git: f69b9760c202 - stable/13 - tcp: Use PRR for ECN congestion recovery

[Richard Scheffenegger]

The branch stable/13 has been updated by rscheff:

URL: https://cgit.FreeBSD.org/src/commit/?id=f69b9760c202b9e3a320915f1c9e75ed96142872

commit f69b9760c202b9e3a320915f1c9e75ed96142872
Author:     Richard Scheffenegger <rscheff at FreeBSD.org>
AuthorDate: 2021-03-26 01:05:22 +0000
Commit:     Richard Scheffenegger <rscheff at FreeBSD.org>
CommitDate: 2021-04-22 18:28:54 +0000

    tcp: Use PRR for ECN congestion recovery
    
    MFC after: 2 weeks
    Reviewed By: #transport, rrs
    Sponsored by: NetApp, Inc.
    Differential Revision: https://reviews.freebsd.org/D28972
    
    (cherry picked from commit b9f803b7d4b7ee3799ab94f66c02c3b6e58c153a)
---
 sys/netinet/tcp_input.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 3f2df998fd9e..67f16b77d041 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -2786,6 +2786,16 @@ resume_partialack:
 					tcp_newreno_partial_ack(tp, th);
 			} else
 				cc_post_recovery(tp, th);
+		} else if (IN_CONGRECOVERY(tp->t_flags)) {
+			if (SEQ_LT(th->th_ack, tp->snd_recover)) {
+				if (V_tcp_do_prr) {
+					tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th);
+					tp->snd_fack = th->th_ack;
+					tcp_do_prr_ack(tp, th);
+					(void) tcp_output(tp);
+				}
+			} else
+				cc_post_recovery(tp, th);
 		}
 		/*
 		 * If we reach this point, ACK is not a duplicate,
@@ -3952,8 +3962,12 @@ tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th)
 	 * If there is going to be a SACK retransmission, adjust snd_cwnd
 	 * accordingly.
 	 */
-	tp->snd_cwnd = imax(maxseg, tp->snd_nxt - tp->snd_recover +
-		tp->sackhint.sack_bytes_rexmit + (snd_cnt * maxseg));
+	if (IN_FASTRECOVERY(tp->t_flags)) {
+		tp->snd_cwnd = imax(maxseg, tp->snd_nxt - tp->snd_recover +
+			tp->sackhint.sack_bytes_rexmit + (snd_cnt * maxseg));
+	} else if (IN_CONGRECOVERY(tp->t_flags))
+		tp->snd_cwnd = imax(maxseg, pipe - del_data +
+				    (snd_cnt * maxseg));
 }
 
 /*