xref: /freebsd/sys/netinet/cc/cc.c (revision b8d60729deefa0bd13e6a395fcab4928e6e10445)
1dbc42409SLawrence Stewart /*-
2fe267a55SPedro F. Giffuni  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3fe267a55SPedro F. Giffuni  *
4dbc42409SLawrence Stewart  * Copyright (c) 2007-2008
5dbc42409SLawrence Stewart  *	Swinburne University of Technology, Melbourne, Australia.
6dbc42409SLawrence Stewart  * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org>
7dbc42409SLawrence Stewart  * Copyright (c) 2010 The FreeBSD Foundation
8dbc42409SLawrence Stewart  * All rights reserved.
9dbc42409SLawrence Stewart  *
10dbc42409SLawrence Stewart  * This software was developed at the Centre for Advanced Internet
11891b8ed4SLawrence Stewart  * Architectures, Swinburne University of Technology, by Lawrence Stewart and
12891b8ed4SLawrence Stewart  * James Healy, made possible in part by a grant from the Cisco University
13891b8ed4SLawrence Stewart  * Research Program Fund at Community Foundation Silicon Valley.
14dbc42409SLawrence Stewart  *
15dbc42409SLawrence Stewart  * Portions of this software were developed at the Centre for Advanced
16dbc42409SLawrence Stewart  * Internet Architectures, Swinburne University of Technology, Melbourne,
17dbc42409SLawrence Stewart  * Australia by David Hayes under sponsorship from the FreeBSD Foundation.
18dbc42409SLawrence Stewart  *
19dbc42409SLawrence Stewart  * Redistribution and use in source and binary forms, with or without
20dbc42409SLawrence Stewart  * modification, are permitted provided that the following conditions
21dbc42409SLawrence Stewart  * are met:
22dbc42409SLawrence Stewart  * 1. Redistributions of source code must retain the above copyright
23dbc42409SLawrence Stewart  *    notice, this list of conditions and the following disclaimer.
24dbc42409SLawrence Stewart  * 2. Redistributions in binary form must reproduce the above copyright
25dbc42409SLawrence Stewart  *    notice, this list of conditions and the following disclaimer in the
26dbc42409SLawrence Stewart  *    documentation and/or other materials provided with the distribution.
27dbc42409SLawrence Stewart  *
28dbc42409SLawrence Stewart  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
29dbc42409SLawrence Stewart  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30dbc42409SLawrence Stewart  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31dbc42409SLawrence Stewart  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
32dbc42409SLawrence Stewart  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33dbc42409SLawrence Stewart  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34dbc42409SLawrence Stewart  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35dbc42409SLawrence Stewart  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36dbc42409SLawrence Stewart  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37dbc42409SLawrence Stewart  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38dbc42409SLawrence Stewart  * SUCH DAMAGE.
39dbc42409SLawrence Stewart  */
40dbc42409SLawrence Stewart 
41dbc42409SLawrence Stewart /*
42dbc42409SLawrence Stewart  * This software was first released in 2007 by James Healy and Lawrence Stewart
43891b8ed4SLawrence Stewart  * whilst working on the NewTCP research project at Swinburne University of
44891b8ed4SLawrence Stewart  * Technology's Centre for Advanced Internet Architectures, Melbourne,
45891b8ed4SLawrence Stewart  * Australia, which was made possible in part by a grant from the Cisco
46891b8ed4SLawrence Stewart  * University Research Program Fund at Community Foundation Silicon Valley.
47891b8ed4SLawrence Stewart  * More details are available at:
48dbc42409SLawrence Stewart  *   http://caia.swin.edu.au/urp/newtcp/
49dbc42409SLawrence Stewart  */
50dbc42409SLawrence Stewart 
51dbc42409SLawrence Stewart #include <sys/cdefs.h>
52dbc42409SLawrence Stewart __FBSDID("$FreeBSD$");
53*b8d60729SRandall Stewart #include <opt_cc.h>
54dbc42409SLawrence Stewart #include <sys/param.h>
55dbc42409SLawrence Stewart #include <sys/kernel.h>
56dbc42409SLawrence Stewart #include <sys/libkern.h>
57dbc42409SLawrence Stewart #include <sys/lock.h>
58dbc42409SLawrence Stewart #include <sys/malloc.h>
59dbc42409SLawrence Stewart #include <sys/module.h>
60dbc42409SLawrence Stewart #include <sys/mutex.h>
61dbc42409SLawrence Stewart #include <sys/queue.h>
62dbc42409SLawrence Stewart #include <sys/rwlock.h>
63dbc42409SLawrence Stewart #include <sys/sbuf.h>
64dbc42409SLawrence Stewart #include <sys/socket.h>
65dbc42409SLawrence Stewart #include <sys/socketvar.h>
66dbc42409SLawrence Stewart #include <sys/sysctl.h>
67dbc42409SLawrence Stewart 
68b66d74c1SGleb Smirnoff #include <net/vnet.h>
69dbc42409SLawrence Stewart 
70dbc42409SLawrence Stewart #include <netinet/in.h>
71dbc42409SLawrence Stewart #include <netinet/in_pcb.h>
722de3e790SGleb Smirnoff #include <netinet/tcp.h>
73*b8d60729SRandall Stewart #include <netinet/tcp_seq.h>
74dbc42409SLawrence Stewart #include <netinet/tcp_var.h>
75*b8d60729SRandall Stewart #include <netinet/tcp_log_buf.h>
76*b8d60729SRandall Stewart #include <netinet/tcp_hpts.h>
774644fda3SGleb Smirnoff #include <netinet/cc/cc.h>
78dbc42409SLawrence Stewart #include <netinet/cc/cc_module.h>
79dbc42409SLawrence Stewart 
80*b8d60729SRandall Stewart MALLOC_DEFINE(M_CC_MEM, "CC Mem", "Congestion Control State memory");
81*b8d60729SRandall Stewart 
82dbc42409SLawrence Stewart /*
83dbc42409SLawrence Stewart  * List of available cc algorithms on the current system. First element
84dbc42409SLawrence Stewart  * is used as the system default CC algorithm.
