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1 /* SCTP kernel implementation
2 * Copyright (c) 1999-2000 Cisco, Inc.
3 * Copyright (c) 1999-2001 Motorola, Inc.
4 * Copyright (c) 2001-2003 International Business Machines Corp.
5 * Copyright (c) 2001 Intel Corp.
6 * Copyright (c) 2001 La Monte H.P. Yarroll
7 *
8 * This file is part of the SCTP kernel implementation
9 *
10 * This module provides the abstraction for an SCTP tranport representing
11 * a remote transport address. For local transport addresses, we just use
12 * union sctp_addr.
13 *
14 * This SCTP implementation is free software;
15 * you can redistribute it and/or modify it under the terms of
16 * the GNU General Public License as published by
17 * the Free Software Foundation; either version 2, or (at your option)
18 * any later version.
19 *
20 * This SCTP implementation is distributed in the hope that it
21 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
22 * ************************
23 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
24 * See the GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with GNU CC; see the file COPYING. If not, see
28 * <http://www.gnu.org/licenses/>.
29 *
30 * Please send any bug reports or fixes you make to the
31 * email address(es):
32 * lksctp developers <linux-sctp@vger.kernel.org>
33 *
34 * Written or modified by:
35 * La Monte H.P. Yarroll <piggy@acm.org>
36 * Karl Knutson <karl@athena.chicago.il.us>
37 * Jon Grimm <jgrimm@us.ibm.com>
38 * Xingang Guo <xingang.guo@intel.com>
39 * Hui Huang <hui.huang@nokia.com>
40 * Sridhar Samudrala <sri@us.ibm.com>
41 * Ardelle Fan <ardelle.fan@intel.com>
42 */
43
44 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
45
46 #include <linux/slab.h>
47 #include <linux/types.h>
48 #include <linux/random.h>
49 #include <net/sctp/sctp.h>
50 #include <net/sctp/sm.h>
51
52 /* 1st Level Abstractions. */
53
54 /* Initialize a new transport from provided memory. */
55 static struct sctp_transport *sctp_transport_init(struct net *net,
56 struct sctp_transport *peer,
57 const union sctp_addr *addr,
58 gfp_t gfp)
59 {
60 /* Copy in the address. */
61 peer->ipaddr = *addr;
62 peer->af_specific = sctp_get_af_specific(addr->sa.sa_family);
63 memset(&peer->saddr, 0, sizeof(union sctp_addr));
64
65 peer->sack_generation = 0;
66
67 /* From 6.3.1 RTO Calculation:
68 *
69 * C1) Until an RTT measurement has been made for a packet sent to the
70 * given destination transport address, set RTO to the protocol
71 * parameter 'RTO.Initial'.
72 */
73 peer->rto = msecs_to_jiffies(net->sctp.rto_initial);
74
75 peer->last_time_heard = 0;
76 peer->last_time_ecne_reduced = jiffies;
77
78 peer->param_flags = SPP_HB_DISABLE |
79 SPP_PMTUD_ENABLE |
80 SPP_SACKDELAY_ENABLE;
81
82 /* Initialize the default path max_retrans. */
83 peer->pathmaxrxt = net->sctp.max_retrans_path;
84 peer->pf_retrans = net->sctp.pf_retrans;
85
86 INIT_LIST_HEAD(&peer->transmitted);
87 INIT_LIST_HEAD(&peer->send_ready);
88 INIT_LIST_HEAD(&peer->transports);
89
90 setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event,
91 (unsigned long)peer);
92 setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event,
93 (unsigned long)peer);
94 setup_timer(&peer->reconf_timer, sctp_generate_reconf_event,
95 (unsigned long)peer);
96 setup_timer(&peer->proto_unreach_timer,
97 sctp_generate_proto_unreach_event, (unsigned long)peer);
98
99 /* Initialize the 64-bit random nonce sent with heartbeat. */
100 get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce));
101
102 atomic_set(&peer->refcnt, 1);
103
104 return peer;
105 }
106
107 /* Allocate and initialize a new transport. */
108 struct sctp_transport *sctp_transport_new(struct net *net,
109 const union sctp_addr *addr,
110 gfp_t gfp)
111 {
112 struct sctp_transport *transport;
113
114 transport = kzalloc(sizeof(*transport), gfp);
115 if (!transport)
116 goto fail;
117
118 if (!sctp_transport_init(net, transport, addr, gfp))
119 goto fail_init;
120
121 SCTP_DBG_OBJCNT_INC(transport);
122
123 return transport;
124
125 fail_init:
126 kfree(transport);
127
128 fail:
129 return NULL;
130 }
131
132 /* This transport is no longer needed. Free up if possible, or
133 * delay until it last reference count.
