tun_p_to_eth_p
*protocol = tun_p_to_eth_p(gpe->next_protocol);
inner_proto = tun_p_to_eth_p(nh->np);
proto = tun_p_to_eth_p(nsh_hdr(skb)->np);
inner_proto = tun_p_to_eth_p(key->nsh.base.np);