85dbc42409SLawrence Stewart  */
86dbc42409SLawrence Stewart struct cc_head cc_list = STAILQ_HEAD_INITIALIZER(cc_list);
87dbc42409SLawrence Stewart 
88dbc42409SLawrence Stewart /* Protects the cc_list TAILQ. */
89dbc42409SLawrence Stewart struct rwlock cc_list_lock;
90dbc42409SLawrence Stewart 
91*b8d60729SRandall Stewart VNET_DEFINE(struct cc_algo *, default_cc_ptr) = NULL;
92*b8d60729SRandall Stewart 
93*b8d60729SRandall Stewart VNET_DEFINE(uint32_t, newreno_beta) = 50;
94*b8d60729SRandall Stewart #define V_newreno_beta VNET(newreno_beta)
95dbc42409SLawrence Stewart 
96dbc42409SLawrence Stewart /*
97dbc42409SLawrence Stewart  * Sysctl handler to show and change the default CC algorithm.
98dbc42409SLawrence Stewart  */
99dbc42409SLawrence Stewart static int
100dbc42409SLawrence Stewart cc_default_algo(SYSCTL_HANDLER_ARGS)
101dbc42409SLawrence Stewart {
102ebf92e86SLawrence Stewart 	char default_cc[TCP_CA_NAME_MAX];
103dbc42409SLawrence Stewart 	struct cc_algo *funcs;
1040e1152fcSHans Petter Selasky 	int error;
105dbc42409SLawrence Stewart 
1060e1152fcSHans Petter Selasky 	/* Get the current default: */
107dbc42409SLawrence Stewart 	CC_LIST_RLOCK();
108*b8d60729SRandall Stewart 	if (CC_DEFAULT_ALGO() != NULL)
109*b8d60729SRandall Stewart 		strlcpy(default_cc, CC_DEFAULT_ALGO()->name, sizeof(default_cc));
110*b8d60729SRandall Stewart 	else
111*b8d60729SRandall Stewart 		memset(default_cc, 0, TCP_CA_NAME_MAX);
112dbc42409SLawrence Stewart 	CC_LIST_RUNLOCK();
1130e1152fcSHans Petter Selasky 
1140e1152fcSHans Petter Selasky 	error = sysctl_handle_string(oidp, default_cc, sizeof(default_cc), req);
1150e1152fcSHans Petter Selasky 
1160e1152fcSHans Petter Selasky 	/* Check for error or no change */
1170e1152fcSHans Petter Selasky 	if (error != 0 || req->newptr == NULL)
1180e1152fcSHans Petter Selasky 		goto done;
1190e1152fcSHans Petter Selasky 
1200e1152fcSHans Petter Selasky 	error = ESRCH;
121dbc42409SLawrence Stewart 	/* Find algo with specified name and set it to default. */
12278b01840SLawrence Stewart 	CC_LIST_RLOCK();
123dbc42409SLawrence Stewart 	STAILQ_FOREACH(funcs, &cc_list, entries) {
1240e1152fcSHans Petter Selasky 		if (strncmp(default_cc, funcs->name, sizeof(default_cc)))
12560a945f9SHans Petter Selasky 			continue;
12678b01840SLawrence Stewart 		V_default_cc_ptr = funcs;
1270e1152fcSHans Petter Selasky 		error = 0;
1280e1152fcSHans Petter Selasky 		break;
129dbc42409SLawrence Stewart 	}
13078b01840SLawrence Stewart 	CC_LIST_RUNLOCK();
1310e1152fcSHans Petter Selasky done:
1320e1152fcSHans Petter Selasky 	return (error);
133dbc42409SLawrence Stewart }
134dbc42409SLawrence Stewart 
135dbc42409SLawrence Stewart /*
136dbc42409SLawrence Stewart  * Sysctl handler to display the list of available CC algorithms.
