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NetBSD/sys/netinet/tcp_congctl.c
yamt 7253aad93f constify.
2006-10-21 10:24:47 +00:00

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/* $NetBSD: tcp_congctl.c,v 1.11 2006/10/21 10:24:47 yamt Exp $ */
/*-
* Copyright (c) 1997, 1998, 1999, 2001, 2005, 2006 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation
* Facility, NASA Ames Research Center.
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
* This code is derived from software contributed to The NetBSD Foundation
* by Rui Paulo.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* @(#)COPYRIGHT 1.1 (NRL) 17 January 1995
*
* NRL grants permission for redistribution and use in source and binary
* forms, with or without modification, of the software and documentation
* created at NRL provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgements:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* This product includes software developed at the Information
* Technology Division, US Naval Research Laboratory.
* 4. Neither the name of the NRL nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation
* are those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of the US Naval
* Research Laboratory (NRL).
*/
/*
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: tcp_congctl.c,v 1.11 2006/10/21 10:24:47 yamt Exp $");
#include "opt_inet.h"
#include "opt_tcp_debug.h"
#include "opt_tcp_congctl.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/pool.h>
#include <sys/domain.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#ifdef INET6
#ifndef INET
#include <netinet/in.h>
#endif
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>
#endif
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/tcp_congctl.h>
#ifdef TCP_DEBUG
#include <netinet/tcp_debug.h>
#endif
/*
* TODO:
* consider separating the actual implementations in another file.
*/
static int tcp_reno_fast_retransmit(struct tcpcb *, const struct tcphdr *);
static void tcp_reno_slow_retransmit(struct tcpcb *);
static void tcp_reno_fast_retransmit_newack(struct tcpcb *,
const struct tcphdr *);
static void tcp_reno_newack(struct tcpcb *, const struct tcphdr *);
static void tcp_reno_congestion_exp(struct tcpcb *tp);
static int tcp_newreno_fast_retransmit(struct tcpcb *, const struct tcphdr *);
static void tcp_newreno_fast_retransmit_newack(struct tcpcb *,
const struct tcphdr *);
static void tcp_newreno_newack(struct tcpcb *, const struct tcphdr *);
static void tcp_congctl_fillnames(void);
extern int tcprexmtthresh;
MALLOC_DEFINE(M_TCPCONGCTL, "tcpcongctl", "TCP congestion control structures");
/*
* Used to list the available congestion control algorithms.
*/
struct tcp_congctlent {
TAILQ_ENTRY(tcp_congctlent) congctl_ent;
char congctl_name[TCPCC_MAXLEN];
struct tcp_congctl *congctl_ctl;
};
TAILQ_HEAD(, tcp_congctlent) tcp_congctlhd;
struct simplelock tcp_congctl_slock;
void
tcp_congctl_init(void)
{
int r;
TAILQ_INIT(&tcp_congctlhd);
simple_lock_init(&tcp_congctl_slock);
/* Base algorithms. */
r = tcp_congctl_register("reno", &tcp_reno_ctl);
KASSERT(r == 0);
r = tcp_congctl_register("newreno", &tcp_newreno_ctl);
KASSERT(r == 0);
/* NewReno is the default. */
#ifndef TCP_CONGCTL_DEFAULT
#define TCP_CONGCTL_DEFAULT "newreno"
#endif
r = tcp_congctl_select(NULL, TCP_CONGCTL_DEFAULT);
KASSERT(r == 0);
}
/*
* Register a congestion algorithm and select it if we have none.