134 */
135 void sctp_transport_free(struct sctp_transport *transport)
136 {
137 /* Try to delete the heartbeat timer. */
138 if (del_timer(&transport->hb_timer))
139 sctp_transport_put(transport);
140
141 /* Delete the T3_rtx timer if it's active.
142 * There is no point in not doing this now and letting
143 * structure hang around in memory since we know
144 * the tranport is going away.
145 */
146 if (del_timer(&transport->T3_rtx_timer))
147 sctp_transport_put(transport);
148
149 if (del_timer(&transport->reconf_timer))
150 sctp_transport_put(transport);
151
152 /* Delete the ICMP proto unreachable timer if it's active. */
153 if (del_timer(&transport->proto_unreach_timer))
154 sctp_association_put(transport->asoc);
155
156 sctp_transport_put(transport);
157 }
158
159 static void sctp_transport_destroy_rcu(struct rcu_head *head)
160 {
161 struct sctp_transport *transport;
162
163 transport = container_of(head, struct sctp_transport, rcu);
164
165 dst_release(transport->dst);
166 kfree(transport);
167 SCTP_DBG_OBJCNT_DEC(transport);
168 }
169
170 /* Destroy the transport data structure.
171 * Assumes there are no more users of this structure.
172 */
173 static void sctp_transport_destroy(struct sctp_transport *transport)
174 {
175 if (unlikely(atomic_read(&transport->refcnt))) {
176 WARN(1, "Attempt to destroy undead transport %p!\n", transport);
177 return;
178 }
179
180 sctp_packet_free(&transport->packet);
181
182 if (transport->asoc)
183 sctp_association_put(transport->asoc);
184
185 call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
186 }
187
188 /* Start T3_rtx timer if it is not already running and update the heartbeat
189 * timer. This routine is called every time a DATA chunk is sent.
190 */
191 void sctp_transport_reset_t3_rtx(struct sctp_transport *transport)
192 {
193 /* RFC 2960 6.3.2 Retransmission Timer Rules
194 *
195 * R1) Every time a DATA chunk is sent to any address(including a
196 * retransmission), if the T3-rtx timer of that address is not running
197 * start it running so that it will expire after the RTO of that
198 * address.
199 */
200
201 if (!timer_pending(&transport->T3_rtx_timer))
202 if (!mod_timer(&transport->T3_rtx_timer,
203 jiffies + transport->rto))
204 sctp_transport_hold(transport);
205 }
206
207 void sctp_transport_reset_hb_timer(struct sctp_transport *transport)
208 {
209 unsigned long expires;
210
211 /* When a data chunk is sent, reset the heartbeat interval. */
212 expires = jiffies + sctp_transport_timeout(transport);
213 if (time_before(transport->hb_timer.expires, expires) &&
214 !mod_timer(&transport->hb_timer,
215 expires + prandom_u32_max(transport->rto)))
216 sctp_transport_hold(transport);
217 }
218
219 void sctp_transport_reset_reconf_timer(struct sctp_transport *transport)
220 {
221 if (!timer_pending(&transport->reconf_timer))
222 if (!mod_timer(&transport->reconf_timer,
223 jiffies + transport->rto))
224 sctp_transport_hold(transport);
225 }
226
227 /* This transport has been assigned to an association.
228 * Initialize fields from the association or from the sock itself.
229 * Register the reference count in the association.
