1 files changed, 27 insertions, 13 deletions

diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index 3a81720..1c1bdf1 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -21,6 +21,32 @@ static bool tcp_rack_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
 	return t1 > t2 || (t1 == t2 && after(seq1, seq2));
 }
 
+u32 tcp_rack_reo_wnd(const struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (!tp->rack.reord) {
+		/* If reordering has not been observed, be aggressive during
+		 * the recovery or starting the recovery by DUPACK threshold.
+		 */
+		if (inet_csk(sk)->icsk_ca_state >= TCP_CA_Recovery)
+			return 0;
+
+		if (tp->sacked_out >= tp->reordering &&
+		    !(sock_net(sk)->ipv4.sysctl_tcp_recovery & TCP_RACK_NO_DUPTHRESH))
+			return 0;
+	}
+
+	/* To be more reordering resilient, allow min_rtt/4 settling delay.
+	 * Use min_rtt instead of the smoothed RTT because reordering is
+	 * often a path property and less related to queuing or delayed ACKs.
+	 * Upon receiving DSACKs, linearly increase the window up to the
+	 * smoothed RTT.
+	 */
+	return min((tcp_min_rtt(tp) >> 2) * tp->rack.reo_wnd_steps,
+		   tp->srtt_us >> 3);
+}
+
 /* RACK loss detection (IETF draft draft-ietf-tcpm-rack-01):
  *
  * Marks a packet lost, if some packet sent later has been (s)acked.
@@ -44,23 +70,11 @@ static bool tcp_rack_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
 static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	u32 min_rtt = tcp_min_rtt(tp);
 	struct sk_buff *skb, *n;
 	u32 reo_wnd;
 
 	*reo_timeout = 0;
-	/* To be more reordering resilient, allow min_rtt/4 settling delay
-	 * (lower-bounded to 1000uS). We use min_rtt instead of the smoothed
-	 * RTT because reordering is often a path property and less related
-	 * to queuing or delayed ACKs.
-	 */
-	reo_wnd = 1000;
-	if ((tp->rack.reord || inet_csk(sk)->icsk_ca_state < TCP_CA_Recovery) &&
-	    min_rtt != ~0U) {
-		reo_wnd = max((min_rtt >> 2) * tp->rack.reo_wnd_steps, reo_wnd);
-		reo_wnd = min(reo_wnd, tp->srtt_us >> 3);
-	}
-
+	reo_wnd = tcp_rack_reo_wnd(sk);
 	list_for_each_entry_safe(skb, n, &tp->tsorted_sent_queue,
 				 tcp_tsorted_anchor) {
 		struct tcp_skb_cb *scb = TCP_SKB_CB(skb);