tunnels_wc
rcu_assign_pointer(ign->tunnels_wc[0],
for_each_ip_tunnel_rcu(t, ign->tunnels_wc[h1]) {
t = rcu_dereference(sitn->tunnels_wc[0]);
rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
sitn->tunnels[0] = sitn->tunnels_wc;
RCU_INIT_POINTER(sitn->tunnels_wc[0], NULL);
struct ip_tunnel __rcu *tunnels_wc[1];