137dbc42409SLawrence Stewart  */
138dbc42409SLawrence Stewart static int
139dbc42409SLawrence Stewart cc_list_available(SYSCTL_HANDLER_ARGS)
140dbc42409SLawrence Stewart {
141dbc42409SLawrence Stewart 	struct cc_algo *algo;
142dbc42409SLawrence Stewart 	struct sbuf *s;
143a66ac850SLawrence Stewart 	int err, first, nalgos;
144dbc42409SLawrence Stewart 
145a66ac850SLawrence Stewart 	err = nalgos = 0;
146dbc42409SLawrence Stewart 	first = 1;
147a66ac850SLawrence Stewart 
148a66ac850SLawrence Stewart 	CC_LIST_RLOCK();
149a66ac850SLawrence Stewart 	STAILQ_FOREACH(algo, &cc_list, entries) {
150a66ac850SLawrence Stewart 		nalgos++;
151a66ac850SLawrence Stewart 	}
152a66ac850SLawrence Stewart 	CC_LIST_RUNLOCK();
153*b8d60729SRandall Stewart 	if (nalgos == 0) {
154*b8d60729SRandall Stewart 		return (ENOENT);
155*b8d60729SRandall Stewart 	}
156a66ac850SLawrence Stewart 	s = sbuf_new(NULL, NULL, nalgos * TCP_CA_NAME_MAX, SBUF_FIXEDLEN);
157dbc42409SLawrence Stewart 
158dbc42409SLawrence Stewart 	if (s == NULL)
159dbc42409SLawrence Stewart 		return (ENOMEM);
160dbc42409SLawrence Stewart 
161a66ac850SLawrence Stewart 	/*
162a66ac850SLawrence Stewart 	 * It is theoretically possible for the CC list to have grown in size
163a66ac850SLawrence Stewart 	 * since the call to sbuf_new() and therefore for the sbuf to be too
164a66ac850SLawrence Stewart 	 * small. If this were to happen (incredibly unlikely), the sbuf will
165a66ac850SLawrence Stewart 	 * reach an overflow condition, sbuf_printf() will return an error and
166a66ac850SLawrence Stewart 	 * the sysctl will fail gracefully.
167a66ac850SLawrence Stewart 	 */
168dbc42409SLawrence Stewart 	CC_LIST_RLOCK();
169dbc42409SLawrence Stewart 	STAILQ_FOREACH(algo, &cc_list, entries) {
170dbc42409SLawrence Stewart 		err = sbuf_printf(s, first ? "%s" : ", %s", algo->name);
171a66ac850SLawrence Stewart 		if (err) {
172a66ac850SLawrence Stewart 			/* Sbuf overflow condition. */
173a66ac850SLawrence Stewart 			err = EOVERFLOW;
174dbc42409SLawrence Stewart 			break;
175a66ac850SLawrence Stewart 		}
176dbc42409SLawrence Stewart 		first = 0;
177dbc42409SLawrence Stewart 	}
178dbc42409SLawrence Stewart 	CC_LIST_RUNLOCK();
179dbc42409SLawrence Stewart 
180dbc42409SLawrence Stewart 	if (!err) {
181dbc42409SLawrence Stewart 		sbuf_finish(s);
182e167cb89SHans Petter Selasky 		err = sysctl_handle_string(oidp, sbuf_data(s), 0, req);
183dbc42409SLawrence Stewart 	}
184dbc42409SLawrence Stewart 
185dbc42409SLawrence Stewart 	sbuf_delete(s);
186dbc42409SLawrence Stewart 	return (err);
187dbc42409SLawrence Stewart }
188dbc42409SLawrence Stewart 
189dbc42409SLawrence Stewart /*
190*b8d60729SRandall Stewart  * Return the number of times a proposed removal_cc is
191*b8d60729SRandall Stewart  * being used as the default.
19278b01840SLawrence Stewart  */
193*b8d60729SRandall Stewart static int
194*b8d60729SRandall Stewart cc_check_default(struct cc_algo *remove_cc)
19578b01840SLawrence Stewart {
196*b8d60729SRandall Stewart 	int cnt = 0;
19778b01840SLawrence Stewart 	VNET_ITERATOR_DECL(vnet_iter);
19878b01840SLawrence Stewart 
19978b01840SLawrence Stewart 	CC_LIST_LOCK_ASSERT();
20078b01840SLawrence Stewart 
20178b01840SLawrence Stewart 	VNET_LIST_RLOCK_NOSLEEP();
20278b01840SLawrence Stewart 	VNET_FOREACH(vnet_iter) {
20378b01840SLawrence Stewart 		CURVNET_SET(vnet_iter);
204*b8d60729SRandall Stewart 		if ((CC_DEFAULT_ALGO() != NULL) &&
205*b8d60729SRandall Stewart 		    strncmp(CC_DEFAULT_ALGO()->name,
206*b8d60729SRandall Stewart 			    remove_cc->name,
207*b8d60729SRandall Stewart 			    TCP_CA_NAME_MAX) == 0) {
208*b8d60729SRandall Stewart 			cnt++;
209*b8d60729SRandall Stewart 		}
21078b01840SLawrence Stewart 		CURVNET_RESTORE();
21178b01840SLawrence Stewart 	}
21278b01840SLawrence Stewart 	VNET_LIST_RUNLOCK_NOSLEEP();
213*b8d60729SRandall Stewart 	return (cnt);
21478b01840SLawrence Stewart }
21578b01840SLawrence Stewart 
21678b01840SLawrence Stewart /*
217dbc42409SLawrence Stewart  * Initialise CC subsystem on system boot.