230 */
231 void sctp_transport_set_owner(struct sctp_transport *transport,
232 struct sctp_association *asoc)
233 {
234 transport->asoc = asoc;
235 sctp_association_hold(asoc);
236 }
237
238 /* Initialize the pmtu of a transport. */
239 void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk)
240 {
241 /* If we don't have a fresh route, look one up */
242 if (!transport->dst || transport->dst->obsolete) {
243 sctp_transport_dst_release(transport);
244 transport->af_specific->get_dst(transport, &transport->saddr,
245 &transport->fl, sk);
246 }
247
248 if (transport->dst) {
249 transport->pathmtu = SCTP_TRUNC4(dst_mtu(transport->dst));
250 } else
251 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
252 }
253
254 void sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
255 {
256 struct dst_entry *dst = sctp_transport_dst_check(t);
257
258 if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
259 pr_warn("%s: Reported pmtu %d too low, using default minimum of %d\n",
260 __func__, pmtu, SCTP_DEFAULT_MINSEGMENT);
261 /* Use default minimum segment size and disable
262 * pmtu discovery on this transport.
263 */
264 t->pathmtu = SCTP_DEFAULT_MINSEGMENT;
265 } else {
266 t->pathmtu = pmtu;
267 }
268
269 if (dst) {
270 dst->ops->update_pmtu(dst, t->asoc->base.sk, NULL, pmtu);
271 dst = sctp_transport_dst_check(t);
272 }
273
274 if (!dst)
275 t->af_specific->get_dst(t, &t->saddr, &t->fl, t->asoc->base.sk);
276 }
277
278 /* Caches the dst entry and source address for a transport's destination
279 * address.
280 */
281 void sctp_transport_route(struct sctp_transport *transport,
282 union sctp_addr *saddr, struct sctp_sock *opt)
283 {
284 struct sctp_association *asoc = transport->asoc;
285 struct sctp_af *af = transport->af_specific;
286
287 af->get_dst(transport, saddr, &transport->fl, sctp_opt2sk(opt));
288
289 if (saddr)
290 memcpy(&transport->saddr, saddr, sizeof(union sctp_addr));
291 else
292 af->get_saddr(opt, transport, &transport->fl);
293
294 if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) {
295 return;
296 }
297 if (transport->dst) {
298 transport->pathmtu = SCTP_TRUNC4(dst_mtu(transport->dst));
299
300 /* Initialize sk->sk_rcv_saddr, if the transport is the
301 * association's active path for getsockname().
302 */
303 if (asoc && (!asoc->peer.primary_path ||
304 (transport == asoc->peer.active_path)))
305 opt->pf->to_sk_saddr(&transport->saddr,
306 asoc->base.sk);
307 } else
308 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
309 }
310
311 /* Hold a reference to a transport. */
312 int sctp_transport_hold(struct sctp_transport *transport)
313 {
314 return atomic_add_unless(&transport->refcnt, 1, 0);
315 }
316
317 /* Release a reference to a transport and clean up
318 * if there are no more references.
319 */
320 void sctp_transport_put(struct sctp_transport *transport)
321 {
322 if (atomic_dec_and_test(&transport->refcnt))
323 sctp_transport_destroy(transport);
324 }
325
326 /* Update transport's RTO based on the newly calculated RTT. */
327 void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
328 {
329 if (unlikely(!tp->rto_pending))
330 /* We should not be doing any RTO updates unless rto_pending is set. */
331 pr_debug("%s: rto_pending not set on transport %p!\n", __func__, tp);
332
333 if (tp->rttvar || tp->srtt) {
334 struct net *net = sock_net(tp->asoc->base.sk);
335 /* 6.3.1 C3) When a new RTT measurement R' is made, set
336 * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'|
337 * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R'
338 */
339
340 /* Note: The above algorithm has been rewritten to
341 * express rto_beta and rto_alpha as inverse powers
342 * of two.
343 * For example, assuming the default value of RTO.Alpha of
344 * 1/8, rto_alpha would be expressed as 3.
345 */
346 tp->rttvar = tp->rttvar - (tp->rttvar >> net->sctp.rto_beta)
347 + (((__u32)abs((__s64)tp->srtt - (__s64)rtt)) >> net->sctp.rto_beta);
348 tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha)
349 + (rtt >> net->sctp.rto_alpha);
350 } else {
351 /* 6.3.1 C2) When the first RTT measurement R is made, set
352 * SRTT <- R, RTTVAR <- R/2.
