+/* Update alpha and beta values once per RTT */
+static void update_params(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct illinois *ca = inet_csk_ca(sk);
+
+ if (tp->snd_cwnd < win_thresh) {
+ ca->alpha = ALPHA_BASE;
+ ca->beta = BETA_BASE;
+ } else if (ca->cnt_rtt > 0) {
+ u32 dm = max_delay(ca);
+ u32 da = avg_delay(ca);
+
+ ca->alpha = alpha(ca, da, dm);
+ ca->beta = beta(da, dm);
+ }
+
+ rtt_reset(sk);
+}
+
+/*
+ * In case of loss, reset to default values
+ */
+static void tcp_illinois_state(struct sock *sk, u8 new_state)
+{
+ struct illinois *ca = inet_csk_ca(sk);
+
+ if (new_state == TCP_CA_Loss) {
+ ca->alpha = ALPHA_BASE;
+ ca->beta = BETA_BASE;
+ ca->rtt_low = 0;
+ ca->rtt_above = 0;
+ rtt_reset(sk);
+ }
+}
+
+/*
+ * Increase window in response to successful acknowledgment.
+ */
+static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
+ u32 in_flight, int flag)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct illinois *ca = inet_csk_ca(sk);
+
+ if (after(ack, ca->end_seq))
+ update_params(sk);
+
+ /* RFC2861 only increase cwnd if fully utilized */
+ if (!tcp_is_cwnd_limited(sk, in_flight))
+ return;
+
+ /* In slow start */
+ if (tp->snd_cwnd <= tp->snd_ssthresh)
+ tcp_slow_start(tp);
+
+ else {
+ u32 delta;
+
+ /* snd_cwnd_cnt is # of packets since last cwnd increment */
+ tp->snd_cwnd_cnt += ca->acked;
+ ca->acked = 1;
+
+ /* This is close approximation of:
+ * tp->snd_cwnd += alpha/tp->snd_cwnd
+ */
+ delta = (tp->snd_cwnd_cnt * ca->alpha) >> ALPHA_SHIFT;
+ if (delta >= tp->snd_cwnd) {
+ tp->snd_cwnd = min(tp->snd_cwnd + delta / tp->snd_cwnd,
+ (u32) tp->snd_cwnd_clamp);
+ tp->snd_cwnd_cnt = 0;
+ }
+ }
+}
+