218dbc42409SLawrence Stewart  */
21914f57a8bSLawrence Stewart static void
22014f57a8bSLawrence Stewart cc_init(void)
221dbc42409SLawrence Stewart {
222dbc42409SLawrence Stewart 	CC_LIST_LOCK_INIT();
223dbc42409SLawrence Stewart 	STAILQ_INIT(&cc_list);
224dbc42409SLawrence Stewart }
225dbc42409SLawrence Stewart 
226dbc42409SLawrence Stewart /*
227dbc42409SLawrence Stewart  * Returns non-zero on success, 0 on failure.
228dbc42409SLawrence Stewart  */
229dbc42409SLawrence Stewart int
230dbc42409SLawrence Stewart cc_deregister_algo(struct cc_algo *remove_cc)
231dbc42409SLawrence Stewart {
232dbc42409SLawrence Stewart 	struct cc_algo *funcs, *tmpfuncs;
233dbc42409SLawrence Stewart 	int err;
234dbc42409SLawrence Stewart 
235dbc42409SLawrence Stewart 	err = ENOENT;
236dbc42409SLawrence Stewart 
237dbc42409SLawrence Stewart 	/* Remove algo from cc_list so that new connections can't use it. */
238dbc42409SLawrence Stewart 	CC_LIST_WLOCK();
239dbc42409SLawrence Stewart 	STAILQ_FOREACH_SAFE(funcs, &cc_list, entries, tmpfuncs) {
240dbc42409SLawrence Stewart 		if (funcs == remove_cc) {
241*b8d60729SRandall Stewart 			if (cc_check_default(remove_cc)) {
242*b8d60729SRandall Stewart 				err = EBUSY;
243*b8d60729SRandall Stewart 				break;
244*b8d60729SRandall Stewart 			}
245*b8d60729SRandall Stewart 			/* Add a temp flag to stop new adds to it */
246*b8d60729SRandall Stewart 			funcs->flags |= CC_MODULE_BEING_REMOVED;
247dbc42409SLawrence Stewart 			break;
248dbc42409SLawrence Stewart 		}
249dbc42409SLawrence Stewart 	}
250dbc42409SLawrence Stewart 	CC_LIST_WUNLOCK();
251*b8d60729SRandall Stewart 	err = tcp_ccalgounload(remove_cc);
252dbc42409SLawrence Stewart 	/*
253*b8d60729SRandall Stewart 	 * Now back through and we either remove the temp flag
254*b8d60729SRandall Stewart 	 * or pull the registration.
255dbc42409SLawrence Stewart 	 */
256*b8d60729SRandall Stewart 	CC_LIST_WLOCK();
257*b8d60729SRandall Stewart 	STAILQ_FOREACH_SAFE(funcs, &cc_list, entries, tmpfuncs) {
258*b8d60729SRandall Stewart 		if (funcs == remove_cc) {
259*b8d60729SRandall Stewart 			if (err == 0)
260*b8d60729SRandall Stewart 				STAILQ_REMOVE(&cc_list, funcs, cc_algo, entries);
261*b8d60729SRandall Stewart 			else
262*b8d60729SRandall Stewart 				funcs->flags &= ~CC_MODULE_BEING_REMOVED;
263*b8d60729SRandall Stewart 			break;
264*b8d60729SRandall Stewart 		}
265*b8d60729SRandall Stewart 	}
266*b8d60729SRandall Stewart 	CC_LIST_WUNLOCK();
267dbc42409SLawrence Stewart 	return (err);
268dbc42409SLawrence Stewart }
269dbc42409SLawrence Stewart 
270dbc42409SLawrence Stewart /*
271dbc42409SLawrence Stewart  * Returns 0 on success, non-zero on failure.
272dbc42409SLawrence Stewart  */
273dbc42409SLawrence Stewart int
274dbc42409SLawrence Stewart cc_register_algo(struct cc_algo *add_cc)
275dbc42409SLawrence Stewart {
276dbc42409SLawrence Stewart 	struct cc_algo *funcs;
277dbc42409SLawrence Stewart 	int err;
278dbc42409SLawrence Stewart 
279dbc42409SLawrence Stewart 	err = 0;
280dbc42409SLawrence Stewart 
281dbc42409SLawrence Stewart 	/*
282dbc42409SLawrence Stewart 	 * Iterate over list of registered CC algorithms and make sure
283dbc42409SLawrence Stewart 	 * we're not trying to add a duplicate.
284dbc42409SLawrence Stewart 	 */
285dbc42409SLawrence Stewart 	CC_LIST_WLOCK();
286dbc42409SLawrence Stewart 	STAILQ_FOREACH(funcs, &cc_list, entries) {
287*b8d60729SRandall Stewart 		if (funcs == add_cc ||
288*b8d60729SRandall Stewart 		    strncmp(funcs->name, add_cc->name,
289*b8d60729SRandall Stewart 			    TCP_CA_NAME_MAX) == 0) {
290dbc42409SLawrence Stewart 			err = EEXIST;
291*b8d60729SRandall Stewart 			break;
292dbc42409SLawrence Stewart 		}
293*b8d60729SRandall Stewart 	}
294*b8d60729SRandall Stewart 	/*
295*b8d60729SRandall Stewart 	 * The first loaded congestion control module will become
296*b8d60729SRandall Stewart 	 * the default until we find the "CC_DEFAULT" defined in
297*b8d60729SRandall Stewart 	 * the config (if we do).
