git: c3915f848b56 - stable/13 - tcp: Tidying up the conditionals for unwinding a spurious RTO

The branch stable/13 has been updated by rscheff:

URL: https://cgit.FreeBSD.org/src/commit/?id=c3915f848b56221836bb95dfa293a43ca5f1e630

commit c3915f848b56221836bb95dfa293a43ca5f1e630
Author:     Richard Scheffenegger <rscheff@FreeBSD.org>
AuthorDate: 2022-01-27 17:59:21 +0000
Commit:     Richard Scheffenegger <rscheff@FreeBSD.org>
CommitDate: 2022-01-30 10:41:16 +0000

    tcp: Tidying up the conditionals for unwinding a spurious RTO
    
    - Use the semantically correct TSTMP_xx macro when comparing
      timestamps. (No functional change)
    - check for bad retransmits only when TSopt is present in ACK
      (don't assume there will be a valid TSopt in the TCP options struct)
    - exclude tsecr == 0, since that most likely indicates an
      invalid ts echo return (tsecr) value.
    
    Reviewed By: tuexen, #transport
    MFC after:   3 days
    Sponsored by:        NetApp, Inc.
    Differential Revision: https://reviews.freebsd.org/D34062
    
    (cherry picked from commit 4531b3450b23a01de04b3bb393e475cf734793c8)
---
 sys/netinet/tcp_input.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 0848afd3c2b0..2c7d15368483 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -1653,9 +1653,10 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
 		to.to_tsecr -= tp->ts_offset;
 		if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks()))
 			to.to_tsecr = 0;
-		else if (tp->t_flags & TF_PREVVALID &&
-			 tp->t_rxtshift == 1 &&
-			 tp->t_badrxtwin != 0 && SEQ_LT(to.to_tsecr, tp->t_badrxtwin))
+		else if (tp->t_rxtshift == 1 &&
+			 tp->t_flags & TF_PREVVALID &&
+			 tp->t_badrxtwin != 0 &&
+			 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin))
 			cc_cong_signal(tp, th, CC_RTO_ERR);
 	}
 	/*
@@ -1812,7 +1813,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
 				if ((to.to_flags & TOF_TS) == 0 &&
 				    tp->t_rxtshift == 1 &&
 				    tp->t_flags & TF_PREVVALID &&
-				    (int)(ticks - tp->t_badrxtwin) < 0) {
+				    tp->t_badrxtwin != 0 &&
+				    TSTMP_LT(ticks, tp->t_badrxtwin)) {
 					cc_cong_signal(tp, th, CC_RTO_ERR);
 				}
 
@@ -2886,8 +2888,10 @@ process_ACK:
 		 */
 		if (tp->t_rxtshift == 1 &&
 		    tp->t_flags & TF_PREVVALID &&
-		    tp->t_badrxtwin &&
-		    SEQ_LT(to.to_tsecr, tp->t_badrxtwin))
+		    tp->t_badrxtwin != 0 &&
+		    to.to_flags & TOF_TS &&
+		    to.to_tsecr != 0 &&
+		    TSTMP_LT(to.to_tsecr, tp->t_badrxtwin))
 			cc_cong_signal(tp, th, CC_RTO_ERR);
 
 		/*