static bool tcp_fast_parse_options(const struct sk_buff *skb,
				   const struct tcphdr *th, struct tcp_sock *tp)
{
	/* In the spirit of fast parsing, compare doff directly to constant
	 * values.  Because equality is used, short doff can be ignored here.
	 */
	if (th->doff == (sizeof(*th) / 4)) {
		tp->rx_opt.saw_tstamp = 0;
		return false;
	} else if (tp->rx_opt.tstamp_ok &&
		   th->doff == ((sizeof(*th) + TCPOLEN_TSTAMP_ALIGNED) / 4)) {
		if (tcp_parse_aligned_timestamp(tp, th))
			return true;
	}

	tcp_parse_options(skb, &tp->rx_opt, 1, NULL);
	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
		tp->rx_opt.rcv_tsecr -= tp->tsoffset;

	return true;
}
Unknown