xref: /freebsd/sys/netinet/sctp_cc_functions.c (revision 5dcd9c10612684d1c823670cbb5b4715028784e7)
1 /*-
2  * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
3  * Copyright (c) 2008-2011, by Randall Stewart. All rights reserved.
4  * Copyright (c) 2008-2011, by Michael Tuexen. All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions are met:
8  *
9  * a) Redistributions of source code must retain the above copyright notice,
10  *   this list of conditions and the following disclaimer.
11  *
12  * b) Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in
14  *   the documentation and/or other materials provided with the distribution.
15  *
16  * c) Neither the name of Cisco Systems, Inc. nor the names of its
17  *    contributors may be used to endorse or promote products derived
18  *    from this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
22  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
30  * THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #include <netinet/sctp_os.h>
34 #include <netinet/sctp_var.h>
35 #include <netinet/sctp_sysctl.h>
36 #include <netinet/sctp_pcb.h>
37 #include <netinet/sctp_header.h>
38 #include <netinet/sctputil.h>
39 #include <netinet/sctp_output.h>
40 #include <netinet/sctp_input.h>
41 #include <netinet/sctp_indata.h>
42 #include <netinet/sctp_uio.h>
43 #include <netinet/sctp_timer.h>
44 #include <netinet/sctp_auth.h>
45 #include <netinet/sctp_asconf.h>
46 #include <netinet/sctp_dtrace_declare.h>
47 #include <sys/cdefs.h>
48 __FBSDID("$FreeBSD$");
49 
50 static void
51 sctp_set_initial_cc_param(struct sctp_tcb *stcb, struct sctp_nets *net)
52 {
53 	struct sctp_association *assoc;
54 	uint32_t cwnd_in_mtu;
55 
56 	assoc = &stcb->asoc;
57 	cwnd_in_mtu = SCTP_BASE_SYSCTL(sctp_initial_cwnd);
58 	if (cwnd_in_mtu == 0) {
59 		/* Using 0 means that the value of RFC 4960 is used. */
60 		net->cwnd = min((net->mtu * 4), max((2 * net->mtu), SCTP_INITIAL_CWND));
61 	} else {
62 		/*
63 		 * We take the minimum of the burst limit and the initial
64 		 * congestion window.
65 		 */
66 		if ((assoc->max_burst > 0) && (cwnd_in_mtu > assoc->max_burst))
67 			cwnd_in_mtu = assoc->max_burst;
68 		net->cwnd = (net->mtu - sizeof(struct sctphdr)) * cwnd_in_mtu;
69 	}
70 	if (stcb->asoc.sctp_cmt_on_off == 2) {
71 		/* In case of resource pooling initialize appropriately */
72 		net->cwnd /= assoc->numnets;
73 		if (net->cwnd < (net->mtu - sizeof(struct sctphdr))) {
74 			net->cwnd = net->mtu - sizeof(struct sctphdr);
75 		}
76 	}
77 	net->ssthresh = assoc->peers_rwnd;
78 
79 	SDT_PROBE(sctp, cwnd, net, init,
80 	    stcb->asoc.my_vtag, ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)), net,
81 	    0, net->cwnd);
82 	if (SCTP_BASE_SYSCTL(sctp_logging_level) &
83 	    (SCTP_CWND_MONITOR_ENABLE | SCTP_CWND_LOGGING_ENABLE)) {
84 		sctp_log_cwnd(stcb, net, 0, SCTP_CWND_INITIALIZATION);
85 	}
86 }
87 
88 static void
89 sctp_cwnd_update_after_fr(struct sctp_tcb *stcb,
90     struct sctp_association *asoc)
91 {
92 	struct sctp_nets *net;
93 	uint32_t t_ssthresh, t_cwnd;
94 
95 	/* MT FIXME: Don't compute this over and over again */
96 	t_ssthresh = 0;
97 	t_cwnd = 0;
98 	if (asoc->sctp_cmt_on_off == 2) {
99 		TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
100 			t_ssthresh += net->ssthresh;
101 			t_cwnd += net->cwnd;
102 		}
103 	}
104 	/*-
105 	 * CMT fast recovery code. Need to debug. ((sctp_cmt_on_off > 0) &&
106 	 * (net->fast_retran_loss_recovery == 0)))
107 	 */
108 	TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
109 		if ((asoc->fast_retran_loss_recovery == 0) ||
110 		    (asoc->sctp_cmt_on_off > 0)) {
111 			/* out of a RFC2582 Fast recovery window? */
112 			if (net->net_ack > 0) {
113 				/*
114 				 * per section 7.2.3, are there any
115 				 * destinations that had a fast retransmit
116 				 * to them. If so what we need to do is
117 				 * adjust ssthresh and cwnd.
118 				 */
119 				struct sctp_tmit_chunk *lchk;
120 				int old_cwnd = net->cwnd;
121 
122 				if (asoc->sctp_cmt_on_off == 2) {
123 					net->ssthresh = (uint32_t) (((uint64_t) 4 *
124 					    (uint64_t) net->mtu *
125 					    (uint64_t) net->ssthresh) /
126 					    (uint64_t) t_ssthresh);
127 					if ((net->cwnd > t_cwnd / 2) &&
128 					    (net->ssthresh < net->cwnd - t_cwnd / 2)) {
129 						net->ssthresh = net->cwnd - t_cwnd / 2;
130 					}
131 					if (net->ssthresh < net->mtu) {
132 						net->ssthresh = net->mtu;
133 					}
134 				} else {
135 					net->ssthresh = net->cwnd / 2;
136 					if (net->ssthresh < (net->mtu * 2)) {
137 						net->ssthresh = 2 * net->mtu;
138 					}
139 				}
140 				net->cwnd = net->ssthresh;
141 				SDT_PROBE(sctp, cwnd, net, fr,
142 				    stcb->asoc.my_vtag, ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)), net,
143 				    old_cwnd, net->cwnd);
144 				if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
145 					sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd),
146 					    SCTP_CWND_LOG_FROM_FR);
147 				}
148 				lchk = TAILQ_FIRST(&asoc->send_queue);
149 
150 				net->partial_bytes_acked = 0;
151 				/* Turn on fast recovery window */
152 				asoc->fast_retran_loss_recovery = 1;
153 				if (lchk == NULL) {
154 					/* Mark end of the window */
155 					asoc->fast_recovery_tsn = asoc->sending_seq - 1;
156 				} else {
157 					asoc->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
158 				}
159 
160 				/*
161 				 * CMT fast recovery -- per destination
162 				 * recovery variable.
163 				 */
164 				net->fast_retran_loss_recovery = 1;
165 
166 				if (lchk == NULL) {
167 					/* Mark end of the window */
168 					net->fast_recovery_tsn = asoc->sending_seq - 1;
169 				} else {
170 					net->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
171 				}
172 
173 				sctp_timer_stop(SCTP_TIMER_TYPE_SEND,
174 				    stcb->sctp_ep, stcb, net, SCTP_FROM_SCTP_INDATA + SCTP_LOC_32);
175 				sctp_timer_start(SCTP_TIMER_TYPE_SEND,
176 				    stcb->sctp_ep, stcb, net);
177 			}
178 		} else if (net->net_ack > 0) {
179 			/*
180 			 * Mark a peg that we WOULD have done a cwnd
181 			 * reduction but RFC2582 prevented this action.
182 			 */
183 			SCTP_STAT_INCR(sctps_fastretransinrtt);
184 		}
185 	}
186 }
187 
188 
189 /* RTCC Algoritm to limit growth of cwnd, return
190  * true if you want to NOT allow cwnd growth
191  */
192 static int
193 cc_bw_limit(struct sctp_tcb *stcb, struct sctp_nets *net, uint64_t nbw)
194 {
195 	uint64_t bw_offset, rtt_offset, rtt, vtag, probepoint;
196 
197 	/*-
198 	 * Here we need to see if we want
199 	 * to limit cwnd growth due to increase
200 	 * in overall rtt but no increase in bw.
201 	 * We use the following table to figure
202 	 * out what we should do. When we return
203 	 * 0, cc update goes on as planned. If we
204 	 * return 1, then no cc update happens and cwnd
205 	 * stays where it is at.
206 	 * ----------------------------------
207 	 *   BW    |    RTT   | Action
208 	 * *********************************
209 	 *   INC   |    INC   | return 0
210 	 * ----------------------------------
211 	 *   INC   |    SAME  | return 0
212 	 * ----------------------------------
213 	 *   INC   |    DECR  | return 0
214 	 * ----------------------------------
215 	 *   SAME  |    INC   | return 1
216 	 * ----------------------------------
217 	 *   SAME  |    SAME  | return 1
218 	 * ----------------------------------
219 	 *   SAME  |    DECR  | return 0
220 	 * ----------------------------------
221 	 *   DECR  |    INC   | return 0 or 1 based on if we caused.
222 	 * ----------------------------------
223 	 *   DECR  |    SAME  | return 0
224 	 * ----------------------------------
225 	 *   DECR  |    DECR  | return 0
226 	 * ----------------------------------
227 	 *
228 	 * We are a bit fuzz on what an increase or
229 	 * decrease is. For BW it is the same if
230 	 * it did not change within 1/64th. For
231 	 * RTT it stayed the same if it did not
232 	 * change within 1/32nd
233 	 */
234 	rtt = stcb->asoc.my_vtag;
235 	vtag = (rtt << 32) | (((uint32_t) (stcb->sctp_ep->sctp_lport)) << 16) | (stcb->rport);
236 	probepoint = (((uint64_t) net->cwnd) << 32);
237 	rtt = net->rtt;
238 	bw_offset = net->cc_mod.rtcc.lbw >> SCTP_BASE_SYSCTL(sctp_rttvar_bw);
239 	if (nbw > net->cc_mod.rtcc.lbw + bw_offset) {
240 		/*
241 		 * BW increased, so update and return 0, since all actions
242 		 * in our table say to do the normal CC update
243 		 */
244 		/* PROBE POINT 0 */
245 		SDT_PROBE(sctp, cwnd, net, rttvar,
246 		    vtag,
247 		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
248 		    net->cc_mod.rtcc.lbw_rtt,
249 		    rtt,
250 		    probepoint);
251 		net->cc_mod.rtcc.lbw = nbw;
252 		net->cc_mod.rtcc.lbw_rtt = rtt;
253 		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
254 		return (0);
255 	}
256 	rtt_offset = net->cc_mod.rtcc.lbw_rtt >> SCTP_BASE_SYSCTL(sctp_rttvar_rtt);
257 	if (nbw < net->cc_mod.rtcc.lbw - bw_offset) {
258 		/* Bandwidth decreased. */
259 		if (rtt > net->cc_mod.rtcc.lbw_rtt + rtt_offset) {
260 			/* rtt increased */
261 			/* Did we add more */
262 			if (net->cwnd > net->cc_mod.rtcc.cwnd_at_bw_set) {
263 				/* We caused it maybe.. back off */
264 				/* PROBE POINT 1 */
265 				probepoint |= ((1 << 16) | 1);
266 				SDT_PROBE(sctp, cwnd, net, rttvar,
267 				    vtag,
268 				    ((net->cc_mod.rtcc.lbw << 32) | nbw),
269 				    net->cc_mod.rtcc.lbw_rtt,
270 				    rtt,
271 				    probepoint);
272 
273 				net->cc_mod.rtcc.lbw = nbw;
274 				net->cc_mod.rtcc.lbw_rtt = rtt;
275 				net->cwnd = net->cc_mod.rtcc.cwnd_at_bw_set;
276 				if (net->cc_mod.rtcc.ret_from_eq) {
277 					/*
278 					 * Switch over to CA if we are less
279 					 * aggressive
280 					 */
281 					net->ssthresh = net->cwnd - 1;
282 					net->partial_bytes_acked = 0;
283 				}
284 				return (1);
285 			}
286 			/* Probe point 2 */
287 			probepoint |= ((2 << 16) | 0);
288 			SDT_PROBE(sctp, cwnd, net, rttvar,
289 			    vtag,
290 			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
291 			    net->cc_mod.rtcc.lbw_rtt,
292 			    rtt,
293 			    probepoint);
294 
295 			/* Someone else - fight for more? */
296 			net->cc_mod.rtcc.lbw = nbw;
297 			net->cc_mod.rtcc.lbw_rtt = rtt;
298 			net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
299 			return (0);
300 		} else if (rtt < net->cc_mod.rtcc.lbw_rtt - rtt_offset) {
301 			/* rtt decreased */
302 			/* Probe point 3 */
303 			probepoint |= ((3 << 16) | 0);
304 			SDT_PROBE(sctp, cwnd, net, rttvar,
305 			    vtag,
306 			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
307 			    net->cc_mod.rtcc.lbw_rtt,
308 			    rtt,
309 			    probepoint);
310 			net->cc_mod.rtcc.lbw = nbw;
311 			net->cc_mod.rtcc.lbw_rtt = rtt;
312 			net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
313 			return (0);
314 		}
315 		/* The bw decreased but rtt stayed the same */
316 		net->cc_mod.rtcc.lbw = nbw;
317 		net->cc_mod.rtcc.lbw_rtt = rtt;
318 		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
319 		/* Probe point 4 */
320 		probepoint |= ((4 << 16) | 0);
321 		SDT_PROBE(sctp, cwnd, net, rttvar,
322 		    vtag,
323 		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
324 		    net->cc_mod.rtcc.lbw_rtt,
325 		    rtt,
326 		    probepoint);
327 		return (0);
328 	}
329 	/*
330 	 * If we reach here then we are in a situation where the bw stayed
331 	 * the same.
