1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* SCTP kernel implementation 3 * Copyright (c) 1999-2000 Cisco, Inc. 4 * Copyright (c) 1999-2001 Motorola, Inc. 5 * Copyright (c) 2001-2003 International Business Machines Corp. 6 * Copyright (c) 2001 Intel Corp. 7 * Copyright (c) 2001 La Monte H.P. Yarroll 8 * 9 * This file is part of the SCTP kernel implementation 10 * 11 * This module provides the abstraction for an SCTP tranport representing 12 * a remote transport address. For local transport addresses, we just use 13 * union sctp_addr. 14 * 15 * Please send any bug reports or fixes you make to the 16 * email address(es): 17 * lksctp developers <linux-sctp@vger.kernel.org> 18 * 19 * Written or modified by: 20 * La Monte H.P. Yarroll <piggy@acm.org> 21 * Karl Knutson <karl@athena.chicago.il.us> 22 * Jon Grimm <jgrimm@us.ibm.com> 23 * Xingang Guo <xingang.guo@intel.com> 24 * Hui Huang <hui.huang@nokia.com> 25 * Sridhar Samudrala <sri@us.ibm.com> 26 * Ardelle Fan <ardelle.fan@intel.com> 27 */ 28 29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 30 31 #include <linux/slab.h> 32 #include <linux/types.h> 33 #include <linux/random.h> 34 #include <net/sctp/sctp.h> 35 #include <net/sctp/sm.h> 36 37 /* 1st Level Abstractions. */ 38 39 /* Initialize a new transport from provided memory. */ 40 static struct sctp_transport *sctp_transport_init(struct net *net, 41 struct sctp_transport *peer, 42 const union sctp_addr *addr, 43 gfp_t gfp) 44 { 45 /* Copy in the address. */ 46 peer->af_specific = sctp_get_af_specific(addr->sa.sa_family); 47 memcpy(&peer->ipaddr, addr, peer->af_specific->sockaddr_len); 48 memset(&peer->saddr, 0, sizeof(union sctp_addr)); 49 50 peer->sack_generation = 0; 51 52 /* From 6.3.1 RTO Calculation: 53 * 54 * C1) Until an RTT measurement has been made for a packet sent to the 55 * given destination transport address, set RTO to the protocol 56 * parameter 'RTO.Initial'. 57 */ 58 peer->rto = msecs_to_jiffies(net->sctp.rto_initial); 59 60 peer->last_time_heard = 0; 61 peer->last_time_ecne_reduced = jiffies; 62 63 peer->param_flags = SPP_HB_DISABLE | 64 SPP_PMTUD_ENABLE | 65 SPP_SACKDELAY_ENABLE; 66 67 /* Initialize the default path max_retrans. */ 68 peer->pathmaxrxt = net->sctp.max_retrans_path; 69 peer->pf_retrans = net->sctp.pf_retrans; 70 71 INIT_LIST_HEAD(&peer->transmitted); 72 INIT_LIST_HEAD(&peer->send_ready); 73 INIT_LIST_HEAD(&peer->transports); 74 75 timer_setup(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event, 0); 76 timer_setup(&peer->hb_timer, sctp_generate_heartbeat_event, 0); 77 timer_setup(&peer->reconf_timer, sctp_generate_reconf_event, 0); 78 timer_setup(&peer->proto_unreach_timer, 79 sctp_generate_proto_unreach_event, 0); 80 81 /* Initialize the 64-bit random nonce sent with heartbeat. */ 82 get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce)); 83 84 refcount_set(&peer->refcnt, 1); 85 86 return peer; 87 } 88 89 /* Allocate and initialize a new transport. */ 90 struct sctp_transport *sctp_transport_new(struct net *net, 91 const union sctp_addr *addr, 92 gfp_t gfp) 93 { 94 struct sctp_transport *transport; 95 96 transport = kzalloc(sizeof(*transport), gfp); 97 if (!transport) 98 goto fail; 99 100 if (!sctp_transport_init(net, transport, addr, gfp)) 101 goto fail_init; 102 103 SCTP_DBG_OBJCNT_INC(transport); 104 105 return transport; 106 107 fail_init: 108 kfree(transport); 109 110 fail: 111 return NULL; 112 } 113 114 /* This transport is no longer needed. Free up if possible, or 115 * delay until it last reference count. 