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 refcount_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(refcount_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 refcount_inc_not_zero(&transport->refcnt); 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 (refcount_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 ssthresh = transport->ssthresh; 409 pba = transport->partial_bytes_acked; 410 pmtu = transport->asoc->pathmtu; 411 412 if (cwnd <= ssthresh) { 413 /* RFC 4960 7.2.1 414 * o When cwnd is less than or equal to ssthresh, an SCTP 415 * endpoint MUST use the slow-start algorithm to increase 416 * cwnd only if the current congestion window is being fully 417 * utilized, an incoming SACK advances the Cumulative TSN 418 * Ack Point, and the data sender is not in Fast Recovery. 419 * Only when these three conditions are met can the cwnd be 420 * increased; otherwise, the cwnd MUST not be increased. 421 * If these conditions are met, then cwnd MUST be increased 422 * by, at most, the lesser of 1) the total size of the 423 * previously outstanding DATA chunk(s) acknowledged, and 424 * 2) the destination's path MTU. This upper bound protects 425 * against the ACK-Splitting attack outlined in [SAVAGE99]. 426 */ 427 if (asoc->fast_recovery) 428 return; 429 430 /* The appropriate cwnd increase algorithm is performed 431 * if, and only if the congestion window is being fully 432 * utilized. Note that RFC4960 Errata 3.22 removed the 433 * other condition on ctsn moving. 434 */ 435 if (flight_size < cwnd) 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, increase partial_bytes_acked 450 * by the total number of bytes of all new chunks 451 * acknowledged in that SACK including chunks 452 * acknowledged by the new Cumulative TSN Ack and by Gap 453 * Ack Blocks. (updated by RFC4960 Errata 3.22) 454 * 455 * When partial_bytes_acked is greater than cwnd and 456 * before the arrival of the SACK the sender had less 457 * bytes of data outstanding than cwnd (i.e., before 458 * arrival of the SACK, flightsize was less than cwnd), 459 * reset partial_bytes_acked to cwnd. (RFC 4960 Errata 460 * 3.26) 461 * 462 * When partial_bytes_acked is equal to or greater than 463 * cwnd and before the arrival of the SACK the sender 464 * had cwnd or more bytes of data outstanding (i.e., 465 * before arrival of the SACK, flightsize was greater 466 * than or equal to cwnd), partial_bytes_acked is reset 467 * to (partial_bytes_acked - cwnd). Next, cwnd is 468 * increased by MTU. (RFC 4960 Errata 3.12) 469 */ 470 pba += bytes_acked; 471 if (pba > cwnd && flight_size < cwnd) 472 pba = cwnd; 473 if (pba >= cwnd && flight_size >= cwnd) { 474 pba = pba - cwnd; 475 cwnd += pmtu; 476 } 477 478 pr_debug("%s: congestion avoidance: transport:%p, " 479 "bytes_acked:%d, cwnd:%d, ssthresh:%d, " 480 "flight_size:%d, pba:%d\n", __func__, 481 transport, bytes_acked, cwnd, ssthresh, 482 flight_size, pba); 483 } 484 485 transport->cwnd = cwnd; 486 transport->partial_bytes_acked = pba; 487 } 488 489 /* This routine is used to lower the transport's cwnd when congestion is 490 * detected. 491 */ 492 void sctp_transport_lower_cwnd(struct sctp_transport *transport, 493 enum sctp_lower_cwnd reason) 494 { 495 struct sctp_association *asoc = transport->asoc; 496 497 switch (reason) { 498 case SCTP_LOWER_CWND_T3_RTX: 499 /* RFC 2960 Section 7.2.3, sctpimpguide 500 * When the T3-rtx timer expires on an address, SCTP should 501 * perform slow start by: 502 * ssthresh = max(cwnd/2, 4*MTU) 503 * cwnd = 1*MTU 504 * partial_bytes_acked = 0 505 */ 506 transport->ssthresh = max(transport->cwnd/2, 507 4*asoc->pathmtu); 508 transport->cwnd = asoc->pathmtu; 509 510 /* T3-rtx also clears fast recovery */ 511 asoc->fast_recovery = 0; 512 break; 513 514 case SCTP_LOWER_CWND_FAST_RTX: 515 /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the 516 * destination address(es) to which the missing DATA chunks 517 * were last sent, according to the formula described in 518 * Section 7.2.3. 519 * 520 * RFC 2960 7.2.3, sctpimpguide Upon detection of packet 521 * losses from SACK (see Section 7.2.4), An endpoint 522 * should do the following: 523 * ssthresh = max(cwnd/2, 4*MTU) 524 * cwnd = ssthresh 525 * partial_bytes_acked = 0 526 */ 527 if (asoc->fast_recovery) 528 return; 529 530 /* Mark Fast recovery */ 531 asoc->fast_recovery = 1; 532 asoc->fast_recovery_exit = asoc->next_tsn - 1; 533 534 transport->ssthresh = max(transport->cwnd/2, 535 4*asoc->pathmtu); 536 transport->cwnd = transport->ssthresh; 537 break; 538 539 case SCTP_LOWER_CWND_ECNE: 540 /* RFC 2481 Section 6.1.2. 