332 	 */
333 	if (rtt > net->cc_mod.rtcc.lbw_rtt + rtt_offset) {
334 		/*
335 		 * rtt increased we don't update bw.. so we don't update the
336 		 * rtt either.
337 		 */
338 		/* Probe point 5 */
339 		probepoint |= ((5 << 16) | 1);
340 		SDT_PROBE(sctp, cwnd, net, rttvar,
341 		    vtag,
342 		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
343 		    net->cc_mod.rtcc.lbw_rtt,
344 		    rtt,
345 		    probepoint);
346 		return (1);
347 	}
348 	if (rtt < net->cc_mod.rtcc.lbw_rtt - rtt_offset) {
349 		/*
350 		 * rtt decreased, there could be more room. we update both
351 		 * the bw and the rtt here.
352 		 */
353 		/* Probe point 6 */
354 		probepoint |= ((6 << 16) | 0);
355 		SDT_PROBE(sctp, cwnd, net, rttvar,
356 		    vtag,
357 		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
358 		    net->cc_mod.rtcc.lbw_rtt,
359 		    rtt,
360 		    probepoint);
361 		net->cc_mod.rtcc.lbw = nbw;
362 		net->cc_mod.rtcc.lbw_rtt = rtt;
363 		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
364 		return (0);
365 	}
366 	/*
367 	 * Ok bw and rtt remained the same .. no update to any but save the
368 	 * latest cwnd.
369 	 */
370 	/* Probe point 7 */
371 	probepoint |= ((7 << 16) | net->cc_mod.rtcc.ret_from_eq);
372 	SDT_PROBE(sctp, cwnd, net, rttvar,
373 	    vtag,
374 	    ((net->cc_mod.rtcc.lbw << 32) | nbw),
375 	    net->cc_mod.rtcc.lbw_rtt,
376 	    rtt,
377 	    probepoint);
378 	return ((int)net->cc_mod.rtcc.ret_from_eq);
379 }
380 
381 static void
382 sctp_cwnd_update_after_sack_common(struct sctp_tcb *stcb,
383     struct sctp_association *asoc,
384     int accum_moved, int reneged_all, int will_exit, int use_rtcc)
385 {
386 	struct sctp_nets *net;
387 	int old_cwnd;
388 	uint32_t t_ssthresh, t_cwnd, incr;
389 
390 	/* MT FIXME: Don't compute this over and over again */
391 	t_ssthresh = 0;
392 	t_cwnd = 0;
393 	if (stcb->asoc.sctp_cmt_on_off == 2) {
394 		TAILQ_FOREACH(net, &stcb->asoc.nets, sctp_next) {
395 			t_ssthresh += net->ssthresh;
396 			t_cwnd += net->cwnd;
397 		}
398 	}
399 	/******************************/
400 	/* update cwnd and Early FR   */
401 	/******************************/
402 	TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
403 
404 #ifdef JANA_CMT_FAST_RECOVERY
405 		/*
406 		 * CMT fast recovery code. Need to debug.
407 		 */
408 		if (net->fast_retran_loss_recovery && net->new_pseudo_cumack) {
409 			if (SCTP_TSN_GE(asoc->last_acked_seq, net->fast_recovery_tsn) ||
410 			    SCTP_TSN_GE(net->pseudo_cumack, net->fast_recovery_tsn)) {
411 				net->will_exit_fast_recovery = 1;
412 			}
413 		}
414 #endif
415 		if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
416 			/*
417 			 * So, first of all do we need to have a Early FR
418 			 * timer running?
419 			 */
420 			if ((!TAILQ_EMPTY(&asoc->sent_queue) &&
421 			    (net->ref_count > 1) &&
422 			    (net->flight_size < net->cwnd)) ||
423 			    (reneged_all)) {
424 				/*
425 				 * yes, so in this case stop it if its
426 				 * running, and then restart it. Reneging
427 				 * all is a special case where we want to
428 				 * run the Early FR timer and then force the
429 				 * last few unacked to be sent, causing us
430 				 * to illicit a sack with gaps to force out
431 				 * the others.
432 				 */
433 				if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
434 					SCTP_STAT_INCR(sctps_earlyfrstpidsck2);
435 					sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
436 					    SCTP_FROM_SCTP_INDATA + SCTP_LOC_20);
437 				}
438 				SCTP_STAT_INCR(sctps_earlyfrstrid);
439 				sctp_timer_start(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net);
440 			} else {
441 				/* No, stop it if its running */
442 				if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
443 					SCTP_STAT_INCR(sctps_earlyfrstpidsck3);
444 					sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
445 					    SCTP_FROM_SCTP_INDATA + SCTP_LOC_21);
446 				}
447 			}
448 		}
449 		/* if nothing was acked on this destination skip it */
450 		if (net->net_ack == 0) {
451 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
452 				sctp_log_cwnd(stcb, net, 0, SCTP_CWND_LOG_FROM_SACK);
453 			}
454 			continue;
455 		}
456 		if (net->net_ack2 > 0) {
457 			/*
458 			 * Karn's rule applies to clearing error count, this
459 			 * is optional.
460 			 */
461 			net->error_count = 0;
462 			if ((net->dest_state & SCTP_ADDR_NOT_REACHABLE) ==
463 			    SCTP_ADDR_NOT_REACHABLE) {
464 				/* addr came good */
465 				net->dest_state &= ~SCTP_ADDR_NOT_REACHABLE;
466 				net->dest_state |= SCTP_ADDR_REACHABLE;
467 				sctp_ulp_notify(SCTP_NOTIFY_INTERFACE_UP, stcb,
468 				    SCTP_RECEIVED_SACK, (void *)net, SCTP_SO_NOT_LOCKED);
469 				/* now was it the primary? if so restore */
470 				if (net->dest_state & SCTP_ADDR_WAS_PRIMARY) {
471 					(void)sctp_set_primary_addr(stcb, (struct sockaddr *)NULL, net);
472 				}
473 			}
474 			/*
475 			 * JRS 5/14/07 - If CMT PF is on and the destination
476 			 * is in PF state, set the destination to active
477 			 * state and set the cwnd to one or two MTU's based
478 			 * on whether PF1 or PF2 is being used.
479 			 *
480 			 * Should we stop any running T3 timer here?
481 			 */
482 			if ((asoc->sctp_cmt_on_off > 0) &&
483 			    (asoc->sctp_cmt_pf > 0) &&
484 			    ((net->dest_state & SCTP_ADDR_PF) == SCTP_ADDR_PF)) {
485 				net->dest_state &= ~SCTP_ADDR_PF;
486 				old_cwnd = net->cwnd;
487 				net->cwnd = net->mtu * asoc->sctp_cmt_pf;
488 				SDT_PROBE(sctp, cwnd, net, ack,
489 				    stcb->asoc.my_vtag, ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)), net,
490 				    old_cwnd, net->cwnd);
491 				SCTPDBG(SCTP_DEBUG_INDATA1, "Destination %p moved from PF to reachable with cwnd %d.\n",
492 				    net, net->cwnd);
493 				/*
494 				 * Since the cwnd value is explicitly set,
495 				 * skip the code that updates the cwnd
496 				 * value.
497 				 */
498 				goto skip_cwnd_update;
499 			}
500 		}
501 #ifdef JANA_CMT_FAST_RECOVERY
502 		/*
503 		 * CMT fast recovery code
504 		 */
505 		/*
506 		 * if (sctp_cmt_on_off > 0 && net->fast_retran_loss_recovery
507 		 * && net->will_exit_fast_recovery == 0) { @@@ Do something
508 		 * } else if (sctp_cmt_on_off == 0 &&
509 		 * asoc->fast_retran_loss_recovery && will_exit == 0) {
510 		 */
511 #endif
512 
513 		if (asoc->fast_retran_loss_recovery &&
514 		    (will_exit == 0) &&
515 		    (asoc->sctp_cmt_on_off == 0)) {
516 			/*
517 			 * If we are in loss recovery we skip any cwnd
518 			 * update
519 			 */
520 			goto skip_cwnd_update;
521 		}
522 		/*
523 		 * Did any measurements go on for this network?
524 		 */
525 		if (use_rtcc && (net->cc_mod.rtcc.tls_needs_set > 0)) {
526 			uint64_t nbw;
527 
528 			/*
529 			 * At this point our bw_bytes has been updated by
530 			 * incoming sack information.
531 			 *
532 			 * But our bw may not yet be set.
533 			 *
534 			 */
535 			if ((net->cc_mod.rtcc.new_tot_time / 1000) > 0) {
536 				nbw = net->cc_mod.rtcc.bw_bytes / (net->cc_mod.rtcc.new_tot_time / 1000);
537 			} else {
538 				nbw = net->cc_mod.rtcc.bw_bytes;
539 			}
540 			if (net->cc_mod.rtcc.lbw) {
541 				if (cc_bw_limit(stcb, net, nbw)) {
542 					/* Hold here, no update */
543 					goto skip_cwnd_update;
544 				}
545 			} else {
546 				uint64_t vtag, probepoint;
547 
548 				probepoint = (((uint64_t) net->cwnd) << 32);
549 				probepoint |= ((0xa << 16) | 0);
550 				vtag = (net->rtt << 32) |
551 				    (((uint32_t) (stcb->sctp_ep->sctp_lport)) << 16) |
552 				    (stcb->rport);
553 
554 				SDT_PROBE(sctp, cwnd, net, rttvar,
555 				    vtag,
556 				    nbw,
557 				    0,
558 				    net->rtt,
559 				    probepoint);
560 				net->cc_mod.rtcc.lbw = nbw;
561 				net->cc_mod.rtcc.lbw_rtt = net->rtt;
562 			}
563 		}
564 		/*
565 		 * CMT: CUC algorithm. Update cwnd if pseudo-cumack has
566 		 * moved.