*/
int
tcp_congctl_register(const char *name, struct tcp_congctl *tcc)
{
struct tcp_congctlent *ntcc, *tccp;
TAILQ_FOREACH(tccp, &tcp_congctlhd, congctl_ent)
if (!strcmp(name, tccp->congctl_name)) {
/* name already registered */
return EEXIST;
}
ntcc = malloc(sizeof(*ntcc), M_TCPCONGCTL, M_WAITOK);
strlcpy(ntcc->congctl_name, name, sizeof(ntcc->congctl_name) - 1);
ntcc->congctl_ctl = tcc;
TAILQ_INSERT_TAIL(&tcp_congctlhd, ntcc, congctl_ent);
tcp_congctl_fillnames();
if (TAILQ_FIRST(&tcp_congctlhd) == ntcc)
tcp_congctl_select(NULL, name);
return 0;
}
int
tcp_congctl_unregister(const char *name)
{
struct tcp_congctlent *tccp, *rtccp;
unsigned int size;
rtccp = NULL;
size = 0;
TAILQ_FOREACH(tccp, &tcp_congctlhd, congctl_ent) {
if (!strcmp(name, tccp->congctl_name))
rtccp = tccp;
size++;
}
if (!rtccp)
return ENOENT;
if (size <= 1 || tcp_congctl_global == rtccp->congctl_ctl ||
rtccp->congctl_ctl->refcnt)
return EBUSY;
TAILQ_REMOVE(&tcp_congctlhd, rtccp, congctl_ent);
free(rtccp, M_TCPCONGCTL);
tcp_congctl_fillnames();
return 0;
}
/*
* Select a congestion algorithm by name.
*/
int
tcp_congctl_select(struct tcpcb *tp, const char *name)
{
struct tcp_congctlent *tccp;
KASSERT(name);
TAILQ_FOREACH(tccp, &tcp_congctlhd, congctl_ent)
if (!strcmp(name, tccp->congctl_name)) {
if (tp) {
simple_lock(&tcp_congctl_slock);
tp->t_congctl->refcnt--;
tp->t_congctl = tccp->congctl_ctl;
tp->t_congctl->refcnt++;
simple_unlock(&tcp_congctl_slock);
} else {
tcp_congctl_global = tccp->congctl_ctl;
strlcpy(tcp_congctl_global_name,
tccp->congctl_name,
sizeof(tcp_congctl_global_name) - 1);
}
return 0;
}
return EINVAL;
}
/*
* Returns the name of a congestion algorithm.
*/
const char *
tcp_congctl_bystruct(const struct tcp_congctl *tcc)
{
struct tcp_congctlent *tccp;
KASSERT(tcc);
TAILQ_FOREACH(tccp, &tcp_congctlhd, congctl_ent)
if (tccp->congctl_ctl == tcc)
return tccp->congctl_name;
return NULL;
}
static void
tcp_congctl_fillnames(void)
{
struct tcp_congctlent *tccp;
const char *delim = " ";
tcp_congctl_avail[0] = '\0';
TAILQ_FOREACH(tccp, &tcp_congctlhd, congctl_ent) {
strlcat(tcp_congctl_avail, tccp->congctl_name,
sizeof(tcp_congctl_avail) - 1);
if (TAILQ_NEXT(tccp, congctl_ent))
strlcat(tcp_congctl_avail, delim,
sizeof(tcp_congctl_avail) - 1);
}
}
/* ------------------------------------------------------------------------ */
/*
* TCP/Reno congestion control.
*/
static void
tcp_reno_congestion_exp(struct tcpcb *tp)
{
u_int win;
/*
* Halve the congestion window and reduce the
* slow start threshold.
*/
win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_segsz;
if (win < 2)
win = 2;
tp->snd_ssthresh = win * tp->t_segsz;
tp->snd_recover = tp->snd_max;
tp->snd_cwnd = tp->snd_ssthresh;
/*
* When using TCP ECN, notify the peer that
* we reduced the cwnd.
*/
if (TCP_ECN_ALLOWED(tp))
tp->t_flags |= TF_ECN_SND_CWR;
}
static int
tcp_reno_fast_retransmit(struct tcpcb *tp, const struct tcphdr *th)
{
/*
* We know we're losing at the current
* window size so do congestion avoidance
* (set ssthresh to half the current window
* and pull our congestion window back to
* the new ssthresh).
*
* Dup acks mean that packets have left the
* network (they're now cached at the receiver)
* so bump cwnd by the amount in the receiver
* to keep a constant cwnd packets in the
* network.