298*b8d60729SRandall Stewart 	 */
299*b8d60729SRandall Stewart 	if (!err) {
300dbc42409SLawrence Stewart 		STAILQ_INSERT_TAIL(&cc_list, add_cc, entries);
301*b8d60729SRandall Stewart 		if (strcmp(add_cc->name, CC_DEFAULT) == 0) {
302*b8d60729SRandall Stewart 			V_default_cc_ptr = add_cc;
303*b8d60729SRandall Stewart 		} else if (V_default_cc_ptr == NULL) {
304*b8d60729SRandall Stewart 			V_default_cc_ptr = add_cc;
305*b8d60729SRandall Stewart 		}
306*b8d60729SRandall Stewart 	}
307dbc42409SLawrence Stewart 	CC_LIST_WUNLOCK();
308dbc42409SLawrence Stewart 
309dbc42409SLawrence Stewart 	return (err);
310dbc42409SLawrence Stewart }
311dbc42409SLawrence Stewart 
312dbc42409SLawrence Stewart /*
313*b8d60729SRandall Stewart  * Perform any necessary tasks before we exit congestion recovery.
314*b8d60729SRandall Stewart  */
315*b8d60729SRandall Stewart void
316*b8d60729SRandall Stewart newreno_cc_post_recovery(struct cc_var *ccv)
317*b8d60729SRandall Stewart {
318*b8d60729SRandall Stewart 	int pipe;
319*b8d60729SRandall Stewart 
320*b8d60729SRandall Stewart 	if (IN_FASTRECOVERY(CCV(ccv, t_flags))) {
321*b8d60729SRandall Stewart 		/*
322*b8d60729SRandall Stewart 		 * Fast recovery will conclude after returning from this
323*b8d60729SRandall Stewart 		 * function. Window inflation should have left us with
324*b8d60729SRandall Stewart 		 * approximately snd_ssthresh outstanding data. But in case we
325*b8d60729SRandall Stewart 		 * would be inclined to send a burst, better to do it via the
326*b8d60729SRandall Stewart 		 * slow start mechanism.
327*b8d60729SRandall Stewart 		 *
328*b8d60729SRandall Stewart 		 * XXXLAS: Find a way to do this without needing curack
329*b8d60729SRandall Stewart 		 */
330*b8d60729SRandall Stewart 		if (V_tcp_do_newsack)
331*b8d60729SRandall Stewart 			pipe = tcp_compute_pipe(ccv->ccvc.tcp);
332*b8d60729SRandall Stewart 		else
333*b8d60729SRandall Stewart 			pipe = CCV(ccv, snd_max) - ccv->curack;
334*b8d60729SRandall Stewart 		if (pipe < CCV(ccv, snd_ssthresh))
335*b8d60729SRandall Stewart 			/*
336*b8d60729SRandall Stewart 			 * Ensure that cwnd does not collapse to 1 MSS under
337*b8d60729SRandall Stewart 			 * adverse conditons. Implements RFC6582
338*b8d60729SRandall Stewart 			 */
339*b8d60729SRandall Stewart 			CCV(ccv, snd_cwnd) = max(pipe, CCV(ccv, t_maxseg)) +
340*b8d60729SRandall Stewart 			    CCV(ccv, t_maxseg);
341*b8d60729SRandall Stewart 		else
342*b8d60729SRandall Stewart 			CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);
343*b8d60729SRandall Stewart 	}
344*b8d60729SRandall Stewart }
345*b8d60729SRandall Stewart 
346*b8d60729SRandall Stewart void
347*b8d60729SRandall Stewart newreno_cc_after_idle(struct cc_var *ccv)
348*b8d60729SRandall Stewart {
349*b8d60729SRandall Stewart 	uint32_t rw;
350*b8d60729SRandall Stewart 	/*
351*b8d60729SRandall Stewart 	 * If we've been idle for more than one retransmit timeout the old
352*b8d60729SRandall Stewart 	 * congestion window is no longer current and we have to reduce it to
353*b8d60729SRandall Stewart 	 * the restart window before we can transmit again.
354*b8d60729SRandall Stewart 	 *
355*b8d60729SRandall Stewart 	 * The restart window is the initial window or the last CWND, whichever
356*b8d60729SRandall Stewart 	 * is smaller.
357*b8d60729SRandall Stewart 	 *
358*b8d60729SRandall Stewart 	 * This is done to prevent us from flooding the path with a full CWND at
359*b8d60729SRandall Stewart 	 * wirespeed, overloading router and switch buffers along the way.
360*b8d60729SRandall Stewart 	 *
361*b8d60729SRandall Stewart 	 * See RFC5681 Section 4.1. "Restarting Idle Connections".
362*b8d60729SRandall Stewart 	 *
363*b8d60729SRandall Stewart 	 * In addition, per RFC2861 Section 2, the ssthresh is set to the
364*b8d60729SRandall Stewart 	 * maximum of the former ssthresh or 3/4 of the old cwnd, to
365*b8d60729SRandall Stewart 	 * not exit slow-start prematurely.
