vxlan_igmp_join
ret = vxlan_igmp_join(vxlan, &v->remote_ip, 0);
ret = vxlan_igmp_join(vxlan, &vxlan->default_dst.remote_ip,
int vxlan_igmp_join(struct vxlan_dev *vxlan, union vxlan_addr *rip,
ret = vxlan_igmp_join(vxlan, &vninode->remote_ip, 0);