567 		 */
568 		if (accum_moved ||
569 		    ((asoc->sctp_cmt_on_off > 0) && net->new_pseudo_cumack)) {
570 			/* If the cumulative ack moved we can proceed */
571 			if (net->cwnd <= net->ssthresh) {
572 				/* We are in slow start */
573 				if (net->flight_size + net->net_ack >= net->cwnd) {
574 					old_cwnd = net->cwnd;
575 					if (stcb->asoc.sctp_cmt_on_off == 2) {
576 						uint32_t limit;
577 
578 						limit = (uint32_t) (((uint64_t) net->mtu *
579 						    (uint64_t) SCTP_BASE_SYSCTL(sctp_L2_abc_variable) *
580 						    (uint64_t) net->ssthresh) /
581 						    (uint64_t) t_ssthresh);
582 						incr = (uint32_t) (((uint64_t) net->net_ack *
583 						    (uint64_t) net->ssthresh) /
584 						    (uint64_t) t_ssthresh);
585 						if (incr > limit) {
586 							incr = limit;
587 						}
588 						if (incr == 0) {
589 							incr = 1;
590 						}
591 					} else {
592 						incr = net->net_ack;
593 						if (incr > net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable)) {
594 							incr = net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable);
595 						}
596 					}
597 					net->cwnd += incr;
598 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
599 						sctp_log_cwnd(stcb, net, incr,
600 						    SCTP_CWND_LOG_FROM_SS);
601 					}
602 					SDT_PROBE(sctp, cwnd, net, ack,
603 					    stcb->asoc.my_vtag,
604 					    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
605 					    net,
606 					    old_cwnd, net->cwnd);
607 				} else {
608 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
609 						sctp_log_cwnd(stcb, net, net->net_ack,
610 						    SCTP_CWND_LOG_NOADV_SS);
611 					}
612 				}
613 			} else {
614 				/* We are in congestion avoidance */
615 				/*
616 				 * Add to pba
617 				 */
618 				net->partial_bytes_acked += net->net_ack;
619 
620 				if ((net->flight_size + net->net_ack >= net->cwnd) &&
621 				    (net->partial_bytes_acked >= net->cwnd)) {
622 					net->partial_bytes_acked -= net->cwnd;
623 					old_cwnd = net->cwnd;
624 					if (asoc->sctp_cmt_on_off == 2) {
625 						incr = (uint32_t) (((uint64_t) net->mtu *
626 						    (uint64_t) net->ssthresh) /
627 						    (uint64_t) t_ssthresh);
628 						if (incr == 0) {
629 							incr = 1;
630 						}
631 					} else {
632 						incr = net->mtu;
633 					}
634 					net->cwnd += incr;
635 					SDT_PROBE(sctp, cwnd, net, ack,
636 					    stcb->asoc.my_vtag,
637 					    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
638 					    net,
639 					    old_cwnd, net->cwnd);
640 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
641 						sctp_log_cwnd(stcb, net, net->mtu,
642 						    SCTP_CWND_LOG_FROM_CA);
643 					}
644 				} else {
645 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
646 						sctp_log_cwnd(stcb, net, net->net_ack,
647 						    SCTP_CWND_LOG_NOADV_CA);
648 					}
649 				}
650 			}
651 		} else {
652 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
653 				sctp_log_cwnd(stcb, net, net->mtu,
654 				    SCTP_CWND_LOG_NO_CUMACK);
655 			}
656 		}
657 skip_cwnd_update:
658 		/*
659 		 * NOW, according to Karn's rule do we need to restore the
660 		 * RTO timer back? Check our net_ack2. If not set then we
661 		 * have a ambiguity.. i.e. all data ack'd was sent to more
662 		 * than one place.
663 		 */
664 		if (net->net_ack2) {
665 			/* restore any doubled timers */
666 			net->RTO = (net->lastsa >> SCTP_RTT_SHIFT) + net->lastsv;
667 			if (net->RTO < stcb->asoc.minrto) {
668 				net->RTO = stcb->asoc.minrto;
669 			}
670 			if (net->RTO > stcb->asoc.maxrto) {
671 				net->RTO = stcb->asoc.maxrto;
672 			}
673 		}
674 	}
675 }
676 
677 static void
678 sctp_cwnd_update_after_timeout(struct sctp_tcb *stcb, struct sctp_nets *net)
679 {
680 	int old_cwnd = net->cwnd;
681 	uint32_t t_ssthresh, t_cwnd;
682 
683 	/* MT FIXME: Don't compute this over and over again */
684 	t_ssthresh = 0;
685 	t_cwnd = 0;
686 	if (stcb->asoc.sctp_cmt_on_off == 2) {
687 		struct sctp_nets *lnet;
688 
689 		TAILQ_FOREACH(lnet, &stcb->asoc.nets, sctp_next) {
690 			t_ssthresh += lnet->ssthresh;
691 			t_cwnd += lnet->cwnd;
692 		}
693 		net->ssthresh = (uint32_t) (((uint64_t) 4 *
694 		    (uint64_t) net->mtu *
695 		    (uint64_t) net->ssthresh) /
696 		    (uint64_t) t_ssthresh);
697 		if ((net->cwnd > t_cwnd / 2) &&
698 		    (net->ssthresh < net->cwnd - t_cwnd / 2)) {
699 			net->ssthresh = net->cwnd - t_cwnd / 2;
700 		}
701 		if (net->ssthresh < net->mtu) {
702 			net->ssthresh = net->mtu;
703 		}
704 	} else {
705 		net->ssthresh = max(net->cwnd / 2, 4 * net->mtu);
706 	}
707 	net->cwnd = net->mtu;
708 	net->partial_bytes_acked = 0;
709 	SDT_PROBE(sctp, cwnd, net, to,
710 	    stcb->asoc.my_vtag,
711 	    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
712 	    net,
713 	    old_cwnd, net->cwnd);
714 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
715 		sctp_log_cwnd(stcb, net, net->cwnd - old_cwnd, SCTP_CWND_LOG_FROM_RTX);
716 	}
717 }
718 
719 static void
720 sctp_cwnd_update_after_ecn_echo_common(struct sctp_tcb *stcb, struct sctp_nets *net,
721     int in_window, int num_pkt_lost, int use_rtcc)
722 {
723 	int old_cwnd = net->cwnd;
724 
725 	if ((use_rtcc) && (net->lan_type == SCTP_LAN_LOCAL) && (net->cc_mod.rtcc.use_dccc_ecn)) {
726 		/* Data center Congestion Control */
727 		if (in_window == 0) {
728 			/*
729 			 * Go to CA with the cwnd at the point we sent the
730 			 * TSN that was marked with a CE.
731 			 */
732 			if (net->ecn_prev_cwnd < net->cwnd) {
733 				/* Restore to prev cwnd */
734 				net->cwnd = net->ecn_prev_cwnd - (net->mtu * num_pkt_lost);
735 			} else {
736 				/* Just cut in 1/2 */
737 				net->cwnd /= 2;
738 			}
739 			/* Drop to CA */
740 			net->ssthresh = net->cwnd - (num_pkt_lost * net->mtu);
741 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
742 				sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_SAT);
743 			}
744 		} else {
745 			/*
746 			 * Further tuning down required over the drastic
747 			 * orginal cut
748 			 */
749 			net->ssthresh -= (net->mtu * num_pkt_lost);
750 			net->cwnd -= (net->mtu * num_pkt_lost);
751 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
752 				sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_SAT);
753 			}
754 		}
755 		SCTP_STAT_INCR(sctps_ecnereducedcwnd);
756 	} else {
757 		if (in_window == 0) {
758 			SCTP_STAT_INCR(sctps_ecnereducedcwnd);
759 			net->ssthresh = net->cwnd / 2;
760 			if (net->ssthresh < net->mtu) {
761 				net->ssthresh = net->mtu;
762 				/*
763 				 * here back off the timer as well, to slow
764 				 * us down
765 				 */
766 				net->RTO <<= 1;
767 			}
768 			net->cwnd = net->ssthresh;
769 			SDT_PROBE(sctp, cwnd, net, ecn,
770 			    stcb->asoc.my_vtag,
771 			    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
772 			    net,
773 			    old_cwnd, net->cwnd);
774 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
775 				sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_SAT);
776 			}
777 		}
778 	}
779 
780 }
781 
782 static void
783 sctp_cwnd_update_after_packet_dropped(struct sctp_tcb *stcb,
784     struct sctp_nets *net, struct sctp_pktdrop_chunk *cp,
785     uint32_t * bottle_bw, uint32_t * on_queue)
786 {
787 	uint32_t bw_avail;
788 	int rtt;
789 	unsigned int incr;
790 	int old_cwnd = net->cwnd;
791 
792 	/* need real RTT in msd for this calc */
793 	rtt = net->rtt / 1000;
794 	/* get bottle neck bw */
795 	*bottle_bw = ntohl(cp->bottle_bw);
796 	/* and whats on queue */
797 	*on_queue = ntohl(cp->current_onq);
798 	/*
799 	 * adjust the on-queue if our flight is more it could be that the
800 	 * router has not yet gotten data "in-flight" to it
801 	 */
802 	if (*on_queue < net->flight_size)
803 		*on_queue = net->flight_size;
804 	/* calculate the available space */
805 	bw_avail = (*bottle_bw * rtt) / 1000;
806 	if (bw_avail > *bottle_bw) {
807 		/*
808 		 * Cap the growth to no more than the bottle neck. This can
809 		 * happen as RTT slides up due to queues. It also means if
810 		 * you have more than a 1 second RTT with a empty queue you
811 		 * will be limited to the bottle_bw per second no matter if
812 		 * other points have 1/2 the RTT and you could get more
813 		 * out...
814 		 */
815 		bw_avail = *bottle_bw;
816 	}
817 	if (*on_queue > bw_avail) {
818 		/*
819 		 * No room for anything else don't allow anything else to be
820 		 * "added to the fire".
821 		 */
822 		int seg_inflight, seg_onqueue, my_portion;
823 
824 		net->partial_bytes_acked = 0;
825 
826 		/* how much are we over queue size? */
827 		incr = *on_queue - bw_avail;
828 		if (stcb->asoc.seen_a_sack_this_pkt) {
829 			/*
830 			 * undo any cwnd adjustment that the sack might have
831 			 * made
832 			 */
833 			net->cwnd = net->prev_cwnd;
834 		}
835 		/* Now how much of that is mine? */
836 		seg_inflight = net->flight_size / net->mtu;
837 		seg_onqueue = *on_queue / net->mtu;
838 		my_portion = (incr * seg_inflight) / seg_onqueue;
839 
840 		/* Have I made an adjustment already */
841 		if (net->cwnd > net->flight_size) {
842 			/*
843 			 * for this flight I made an adjustment we need to
844 			 * decrease the portion by a share our previous
845 			 * adjustment.
846 			 */
847 			int diff_adj;
848 
849 			diff_adj = net->cwnd - net->flight_size;
850 			if (diff_adj > my_portion)
851 				my_portion = 0;
852 			else
853 				my_portion -= diff_adj;
854 		}
855 		/*
856 		 * back down to the previous cwnd (assume we have had a sack
857 		 * before this packet). minus what ever portion of the
858 		 * overage is my fault.
859 		 */
860 		net->cwnd -= my_portion;
861 
862 		/* we will NOT back down more than 1 MTU */
863 		if (net->cwnd <= net->mtu) {
864 			net->cwnd = net->mtu;
865 		}
866 		/* force into CA */
867 		net->ssthresh = net->cwnd - 1;
868 	} else {
869 		/*
870 		 * Take 1/4 of the space left or max burst up .. whichever
871 		 * is less.
872 		 */
873 		incr = (bw_avail - *on_queue) >> 2;
874 		if ((stcb->asoc.max_burst > 0) &&
875 		    (stcb->asoc.max_burst * net->mtu < incr)) {
876 			incr = stcb->asoc.max_burst * net->mtu;
877 		}
878 		net->cwnd += incr;
879 	}
880 	if (net->cwnd > bw_avail) {
881 		/* We can't exceed the pipe size */
882 		net->cwnd = bw_avail;
883 	}
884 	if (net->cwnd < net->mtu) {
885 		/* We always have 1 MTU */
886 		net->cwnd = net->mtu;
887 	}
888 	if (net->cwnd - old_cwnd != 0) {
889 		/* log only changes */
890 		SDT_PROBE(sctp, cwnd, net, pd,
891 		    stcb->asoc.my_vtag,
892 		    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
893 		    net,
894 		    old_cwnd, net->cwnd);
895 		if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
896 			sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd),
897 			    SCTP_CWND_LOG_FROM_SAT);
898 		}
899 	}
900 }
901 
902 static void
903 sctp_cwnd_update_after_output(struct sctp_tcb *stcb,
904     struct sctp_nets *net, int burst_limit)
905 {
906 	int old_cwnd = net->cwnd;
907 
908 	if (net->ssthresh < net->cwnd)
909 		net->ssthresh = net->cwnd;
910 	if (burst_limit) {
911 		net->cwnd = (net->flight_size + (burst_limit * net->mtu));
912 		SDT_PROBE(sctp, cwnd, net, bl,
913 		    stcb->asoc.my_vtag,
914 		    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
915 		    net,
916 		    old_cwnd, net->cwnd);
917 		if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
918 			sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_BRST);
919 		}
920 	}
921 }
922 
923 static void
924 sctp_cwnd_update_after_fr_timer(struct sctp_inpcb *inp,
925     struct sctp_tcb *stcb, struct sctp_nets *net)
926 {
927 	int old_cwnd = net->cwnd;
928 
929 	sctp_chunk_output(inp, stcb, SCTP_OUTPUT_FROM_EARLY_FR_TMR, SCTP_SO_NOT_LOCKED);
930 	/*
931 	 * make a small adjustment to cwnd and force to CA.
