static void ip_encap(struct sk_buff *skb, __be32 saddr, __be32 daddr)
{
struct iphdr *iph;
- struct iphdr *old_iph = ip_hdr(skb);
+ const struct iphdr *old_iph = ip_hdr(skb);
skb_push(skb, sizeof(struct iphdr));
skb->transport_header = skb->network_header;