ip6_route_info_create_nh
err = ip6_route_info_create_nh(rt, cfg, gfp_flags, extack);
err = ip6_route_info_create_nh(f6i, &cfg, gfp_flags, extack);
err = ip6_route_info_create_nh(rt, &r_cfg, GFP_KERNEL, extack);