932 	 */
933 	if (net->cwnd > net->mtu)
934 		/* drop down one MTU after sending */
935 		net->cwnd -= net->mtu;
936 	if (net->cwnd < net->ssthresh)
937 		/* still in SS move to CA */
938 		net->ssthresh = net->cwnd - 1;
939 	SDT_PROBE(sctp, cwnd, net, fr,
940 	    stcb->asoc.my_vtag,
941 	    ((stcb->sctp_ep->sctp_lport << 16) | (stcb->rport)),
942 	    net,
943 	    old_cwnd, net->cwnd);
944 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
945 		sctp_log_cwnd(stcb, net, (old_cwnd - net->cwnd), SCTP_CWND_LOG_FROM_FR);
946 	}
947 }
948 
949 static void
950 sctp_cwnd_update_after_sack(struct sctp_tcb *stcb,
951     struct sctp_association *asoc,
952     int accum_moved, int reneged_all, int will_exit)
953 {
954 	/* Passing a zero argument in last disables the rtcc algoritm */
955 	sctp_cwnd_update_after_sack_common(stcb, asoc, accum_moved, reneged_all, will_exit, 0);
956 }
957 
958 static void
959 sctp_cwnd_update_after_ecn_echo(struct sctp_tcb *stcb, struct sctp_nets *net,
960     int in_window, int num_pkt_lost)
961 {
962 	/* Passing a zero argument in last disables the rtcc algoritm */
963 	sctp_cwnd_update_after_ecn_echo_common(stcb, net, in_window, num_pkt_lost, 0);
964 }
965 
966 /* Here starts the RTCCVAR type CC invented by RRS which
967  * is a slight mod to RFC2581. We reuse a common routine or
968  * two since these algoritms are so close and need to
969  * remain the same.
970  */
971 static void
972 sctp_cwnd_update_rtcc_after_ecn_echo(struct sctp_tcb *stcb, struct sctp_nets *net,
973     int in_window, int num_pkt_lost)
974 {
975 	sctp_cwnd_update_after_ecn_echo_common(stcb, net, in_window, num_pkt_lost, 1);
976 }
977 
978 
979 static
980 void
981 sctp_cwnd_update_rtcc_tsn_acknowledged(struct sctp_nets *net,
982     struct sctp_tmit_chunk *tp1)
983 {
984 	net->cc_mod.rtcc.bw_bytes += tp1->send_size;
985 }
986 
987 static void
988 sctp_cwnd_prepare_rtcc_net_for_sack(struct sctp_tcb *stcb,
989     struct sctp_nets *net)
990 {
991 	if (net->cc_mod.rtcc.tls_needs_set > 0) {
992 		/* We had a bw measurment going on */
993 		struct timeval ltls;
994 
995 		SCTP_GETPTIME_TIMEVAL(&ltls);
996 		timevalsub(&ltls, &net->cc_mod.rtcc.tls);
997 		net->cc_mod.rtcc.new_tot_time = (ltls.tv_sec * 1000000) + ltls.tv_usec;
998 	}
999 }
1000 
1001 static void
1002 sctp_cwnd_new_rtcc_transmission_begins(struct sctp_tcb *stcb,
1003     struct sctp_nets *net)
1004 {
1005 	uint64_t vtag, probepoint;
1006 
1007 	if (net->cc_mod.rtcc.lbw) {
1008 		/* Clear the old bw.. we went to 0 in-flight */
1009 		vtag = (net->rtt << 32) | (((uint32_t) (stcb->sctp_ep->sctp_lport)) << 16) |
1010 		    (stcb->rport);
1011 		probepoint = (((uint64_t) net->cwnd) << 32);
1012 		/* Probe point 8 */
1013 		probepoint |= ((8 << 16) | 0);
1014 		SDT_PROBE(sctp, cwnd, net, rttvar,
1015 		    vtag,
1016 		    ((net->cc_mod.rtcc.lbw << 32) | 0),
1017 		    net->cc_mod.rtcc.lbw_rtt,
1018 		    0,
1019 		    probepoint);
1020 		net->cc_mod.rtcc.lbw_rtt = 0;
1021 		net->cc_mod.rtcc.cwnd_at_bw_set = 0;
1022 		net->cc_mod.rtcc.lbw = 0;
1023 		net->cc_mod.rtcc.bw_tot_time = 0;
1024 		net->cc_mod.rtcc.bw_bytes = 0;
1025 		net->cc_mod.rtcc.tls_needs_set = 0;
1026 		if (net->cc_mod.rtcc.ret_from_eq) {
1027 			/* less aggressive one - reset cwnd too */
1028 			uint32_t cwnd_in_mtu, cwnd;
1029 
1030 			cwnd_in_mtu = SCTP_BASE_SYSCTL(sctp_initial_cwnd);
1031 			if (cwnd_in_mtu == 0) {
1032 				/*
1033 				 * Using 0 means that the value of RFC 4960
1034 				 * is used.
1035 				 */
1036 				cwnd = min((net->mtu * 4), max((2 * net->mtu), SCTP_INITIAL_CWND));
1037 			} else {
1038 				/*
1039 				 * We take the minimum of the burst limit
1040 				 * and the initial congestion window.
1041 				 */
1042 				if ((stcb->asoc.max_burst > 0) && (cwnd_in_mtu > stcb->asoc.max_burst))
1043 					cwnd_in_mtu = stcb->asoc.max_burst;
1044 				cwnd = (net->mtu - sizeof(struct sctphdr)) * cwnd_in_mtu;
1045 			}
1046 			if (net->cwnd > cwnd) {
1047 				/*
1048 				 * Only set if we are not a timeout (i.e.
1049 				 * down to 1 mtu)
1050 				 */
1051 				net->cwnd = cwnd;
1052 			}
1053 		}
1054 	}
1055 }
1056 
1057 static void
1058 sctp_set_rtcc_initial_cc_param(struct sctp_tcb *stcb,
1059     struct sctp_nets *net)
1060 {
1061 	uint64_t vtag, probepoint;
1062 
1063 	sctp_set_initial_cc_param(stcb, net);
1064 	stcb->asoc.use_precise_time = 1;
1065 	probepoint = (((uint64_t) net->cwnd) << 32);
1066 	probepoint |= ((9 << 16) | 0);
1067 	vtag = (net->rtt << 32) |
1068 	    (((uint32_t) (stcb->sctp_ep->sctp_lport)) << 16) |
1069 	    (stcb->rport);
1070 	SDT_PROBE(sctp, cwnd, net, rttvar,
1071 	    vtag,
1072 	    0,
1073 	    0,
1074 	    0,
1075 	    probepoint);
1076 	net->cc_mod.rtcc.lbw_rtt = 0;
1077 	net->cc_mod.rtcc.cwnd_at_bw_set = 0;
1078 	net->cc_mod.rtcc.lbw = 0;
1079 	net->cc_mod.rtcc.bw_tot_time = 0;
1080 	net->cc_mod.rtcc.bw_bytes = 0;
1081 	net->cc_mod.rtcc.tls_needs_set = 0;
1082 	net->cc_mod.rtcc.ret_from_eq = SCTP_BASE_SYSCTL(sctp_rttvar_eqret);
1083 }
1084 
1085 static int
1086 sctp_cwnd_rtcc_socket_option(struct sctp_tcb *stcb, int setorget,
1087     struct sctp_cc_option *cc_opt)
1088 {
1089 	struct sctp_nets *net;
1090 
1091 	if (setorget == 1) {
1092 		/* a set */
1093 		if (cc_opt->option == SCTP_CC_OPT_RTCC_SETMODE) {
1094 			if ((cc_opt->aid_value.assoc_value != 0) &&
1095 			    (cc_opt->aid_value.assoc_value != 1)) {
1096 				return (EINVAL);
1097 			}
1098 			TAILQ_FOREACH(net, &stcb->asoc.nets, sctp_next) {
1099 				net->cc_mod.rtcc.ret_from_eq = cc_opt->aid_value.assoc_value;
1100 			}
1101 		} else if (cc_opt->option == SCTP_CC_OPT_USE_DCCC_ECN) {
1102 			if ((cc_opt->aid_value.assoc_value != 0) &&
1103 			    (cc_opt->aid_value.assoc_value != 1)) {
1104 				return (EINVAL);
1105 			}
1106 			TAILQ_FOREACH(net, &stcb->asoc.nets, sctp_next) {
1107 				net->cc_mod.rtcc.use_dccc_ecn = cc_opt->aid_value.assoc_value;
1108 			}
1109 		} else {
1110 			return (EINVAL);
1111 		}
1112 	} else {
1113 		/* a get */
1114 		if (cc_opt->option == SCTP_CC_OPT_RTCC_SETMODE) {
1115 			net = TAILQ_FIRST(&stcb->asoc.nets);
1116 			if (net == NULL) {
1117 				return (EFAULT);
1118 			}
1119 			cc_opt->aid_value.assoc_value = net->cc_mod.rtcc.ret_from_eq;
1120 		} else if (cc_opt->option == SCTP_CC_OPT_USE_DCCC_ECN) {
1121 			net = TAILQ_FIRST(&stcb->asoc.nets);
1122 			if (net == NULL) {
1123 				return (EFAULT);
1124 			}
1125 			cc_opt->aid_value.assoc_value = net->cc_mod.rtcc.use_dccc_ecn;
1126 		} else {
1127 			return (EINVAL);
1128 		}
1129 	}
1130 	return (0);
1131 }
1132 
1133 static void
1134 sctp_cwnd_update_rtcc_packet_transmitted(struct sctp_tcb *stcb,
1135     struct sctp_nets *net)
1136 {
1137 	if (net->cc_mod.rtcc.tls_needs_set == 0) {
1138 		SCTP_GETPTIME_TIMEVAL(&net->cc_mod.rtcc.tls);
1139 		net->cc_mod.rtcc.tls_needs_set = 2;
1140 	}
1141 }
1142 
1143 static void
1144 sctp_cwnd_update_rtcc_after_sack(struct sctp_tcb *stcb,
1145     struct sctp_association *asoc,
1146     int accum_moved, int reneged_all, int will_exit)
1147 {
1148 	/* Passing a one argument at the last enables the rtcc algoritm */
1149 	sctp_cwnd_update_after_sack_common(stcb, asoc, accum_moved, reneged_all, will_exit, 1);
1150 }
1151 
1152 
1153 /* Here starts Sally Floyds HS-TCP */
1154 
1155 struct sctp_hs_raise_drop {
1156 	int32_t cwnd;
1157 	int32_t increase;
1158 	int32_t drop_percent;
1159 };
1160 
1161 #define SCTP_HS_TABLE_SIZE 73
1162 
1163 struct sctp_hs_raise_drop sctp_cwnd_adjust[SCTP_HS_TABLE_SIZE] = {
1164 	{38, 1, 50},		/* 0   */
1165 	{118, 2, 44},		/* 1   */
1166 	{221, 3, 41},		/* 2   */
1167 	{347, 4, 38},		/* 3   */
1168 	{495, 5, 37},		/* 4   */
1169 	{663, 6, 35},		/* 5   */
1170 	{851, 7, 34},		/* 6   */
1171 	{1058, 8, 33},		/* 7   */
1172 	{1284, 9, 32},		/* 8   */
1173 	{1529, 10, 31},		/* 9   */
1174 	{1793, 11, 30},		/* 10  */
1175 	{2076, 12, 29},		/* 11  */
1176 	{2378, 13, 28},		/* 12  */
1177 	{2699, 14, 28},		/* 13  */
1178 	{3039, 15, 27},		/* 14  */
1179 	{3399, 16, 27},		/* 15  */
1180 	{3778, 17, 26},		/* 16  */
1181 	{4177, 18, 26},		/* 17  */
1182 	{4596, 19, 25},		/* 18  */
1183 	{5036, 20, 25},		/* 19  */
1184 	{5497, 21, 24},		/* 20  */
1185 	{5979, 22, 24},		/* 21  */
1186 	{6483, 23, 23},		/* 22  */
1187 	{7009, 24, 23},		/* 23  */
1188 	{7558, 25, 22},		/* 24  */
1189 	{8130, 26, 22},		/* 25  */
1190 	{8726, 27, 22},		/* 26  */
1191 	{9346, 28, 21},		/* 27  */
1192 	{9991, 29, 21},		/* 28  */
1193 	{10661, 30, 21},	/* 29  */
1194 	{11358, 31, 20},	/* 30  */