116 */ 117 void sctp_transport_free(struct sctp_transport *transport) 118 { 119 /* Try to delete the heartbeat timer. */ 120 if (del_timer(&transport->hb_timer)) 121 sctp_transport_put(transport); 122 123 /* Delete the T3_rtx timer if it's active. 124 * There is no point in not doing this now and letting 125 * structure hang around in memory since we know 126 * the tranport is going away. 127 */ 128 if (del_timer(&transport->T3_rtx_timer)) 129 sctp_transport_put(transport); 130 131 if (del_timer(&transport->reconf_timer)) 132 sctp_transport_put(transport); 133 134 /* Delete the ICMP proto unreachable timer if it's active. */ 135 if (del_timer(&transport->proto_unreach_timer)) 136 sctp_association_put(transport->asoc); 137 138 sctp_transport_put(transport); 139 } 140 141 static void sctp_transport_destroy_rcu(struct rcu_head *head) 142 { 143 struct sctp_transport *transport; 144 145 transport = container_of(head, struct sctp_transport, rcu); 146 147 dst_release(transport->dst); 148 kfree(transport); 149 SCTP_DBG_OBJCNT_DEC(transport); 150 } 151 152 /* Destroy the transport data structure. 153 * Assumes there are no more users of this structure. 154 */ 155 static void sctp_transport_destroy(struct sctp_transport *transport) 156 { 157 if (unlikely(refcount_read(&transport->refcnt))) { 158 WARN(1, "Attempt to destroy undead transport %p!\n", transport); 159 return; 160 } 161 162 sctp_packet_free(&transport->packet); 163 164 if (transport->asoc) 165 sctp_association_put(transport->asoc); 166 167 call_rcu(&transport->rcu, sctp_transport_destroy_rcu); 168 } 169 170 /* Start T3_rtx timer if it is not already running and update the heartbeat 171 * timer. This routine is called every time a DATA chunk is sent. 172 */ 173 void sctp_transport_reset_t3_rtx(struct sctp_transport *transport) 174 { 175 /* RFC 2960 6.3.2 Retransmission Timer Rules 176 * 177 * R1) Every time a DATA chunk is sent to any address(including a 178 * retransmission), if the T3-rtx timer of that address is not running 179 * start it running so that it will expire after the RTO of that 180 * address. 181 */ 182 183 if (!timer_pending(&transport->T3_rtx_timer)) 184 if (!mod_timer(&transport->T3_rtx_timer, 185 jiffies + transport->rto)) 186 sctp_transport_hold(transport); 187 } 188 189 void sctp_transport_reset_hb_timer(struct sctp_transport *transport) 190 { 191 unsigned long expires; 192 193 /* When a data chunk is sent, reset the heartbeat interval. */ 194 expires = jiffies + sctp_transport_timeout(transport); 195 if ((time_before(transport->hb_timer.expires, expires) || 196 !timer_pending(&transport->hb_timer)) && 197 !mod_timer(&transport->hb_timer, 198 expires + prandom_u32_max(transport->rto))) 199 sctp_transport_hold(transport); 200 } 201 202 void sctp_transport_reset_reconf_timer(struct sctp_transport *transport) 203 { 204 if (!timer_pending(&transport->reconf_timer)) 205 if (!mod_timer(&transport->reconf_timer, 206 jiffies + transport->rto)) 207 sctp_transport_hold(transport); 208 } 209 210 /* This transport has been assigned to an association. 211 * Initialize fields from the association or from the sock itself. 212 * Register the reference count in the association. 