*
* If we are using TCP/SACK, then enter
* Fast Recovery if the receiver SACKs
* data that is tcprexmtthresh * MSS
* bytes past the last ACKed segment,
* irrespective of the number of DupAcks.
*/
tcp_seq onxt;
onxt = tp->snd_nxt;
tcp_reno_congestion_exp(tp);
tp->t_partialacks = 0;
TCP_TIMER_DISARM(tp, TCPT_REXMT);
tp->t_rtttime = 0;
if (TCP_SACK_ENABLED(tp)) {
tp->t_dupacks = tcprexmtthresh;
tp->sack_newdata = tp->snd_nxt;
tp->snd_cwnd = tp->t_segsz;
(void) tcp_output(tp);
return 0;
}
tp->snd_nxt = th->th_ack;
tp->snd_cwnd = tp->t_segsz;
(void) tcp_output(tp);
tp->snd_cwnd = tp->snd_ssthresh + tp->t_segsz * tp->t_dupacks;
if (SEQ_GT(onxt, tp->snd_nxt))
tp->snd_nxt = onxt;
return 0;
}
static void
tcp_reno_slow_retransmit(struct tcpcb *tp)
{
u_int win;
/*
* Close the congestion window down to one segment
* (we'll open it by one segment for each ack we get).
* Since we probably have a window's worth of unacked
* data accumulated, this "slow start" keeps us from
* dumping all that data as back-to-back packets (which
* might overwhelm an intermediate gateway).
*
* There are two phases to the opening: Initially we
* open by one mss on each ack. This makes the window
* size increase exponentially with time. If the
* window is larger than the path can handle, this
* exponential growth results in dropped packet(s)
* almost immediately. To get more time between
* drops but still "push" the network to take advantage
* of improving conditions, we switch from exponential
* to linear window opening at some threshhold size.
* For a threshhold, we use half the current window
* size, truncated to a multiple of the mss.
*
* (the minimum cwnd that will give us exponential
* growth is 2 mss. We don't allow the threshhold
* to go below this.)
*/
win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_segsz;
if (win < 2)
win = 2;
/* Loss Window MUST be one segment. */
tp->snd_cwnd = tp->t_segsz;
tp->snd_ssthresh = win * tp->t_segsz;
tp->t_partialacks = -1;
tp->t_dupacks = 0;
tp->t_bytes_acked = 0;
}
static void
tcp_reno_fast_retransmit_newack(struct tcpcb *tp,
const struct tcphdr *th __unused)
{
if (tp->t_partialacks < 0) {
/*
* We were not in fast recovery. Reset the duplicate ack
* counter.
*/
tp->t_dupacks = 0;
} else {
/*
* Clamp the congestion window to the crossover point and
* exit fast recovery.
*/
if (tp->snd_cwnd > tp->snd_ssthresh)
tp->snd_cwnd = tp->snd_ssthresh;
tp->t_partialacks = -1;
tp->t_dupacks = 0;
tp->t_bytes_acked = 0;
}
}
static void
tcp_reno_newack(struct tcpcb *tp, const struct tcphdr *th)
{
/*
* When new data is acked, open the congestion window.
*/
u_int cw = tp->snd_cwnd;
u_int incr = tp->t_segsz;
if (tcp_do_abc) {
/*
* RFC 3465 Appropriate Byte Counting (ABC)
*/
int acked = th->th_ack - tp->snd_una;
if (cw >= tp->snd_ssthresh) {
tp->t_bytes_acked += acked;
if (tp->t_bytes_acked >= cw) {
/* Time to increase the window. */
tp->t_bytes_acked -= cw;
} else {
/* No need to increase yet. */
incr = 0;
}
} else {
/*
* use 2*SMSS or 1*SMSS for the "L" param,
* depending on sysctl setting.
*
* (See RFC 3465 2.3 Choosing the Limit)
*/
u_int abc_lim;
abc_lim = (tcp_abc_aggressive == 0 ||
tp->snd_nxt != tp->snd_max) ? incr : incr * 2;
incr = min(acked, abc_lim);
}
} else {
/*
* If the window gives us less than ssthresh packets
* in flight, open exponentially (segsz per packet).
