git: 0533fab89e37 - main - tcp: Perform simple fast retransmit when SACK Blocks are missing on SACK session

[Richard Scheffenegger]

The branch main has been updated by rscheff:

URL: https://cgit.FreeBSD.org/src/commit/?id=0533fab89e37caab886568df88d9f939e85eeb6c

commit 0533fab89e37caab886568df88d9f939e85eeb6c
Author:     Richard Scheffenegger <rscheff at FreeBSD.org>
AuthorDate: 2021-03-25 22:18:06 +0000
Commit:     Richard Scheffenegger <rscheff at FreeBSD.org>
CommitDate: 2021-03-25 22:23:48 +0000

    tcp: Perform simple fast retransmit when SACK Blocks are missing on SACK session
    
    MFC after: 2 weeks
    Reviewed By: #transport, rrs
    Sponsored by: NetApp, Inc.
    Differential Revision: https://reviews.freebsd.org/D28634
---
 sys/netinet/tcp_input.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index bdc0e872c36e..685a5e020c3b 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -2564,6 +2564,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
 				 */
 				if (th->th_ack != tp->snd_una ||
 				    ((tp->t_flags & TF_SACK_PERMIT) &&
+				    (to.to_flags & TOF_SACK) &&
 				    !sack_changed))
 					break;
 				else if (!tcp_timer_active(tp, TT_REXMT))
@@ -2617,6 +2618,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
 						tp->snd_cwnd = imax(maxseg, tp->snd_nxt - tp->snd_recover +
 						    tp->sackhint.sack_bytes_rexmit + (snd_cnt * maxseg));
 					} else if ((tp->t_flags & TF_SACK_PERMIT) &&
+					    (to.to_flags & TOF_SACK) &&
 					    IN_FASTRECOVERY(tp->t_flags)) {
 						int awnd;
 
@@ -2694,7 +2696,8 @@ enter_recovery:
 						tp->sackhint.recover_fs = max(1,
 						    tp->snd_nxt - tp->snd_una);
 					}
-					if (tp->t_flags & TF_SACK_PERMIT) {
+					if ((tp->t_flags & TF_SACK_PERMIT) &&
+					    (to.to_flags & TOF_SACK)) {
 						TCPSTAT_INC(
 						    tcps_sack_recovery_episode);
 						tp->snd_recover = tp->snd_nxt;