213 */ 214 void sctp_transport_set_owner(struct sctp_transport *transport, 215 struct sctp_association *asoc) 216 { 217 transport->asoc = asoc; 218 sctp_association_hold(asoc); 219 } 220 221 /* Initialize the pmtu of a transport. */ 222 void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk) 223 { 224 /* If we don't have a fresh route, look one up */ 225 if (!transport->dst || transport->dst->obsolete) { 226 sctp_transport_dst_release(transport); 227 transport->af_specific->get_dst(transport, &transport->saddr, 228 &transport->fl, sk); 229 } 230 231 if (transport->param_flags & SPP_PMTUD_DISABLE) { 232 struct sctp_association *asoc = transport->asoc; 233 234 if (!transport->pathmtu && asoc && asoc->pathmtu) 235 transport->pathmtu = asoc->pathmtu; 236 if (transport->pathmtu) 237 return; 238 } 239 240 if (transport->dst) 241 transport->pathmtu = sctp_dst_mtu(transport->dst); 242 else 243 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; 244 } 245 246 bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu) 247 { 248 struct dst_entry *dst = sctp_transport_dst_check(t); 249 struct sock *sk = t->asoc->base.sk; 250 bool change = true; 251 252 if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { 253 pr_warn_ratelimited("%s: Reported pmtu %d too low, using default minimum of %d\n", 254 __func__, pmtu, SCTP_DEFAULT_MINSEGMENT); 255 /* Use default minimum segment instead */ 256 pmtu = SCTP_DEFAULT_MINSEGMENT; 257 } 258 pmtu = SCTP_TRUNC4(pmtu); 259 260 if (dst) { 261 struct sctp_pf *pf = sctp_get_pf_specific(dst->ops->family); 262 union sctp_addr addr; 263 264 pf->af->from_sk(&addr, sk); 265 pf->to_sk_daddr(&t->ipaddr, sk); 266 dst->ops->update_pmtu(dst, sk, NULL, pmtu); 267 pf->to_sk_daddr(&addr, sk); 268 269 dst = sctp_transport_dst_check(t); 270 } 271 272 if (!dst) { 273 t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); 274 dst = t->dst; 275 } 276 277 if (dst) { 278 /* Re-fetch, as under layers may have a higher minimum size */ 279 pmtu = sctp_dst_mtu(dst); 280 change = t->pathmtu != pmtu; 281 } 282 t->pathmtu = pmtu; 283 284 return change; 285 } 286 287 /* Caches the dst entry and source address for a transport's destination 288 * address. 289 */ 290 void sctp_transport_route(struct sctp_transport *transport, 291 union sctp_addr *saddr, struct sctp_sock *opt) 292 { 293 struct sctp_association *asoc = transport->asoc; 294 struct sctp_af *af = transport->af_specific; 295 296 sctp_transport_dst_release(transport); 297 af->get_dst(transport, saddr, &transport->fl, sctp_opt2sk(opt)); 298 299 if (saddr) 300 memcpy(&transport->saddr, saddr, sizeof(union sctp_addr)); 301 else 302 af->get_saddr(opt, transport, &transport->fl); 303 304 sctp_transport_pmtu(transport, sctp_opt2sk(opt)); 305 306 /* Initialize sk->sk_rcv_saddr, if the transport is the 307 * association's active path for getsockname(). 308 */ 309 if (transport->dst && asoc && 310 (!asoc->peer.primary_path || transport == asoc->peer.active_path)) 311 opt->pf->to_sk_saddr(&transport->saddr, asoc->base.sk); 312 } 313 314 /* Hold a reference to a transport. */ 315 int sctp_transport_hold(struct sctp_transport *transport) 316 { 317 return refcount_inc_not_zero(&transport->refcnt); 318 } 319 320 /* Release a reference to a transport and clean up 321 * if there are no more references. 322 */ 323 void sctp_transport_put(struct sctp_transport *transport) 324 { 325 if (refcount_dec_and_test(&transport->refcnt)) 326 sctp_transport_destroy(transport); 327 } 328 329 /* Update transport's RTO based on the newly calculated RTT. */ 330 void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) 331 { 332 if (unlikely(!tp->rto_pending)) 333 /* We should not be doing any RTO updates unless rto_pending is set. */ 334 pr_debug("%s: rto_pending not set on transport %p!