366*b8d60729SRandall Stewart 	 */
367*b8d60729SRandall Stewart 	rw = tcp_compute_initwnd(tcp_maxseg(ccv->ccvc.tcp));
368*b8d60729SRandall Stewart 
369*b8d60729SRandall Stewart 	CCV(ccv, snd_ssthresh) = max(CCV(ccv, snd_ssthresh),
370*b8d60729SRandall Stewart 	    CCV(ccv, snd_cwnd)-(CCV(ccv, snd_cwnd)>>2));
371*b8d60729SRandall Stewart 
372*b8d60729SRandall Stewart 	CCV(ccv, snd_cwnd) = min(rw, CCV(ccv, snd_cwnd));
373*b8d60729SRandall Stewart }
374*b8d60729SRandall Stewart 
375*b8d60729SRandall Stewart /*
376*b8d60729SRandall Stewart  * Perform any necessary tasks before we enter congestion recovery.
377*b8d60729SRandall Stewart  */
378*b8d60729SRandall Stewart void
379*b8d60729SRandall Stewart newreno_cc_cong_signal(struct cc_var *ccv, uint32_t type)
380*b8d60729SRandall Stewart {
381*b8d60729SRandall Stewart 	uint32_t cwin, factor;
382*b8d60729SRandall Stewart 	u_int mss;
383*b8d60729SRandall Stewart 
384*b8d60729SRandall Stewart 	cwin = CCV(ccv, snd_cwnd);
385*b8d60729SRandall Stewart 	mss = tcp_fixed_maxseg(ccv->ccvc.tcp);
386*b8d60729SRandall Stewart 	/*
387*b8d60729SRandall Stewart 	 * Other TCP congestion controls use newreno_cong_signal(), but
388*b8d60729SRandall Stewart 	 * with their own private cc_data. Make sure the cc_data is used
389*b8d60729SRandall Stewart 	 * correctly.
390*b8d60729SRandall Stewart 	 */
391*b8d60729SRandall Stewart 	factor = V_newreno_beta;
392*b8d60729SRandall Stewart 
393*b8d60729SRandall Stewart 	/* Catch algos which mistakenly leak private signal types. */
394*b8d60729SRandall Stewart 	KASSERT((type & CC_SIGPRIVMASK) == 0,
395*b8d60729SRandall Stewart 	    ("%s: congestion signal type 0x%08x is private\n", __func__, type));
396*b8d60729SRandall Stewart 
397*b8d60729SRandall Stewart 	cwin = max(((uint64_t)cwin * (uint64_t)factor) / (100ULL * (uint64_t)mss),
398*b8d60729SRandall Stewart 	    2) * mss;
399*b8d60729SRandall Stewart 
400*b8d60729SRandall Stewart 	switch (type) {
401*b8d60729SRandall Stewart 	case CC_NDUPACK:
402*b8d60729SRandall Stewart 		if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
403*b8d60729SRandall Stewart 			if (!IN_CONGRECOVERY(CCV(ccv, t_flags)))
404*b8d60729SRandall Stewart 				CCV(ccv, snd_ssthresh) = cwin;
405*b8d60729SRandall Stewart 			ENTER_RECOVERY(CCV(ccv, t_flags));
406*b8d60729SRandall Stewart 		}
407*b8d60729SRandall Stewart 		break;
408*b8d60729SRandall Stewart 	case CC_ECN:
409*b8d60729SRandall Stewart 		if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
410*b8d60729SRandall Stewart 			CCV(ccv, snd_ssthresh) = cwin;
411*b8d60729SRandall Stewart 			CCV(ccv, snd_cwnd) = cwin;
412*b8d60729SRandall Stewart 			ENTER_CONGRECOVERY(CCV(ccv, t_flags));
413*b8d60729SRandall Stewart 		}
414*b8d60729SRandall Stewart 		break;
415*b8d60729SRandall Stewart 	case CC_RTO:
416*b8d60729SRandall Stewart 		CCV(ccv, snd_ssthresh) = max(min(CCV(ccv, snd_wnd),
417*b8d60729SRandall Stewart 						 CCV(ccv, snd_cwnd)) / 2 / mss,
418*b8d60729SRandall Stewart 					     2) * mss;
419*b8d60729SRandall Stewart 		CCV(ccv, snd_cwnd) = mss;
420*b8d60729SRandall Stewart 		break;
421*b8d60729SRandall Stewart 	}
422*b8d60729SRandall Stewart }
423*b8d60729SRandall Stewart 
424*b8d60729SRandall Stewart void
425*b8d60729SRandall Stewart newreno_cc_ack_received(struct cc_var *ccv, uint16_t type)
426*b8d60729SRandall Stewart {
427*b8d60729SRandall Stewart 	if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&
428*b8d60729SRandall Stewart 	    (ccv->flags & CCF_CWND_LIMITED)) {
429*b8d60729SRandall Stewart 		u_int cw = CCV(ccv, snd_cwnd);
430*b8d60729SRandall Stewart 		u_int incr = CCV(ccv, t_maxseg);
431*b8d60729SRandall Stewart 
432*b8d60729SRandall Stewart 		/*
433*b8d60729SRandall Stewart 		 * Regular in-order ACK, open the congestion window.
434*b8d60729SRandall Stewart 		 * Method depends on which congestion control state we're
435*b8d60729SRandall Stewart 		 * in (slow start or cong avoid) and if ABC (RFC 3465) is
436*b8d60729SRandall Stewart 		 * enabled.
