The branch main has been updated by rscheff:
URL:
https://cgit.FreeBSD.org/src/commit/?id=23c4f232478aa022cad45f2cde349ff56bb2a094
commit 23c4f232478aa022cad45f2cde349ff56bb2a094
Author: Richard Scheffenegger <rsch...@freebsd.org>
AuthorDate: 2024-02-08 18:56:27 +0000
Commit: Richard Scheffenegger <rsch...@freebsd.org>
CommitDate: 2024-02-08 19:40:25 +0000
tcp: ensure tcp_sack_partialack does not inflate cwnd after RTO
The implicit assumption of snd_nxt always being larger than
snd_recover is not true after RTO. In that case, cwnd
would get inflated to ssthresh, which may be much larger
than the current pipe (data in flight).
Reviewed By: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D43653
---
sys/netinet/tcp_sack.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/sys/netinet/tcp_sack.c b/sys/netinet/tcp_sack.c
index 0c557dc4579d..f59cc5fe0d0b 100644
--- a/sys/netinet/tcp_sack.c
+++ b/sys/netinet/tcp_sack.c
@@ -953,8 +953,17 @@ tcp_sack_partialack(struct tcpcb *tp, struct tcphdr *th,
u_int *maxsegp)
/* Send one or 2 segments based on how much new data was acked. */
if ((BYTES_THIS_ACK(tp, th) / maxseg) >= 2)
num_segs = 2;
- tp->snd_cwnd = (tp->sackhint.sack_bytes_rexmit +
- (tp->snd_nxt - tp->snd_recover) + num_segs * maxseg);
+ if (V_tcp_do_newsack) {
+ tp->snd_cwnd = imax(tp->snd_nxt - th->th_ack +
+ tp->sackhint.sack_bytes_rexmit -
+ tp->sackhint.sacked_bytes -
+ tp->sackhint.lost_bytes, maxseg) +
+ num_segs * maxseg;
+ } else {
+ tp->snd_cwnd = (tp->sackhint.sack_bytes_rexmit +
+ imax(0, tp->snd_nxt - tp->snd_recover) +
+ num_segs * maxseg);
+ }
if (tp->snd_cwnd > tp->snd_ssthresh)
tp->snd_cwnd = tp->snd_ssthresh;
tp->t_flags |= TF_ACKNOW;