1195 	{12082, 32, 20},	/* 31  */
1196 	{12834, 33, 20},	/* 32  */
1197 	{13614, 34, 19},	/* 33  */
1198 	{14424, 35, 19},	/* 34  */
1199 	{15265, 36, 19},	/* 35  */
1200 	{16137, 37, 19},	/* 36  */
1201 	{17042, 38, 18},	/* 37  */
1202 	{17981, 39, 18},	/* 38  */
1203 	{18955, 40, 18},	/* 39  */
1204 	{19965, 41, 17},	/* 40  */
1205 	{21013, 42, 17},	/* 41  */
1206 	{22101, 43, 17},	/* 42  */
1207 	{23230, 44, 17},	/* 43  */
1208 	{24402, 45, 16},	/* 44  */
1209 	{25618, 46, 16},	/* 45  */
1210 	{26881, 47, 16},	/* 46  */
1211 	{28193, 48, 16},	/* 47  */
1212 	{29557, 49, 15},	/* 48  */
1213 	{30975, 50, 15},	/* 49  */
1214 	{32450, 51, 15},	/* 50  */
1215 	{33986, 52, 15},	/* 51  */
1216 	{35586, 53, 14},	/* 52  */
1217 	{37253, 54, 14},	/* 53  */
1218 	{38992, 55, 14},	/* 54  */
1219 	{40808, 56, 14},	/* 55  */
1220 	{42707, 57, 13},	/* 56  */
1221 	{44694, 58, 13},	/* 57  */
1222 	{46776, 59, 13},	/* 58  */
1223 	{48961, 60, 13},	/* 59  */
1224 	{51258, 61, 13},	/* 60  */
1225 	{53677, 62, 12},	/* 61  */
1226 	{56230, 63, 12},	/* 62  */
1227 	{58932, 64, 12},	/* 63  */
1228 	{61799, 65, 12},	/* 64  */
1229 	{64851, 66, 11},	/* 65  */
1230 	{68113, 67, 11},	/* 66  */
1231 	{71617, 68, 11},	/* 67  */
1232 	{75401, 69, 10},	/* 68  */
1233 	{79517, 70, 10},	/* 69  */
1234 	{84035, 71, 10},	/* 70  */
1235 	{89053, 72, 10},	/* 71  */
1236 	{94717, 73, 9}		/* 72  */
1237 };
1238 
1239 static void
1240 sctp_hs_cwnd_increase(struct sctp_tcb *stcb, struct sctp_nets *net)
1241 {
1242 	int cur_val, i, indx, incr;
1243 
1244 	cur_val = net->cwnd >> 10;
1245 	indx = SCTP_HS_TABLE_SIZE - 1;
1246 #ifdef SCTP_DEBUG
1247 	printf("HS CC CAlled.\n");
1248 #endif
1249 	if (cur_val < sctp_cwnd_adjust[0].cwnd) {
1250 		/* normal mode */
1251 		if (net->net_ack > net->mtu) {
1252 			net->cwnd += net->mtu;
1253 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1254 				sctp_log_cwnd(stcb, net, net->mtu, SCTP_CWND_LOG_FROM_SS);
1255 			}
1256 		} else {
1257 			net->cwnd += net->net_ack;
1258 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1259 				sctp_log_cwnd(stcb, net, net->net_ack, SCTP_CWND_LOG_FROM_SS);
1260 			}
1261 		}
1262 	} else {
1263 		for (i = net->last_hs_used; i < SCTP_HS_TABLE_SIZE; i++) {
1264 			if (cur_val < sctp_cwnd_adjust[i].cwnd) {
1265 				indx = i;
1266 				break;
1267 			}
1268 		}
1269 		net->last_hs_used = indx;
1270 		incr = ((sctp_cwnd_adjust[indx].increase) << 10);
1271 		net->cwnd += incr;
1272 		if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1273 			sctp_log_cwnd(stcb, net, incr, SCTP_CWND_LOG_FROM_SS);
1274 		}
1275 	}
1276 }
1277 
1278 static void
1279 sctp_hs_cwnd_decrease(struct sctp_tcb *stcb, struct sctp_nets *net)
1280 {
1281 	int cur_val, i, indx;
1282 	int old_cwnd = net->cwnd;
1283 
1284 	cur_val = net->cwnd >> 10;
1285 	if (cur_val < sctp_cwnd_adjust[0].cwnd) {
1286 		/* normal mode */
1287 		net->ssthresh = net->cwnd / 2;
1288 		if (net->ssthresh < (net->mtu * 2)) {
1289 			net->ssthresh = 2 * net->mtu;
1290 		}
1291 		net->cwnd = net->ssthresh;
1292 	} else {
1293 		/* drop by the proper amount */
1294 		net->ssthresh = net->cwnd - (int)((net->cwnd / 100) *
1295 		    sctp_cwnd_adjust[net->last_hs_used].drop_percent);
1296 		net->cwnd = net->ssthresh;
1297 		/* now where are we */
1298 		indx = net->last_hs_used;
1299 		cur_val = net->cwnd >> 10;
1300 		/* reset where we are in the table */
1301 		if (cur_val < sctp_cwnd_adjust[0].cwnd) {
1302 			/* feel out of hs */
1303 			net->last_hs_used = 0;
1304 		} else {
1305 			for (i = indx; i >= 1; i--) {
1306 				if (cur_val > sctp_cwnd_adjust[i - 1].cwnd) {
1307 					break;
1308 				}
1309 			}
1310 			net->last_hs_used = indx;
1311 		}
1312 	}
1313 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1314 		sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_FR);
1315 	}
1316 }
1317 
1318 static void
1319 sctp_hs_cwnd_update_after_fr(struct sctp_tcb *stcb,
1320     struct sctp_association *asoc)
1321 {
1322 	struct sctp_nets *net;
1323 
1324 	/*
1325 	 * CMT fast recovery code. Need to debug. ((sctp_cmt_on_off > 0) &&
1326 	 * (net->fast_retran_loss_recovery == 0)))
1327 	 */
1328 	TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
1329 		if ((asoc->fast_retran_loss_recovery == 0) ||
1330 		    (asoc->sctp_cmt_on_off > 0)) {
1331 			/* out of a RFC2582 Fast recovery window? */
1332 			if (net->net_ack > 0) {
1333 				/*
1334 				 * per section 7.2.3, are there any
1335 				 * destinations that had a fast retransmit
1336 				 * to them. If so what we need to do is
1337 				 * adjust ssthresh and cwnd.
1338 				 */
1339 				struct sctp_tmit_chunk *lchk;
1340 
1341 				sctp_hs_cwnd_decrease(stcb, net);
1342 
1343 				lchk = TAILQ_FIRST(&asoc->send_queue);
1344 
1345 				net->partial_bytes_acked = 0;
1346 				/* Turn on fast recovery window */
1347 				asoc->fast_retran_loss_recovery = 1;
1348 				if (lchk == NULL) {
1349 					/* Mark end of the window */
1350 					asoc->fast_recovery_tsn = asoc->sending_seq - 1;
1351 				} else {
1352 					asoc->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
1353 				}
1354 
1355 				/*
1356 				 * CMT fast recovery -- per destination
1357 				 * recovery variable.
1358 				 */
1359 				net->fast_retran_loss_recovery = 1;
1360 
1361 				if (lchk == NULL) {
1362 					/* Mark end of the window */
1363 					net->fast_recovery_tsn = asoc->sending_seq - 1;
1364 				} else {
1365 					net->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
1366 				}
1367 
1368 				sctp_timer_stop(SCTP_TIMER_TYPE_SEND,
1369 				    stcb->sctp_ep, stcb, net, SCTP_FROM_SCTP_INDATA + SCTP_LOC_32);
1370 				sctp_timer_start(SCTP_TIMER_TYPE_SEND,
1371 				    stcb->sctp_ep, stcb, net);
1372 			}
1373 		} else if (net->net_ack > 0) {
1374 			/*
1375 			 * Mark a peg that we WOULD have done a cwnd
1376 			 * reduction but RFC2582 prevented this action.
1377 			 */
1378 			SCTP_STAT_INCR(sctps_fastretransinrtt);
1379 		}
1380 	}
1381 }
1382 
1383 static void
1384 sctp_hs_cwnd_update_after_sack(struct sctp_tcb *stcb,
1385     struct sctp_association *asoc,
1386     int accum_moved, int reneged_all, int will_exit)
1387 {
1388 	struct sctp_nets *net;
1389 
1390 	/******************************/
1391 	/* update cwnd and Early FR   */
1392 	/******************************/
1393 	TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
1394 
1395 #ifdef JANA_CMT_FAST_RECOVERY
1396 		/*
1397 		 * CMT fast recovery code. Need to debug.
1398 		 */
1399 		if (net->fast_retran_loss_recovery && net->new_pseudo_cumack) {
1400 			if (SCTP_TSN_GE(asoc->last_acked_seq, net->fast_recovery_tsn) ||
1401 			    SCTP_TSN_GE(net->pseudo_cumack, net->fast_recovery_tsn)) {
1402 				net->will_exit_fast_recovery = 1;
1403 			}
1404 		}
1405 #endif
1406 		if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
1407 			/*
1408 			 * So, first of all do we need to have a Early FR
1409 			 * timer running?
1410 			 */
1411 			if ((!TAILQ_EMPTY(&asoc->sent_queue) &&
1412 			    (net->ref_count > 1) &&
1413 			    (net->flight_size < net->cwnd)) ||
1414 			    (reneged_all)) {
1415 				/*
1416 				 * yes, so in this case stop it if its
1417 				 * running, and then restart it. Reneging
1418 				 * all is a special case where we want to
1419 				 * run the Early FR timer and then force the
1420 				 * last few unacked to be sent, causing us
1421 				 * to illicit a sack with gaps to force out
1422 				 * the others.
1423 				 */
1424 				if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
1425 					SCTP_STAT_INCR(sctps_earlyfrstpidsck2);
1426 					sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
1427 					    SCTP_FROM_SCTP_INDATA + SCTP_LOC_20);
1428 				}
1429 				SCTP_STAT_INCR(sctps_earlyfrstrid);
1430 				sctp_timer_start(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net);
1431 			} else {
1432 				/* No, stop it if its running */
1433 				if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
1434 					SCTP_STAT_INCR(sctps_earlyfrstpidsck3);
1435 					sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
1436 					    SCTP_FROM_SCTP_INDATA + SCTP_LOC_21);
1437 				}
1438 			}
1439 		}
1440 		/* if nothing was acked on this destination skip it */
1441 		if (net->net_ack == 0) {
1442 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1443 				sctp_log_cwnd(stcb, net, 0, SCTP_CWND_LOG_FROM_SACK);
1444 			}
1445 			continue;
1446 		}
1447 		if (net->net_ack2 > 0) {
1448 			/*
1449 			 * Karn's rule applies to clearing error count, this
1450 			 * is optional.