\n", __func__, tp); 335 336 if (tp->rttvar || tp->srtt) { 337 struct net *net = tp->asoc->base.net; 338 /* 6.3.1 C3) When a new RTT measurement R' is made, set 339 * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'| 340 * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R' 341 */ 342 343 /* Note: The above algorithm has been rewritten to 344 * express rto_beta and rto_alpha as inverse powers 345 * of two. 346 * For example, assuming the default value of RTO.Alpha of 347 * 1/8, rto_alpha would be expressed as 3. 348 */ 349 tp->rttvar = tp->rttvar - (tp->rttvar >> net->sctp.rto_beta) 350 + (((__u32)abs((__s64)tp->srtt - (__s64)rtt)) >> net->sctp.rto_beta); 351 tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha) 352 + (rtt >> net->sctp.rto_alpha); 353 } else { 354 /* 6.3.1 C2) When the first RTT measurement R is made, set 355 * SRTT <- R, RTTVAR <- R/2. 356 */ 357 tp->srtt = rtt; 358 tp->rttvar = rtt >> 1; 359 } 360 361 /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then 362 * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY. 363 */ 364 if (tp->rttvar == 0) 365 tp->rttvar = SCTP_CLOCK_GRANULARITY; 366 367 /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */ 368 tp->rto = tp->srtt + (tp->rttvar << 2); 369 370 /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min 371 * seconds then it is rounded up to RTO.Min seconds. 372 */ 373 if (tp->rto < tp->asoc->rto_min) 374 tp->rto = tp->asoc->rto_min; 375 376 /* 6.3.1 C7) A maximum value may be placed on RTO provided it is 377 * at least RTO.max seconds. 378 */ 379 if (tp->rto > tp->asoc->rto_max) 380 tp->rto = tp->asoc->rto_max; 381 382 sctp_max_rto(tp->asoc, tp); 383 tp->rtt = rtt; 384 385 /* Reset rto_pending so that a new RTT measurement is started when a 386 * new data chunk is sent. 387 */ 388 tp->rto_pending = 0; 389 390 pr_debug("%s: transport:%p, rtt:%d, srtt:%d rttvar:%d, rto:%ld\n", 391 __func__, tp, rtt, tp->srtt, tp->rttvar, tp->rto); 392 } 393 394 /* This routine updates the transport's cwnd and partial_bytes_acked 395 * parameters based on the bytes acked in the received SACK. 396 */ 397 void sctp_transport_raise_cwnd(struct sctp_transport *transport, 398 __u32 sack_ctsn, __u32 bytes_acked) 399 { 400 struct sctp_association *asoc = transport->asoc; 401 __u32 cwnd, ssthresh, flight_size, pba, pmtu; 402 403 cwnd = transport->cwnd; 404 flight_size = transport->flight_size; 405 406 /* See if we need to exit Fast Recovery first */ 407 if (asoc->fast_recovery && 408 TSN_lte(asoc->fast_recovery_exit, sack_ctsn)) 409 asoc->fast_recovery = 0; 410 411 ssthresh = transport->ssthresh; 412 pba = transport->partial_bytes_acked; 413 pmtu = transport->asoc->pathmtu; 414 415 if (cwnd <= ssthresh) { 416 /* RFC 4960 7.2.1 417 * o When cwnd is less than or equal to ssthresh, an SCTP 418 * endpoint MUST use the slow-start algorithm to increase 419 * cwnd only if the current congestion window is being fully 420 * utilized, an incoming SACK advances the Cumulative TSN 421 * Ack Point, and the data sender is not in Fast Recovery. 422 * Only when these three conditions are met can the cwnd be 423 * increased; otherwise, the cwnd MUST not be increased. 424 * If these conditions are met, then cwnd MUST be increased 425 * by, at most, the lesser of 1) the total size of the 426 * previously outstanding DATA chunk(s) acknowledged, and 427 * 2) the destination's path MTU. This upper bound protects 428 * against the ACK-Splitting attack outlined in [SAVAGE99]. 429 */ 430 if (asoc->fast_recovery) 431 return; 432 433 /* The appropriate cwnd increase algorithm is performed 434 * if, and only if the congestion window is being fully 435 * utilized. Note that RFC4960 Errata 3.22 removed the 436 * other condition on ctsn moving. 