || dst->xfrm->props.mode != XFRM_MODE_TUNNEL)
 		goto tx_err_link_failure;
@@ -399,21 +395,19 @@ static int vti6_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 
-	skb_dst_drop(skb);
-	skb_dst_set_noref(skb, dst);
+	memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+	skb_scrub_packet(skb, !net_eq(t->net, dev_net(dev)));
+	skb_dst_set(skb, dst);
+	skb->dev = skb_dst(skb)->dev;
 
 	ip6tunnel_xmit(skb, dev);
-	if (ndst) {
-		dev->mtu = dst_mtu(ndst);
-		ip6_tnl_dst_store(t, ndst);
-	}
 
 	return 0;
 tx_err_link_failure:
 	stats->tx_carrier_errors++;
 	dst_link_failure(skb);
 tx_err_dst_release:
-	dst_release(ndst);
+	dst_release(dst);
 	return err;
 }