1451 			 */
1452 			net->error_count = 0;
1453 			if ((net->dest_state & SCTP_ADDR_NOT_REACHABLE) ==
1454 			    SCTP_ADDR_NOT_REACHABLE) {
1455 				/* addr came good */
1456 				net->dest_state &= ~SCTP_ADDR_NOT_REACHABLE;
1457 				net->dest_state |= SCTP_ADDR_REACHABLE;
1458 				sctp_ulp_notify(SCTP_NOTIFY_INTERFACE_UP, stcb,
1459 				    SCTP_RECEIVED_SACK, (void *)net, SCTP_SO_NOT_LOCKED);
1460 				/* now was it the primary? if so restore */
1461 				if (net->dest_state & SCTP_ADDR_WAS_PRIMARY) {
1462 					(void)sctp_set_primary_addr(stcb, (struct sockaddr *)NULL, net);
1463 				}
1464 			}
1465 			/*
1466 			 * JRS 5/14/07 - If CMT PF is on and the destination
1467 			 * is in PF state, set the destination to active
1468 			 * state and set the cwnd to one or two MTU's based
1469 			 * on whether PF1 or PF2 is being used.
1470 			 *
1471 			 * Should we stop any running T3 timer here?
1472 			 */
1473 			if ((asoc->sctp_cmt_on_off > 0) &&
1474 			    (asoc->sctp_cmt_pf > 0) &&
1475 			    ((net->dest_state & SCTP_ADDR_PF) == SCTP_ADDR_PF)) {
1476 				net->dest_state &= ~SCTP_ADDR_PF;
1477 				net->cwnd = net->mtu * asoc->sctp_cmt_pf;
1478 				SCTPDBG(SCTP_DEBUG_INDATA1, "Destination %p moved from PF to reachable with cwnd %d.\n",
1479 				    net, net->cwnd);
1480 				/*
1481 				 * Since the cwnd value is explicitly set,
1482 				 * skip the code that updates the cwnd
1483 				 * value.
1484 				 */
1485 				goto skip_cwnd_update;
1486 			}
1487 		}
1488 #ifdef JANA_CMT_FAST_RECOVERY
1489 		/*
1490 		 * CMT fast recovery code
1491 		 */
1492 		/*
1493 		 * if (sctp_cmt_on_off > 0 && net->fast_retran_loss_recovery
1494 		 * && net->will_exit_fast_recovery == 0) { @@@ Do something
1495 		 * } else if (sctp_cmt_on_off == 0 &&
1496 		 * asoc->fast_retran_loss_recovery && will_exit == 0) {
1497 		 */
1498 #endif
1499 
1500 		if (asoc->fast_retran_loss_recovery &&
1501 		    (will_exit == 0) &&
1502 		    (asoc->sctp_cmt_on_off == 0)) {
1503 			/*
1504 			 * If we are in loss recovery we skip any cwnd
1505 			 * update
1506 			 */
1507 			goto skip_cwnd_update;
1508 		}
1509 		/*
1510 		 * CMT: CUC algorithm. Update cwnd if pseudo-cumack has
1511 		 * moved.
1512 		 */
1513 		if (accum_moved ||
1514 		    ((asoc->sctp_cmt_on_off > 0) && net->new_pseudo_cumack)) {
1515 			/* If the cumulative ack moved we can proceed */
1516 			if (net->cwnd <= net->ssthresh) {
1517 				/* We are in slow start */
1518 				if (net->flight_size + net->net_ack >= net->cwnd) {
1519 
1520 					sctp_hs_cwnd_increase(stcb, net);
1521 
1522 				} else {
1523 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1524 						sctp_log_cwnd(stcb, net, net->net_ack,
1525 						    SCTP_CWND_LOG_NOADV_SS);
1526 					}
1527 				}
1528 			} else {
1529 				/* We are in congestion avoidance */
1530 				net->partial_bytes_acked += net->net_ack;
1531 				if ((net->flight_size + net->net_ack >= net->cwnd) &&
1532 				    (net->partial_bytes_acked >= net->cwnd)) {
1533 					net->partial_bytes_acked -= net->cwnd;
1534 					net->cwnd += net->mtu;
1535 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1536 						sctp_log_cwnd(stcb, net, net->mtu,
1537 						    SCTP_CWND_LOG_FROM_CA);
1538 					}
1539 				} else {
1540 					if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1541 						sctp_log_cwnd(stcb, net, net->net_ack,
1542 						    SCTP_CWND_LOG_NOADV_CA);
1543 					}
1544 				}
1545 			}
1546 		} else {
1547 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1548 				sctp_log_cwnd(stcb, net, net->mtu,
1549 				    SCTP_CWND_LOG_NO_CUMACK);
1550 			}
1551 		}
1552 skip_cwnd_update:
1553 		/*
1554 		 * NOW, according to Karn's rule do we need to restore the
1555 		 * RTO timer back? Check our net_ack2. If not set then we
1556 		 * have a ambiguity.. i.e. all data ack'd was sent to more
1557 		 * than one place.
1558 		 */
1559 		if (net->net_ack2) {
1560 			/* restore any doubled timers */
1561 			net->RTO = (net->lastsa >> SCTP_RTT_SHIFT) + net->lastsv;
1562 			if (net->RTO < stcb->asoc.minrto) {
1563 				net->RTO = stcb->asoc.minrto;
1564 			}
1565 			if (net->RTO > stcb->asoc.maxrto) {
1566 				net->RTO = stcb->asoc.maxrto;
1567 			}
1568 		}
1569 	}
1570 }
1571 
1572 
1573 /*
1574  * H-TCP congestion control. The algorithm is detailed in:
1575  * R.N.Shorten, D.J.Leith:
1576  *   "H-TCP: TCP for high-speed and long-distance networks"
1577  *   Proc. PFLDnet, Argonne, 2004.
1578  * http://www.hamilton.ie/net/htcp3.pdf
1579  */
1580 
1581 
1582 static int use_rtt_scaling = 1;
1583 static int use_bandwidth_switch = 1;
1584 
1585 static inline int
1586 between(uint32_t seq1, uint32_t seq2, uint32_t seq3)
1587 {
1588 	return seq3 - seq2 >= seq1 - seq2;
1589 }
1590 
1591 static inline uint32_t
1592 htcp_cong_time(struct htcp *ca)
1593 {
1594 	return sctp_get_tick_count() - ca->last_cong;
1595 }
1596 
1597 static inline uint32_t
1598 htcp_ccount(struct htcp *ca)
1599 {
1600 	return htcp_cong_time(ca) / ca->minRTT;
1601 }
1602 
1603 static inline void
1604 htcp_reset(struct htcp *ca)
1605 {
1606 	ca->undo_last_cong = ca->last_cong;
1607 	ca->undo_maxRTT = ca->maxRTT;
1608 	ca->undo_old_maxB = ca->old_maxB;
1609 	ca->last_cong = sctp_get_tick_count();
1610 }
1611 
1612 #ifdef SCTP_NOT_USED
1613 
1614 static uint32_t
1615 htcp_cwnd_undo(struct sctp_tcb *stcb, struct sctp_nets *net)
1616 {
1617 	net->cc_mod.htcp_ca.last_cong = net->cc_mod.htcp_ca.undo_last_cong;
1618 	net->cc_mod.htcp_ca.maxRTT = net->cc_mod.htcp_ca.undo_maxRTT;
1619 	net->cc_mod.htcp_ca.old_maxB = net->cc_mod.htcp_ca.undo_old_maxB;
1620 	return max(net->cwnd, ((net->ssthresh / net->mtu << 7) / net->cc_mod.htcp_ca.beta) * net->mtu);
1621 }
1622 
1623 #endif
1624 
1625 static inline void
1626 measure_rtt(struct sctp_tcb *stcb, struct sctp_nets *net)
1627 {
1628 	uint32_t srtt = net->lastsa >> SCTP_RTT_SHIFT;
1629 
1630 	/* keep track of minimum RTT seen so far, minRTT is zero at first */
1631 	if (net->cc_mod.htcp_ca.minRTT > srtt || !net->cc_mod.htcp_ca.minRTT)
1632 		net->cc_mod.htcp_ca.minRTT = srtt;
1633 
1634 	/* max RTT */
1635 	if (net->fast_retran_ip == 0 && net->ssthresh < 0xFFFF && htcp_ccount(&net->cc_mod.htcp_ca) > 3) {
1636 		if (net->cc_mod.htcp_ca.maxRTT < net->cc_mod.htcp_ca.minRTT)
1637 			net->cc_mod.htcp_ca.maxRTT = net->cc_mod.htcp_ca.minRTT;
1638 		if (net->cc_mod.htcp_ca.maxRTT < srtt && srtt <= net->cc_mod.htcp_ca.maxRTT + MSEC_TO_TICKS(20))
1639 			net->cc_mod.htcp_ca.maxRTT = srtt;
1640 	}
1641 }
1642 
1643 static void
1644 measure_achieved_throughput(struct sctp_tcb *stcb, struct sctp_nets *net)
1645 {
1646 	uint32_t now = sctp_get_tick_count();
1647 
1648 	if (net->fast_retran_ip == 0)
1649 		net->cc_mod.htcp_ca.bytes_acked = net->net_ack;
1650 
1651 	if (!use_bandwidth_switch)
1652 		return;
1653 
1654 	/* achieved throughput calculations */
1655 	/* JRS - not 100% sure of this statement */
1656 	if (net->fast_retran_ip == 1) {
1657 		net->cc_mod.htcp_ca.bytecount = 0;
1658 		net->cc_mod.htcp_ca.lasttime = now;
1659 		return;
1660 	}
1661 	net->cc_mod.htcp_ca.bytecount += net->net_ack;
1662 
1663 	if (net->cc_mod.htcp_ca.bytecount >= net->cwnd - ((net->cc_mod.htcp_ca.alpha >> 7 ? : 1) * net->mtu)
1664 	    && now - net->cc_mod.htcp_ca.lasttime >= net->cc_mod.htcp_ca.minRTT
1665 	    && net->cc_mod.htcp_ca.minRTT > 0) {
1666 		uint32_t cur_Bi = net->cc_mod.htcp_ca.bytecount / net->mtu * hz / (now - net->cc_mod.htcp_ca.lasttime);
1667 
1668 		if (htcp_ccount(&net->cc_mod.htcp_ca) <= 3) {
1669 			/* just after backoff */
1670 			net->cc_mod.htcp_ca.minB = net->cc_mod.htcp_ca.maxB = net->cc_mod.htcp_ca.Bi = cur_Bi;
1671 		} else {
1672 			net->cc_mod.htcp_ca.Bi = (3 * net->cc_mod.htcp_ca.Bi + cur_Bi) / 4;
1673 			if (net->cc_mod.htcp_ca.Bi > net->cc_mod.htcp_ca.maxB)
1674 				net->cc_mod.htcp_ca.maxB = net->cc_mod.htcp_ca.Bi;
1675 			if (net->cc_mod.htcp_ca.minB > net->cc_mod.htcp_ca.maxB)
1676 				net->cc_mod.htcp_ca.minB = net->cc_mod.htcp_ca.maxB;
1677 		}
1678 		net->cc_mod.htcp_ca.bytecount = 0;
1679 		net->cc_mod.htcp_ca.lasttime = now;
1680 	}
1681 }
1682 
1683 static inline void
1684 htcp_beta_update(struct htcp *ca, uint32_t minRTT, uint32_t maxRTT)
1685 {
1686 	if (use_bandwidth_switch) {
1687 		uint32_t maxB = ca->maxB;
1688 		uint32_t old_maxB = ca->old_maxB;
1689 
1690 		ca->old_maxB = ca->maxB;
1691 
1692 		if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
1693 			ca->beta = BETA_MIN;
1694 			ca->modeswitch = 0;
1695 			return;
1696 		}
1697 	}
1698 	if (ca->modeswitch && minRTT > (uint32_t) MSEC_TO_TICKS(10) && maxRTT) {
1699 		ca->beta = (minRTT << 7) / maxRTT;
1700 		if (ca->beta < BETA_MIN)
1701 			ca->beta = BETA_MIN;
1702 		else if (ca->beta > BETA_MAX)
1703 			ca->beta = BETA_MAX;
1704 	} else {
1705 		ca->beta = BETA_MIN;
1706 		ca->modeswitch = 1;
1707 	}
1708 }
1709 
1710 static inline void
1711 htcp_alpha_update(struct htcp *ca)
1712 {
1713 	uint32_t minRTT = ca->minRTT;
1714 	uint32_t factor = 1;
1715 	uint32_t diff = htcp_cong_time(ca);
1716 
1717 	if (diff > (uint32_t) hz) {
1718 		diff -= hz;
1719 		factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / hz)) / hz;
1720 	}
1721 	if (use_rtt_scaling && minRTT) {
1722 		uint32_t scale = (hz << 3) / (10 * minRTT);
1723 
1724 		scale = min(max(scale, 1U << 2), 10U << 3);	/* clamping ratio to
1725 								 * interval [0.5,10]<<3 */
1726 		factor = (factor << 3) / scale;
1727 		if (!factor)
1728 			factor = 1;
1729 	}
1730 	ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
1731 	if (!ca->alpha)
1732 		ca->alpha = ALPHA_BASE;
1733 }
1734 
1735 /* After we have the rtt data to calculate beta, we'd still prefer to wait one
1736  * rtt before we adjust our beta to ensure we are working from a consistent
1737  * data.