353 */
354 tp->srtt = rtt;
355 tp->rttvar = rtt >> 1;
356 }
357
358 /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then
359 * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY.
360 */
361 if (tp->rttvar == 0)
362 tp->rttvar = SCTP_CLOCK_GRANULARITY;
363
364 /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */
365 tp->rto = tp->srtt + (tp->rttvar << 2);
366
367 /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min
368 * seconds then it is rounded up to RTO.Min seconds.
369 */
370 if (tp->rto < tp->asoc->rto_min)
371 tp->rto = tp->asoc->rto_min;
372
373 /* 6.3.1 C7) A maximum value may be placed on RTO provided it is
374 * at least RTO.max seconds.
375 */
376 if (tp->rto > tp->asoc->rto_max)
377 tp->rto = tp->asoc->rto_max;
378
379 sctp_max_rto(tp->asoc, tp);
380 tp->rtt = rtt;
381
382 /* Reset rto_pending so that a new RTT measurement is started when a
383 * new data chunk is sent.
384 */
385 tp->rto_pending = 0;
386
387 pr_debug("%s: transport:%p, rtt:%d, srtt:%d rttvar:%d, rto:%ld\n",
388 __func__, tp, rtt, tp->srtt, tp->rttvar, tp->rto);
389 }
390
391 /* This routine updates the transport's cwnd and partial_bytes_acked
392 * parameters based on the bytes acked in the received SACK.
393 */
394 void sctp_transport_raise_cwnd(struct sctp_transport *transport,
395 __u32 sack_ctsn, __u32 bytes_acked)
396 {
397 struct sctp_association *asoc = transport->asoc;
398 __u32 cwnd, ssthresh, flight_size, pba, pmtu;
399
400 cwnd = transport->cwnd;
401 flight_size = transport->flight_size;
402
403 /* See if we need to exit Fast Recovery first */
404 if (asoc->fast_recovery &&
405 TSN_lte(asoc->fast_recovery_exit, sack_ctsn))
406 asoc->fast_recovery = 0;
407
408 /* The appropriate cwnd increase algorithm is performed if, and only
409 * if the cumulative TSN whould advanced and the congestion window is
410 * being fully utilized.
411 */
412 if (TSN_lte(sack_ctsn, transport->asoc->ctsn_ack_point) ||
413 (flight_size < cwnd))
414 return;
415
416 ssthresh = transport->ssthresh;
417 pba = transport->partial_bytes_acked;
418 pmtu = transport->asoc->pathmtu;
419
420 if (cwnd <= ssthresh) {
421 /* RFC 4960 7.2.1
422 * o When cwnd is less than or equal to ssthresh, an SCTP
423 * endpoint MUST use the slow-start algorithm to increase
424 * cwnd only if the current congestion window is being fully
425 * utilized, an incoming SACK advances the Cumulative TSN
426 * Ack Point, and the data sender is not in Fast Recovery.
427 * Only when these three conditions are met can the cwnd be
428 * increased; otherwise, the cwnd MUST not be increased.
429 * If these conditions are met, then cwnd MUST be increased
430 * by, at most, the lesser of 1) the total size of the
431 * previously outstanding DATA chunk(s) acknowledged, and
432 * 2) the destination's path MTU. This upper bound protects
433 * against the ACK-Splitting attack outlined in [SAVAGE99].
434 */
435 if (asoc->fast_recovery)
436 return;
437
438 if (bytes_acked > pmtu)
439 cwnd += pmtu;
440 else
441 cwnd += bytes_acked;
442
443 pr_debug("%s: slow start: transport:%p, bytes_acked:%d, "
444 "cwnd:%d, ssthresh:%d, flight_size:%d, pba:%d\n",
445 __func__, transport, bytes_acked, cwnd, ssthresh,
446 flight_size, pba);
447 } else {
448 /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh,
449 * upon each SACK arrival that advances the Cumulative TSN Ack
450 * Point, increase partial_bytes_acked by the total number of
451 * bytes of all new chunks acknowledged in that SACK including
452 * chunks acknowledged by the new Cumulative TSN Ack and by
453 * Gap Ack Blocks.
