ipv4: Cache net in iptunnel_xmit

Store net in a variable in ip_tunnel_xmit so it does not need
to be recomputed when it is used again.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_tunnel_core.c

@@ -53,6 +53,7 @@ int iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 		  __u8 tos, __u8 ttl, __be16 df, bool xnet)
 {
 	int pkt_len = skb->len - skb_inner_network_offset(skb);
+	struct net *net = dev_net(rt->dst.dev);
 	struct iphdr *iph;
 	int err;
 
@@ -76,8 +77,7 @@ int iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 	iph->daddr	=	dst;
 	iph->saddr	=	src;
 	iph->ttl	=	ttl;
-	__ip_select_ident(dev_net(rt->dst.dev), iph,
-			  skb_shinfo(skb)->gso_segs ?: 1);
+	__ip_select_ident(net, iph, skb_shinfo(skb)->gso_segs ?: 1);
 
 	err = ip_local_out(sk, skb);
 	if (unlikely(net_xmit_eval(err)))