437*b8d60729SRandall Stewart 		 *
438*b8d60729SRandall Stewart 		 * slow start: cwnd <= ssthresh
439*b8d60729SRandall Stewart 		 * cong avoid: cwnd > ssthresh
440*b8d60729SRandall Stewart 		 *
441*b8d60729SRandall Stewart 		 * slow start and ABC (RFC 3465):
442*b8d60729SRandall Stewart 		 *   Grow cwnd exponentially by the amount of data
443*b8d60729SRandall Stewart 		 *   ACKed capping the max increment per ACK to
444*b8d60729SRandall Stewart 		 *   (abc_l_var * maxseg) bytes.
445*b8d60729SRandall Stewart 		 *
446*b8d60729SRandall Stewart 		 * slow start without ABC (RFC 5681):
447*b8d60729SRandall Stewart 		 *   Grow cwnd exponentially by maxseg per ACK.
448*b8d60729SRandall Stewart 		 *
449*b8d60729SRandall Stewart 		 * cong avoid and ABC (RFC 3465):
450*b8d60729SRandall Stewart 		 *   Grow cwnd linearly by maxseg per RTT for each
451*b8d60729SRandall Stewart 		 *   cwnd worth of ACKed data.
452*b8d60729SRandall Stewart 		 *
453*b8d60729SRandall Stewart 		 * cong avoid without ABC (RFC 5681):
454*b8d60729SRandall Stewart 		 *   Grow cwnd linearly by approximately maxseg per RTT using
455*b8d60729SRandall Stewart 		 *   maxseg^2 / cwnd per ACK as the increment.
456*b8d60729SRandall Stewart 		 *   If cwnd > maxseg^2, fix the cwnd increment at 1 byte to
457*b8d60729SRandall Stewart 		 *   avoid capping cwnd.
458*b8d60729SRandall Stewart 		 */
459*b8d60729SRandall Stewart 		if (cw > CCV(ccv, snd_ssthresh)) {
460*b8d60729SRandall Stewart 			if (V_tcp_do_rfc3465) {
461*b8d60729SRandall Stewart 				if (ccv->flags & CCF_ABC_SENTAWND)
462*b8d60729SRandall Stewart 					ccv->flags &= ~CCF_ABC_SENTAWND;
463*b8d60729SRandall Stewart 				else
464*b8d60729SRandall Stewart 					incr = 0;
465*b8d60729SRandall Stewart 			} else
466*b8d60729SRandall Stewart 				incr = max((incr * incr / cw), 1);
467*b8d60729SRandall Stewart 		} else if (V_tcp_do_rfc3465) {
468*b8d60729SRandall Stewart 			/*
469*b8d60729SRandall Stewart 			 * In slow-start with ABC enabled and no RTO in sight?
470*b8d60729SRandall Stewart 			 * (Must not use abc_l_var > 1 if slow starting after
471*b8d60729SRandall Stewart 			 * an RTO. On RTO, snd_nxt = snd_una, so the
472*b8d60729SRandall Stewart 			 * snd_nxt == snd_max check is sufficient to
473*b8d60729SRandall Stewart 			 * handle this).
474*b8d60729SRandall Stewart 			 *
475*b8d60729SRandall Stewart 			 * XXXLAS: Find a way to signal SS after RTO that
476*b8d60729SRandall Stewart 			 * doesn't rely on tcpcb vars.
477*b8d60729SRandall Stewart 			 */
478*b8d60729SRandall Stewart 			uint16_t abc_val;
479*b8d60729SRandall Stewart 
480*b8d60729SRandall Stewart 			if (ccv->flags & CCF_USE_LOCAL_ABC)
481*b8d60729SRandall Stewart 				abc_val = ccv->labc;
482*b8d60729SRandall Stewart 			else
483*b8d60729SRandall Stewart 				abc_val = V_tcp_abc_l_var;
484*b8d60729SRandall Stewart 			if (CCV(ccv, snd_nxt) == CCV(ccv, snd_max))
485*b8d60729SRandall Stewart 				incr = min(ccv->bytes_this_ack,
486*b8d60729SRandall Stewart 				    ccv->nsegs * abc_val *
487*b8d60729SRandall Stewart 				    CCV(ccv, t_maxseg));
488*b8d60729SRandall Stewart 			else
489*b8d60729SRandall Stewart 				incr = min(ccv->bytes_this_ack, CCV(ccv, t_maxseg));
490*b8d60729SRandall Stewart 
491*b8d60729SRandall Stewart 		}
492*b8d60729SRandall Stewart 		/* ABC is on by default, so incr equals 0 frequently. */
493*b8d60729SRandall Stewart 		if (incr > 0)
494*b8d60729SRandall Stewart 			CCV(ccv, snd_cwnd) = min(cw + incr,
495*b8d60729SRandall Stewart 			    TCP_MAXWIN << CCV(ccv, snd_scale));
496*b8d60729SRandall Stewart 	}
497*b8d60729SRandall Stewart }
498*b8d60729SRandall Stewart 
499*b8d60729SRandall Stewart /*
500dbc42409SLawrence Stewart  * Handles kld related events. Returns 0 on success, non-zero on failure.
