ipv4: Remove bogus checks of rt_gateway being zero.

It can never actually happen.  rt_gateway is either the fully resolved
flow lookup key's destination address, or the non-zero FIB entry gateway
address.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ip_gre.c

@@ -724,11 +724,8 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
 			goto tx_error;
 		}
 
-		if (skb->protocol == htons(ETH_P_IP)) {
+		if (skb->protocol == htons(ETH_P_IP))
 			rt = skb_rtable(skb);
-			if ((dst = rt->rt_gateway) == 0)
-				goto tx_error_icmp;
-		}
 #if IS_ENABLED(CONFIG_IPV6)
 		else if (skb->protocol == htons(ETH_P_IPV6)) {
 			struct neighbour *neigh = dst_get_neighbour_noref(skb_dst(skb));
@@ -910,9 +907,10 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
 	__IPTUNNEL_XMIT(tstats, &dev->stats);
 	return NETDEV_TX_OK;
 
+#if IS_ENABLED(CONFIG_IPV6)
 tx_error_icmp:
 	dst_link_failure(skb);
-
+#endif
 tx_error:
 	dev->stats.tx_errors++;
 	dev_kfree_skb(skb);

net/ipv4/ipip.c

@@ -454,8 +454,6 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 			dev->stats.tx_fifo_errors++;
 			goto tx_error;
 		}
-		if ((dst = rt->rt_gateway) == 0)
-			goto tx_error_icmp;
 	}
 
 	rt = ip_route_output_ports(dev_net(dev), &fl4, NULL,