+ bictcp_hystart_reset(sk);
+ }
+}
+
+static void hystart_update(struct sock *sk, u32 delay)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct bictcp *ca = inet_csk_ca(sk);
+
+ if (!(ca->found & hystart_detect)) {
+ u32 curr_jiffies = jiffies;
+
+ /* first detection parameter - ack-train detection */
+ if (curr_jiffies - ca->last_jiffies <= msecs_to_jiffies(2)) {
+ ca->last_jiffies = curr_jiffies;
+ if (curr_jiffies - ca->round_start >= ca->delay_min>>4)
+ ca->found |= HYSTART_ACK_TRAIN;
+ }
+
+ /* obtain the minimum delay of more than sampling packets */
+ if (ca->sample_cnt < HYSTART_MIN_SAMPLES) {
+ if (ca->curr_rtt == 0 || ca->curr_rtt > delay)
+ ca->curr_rtt = delay;
+
+ ca->sample_cnt++;
+ } else {
+ if (ca->curr_rtt > ca->delay_min +
+ HYSTART_DELAY_THRESH(ca->delay_min>>4))
+ ca->found |= HYSTART_DELAY;
+ }
+ /*
+ * Either one of two conditions are met,
+ * we exit from slow start immediately.
+ */
+ if (ca->found & hystart_detect)
+ tp->snd_ssthresh = tp->snd_cwnd;
+ }