Function rack_log_ack

freebsd/netinet/tcp_stacks/rack.c:7455–8071

}

static void
rack_log_ack(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th)
{
	uint32_t changed, entered_recovery = 0;
	struct tcp_rack *rack;
	struct rack_sendmap *rsm, *rm;
	struct sackblk sack, sack_blocks[TCP_MAX_SACK + 1];
	register uint32_t th_ack;
	int32_t i, j, k, num_sack_blks = 0;
	uint32_t cts, acked, ack_point, sack_changed = 0;
	int loop_start = 0, moved_two = 0;
	uint32_t tsused;

	INP_WLOCK_ASSERT(tp->t_inpcb);
	if (th->th_flags & TH_RST) {
		/* We don't log resets */
		return;
	}
	rack = (struct tcp_rack *)tp->t_fb_ptr;
	cts = tcp_ts_getticks();
	rsm = RB_MIN(rack_rb_tree_head, &rack->r_ctl.rc_mtree);
	changed = 0;
	th_ack = th->th_ack;
	if (rack->sack_attack_disable == 0)
		rack_do_decay(rack);
	if (BYTES_THIS_ACK(tp, th) >= ctf_fixed_maxseg(rack->rc_tp)) {
		/*
		 * You only get credit for
		 * MSS and greater (and you get extra
		 * credit for larger cum-ack moves).
		 */
		int ac;

		ac = BYTES_THIS_ACK(tp, th) / ctf_fixed_maxseg(rack->rc_tp);
		rack->r_ctl.ack_count += ac;
		counter_u64_add(rack_ack_total, ac);
	}
	if (rack->r_ctl.ack_count > 0xfff00000) {
		/*
		 * reduce the number to keep us under
		 * a uint32_t.
		 */
		rack->r_ctl.ack_count /= 2;
		rack->r_ctl.sack_count /= 2;
	}
	if (SEQ_GT(th_ack, tp->snd_una)) {
		rack_log_progress_event(rack, tp, ticks, PROGRESS_UPDATE, __LINE__);
		tp->t_acktime = ticks;
	}
	if (rsm && SEQ_GT(th_ack, rsm->r_start))
		changed = th_ack - rsm->r_start;
	if (changed) {
		/*
		 * The ACK point is advancing to th_ack, we must drop off
		 * the packets in the rack log and calculate any eligble
		 * RTT's.
		 */
		rack->r_wanted_output = 1;