501dbc42409SLawrence Stewart  */
502dbc42409SLawrence Stewart int
503dbc42409SLawrence Stewart cc_modevent(module_t mod, int event_type, void *data)
504dbc42409SLawrence Stewart {
505dbc42409SLawrence Stewart 	struct cc_algo *algo;
506dbc42409SLawrence Stewart 	int err;
507dbc42409SLawrence Stewart 
508dbc42409SLawrence Stewart 	err = 0;
509dbc42409SLawrence Stewart 	algo = (struct cc_algo *)data;
510dbc42409SLawrence Stewart 
511dbc42409SLawrence Stewart 	switch(event_type) {
512dbc42409SLawrence Stewart 	case MOD_LOAD:
513*b8d60729SRandall Stewart 		if ((algo->cc_data_sz == NULL) && (algo->cb_init != NULL)) {
514*b8d60729SRandall Stewart 			/*
515*b8d60729SRandall Stewart 			 * A module must have a cc_data_sz function
516*b8d60729SRandall Stewart 			 * even if it has no data it should return 0.
517*b8d60729SRandall Stewart 			 */
518*b8d60729SRandall Stewart 			printf("Module Load Fails, it lacks a cc_data_sz() function but has a cb_init()!\n");
519*b8d60729SRandall Stewart 			err = EINVAL;
520*b8d60729SRandall Stewart 			break;
521*b8d60729SRandall Stewart 		}
522dbc42409SLawrence Stewart 		if (algo->mod_init != NULL)
523dbc42409SLawrence Stewart 			err = algo->mod_init();
524dbc42409SLawrence Stewart 		if (!err)
525dbc42409SLawrence Stewart 			err = cc_register_algo(algo);
526dbc42409SLawrence Stewart 		break;
527dbc42409SLawrence Stewart 
528dbc42409SLawrence Stewart 	case MOD_QUIESCE:
529dbc42409SLawrence Stewart 	case MOD_SHUTDOWN:
530dbc42409SLawrence Stewart 	case MOD_UNLOAD:
531dbc42409SLawrence Stewart 		err = cc_deregister_algo(algo);
532dbc42409SLawrence Stewart 		if (!err && algo->mod_destroy != NULL)
533dbc42409SLawrence Stewart 			algo->mod_destroy();
534dbc42409SLawrence Stewart 		if (err == ENOENT)
535dbc42409SLawrence Stewart 			err = 0;
536dbc42409SLawrence Stewart 		break;
537dbc42409SLawrence Stewart 
538dbc42409SLawrence Stewart 	default:
539dbc42409SLawrence Stewart 		err = EINVAL;
540dbc42409SLawrence Stewart 		break;
541dbc42409SLawrence Stewart 	}
542dbc42409SLawrence Stewart 
543dbc42409SLawrence Stewart 	return (err);
544dbc42409SLawrence Stewart }
545dbc42409SLawrence Stewart 
54614f57a8bSLawrence Stewart SYSINIT(cc, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_FIRST, cc_init, NULL);
54714f57a8bSLawrence Stewart 
548dbc42409SLawrence Stewart /* Declare sysctl tree and populate it. */
5497029da5cSPawel Biernacki SYSCTL_NODE(_net_inet_tcp, OID_AUTO, cc, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
550439e76ecSBrad Davis     "Congestion control related settings");
551dbc42409SLawrence Stewart 
5526df8a710SGleb Smirnoff SYSCTL_PROC(_net_inet_tcp_cc, OID_AUTO, algorithm,
5537029da5cSPawel Biernacki     CTLFLAG_VNET | CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE,
5547029da5cSPawel Biernacki     NULL, 0, cc_default_algo, "A",
5557029da5cSPawel Biernacki     "Default congestion control algorithm");
556dbc42409SLawrence Stewart 
5577029da5cSPawel Biernacki SYSCTL_PROC(_net_inet_tcp_cc, OID_AUTO, available,
5587029da5cSPawel Biernacki     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
559dbc42409SLawrence Stewart     NULL, 0, cc_list_available, "A",
560439e76ecSBrad Davis     "List available congestion control algorithms");
561370efe5aSLawrence Stewart 
562370efe5aSLawrence Stewart VNET_DEFINE(int, cc_do_abe) = 0;
563370efe5aSLawrence Stewart SYSCTL_INT(_net_inet_tcp_cc, OID_AUTO, abe, CTLFLAG_VNET | CTLFLAG_RW,
564370efe5aSLawrence Stewart     &VNET_NAME(cc_do_abe), 0,
565370efe5aSLawrence Stewart     "Enable draft-ietf-tcpm-alternativebackoff-ecn (TCP Alternative Backoff with ECN)");
566370efe5aSLawrence Stewart 
567370efe5aSLawrence Stewart VNET_DEFINE(int, cc_abe_frlossreduce) = 0;
568370efe5aSLawrence Stewart SYSCTL_INT(_net_inet_tcp_cc, OID_AUTO, abe_frlossreduce, CTLFLAG_VNET | CTLFLAG_RW,
569370efe5aSLawrence Stewart     &VNET_NAME(cc_abe_frlossreduce), 0,
570370efe5aSLawrence Stewart     "Apply standard beta instead of ABE-beta during ECN-signalled congestion "
571370efe5aSLawrence Stewart     "recovery episodes if loss also needs to be repaired");
572