1738  *
1739  * This function should be called when we hit a congestion event since only at
1740  * that point do we really have a real sense of maxRTT (the queues en route
1741  * were getting just too full now).
1742  */
1743 static void
1744 htcp_param_update(struct sctp_tcb *stcb, struct sctp_nets *net)
1745 {
1746 	uint32_t minRTT = net->cc_mod.htcp_ca.minRTT;
1747 	uint32_t maxRTT = net->cc_mod.htcp_ca.maxRTT;
1748 
1749 	htcp_beta_update(&net->cc_mod.htcp_ca, minRTT, maxRTT);
1750 	htcp_alpha_update(&net->cc_mod.htcp_ca);
1751 
1752 	/*
1753 	 * add slowly fading memory for maxRTT to accommodate routing
1754 	 * changes etc
1755 	 */
1756 	if (minRTT > 0 && maxRTT > minRTT)
1757 		net->cc_mod.htcp_ca.maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
1758 }
1759 
1760 static uint32_t
1761 htcp_recalc_ssthresh(struct sctp_tcb *stcb, struct sctp_nets *net)
1762 {
1763 	htcp_param_update(stcb, net);
1764 	return max(((net->cwnd / net->mtu * net->cc_mod.htcp_ca.beta) >> 7) * net->mtu, 2U * net->mtu);
1765 }
1766 
1767 static void
1768 htcp_cong_avoid(struct sctp_tcb *stcb, struct sctp_nets *net)
1769 {
1770 	/*-
1771 	 * How to handle these functions?
1772          *	if (!tcp_is_cwnd_limited(sk, in_flight)) RRS - good question.
1773 	 *		return;
1774 	 */
1775 	if (net->cwnd <= net->ssthresh) {
1776 		/* We are in slow start */
1777 		if (net->flight_size + net->net_ack >= net->cwnd) {
1778 			if (net->net_ack > (net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable))) {
1779 				net->cwnd += (net->mtu * SCTP_BASE_SYSCTL(sctp_L2_abc_variable));
1780 				if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1781 					sctp_log_cwnd(stcb, net, net->mtu,
1782 					    SCTP_CWND_LOG_FROM_SS);
1783 				}
1784 			} else {
1785 				net->cwnd += net->net_ack;
1786 				if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1787 					sctp_log_cwnd(stcb, net, net->net_ack,
1788 					    SCTP_CWND_LOG_FROM_SS);
1789 				}
1790 			}
1791 		} else {
1792 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1793 				sctp_log_cwnd(stcb, net, net->net_ack,
1794 				    SCTP_CWND_LOG_NOADV_SS);
1795 			}
1796 		}
1797 	} else {
1798 		measure_rtt(stcb, net);
1799 
1800 		/*
1801 		 * In dangerous area, increase slowly. In theory this is
1802 		 * net->cwnd += alpha / net->cwnd
1803 		 */
1804 		/* What is snd_cwnd_cnt?? */
1805 		if (((net->partial_bytes_acked / net->mtu * net->cc_mod.htcp_ca.alpha) >> 7) * net->mtu >= net->cwnd) {
1806 			/*-
1807 			 * Does SCTP have a cwnd clamp?
1808 			 * if (net->snd_cwnd < net->snd_cwnd_clamp) - Nope (RRS).
1809 			 */
1810 			net->cwnd += net->mtu;
1811 			net->partial_bytes_acked = 0;
1812 			htcp_alpha_update(&net->cc_mod.htcp_ca);
1813 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
1814 				sctp_log_cwnd(stcb, net, net->mtu,
1815 				    SCTP_CWND_LOG_FROM_CA);
1816 			}
1817 		} else {
1818 			net->partial_bytes_acked += net->net_ack;
1819 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1820 				sctp_log_cwnd(stcb, net, net->net_ack,
1821 				    SCTP_CWND_LOG_NOADV_CA);
1822 			}
1823 		}
1824 
1825 		net->cc_mod.htcp_ca.bytes_acked = net->mtu;
1826 	}
1827 }
1828 
1829 #ifdef SCTP_NOT_USED
1830 /* Lower bound on congestion window. */
1831 static uint32_t
1832 htcp_min_cwnd(struct sctp_tcb *stcb, struct sctp_nets *net)
1833 {
1834 	return net->ssthresh;
1835 }
1836 
1837 #endif
1838 
1839 static void
1840 htcp_init(struct sctp_tcb *stcb, struct sctp_nets *net)
1841 {
1842 	memset(&net->cc_mod.htcp_ca, 0, sizeof(struct htcp));
1843 	net->cc_mod.htcp_ca.alpha = ALPHA_BASE;
1844 	net->cc_mod.htcp_ca.beta = BETA_MIN;
1845 	net->cc_mod.htcp_ca.bytes_acked = net->mtu;
1846 	net->cc_mod.htcp_ca.last_cong = sctp_get_tick_count();
1847 }
1848 
1849 static void
1850 sctp_htcp_set_initial_cc_param(struct sctp_tcb *stcb, struct sctp_nets *net)
1851 {
1852 	/*
1853 	 * We take the max of the burst limit times a MTU or the
1854 	 * INITIAL_CWND. We then limit this to 4 MTU's of sending.
1855 	 */
1856 	net->cwnd = min((net->mtu * 4), max((2 * net->mtu), SCTP_INITIAL_CWND));
1857 	net->ssthresh = stcb->asoc.peers_rwnd;
1858 	htcp_init(stcb, net);
1859 
1860 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & (SCTP_CWND_MONITOR_ENABLE | SCTP_CWND_LOGGING_ENABLE)) {
1861 		sctp_log_cwnd(stcb, net, 0, SCTP_CWND_INITIALIZATION);
1862 	}
1863 }
1864 
1865 static void
1866 sctp_htcp_cwnd_update_after_sack(struct sctp_tcb *stcb,
1867     struct sctp_association *asoc,
1868     int accum_moved, int reneged_all, int will_exit)
1869 {
1870 	struct sctp_nets *net;
1871 
1872 	/******************************/
1873 	/* update cwnd and Early FR   */
1874 	/******************************/
1875 	TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
1876 
1877 #ifdef JANA_CMT_FAST_RECOVERY
1878 		/*
1879 		 * CMT fast recovery code. Need to debug.
1880 		 */
1881 		if (net->fast_retran_loss_recovery && net->new_pseudo_cumack) {
1882 			if (SCTP_TSN_GE(asoc->last_acked_seq, net->fast_recovery_tsn) ||
1883 			    SCTP_TSN_GE(net->pseudo_cumack, net->fast_recovery_tsn)) {
1884 				net->will_exit_fast_recovery = 1;
1885 			}
1886 		}
1887 #endif
1888 		if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
1889 			/*
1890 			 * So, first of all do we need to have a Early FR
1891 			 * timer running?
1892 			 */
1893 			if ((!TAILQ_EMPTY(&asoc->sent_queue) &&
1894 			    (net->ref_count > 1) &&
1895 			    (net->flight_size < net->cwnd)) ||
1896 			    (reneged_all)) {
1897 				/*
1898 				 * yes, so in this case stop it if its
1899 				 * running, and then restart it. Reneging
1900 				 * all is a special case where we want to
1901 				 * run the Early FR timer and then force the
1902 				 * last few unacked to be sent, causing us
1903 				 * to illicit a sack with gaps to force out
1904 				 * the others.
1905 				 */
1906 				if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
1907 					SCTP_STAT_INCR(sctps_earlyfrstpidsck2);
1908 					sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
1909 					    SCTP_FROM_SCTP_INDATA + SCTP_LOC_20);
1910 				}
1911 				SCTP_STAT_INCR(sctps_earlyfrstrid);
1912 				sctp_timer_start(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net);
1913 			} else {
1914 				/* No, stop it if its running */
1915 				if (SCTP_OS_TIMER_PENDING(&net->fr_timer.timer)) {
1916 					SCTP_STAT_INCR(sctps_earlyfrstpidsck3);
1917 					sctp_timer_stop(SCTP_TIMER_TYPE_EARLYFR, stcb->sctp_ep, stcb, net,
1918 					    SCTP_FROM_SCTP_INDATA + SCTP_LOC_21);
1919 				}
1920 			}
1921 		}
1922 		/* if nothing was acked on this destination skip it */
1923 		if (net->net_ack == 0) {
1924 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
1925 				sctp_log_cwnd(stcb, net, 0, SCTP_CWND_LOG_FROM_SACK);
1926 			}
1927 			continue;
1928 		}
1929 		if (net->net_ack2 > 0) {
1930 			/*
1931 			 * Karn's rule applies to clearing error count, this
1932 			 * is optional.
1933 			 */
1934 			net->error_count = 0;
1935 			if ((net->dest_state & SCTP_ADDR_NOT_REACHABLE) ==
1936 			    SCTP_ADDR_NOT_REACHABLE) {
1937 				/* addr came good */
1938 				net->dest_state &= ~SCTP_ADDR_NOT_REACHABLE;
1939 				net->dest_state |= SCTP_ADDR_REACHABLE;
1940 				sctp_ulp_notify(SCTP_NOTIFY_INTERFACE_UP, stcb,
1941 				    SCTP_RECEIVED_SACK, (void *)net, SCTP_SO_NOT_LOCKED);
1942 				/* now was it the primary? if so restore */
1943 				if (net->dest_state & SCTP_ADDR_WAS_PRIMARY) {
1944 					(void)sctp_set_primary_addr(stcb, (struct sockaddr *)NULL, net);
1945 				}
1946 			}
1947 			/*
1948 			 * JRS 5/14/07 - If CMT PF is on and the destination
1949 			 * is in PF state, set the destination to active
1950 			 * state and set the cwnd to one or two MTU's based
1951 			 * on whether PF1 or PF2 is being used.
1952 			 *
1953 			 * Should we stop any running T3 timer here?
1954 			 */
1955 			if ((asoc->sctp_cmt_on_off > 0) &&
1956 			    (asoc->sctp_cmt_pf > 0) &&
1957 			    ((net->dest_state & SCTP_ADDR_PF) == SCTP_ADDR_PF)) {
1958 				net->dest_state &= ~SCTP_ADDR_PF;
1959 				net->cwnd = net->mtu * asoc->sctp_cmt_pf;
1960 				SCTPDBG(SCTP_DEBUG_INDATA1, "Destination %p moved from PF to reachable with cwnd %d.\n",
1961 				    net, net->cwnd);
1962 				/*
1963 				 * Since the cwnd value is explicitly set,
1964 				 * skip the code that updates the cwnd
1965 				 * value.