454 *
455 * When partial_bytes_acked is equal to or greater than cwnd
456 * and before the arrival of the SACK the sender had cwnd or
457 * more bytes of data outstanding (i.e., before arrival of the
458 * SACK, flightsize was greater than or equal to cwnd),
459 * increase cwnd by MTU, and reset partial_bytes_acked to
460 * (partial_bytes_acked - cwnd).
461 */
462 pba += bytes_acked;
463 if (pba >= cwnd) {
464 cwnd += pmtu;
465 pba = ((cwnd < pba) ? (pba - cwnd) : 0);
466 }
467
468 pr_debug("%s: congestion avoidance: transport:%p, "
469 "bytes_acked:%d, cwnd:%d, ssthresh:%d, "
470 "flight_size:%d, pba:%d\n", __func__,
471 transport, bytes_acked, cwnd, ssthresh,
472 flight_size, pba);
473 }
474
475 transport->cwnd = cwnd;
476 transport->partial_bytes_acked = pba;
477 }
478
479 /* This routine is used to lower the transport's cwnd when congestion is
480 * detected.
481 */
482 void sctp_transport_lower_cwnd(struct sctp_transport *transport,
483 sctp_lower_cwnd_t reason)
484 {
485 struct sctp_association *asoc = transport->asoc;
486
487 switch (reason) {
488 case SCTP_LOWER_CWND_T3_RTX:
489 /* RFC 2960 Section 7.2.3, sctpimpguide
490 * When the T3-rtx timer expires on an address, SCTP should
491 * perform slow start by:
492 * ssthresh = max(cwnd/2, 4*MTU)
493 * cwnd = 1*MTU
494 * partial_bytes_acked = 0
495 */
496 transport->ssthresh = max(transport->cwnd/2,
497 4*asoc->pathmtu);
498 transport->cwnd = asoc->pathmtu;
499
500 /* T3-rtx also clears fast recovery */
501 asoc->fast_recovery = 0;
502 break;
503
504 case SCTP_LOWER_CWND_FAST_RTX:
505 /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the
506 * destination address(es) to which the missing DATA chunks
507 * were last sent, according to the formula described in
508 * Section 7.2.3.
509 *
510 * RFC 2960 7.2.3, sctpimpguide Upon detection of packet
511 * losses from SACK (see Section 7.2.4), An endpoint
512 * should do the following:
513 * ssthresh = max(cwnd/2, 4*MTU)
514 * cwnd = ssthresh
515 * partial_bytes_acked = 0
516 */
517 if (asoc->fast_recovery)
518 return;
519
520 /* Mark Fast recovery */
521 asoc->fast_recovery = 1;
522 asoc->fast_recovery_exit = asoc->next_tsn - 1;
523
524 transport->ssthresh = max(transport->cwnd/2,
525 4*asoc->pathmtu);
526 transport->cwnd = transport->ssthresh;
527 break;
528
529 case SCTP_LOWER_CWND_ECNE:
530 /* RFC 2481 Section 6.1.2.
531 * If the sender receives an ECN-Echo ACK packet
532 * then the sender knows that congestion was encountered in the
533 * network on the path from the sender to the receiver. The
534 * indication of congestion should be treated just as a
535 * congestion loss in non-ECN Capable TCP. That is, the TCP
536 * source halves the congestion window "cwnd" and reduces the
537 * slow start threshold "ssthresh".
538 * A critical condition is that TCP does not react to
539 * congestion indications more than once every window of
540 * data (or more loosely more than once every round-trip time).
541 */
542 if (time_after(jiffies, transport->last_time_ecne_reduced +
543 transport->rtt)) {
544 transport->ssthresh = max(transport->cwnd/2,
545 4*asoc->pathmtu);
546 transport->cwnd = transport->ssthresh;
547 transport->last_time_ecne_reduced = jiffies;
548 }
549 break;
550
551 case SCTP_LOWER_CWND_INACTIVE:
552 /* RFC 2960 Section 7.2.1, sctpimpguide
553 * When the endpoint does not transmit data on a given
554 * transport address, the cwnd of the transport address
555 * should be adjusted to max(cwnd/2, 4*MTU) per RTO.
556 * NOTE: Although the draft recommends that this check needs
557 * to be done every RTO interval, we do it every hearbeat
558 * interval.
