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authorHugh Graham <hugh@cvs.openbsd.org>1999-11-15 05:51:00 +0000
committerHugh Graham <hugh@cvs.openbsd.org>1999-11-15 05:51:00 +0000
commit3b40ef82602813dc08a94f1d2a9a19d29b0027e4 (patch)
tree13e975ae68a32d6aa3736276bbc46bf1c1c9471c
parentec557b9d0a018d3b4970559b96f35f5852595322 (diff)
Fix tcp retransmit/persist timers, provos@ OK.
Adapted from NetBSD: Fix a retransmission bug introduced by the Brakmo and Peterson RTO estimation changes. Under some circumstances it would return a value of 0, while the old Van Jacobson RTO code would return a minimum of 3. This would result in 12 retransmissions, each 1 second apart. This takes care of those instances, and ensures that t_rttmin is used everywhere as a lower bound.
-rw-r--r--sys/netinet/tcp_input.c14
-rw-r--r--sys/netinet/tcp_output.c4
-rw-r--r--sys/netinet/tcp_timer.c16
3 files changed, 24 insertions, 10 deletions
diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 142452d0849..e2a6b6136d3 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tcp_input.c,v 1.50 1999/11/04 11:24:23 ho Exp $ */
+/* $OpenBSD: tcp_input.c,v 1.51 1999/11/15 05:50:59 hugh Exp $ */
/* $NetBSD: tcp_input.c,v 1.23 1996/02/13 23:43:44 christos Exp $ */
/*
@@ -2551,6 +2551,7 @@ tcp_xmit_timer(tp, rtt)
short rtt;
{
register short delta;
+ short rttmin;
tcpstat.tcps_rttupdated++;
--rtt;
@@ -2603,8 +2604,11 @@ tcp_xmit_timer(tp, rtt)
* statistical, we have to test that we don't drop below
* the minimum feasible timer (which is 2 ticks).
*/
- TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
- rtt + 2, TCPTV_REXMTMAX);
+ if (tp->t_rttmin > rtt + 2)
+ rttmin = tp->t_rttmin;
+ else
+ rttmin = rtt + 2;
+ TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), rttmin, TCPTV_REXMTMAX);
/*
* We received an ack for a packet that wasn't retransmitted;
@@ -2704,7 +2708,9 @@ tcp_mss(tp, offer)
* is also a minimum value; this is subject to time.
*/
if (rt->rt_rmx.rmx_locks & RTV_RTT)
- tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ);
+ TCPT_RANGESET(tp->t_rttmin,
+ rtt / (RTM_RTTUNIT / PR_SLOWHZ),
+ TCPTV_MIN, TCPTV_REXMTMAX);
tp->t_srtt = rtt / (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE));
if (rt->rt_rmx.rmx_rttvar)
tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index 5324d78f931..b204dfe9b50 100644
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tcp_output.c,v 1.22 1999/11/04 11:24:24 ho Exp $ */
+/* $OpenBSD: tcp_output.c,v 1.23 1999/11/15 05:50:59 hugh Exp $ */
/* $NetBSD: tcp_output.c,v 1.16 1997/06/03 16:17:09 kml Exp $ */
/*
@@ -1077,6 +1077,8 @@ tcp_setpersist(tp)
/*
* Start/restart persistance timer.
*/
+ if (t < tp->t_rttmin)
+ t = tp->t_rttmin;
TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
t * tcp_backoff[tp->t_rxtshift],
TCPTV_PERSMIN, TCPTV_PERSMAX);
diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index 79d318637b9..591dc18d7d1 100644
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tcp_timer.c,v 1.14 1999/09/01 21:38:21 provos Exp $ */
+/* $OpenBSD: tcp_timer.c,v 1.15 1999/11/15 05:50:59 hugh Exp $ */
/* $NetBSD: tcp_timer.c,v 1.14 1996/02/13 23:44:09 christos Exp $ */
/*
@@ -177,7 +177,7 @@ tcp_timers(tp, timer)
register struct tcpcb *tp;
int timer;
{
- register int rexmt;
+ short rto;
#ifdef TCP_SACK
struct sackhole *p, *q;
/*
@@ -229,8 +229,11 @@ tcp_timers(tp, timer)
break;
}
tcpstat.tcps_rexmttimeo++;
- rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
- TCPT_RANGESET((long) tp->t_rxtcur, rexmt,
+ rto = TCP_REXMTVAL(tp);
+ if (rto < tp->t_rttmin)
+ rto = tp->t_rttmin;
+ TCPT_RANGESET((long) tp->t_rxtcur,
+ rto * tcp_backoff[tp->t_rxtshift],
tp->t_rttmin, TCPTV_REXMTMAX);
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
/*
@@ -306,9 +309,12 @@ tcp_timers(tp, timer)
* (no responses to probes) reaches the maximum
* backoff that we would use if retransmitting.
*/
+ rto = TCP_REXMTVAL(tp);
+ if (rto < tp->t_rttmin)
+ rto = tp->t_rttmin;
if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
(tp->t_idle >= tcp_maxpersistidle ||
- tp->t_idle >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
+ tp->t_idle >= rto * tcp_totbackoff)) {
tcpstat.tcps_persistdrop++;
tp = tcp_drop(tp, ETIMEDOUT);
break;