541 * If the sender receives an ECN-Echo ACK packet 542 * then the sender knows that congestion was encountered in the 543 * network on the path from the sender to the receiver. The 544 * indication of congestion should be treated just as a 545 * congestion loss in non-ECN Capable TCP. That is, the TCP 546 * source halves the congestion window "cwnd" and reduces the 547 * slow start threshold "ssthresh". 548 * A critical condition is that TCP does not react to 549 * congestion indications more than once every window of 550 * data (or more loosely more than once every round-trip time). 551 */ 552 if (time_after(jiffies, transport->last_time_ecne_reduced + 553 transport->rtt)) { 554 transport->ssthresh = max(transport->cwnd/2, 555 4*asoc->pathmtu); 556 transport->cwnd = transport->ssthresh; 557 transport->last_time_ecne_reduced = jiffies; 558 } 559 break; 560 561 case SCTP_LOWER_CWND_INACTIVE: 562 /* RFC 2960 Section 7.2.1, sctpimpguide 563 * When the endpoint does not transmit data on a given 564 * transport address, the cwnd of the transport address 565 * should be adjusted to max(cwnd/2, 4*MTU) per RTO. 566 * NOTE: Although the draft recommends that this check needs 567 * to be done every RTO interval, we do it every hearbeat 568 * interval. 569 */ 570 transport->cwnd = max(transport->cwnd/2, 571 4*asoc->pathmtu); 572 /* RFC 4960 Errata 3.27.2: also adjust sshthresh */ 573 transport->ssthresh = transport->cwnd; 574 break; 575 } 576 577 transport->partial_bytes_acked = 0; 578 579 pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d\n", 580 __func__, transport, reason, transport->cwnd, 581 transport->ssthresh); 582 } 583 584 /* Apply Max.Burst limit to the congestion window: 585 * sctpimpguide-05 2.14.2 586 * D) When the time comes for the sender to 587 * transmit new DATA chunks, the protocol parameter Max.Burst MUST 588 * first be applied to limit how many new DATA chunks may be sent. 589 * The limit is applied by adjusting cwnd as follows: 590 * if ((flightsize+ Max.Burst * MTU) < cwnd) 591 * cwnd = flightsize + Max.Burst * MTU 592 */ 593 594 void sctp_transport_burst_limited(struct sctp_transport *t) 595 { 596 struct sctp_association *asoc = t->asoc; 597 u32 old_cwnd = t->cwnd; 598 u32 max_burst_bytes; 599 600 if (t->burst_limited || asoc->max_burst == 0) 601 return; 602 603 max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu); 604 if (max_burst_bytes < old_cwnd) { 605 t->cwnd = max_burst_bytes; 606 t->burst_limited = old_cwnd; 607 } 608 } 609 610 /* Restore the old cwnd congestion window, after the burst had it's 611 * desired effect. 612 */ 613 void sctp_transport_burst_reset(struct sctp_transport *t) 614 { 615 if (t->burst_limited) { 616 t->cwnd = t->burst_limited; 617 t->burst_limited = 0; 618 } 619 } 620 621 /* What is the next timeout value for this transport? */ 622 unsigned long sctp_transport_timeout(struct sctp_transport *trans) 623 { 624 /* RTO + timer slack +/- 50% of RTO */ 625 unsigned long timeout = trans->rto >> 1; 626 627 if (trans->state != SCTP_UNCONFIRMED && 628 trans->state != SCTP_PF) 629 timeout += trans->hbinterval; 630 631 return timeout; 632 } 633 634 /* Reset transport variables to their initial values */ 635 void sctp_transport_reset(struct sctp_transport *t) 636 { 637 struct sctp_association *asoc = t->asoc; 638 639 /* RFC 2960 (bis), Section 5.2.4 640 * All the congestion control parameters (e.g., cwnd, ssthresh) 641 * related to this peer MUST be reset to their initial values 642 * (see Section 6.2.1) 643 */ 644 t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380)); 645 t->burst_limited = 0; 646 t->ssthresh = asoc->peer.i.a_rwnd; 647 t->rto = asoc->rto_initial; 648 sctp_max_rto(asoc, t); 649 t->rtt = 0; 650 t->srtt = 0; 651 t->rttvar = 0; 652 653 /* Reset these additional variables so that we have a clean slate. */ 654 t->partial_bytes_acked = 0; 655 t->flight_size = 0; 656 t->error_count = 0; 657 t->rto_pending = 0; 658 t->hb_sent = 0; 659 660 /* Initialize the state information for SFR-CACC */ 661 t->cacc.changeover_active = 0; 662 t->cacc.cycling_changeover = 0; 663 t->cacc.next_tsn_at_change = 0; 664 t->cacc.cacc_saw_newack = 0; 665 } 666 667 /* Schedule retransmission on the given transport */ 668 void sctp_transport_immediate_rtx(struct sctp_transport *t) 669 { 670 /* Stop pending T3_rtx_timer */ 671 if (del_timer(&t->T3_rtx_timer)) 672 sctp_transport_put(t); 673 674 sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX); 675 if (!timer_pending(&t->T3_rtx_timer)) { 676 if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto)) 677 sctp_transport_hold(t); 678 } 679 } 680 681 /* Drop dst */ 682 void sctp_transport_dst_release(struct sctp_transport *t) 683 { 684 dst_release(t->dst); 685 t->dst = NULL; 686 t->dst_pending_confirm = 0; 687 } 688 689 /* Schedule neighbour confirm */ 690 void sctp_transport_dst_confirm(struct sctp_transport *t) 691 { 692 t->dst_pending_confirm = 1; 693 } 694