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Fix a problem discovered by the snd_recover update fix. A bit of the

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New Reno fast recovery code was being executed even when New Reno was
disabled, resulting in an unfortunate interaction with the traditional
fast recovery code, the end resulting being that the very condition
that would trigger the traditional fast recovery mechanism caused fast
recovery to be disabled!

Problem reported by Ted Lemon, and some analytical help from Charles Hannum.
This commit is contained in:
thorpej 1999-08-26 00:04:30 +00:00
parent 65845c9e2a
commit 1e921673e3
1 changed files with 9 additions and 8 deletions

17
sys/netinet/tcp_input.c

@ -1,4 +1,4 @@
/* $NetBSD: tcp_input.c,v 1.93 1999/08/25 15:23:12 itojun Exp $ */
/* $NetBSD: tcp_input.c,v 1.94 1999/08/26 00:04:30 thorpej Exp $ */
/*
%%% portions-copyright-nrl-95
@ -1579,7 +1579,7 @@ after_listen:
u_int win =
min(tp->snd_wnd, tp->snd_cwnd) /
2 / tp->t_segsz;
if (SEQ_LT(th->th_ack,
if (tcp_do_newreno && SEQ_LT(th->th_ack,
tp->snd_recover)) {
/*
* False fast retransmit after
@ -1618,13 +1618,13 @@ after_listen:
* If the congestion window was inflated to account
* for the other side's cached packets, retract it.
*/
if (!tcp_do_newreno) {
if (tcp_do_newreno == 0) {
if (tp->t_dupacks >= tcprexmtthresh &&
tp->snd_cwnd > tp->snd_ssthresh)
tp->snd_cwnd = tp->snd_ssthresh;
tp->t_dupacks = 0;
} else if (tp->t_dupacks >= tcprexmtthresh
&& !tcp_newreno(tp, th)) {
} else if (tp->t_dupacks >= tcprexmtthresh &&
tcp_newreno(tp, th) == 0) {
tp->snd_cwnd = tp->snd_ssthresh;
/*
* Window inflation should have left us with approx.
@ -1634,7 +1634,7 @@ after_listen:
*/
if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh)
tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack)
+ tp->t_segsz;
+ tp->t_segsz;
tp->t_dupacks = 0;
}
if (SEQ_GT(th->th_ack, tp->snd_max)) {
@ -1685,8 +1685,9 @@ after_listen:
if (cw > tp->snd_ssthresh)
incr = incr * incr / cw;
if (!tcp_do_newreno || SEQ_GEQ(th->th_ack, tp->snd_recover))
tp->snd_cwnd = min(cw + incr,TCP_MAXWIN<<tp->snd_scale);
if (tcp_do_newreno == 0 || SEQ_GEQ(th->th_ack, tp->snd_recover))
tp->snd_cwnd = min(cw + incr,
TCP_MAXWIN << tp->snd_scale);
}
if (acked > so->so_snd.sb_cc) {
tp->snd_wnd -= so->so_snd.sb_cc;