* Otherwise open linearly: segsz per window
* (segsz^2 / cwnd per packet).
*/
if (cw >= tp->snd_ssthresh) {
incr = incr * incr / cw;
}
}
tp->snd_cwnd = min(cw + incr, TCP_MAXWIN << tp->snd_scale);
}
struct tcp_congctl tcp_reno_ctl = {
.fast_retransmit = tcp_reno_fast_retransmit,
.slow_retransmit = tcp_reno_slow_retransmit,
.fast_retransmit_newack = tcp_reno_fast_retransmit_newack,
.newack = tcp_reno_newack,
.cong_exp = tcp_reno_congestion_exp,
};
/*
* TCP/NewReno Congestion control.
*/
static int
tcp_newreno_fast_retransmit(struct tcpcb *tp, const struct tcphdr *th)
{
if (SEQ_LT(th->th_ack, tp->snd_high)) {
/*
* False fast retransmit after timeout.
* Do not enter fast recovery
*/
tp->t_dupacks = 0;
return 1;
} else {
/*
* Fast retransmit is same as reno.
*/
return tcp_reno_fast_retransmit(tp, th);
}
return 0;
}
/*
* Implement the NewReno response to a new ack, checking for partial acks in
* fast recovery.
*/
static void
tcp_newreno_fast_retransmit_newack(struct tcpcb *tp, const struct tcphdr *th)
{
if (tp->t_partialacks < 0) {
/*
* We were not in fast recovery. Reset the duplicate ack
* counter.
*/
tp->t_dupacks = 0;
} else if (SEQ_LT(th->th_ack, tp->snd_recover)) {
/*
* This is a partial ack. Retransmit the first unacknowledged
* segment and deflate the congestion window by the amount of
* acknowledged data. Do not exit fast recovery.
*/
tcp_seq onxt = tp->snd_nxt;
u_long ocwnd = tp->snd_cwnd;
/*
* snd_una has not yet been updated and the socket's send
* buffer has not yet drained off the ACK'd data, so we
* have to leave snd_una as it was to get the correct data
* offset in tcp_output().
*/
if (++tp->t_partialacks == 1)
TCP_TIMER_DISARM(tp, TCPT_REXMT);
tp->t_rtttime = 0;
tp->snd_nxt = th->th_ack;
/*
* Set snd_cwnd to one segment beyond ACK'd offset. snd_una
* is not yet updated when we're called.
*/
tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una);
(void) tcp_output(tp);
tp->snd_cwnd = ocwnd;
if (SEQ_GT(onxt, tp->snd_nxt))
tp->snd_nxt = onxt;
/*
* Partial window deflation. Relies on fact that tp->snd_una
* not updated yet.
*/
tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz);
} else {
/*
* Complete ack. Inflate the congestion window to ssthresh
* and exit fast recovery.
*
* Window inflation should have left us with approx.
* snd_ssthresh outstanding data. But in case we
* would be inclined to send a burst, better to do
* it via the slow start mechanism.
*/
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;
else
tp->snd_cwnd = tp->snd_ssthresh;
tp->t_partialacks = -1;
tp->t_dupacks = 0;
tp->t_bytes_acked = 0;
}
}
static void
tcp_newreno_newack(struct tcpcb *tp, const struct tcphdr *th)
{
/*
* If we are still in fast recovery (meaning we are using
* NewReno and we have only received partial acks), do not
* inflate the window yet.
*/
if (tp->t_partialacks < 0)
tcp_reno_newack(tp, th);
}
struct tcp_congctl tcp_newreno_ctl = {
.fast_retransmit = tcp_newreno_fast_retransmit,
.slow_retransmit = tcp_reno_slow_retransmit,
.fast_retransmit_newack = tcp_newreno_fast_retransmit_newack,
.newack = tcp_newreno_newack,
.cong_exp = tcp_reno_congestion_exp,
};
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