static inline size_t ctnetlink_timestamp_size(const struct nf_conn *ct)
{
#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
	if (!nf_ct_ext_exist(ct, NF_CT_EXT_TSTAMP))
		return 0;
	return nla_total_size(0) + 2 * nla_total_size_64bit(sizeof(uint64_t));
#else
	return 0;
#endif
}