559 */
560 transport->cwnd = max(transport->cwnd/2,
561 4*asoc->pathmtu);
562 break;
563 }
564
565 transport->partial_bytes_acked = 0;
566
567 pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d\n",
568 __func__, transport, reason, transport->cwnd,
569 transport->ssthresh);
570 }
571
572 /* Apply Max.Burst limit to the congestion window:
573 * sctpimpguide-05 2.14.2
574 * D) When the time comes for the sender to
575 * transmit new DATA chunks, the protocol parameter Max.Burst MUST
576 * first be applied to limit how many new DATA chunks may be sent.
577 * The limit is applied by adjusting cwnd as follows:
578 * if ((flightsize+ Max.Burst * MTU) < cwnd)
579 * cwnd = flightsize + Max.Burst * MTU
580 */
581
582 void sctp_transport_burst_limited(struct sctp_transport *t)
583 {
584 struct sctp_association *asoc = t->asoc;
585 u32 old_cwnd = t->cwnd;
586 u32 max_burst_bytes;
587
588 if (t->burst_limited || asoc->max_burst == 0)
589 return;
590
591 max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu);
592 if (max_burst_bytes < old_cwnd) {
593 t->cwnd = max_burst_bytes;
594 t->burst_limited = old_cwnd;
595 }
596 }
597
598 /* Restore the old cwnd congestion window, after the burst had it's
599 * desired effect.
600 */
601 void sctp_transport_burst_reset(struct sctp_transport *t)
602 {
603 if (t->burst_limited) {
604 t->cwnd = t->burst_limited;
605 t->burst_limited = 0;
606 }
607 }
608
609 /* What is the next timeout value for this transport? */
610 unsigned long sctp_transport_timeout(struct sctp_transport *trans)
611 {
612 /* RTO + timer slack +/- 50% of RTO */
613 unsigned long timeout = trans->rto >> 1;
614
615 if (trans->state != SCTP_UNCONFIRMED &&
616 trans->state != SCTP_PF)
617 timeout += trans->hbinterval;
618
619 return timeout;
620 }
621
622 /* Reset transport variables to their initial values */
623 void sctp_transport_reset(struct sctp_transport *t)
624 {
625 struct sctp_association *asoc = t->asoc;
626
627 /* RFC 2960 (bis), Section 5.2.4
628 * All the congestion control parameters (e.g., cwnd, ssthresh)
629 * related to this peer MUST be reset to their initial values
630 * (see Section 6.2.1)
631 */
632 t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
633 t->burst_limited = 0;
634 t->ssthresh = asoc->peer.i.a_rwnd;
635 t->rto = asoc->rto_initial;
636 sctp_max_rto(asoc, t);
637 t->rtt = 0;
638 t->srtt = 0;
639 t->rttvar = 0;
640
641 /* Reset these additional variables so that we have a clean slate. */
642 t->partial_bytes_acked = 0;
643 t->flight_size = 0;
644 t->error_count = 0;
645 t->rto_pending = 0;
646 t->hb_sent = 0;
647
648 /* Initialize the state information for SFR-CACC */
649 t->cacc.changeover_active = 0;
650 t->cacc.cycling_changeover = 0;
651 t->cacc.next_tsn_at_change = 0;
652 t->cacc.cacc_saw_newack = 0;
653 }
654
655 /* Schedule retransmission on the given transport */
656 void sctp_transport_immediate_rtx(struct sctp_transport *t)
657 {
658 /* Stop pending T3_rtx_timer */
659 if (del_timer(&t->T3_rtx_timer))
660 sctp_transport_put(t);
661
662 sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX);
663 if (!timer_pending(&t->T3_rtx_timer)) {
664 if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto))
665 sctp_transport_hold(t);
666 }
667 }
668
669 /* Drop dst */
670 void sctp_transport_dst_release(struct sctp_transport *t)
671 {
672 dst_release(t->dst);
673 t->dst = NULL;
674 t->dst_pending_confirm = 0;
675 }
676
677 /* Schedule neighbour confirm */
678 void sctp_transport_dst_confirm(struct sctp_transport *t)
679 {
680 t->dst_pending_confirm = 1;
681 }