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Ensure that TCP_REXMTVAL doesn't return a value less than t_rttmin. This

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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
This commit is contained in:
David Greenman 1998-04-24 09:25:39 +00:00
parent 1667f2b3e5
commit 552b7df4c1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=35419
2 changed files with 9 additions and 14 deletions
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19
sys/netinet/tcp_timer.c
View File

@ -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;

4
sys/netinet/tcp_var.h
View File

@ -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