From 552b7df4c150cdd39d72efbb07b8766bba57174a Mon Sep 17 00:00:00 2001
From: David Greenman <dg@FreeBSD.org>
Date: Fri, 24 Apr 1998 09:25:39 +0000
Subject: [PATCH] Ensure that TCP_REXMTVAL doesn't return a value less than
 t_rttmin. This is believed to have been broken with the Brakmo/Peterson srtt
 calculation changes. The result of this bug is that TCP connections could
 time out extremely quickly (in 12 seconds). Also backed out jdp's partial fix
 for this problem in rev 1.17 of tcp_timer.c as it is obsoleted by this
 commit. Bug was pointed out by Kevin Lehey <kml@roller.nas.nasa.gov>.

PR:	6068
---
 sys/netinet/tcp_timer.c | 19 +++++++------------
 sys/netinet/tcp_var.h   |  4 ++--
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index 65ace37ab6e..112ce578f7b 100644
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)tcp_timer.c	8.2 (Berkeley) 5/24/95
- *	$Id: tcp_timer.c,v 1.26 1998/02/26 05:25:33 dg Exp $
+ *	$Id: tcp_timer.c,v 1.27 1998/04/06 06:52:46 phk Exp $
  */
 
 #include "opt_compat.h"
@@ -308,17 +308,12 @@ tcp_timers(tp, timer)
 		 * (no responses to probes) reaches the maximum
 		 * backoff that we would use if retransmitting.
 		 */
-		if (tp->t_rxtshift == TCP_MAXRXTSHIFT) {
-			u_long maxidle = TCP_REXMTVAL(tp);
-			if (maxidle < tp->t_rttmin)
-				maxidle = tp->t_rttmin;
-			maxidle *= tcp_totbackoff;
-			if (tp->t_idle >= tcp_maxpersistidle ||
-			    tp->t_idle >= maxidle) {
-				tcpstat.tcps_persistdrop++;
-				tp = tcp_drop(tp, ETIMEDOUT);
-				break;
-			}
+		if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
+		    (tp->t_idle >= tcp_maxpersistidle ||
+		    tp->t_idle >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
+			tcpstat.tcps_persistdrop++;
+			tp = tcp_drop(tp, ETIMEDOUT);
+			break;
 		}
 		tcp_setpersist(tp);
 		tp->t_force = 1;
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index fdeeecf4c56..e928449d908 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)tcp_var.h	8.4 (Berkeley) 5/24/95
- * 	$Id: tcp_var.h,v 1.41 1998/02/26 05:25:39 dg Exp $
+ * 	$Id: tcp_var.h,v 1.42 1998/04/06 06:52:47 phk Exp $
  */
 
 #ifndef _NETINET_TCP_VAR_H_
@@ -203,7 +203,7 @@ struct rmxp_tao {
  * fast networks.
  */
 #define	TCP_REXMTVAL(tp) \
-	((((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT))  \
+	max((tp)->t_rttmin, (((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT))  \
 	  + (tp)->t_rttvar) >> TCP_DELTA_SHIFT)
 
 /* XXX