1966 				 */
1967 				goto skip_cwnd_update;
1968 			}
1969 		}
1970 #ifdef JANA_CMT_FAST_RECOVERY
1971 		/*
1972 		 * CMT fast recovery code
1973 		 */
1974 		/*
1975 		 * if (sctp_cmt_on_off > 0 && net->fast_retran_loss_recovery
1976 		 * && net->will_exit_fast_recovery == 0) { @@@ Do something
1977 		 * } else if (sctp_cmt_on_off == 0 &&
1978 		 * asoc->fast_retran_loss_recovery && will_exit == 0) {
1979 		 */
1980 #endif
1981 
1982 		if (asoc->fast_retran_loss_recovery &&
1983 		    will_exit == 0 &&
1984 		    (asoc->sctp_cmt_on_off == 0)) {
1985 			/*
1986 			 * If we are in loss recovery we skip any cwnd
1987 			 * update
1988 			 */
1989 			goto skip_cwnd_update;
1990 		}
1991 		/*
1992 		 * CMT: CUC algorithm. Update cwnd if pseudo-cumack has
1993 		 * moved.
1994 		 */
1995 		if (accum_moved ||
1996 		    ((asoc->sctp_cmt_on_off > 0) && net->new_pseudo_cumack)) {
1997 			htcp_cong_avoid(stcb, net);
1998 			measure_achieved_throughput(stcb, net);
1999 		} else {
2000 			if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_LOGGING_ENABLE) {
2001 				sctp_log_cwnd(stcb, net, net->mtu,
2002 				    SCTP_CWND_LOG_NO_CUMACK);
2003 			}
2004 		}
2005 skip_cwnd_update:
2006 		/*
2007 		 * NOW, according to Karn's rule do we need to restore the
2008 		 * RTO timer back? Check our net_ack2. If not set then we
2009 		 * have a ambiguity.. i.e. all data ack'd was sent to more
2010 		 * than one place.
2011 		 */
2012 		if (net->net_ack2) {
2013 			/* restore any doubled timers */
2014 			net->RTO = (net->lastsa >> SCTP_RTT_SHIFT) + net->lastsv;
2015 			if (net->RTO < stcb->asoc.minrto) {
2016 				net->RTO = stcb->asoc.minrto;
2017 			}
2018 			if (net->RTO > stcb->asoc.maxrto) {
2019 				net->RTO = stcb->asoc.maxrto;
2020 			}
2021 		}
2022 	}
2023 }
2024 
2025 static void
2026 sctp_htcp_cwnd_update_after_fr(struct sctp_tcb *stcb,
2027     struct sctp_association *asoc)
2028 {
2029 	struct sctp_nets *net;
2030 
2031 	/*
2032 	 * CMT fast recovery code. Need to debug. ((sctp_cmt_on_off > 0) &&
2033 	 * (net->fast_retran_loss_recovery == 0)))
2034 	 */
2035 	TAILQ_FOREACH(net, &asoc->nets, sctp_next) {
2036 		if ((asoc->fast_retran_loss_recovery == 0) ||
2037 		    (asoc->sctp_cmt_on_off > 0)) {
2038 			/* out of a RFC2582 Fast recovery window? */
2039 			if (net->net_ack > 0) {
2040 				/*
2041 				 * per section 7.2.3, are there any
2042 				 * destinations that had a fast retransmit
2043 				 * to them. If so what we need to do is
2044 				 * adjust ssthresh and cwnd.
2045 				 */
2046 				struct sctp_tmit_chunk *lchk;
2047 				int old_cwnd = net->cwnd;
2048 
2049 				/* JRS - reset as if state were changed */
2050 				htcp_reset(&net->cc_mod.htcp_ca);
2051 				net->ssthresh = htcp_recalc_ssthresh(stcb, net);
2052 				net->cwnd = net->ssthresh;
2053 				if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
2054 					sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd),
2055 					    SCTP_CWND_LOG_FROM_FR);
2056 				}
2057 				lchk = TAILQ_FIRST(&asoc->send_queue);
2058 
2059 				net->partial_bytes_acked = 0;
2060 				/* Turn on fast recovery window */
2061 				asoc->fast_retran_loss_recovery = 1;
2062 				if (lchk == NULL) {
2063 					/* Mark end of the window */
2064 					asoc->fast_recovery_tsn = asoc->sending_seq - 1;
2065 				} else {
2066 					asoc->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
2067 				}
2068 
2069 				/*
2070 				 * CMT fast recovery -- per destination
2071 				 * recovery variable.
2072 				 */
2073 				net->fast_retran_loss_recovery = 1;
2074 
2075 				if (lchk == NULL) {
2076 					/* Mark end of the window */
2077 					net->fast_recovery_tsn = asoc->sending_seq - 1;
2078 				} else {
2079 					net->fast_recovery_tsn = lchk->rec.data.TSN_seq - 1;
2080 				}
2081 
2082 				sctp_timer_stop(SCTP_TIMER_TYPE_SEND,
2083 				    stcb->sctp_ep, stcb, net, SCTP_FROM_SCTP_INDATA + SCTP_LOC_32);
2084 				sctp_timer_start(SCTP_TIMER_TYPE_SEND,
2085 				    stcb->sctp_ep, stcb, net);
2086 			}
2087 		} else if (net->net_ack > 0) {
2088 			/*
2089 			 * Mark a peg that we WOULD have done a cwnd
2090 			 * reduction but RFC2582 prevented this action.
2091 			 */
2092 			SCTP_STAT_INCR(sctps_fastretransinrtt);
2093 		}
2094 	}
2095 }
2096 
2097 static void
2098 sctp_htcp_cwnd_update_after_timeout(struct sctp_tcb *stcb,
2099     struct sctp_nets *net)
2100 {
2101 	int old_cwnd = net->cwnd;
2102 
2103 	/* JRS - reset as if the state were being changed to timeout */
2104 	htcp_reset(&net->cc_mod.htcp_ca);
2105 	net->ssthresh = htcp_recalc_ssthresh(stcb, net);
2106 	net->cwnd = net->mtu;
2107 	net->partial_bytes_acked = 0;
2108 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
2109 		sctp_log_cwnd(stcb, net, net->cwnd - old_cwnd, SCTP_CWND_LOG_FROM_RTX);
2110 	}
2111 }
2112 
2113 static void
2114 sctp_htcp_cwnd_update_after_fr_timer(struct sctp_inpcb *inp,
2115     struct sctp_tcb *stcb, struct sctp_nets *net)
2116 {
2117 	int old_cwnd;
2118 
2119 	old_cwnd = net->cwnd;
2120 
2121 	sctp_chunk_output(inp, stcb, SCTP_OUTPUT_FROM_EARLY_FR_TMR, SCTP_SO_NOT_LOCKED);
2122 	net->cc_mod.htcp_ca.last_cong = sctp_get_tick_count();
2123 	/*
2124 	 * make a small adjustment to cwnd and force to CA.
2125 	 */
2126 	if (net->cwnd > net->mtu)
2127 		/* drop down one MTU after sending */
2128 		net->cwnd -= net->mtu;
2129 	if (net->cwnd < net->ssthresh)
2130 		/* still in SS move to CA */
2131 		net->ssthresh = net->cwnd - 1;
2132 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
2133 		sctp_log_cwnd(stcb, net, (old_cwnd - net->cwnd), SCTP_CWND_LOG_FROM_FR);
2134 	}
2135 }
2136 
2137 static void
2138 sctp_htcp_cwnd_update_after_ecn_echo(struct sctp_tcb *stcb,
2139     struct sctp_nets *net, int in_window, int num_pkt_lost)
2140 {
2141 	int old_cwnd;
2142 
2143 	old_cwnd = net->cwnd;
2144 
2145 	/* JRS - reset hctp as if state changed */
2146 	if (in_window == 0) {
2147 		htcp_reset(&net->cc_mod.htcp_ca);
2148 		SCTP_STAT_INCR(sctps_ecnereducedcwnd);
2149 		net->ssthresh = htcp_recalc_ssthresh(stcb, net);
2150 		if (net->ssthresh < net->mtu) {
2151 			net->ssthresh = net->mtu;
2152 			/* here back off the timer as well, to slow us down */
2153 			net->RTO <<= 1;
2154 		}
2155 		net->cwnd = net->ssthresh;
2156 		if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_CWND_MONITOR_ENABLE) {
2157 			sctp_log_cwnd(stcb, net, (net->cwnd - old_cwnd), SCTP_CWND_LOG_FROM_SAT);
2158 		}
2159 	}
2160 }
2161 
2162 struct sctp_cc_functions sctp_cc_functions[] = {
2163 	{
2164 		.sctp_set_initial_cc_param = sctp_set_initial_cc_param,
2165 		.sctp_cwnd_update_after_sack = sctp_cwnd_update_after_sack,
2166 		.sctp_cwnd_update_after_fr = sctp_cwnd_update_after_fr,
2167 		.sctp_cwnd_update_after_timeout = sctp_cwnd_update_after_timeout,
2168 		.sctp_cwnd_update_after_ecn_echo = sctp_cwnd_update_after_ecn_echo,
2169 		.sctp_cwnd_update_after_packet_dropped = sctp_cwnd_update_after_packet_dropped,
2170 		.sctp_cwnd_update_after_output = sctp_cwnd_update_after_output,
2171 		.sctp_cwnd_update_after_fr_timer = sctp_cwnd_update_after_fr_timer
2172 	},
2173 	{
2174 		.sctp_set_initial_cc_param = sctp_set_initial_cc_param,
2175 		.sctp_cwnd_update_after_sack = sctp_hs_cwnd_update_after_sack,
2176 		.sctp_cwnd_update_after_fr = sctp_hs_cwnd_update_after_fr,
2177 		.sctp_cwnd_update_after_timeout = sctp_cwnd_update_after_timeout,
2178 		.sctp_cwnd_update_after_ecn_echo = sctp_cwnd_update_after_ecn_echo,
2179 		.sctp_cwnd_update_after_packet_dropped = sctp_cwnd_update_after_packet_dropped,
2180 		.sctp_cwnd_update_after_output = sctp_cwnd_update_after_output,
2181 		.sctp_cwnd_update_after_fr_timer = sctp_cwnd_update_after_fr_timer
2182 	},
2183 	{
2184 		.sctp_set_initial_cc_param = sctp_htcp_set_initial_cc_param,
2185 		.sctp_cwnd_update_after_sack = sctp_htcp_cwnd_update_after_sack,
2186 		.sctp_cwnd_update_after_fr = sctp_htcp_cwnd_update_after_fr,
2187 		.sctp_cwnd_update_after_timeout = sctp_htcp_cwnd_update_after_timeout,
2188 		.sctp_cwnd_update_after_ecn_echo = sctp_htcp_cwnd_update_after_ecn_echo,
2189 		.sctp_cwnd_update_after_packet_dropped = sctp_cwnd_update_after_packet_dropped,
2190 		.sctp_cwnd_update_after_output = sctp_cwnd_update_after_output,
2191 		.sctp_cwnd_update_after_fr_timer = sctp_htcp_cwnd_update_after_fr_timer
2192 	},
2193 	{
2194 		.sctp_set_initial_cc_param = sctp_set_rtcc_initial_cc_param,
2195 		.sctp_cwnd_update_after_sack = sctp_cwnd_update_rtcc_after_sack,
2196 		.sctp_cwnd_update_after_fr = sctp_cwnd_update_after_fr,
2197 		.sctp_cwnd_update_after_timeout = sctp_cwnd_update_after_timeout,
2198 		.sctp_cwnd_update_after_ecn_echo = sctp_cwnd_update_rtcc_after_ecn_echo,
2199 		.sctp_cwnd_update_after_packet_dropped = sctp_cwnd_update_after_packet_dropped,
2200 		.sctp_cwnd_update_after_output = sctp_cwnd_update_after_output,
2201 		.sctp_cwnd_update_after_fr_timer = sctp_cwnd_update_after_fr_timer,
2202 		.sctp_cwnd_update_packet_transmitted = sctp_cwnd_update_rtcc_packet_transmitted,
2203 		.sctp_cwnd_update_tsn_acknowledged = sctp_cwnd_update_rtcc_tsn_acknowledged,
2204 		.sctp_cwnd_new_transmission_begins = sctp_cwnd_new_rtcc_transmission_begins,
2205 		.sctp_cwnd_prepare_net_for_sack = sctp_cwnd_prepare_rtcc_net_for_sack,
2206 		.sctp_cwnd_socket_option = sctp_cwnd_rtcc_socket_option
2207 	}
2208 };
2209