437 */ 438 if (flight_size < cwnd) 439 return; 440 441 if (bytes_acked > pmtu) 442 cwnd += pmtu; 443 else 444 cwnd += bytes_acked; 445 446 pr_debug("%s: slow start: transport:%p, bytes_acked:%d, " 447 "cwnd:%d, ssthresh:%d, flight_size:%d, pba:%d\n", 448 __func__, transport, bytes_acked, cwnd, ssthresh, 449 flight_size, pba); 450 } else { 451 /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh, 452 * upon each SACK arrival, increase partial_bytes_acked 453 * by the total number of bytes of all new chunks 454 * acknowledged in that SACK including chunks 455 * acknowledged by the new Cumulative TSN Ack and by Gap 456 * Ack Blocks. (updated by RFC4960 Errata 3.22) 457 * 458 * When partial_bytes_acked is greater than cwnd and 459 * before the arrival of the SACK the sender had less 460 * bytes of data outstanding than cwnd (i.e., before 461 * arrival of the SACK, flightsize was less than cwnd), 462 * reset partial_bytes_acked to cwnd. (RFC 4960 Errata 463 * 3.26) 464 * 465 * When partial_bytes_acked is equal to or greater than 466 * cwnd and before the arrival of the SACK the sender 467 * had cwnd or more bytes of data outstanding (i.e., 468 * before arrival of the SACK, flightsize was greater 469 * than or equal to cwnd), partial_bytes_acked is reset 470 * to (partial_bytes_acked - cwnd). Next, cwnd is 471 * increased by MTU. (RFC 4960 Errata 3.12) 472 */ 473 pba += bytes_acked; 474 if (pba > cwnd && flight_size < cwnd) 475 pba = cwnd; 476 if (pba >= cwnd && flight_size >= cwnd) { 477 pba = pba - cwnd; 478 cwnd += pmtu; 479 } 480 481 pr_debug("%s: congestion avoidance: transport:%p, " 482 "bytes_acked:%d, cwnd:%d, ssthresh:%d, " 483 "flight_size:%d, pba:%d\n", __func__, 484 transport, bytes_acked, cwnd, ssthresh, 485 flight_size, pba); 486 } 487 488 transport->cwnd = cwnd; 489 transport->partial_bytes_acked = pba; 490 } 491 492 /* This routine is used to lower the transport's cwnd when congestion is 493 * detected. 494 */ 495 void sctp_transport_lower_cwnd(struct sctp_transport *transport, 496 enum sctp_lower_cwnd reason) 497 { 498 struct sctp_association *asoc = transport->asoc; 499 500 switch (reason) { 501 case SCTP_LOWER_CWND_T3_RTX: 502 /* RFC 2960 Section 7.2.3, sctpimpguide 503 * When the T3-rtx timer expires on an address, SCTP should 504 * perform slow start by: 505 * ssthresh = max(cwnd/2, 4*MTU) 506 * cwnd = 1*MTU 507 * partial_bytes_acked = 0 508 */ 509 transport->ssthresh = max(transport->cwnd/2, 510 4*asoc->pathmtu); 511 transport->cwnd = asoc->pathmtu; 512 513 /* T3-rtx also clears fast recovery */ 514 asoc->fast_recovery = 0; 515 break; 516 517 case SCTP_LOWER_CWND_FAST_RTX: 518 /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the 519 * destination address(es) to which the missing DATA chunks 520 * were last sent, according to the formula described in 521 * Section 7.2.3. 522 * 523 * RFC 2960 7.2.3, sctpimpguide Upon detection of packet 524 * losses from SACK (see Section 7.2.4), An endpoint 525 * should do the following: 526 * ssthresh = max(cwnd/2, 4*MTU) 527 * cwnd = ssthresh 528 * partial_bytes_acked = 0 529 */ 530 if (asoc->fast_recovery) 531 return; 532 533 /* Mark Fast recovery */ 534 asoc->fast_recovery = 1; 535 asoc->fast_recovery_exit = asoc->next_tsn - 1; 536 537 transport->ssthresh = max(transport->cwnd/2, 538 4*asoc->pathmtu); 539 transport->cwnd = transport->ssthresh; 540 break; 541 542 case SCTP_LOWER_CWND_ECNE: 543 /* RFC 2481 Section 6.1.2. 544 * If the sender receives an ECN-Echo ACK packet 545 * then the sender knows that congestion was encountered in the 546 * network on the path from the sender to the receiver. The 547 * indication of congestion should be treated just as a 548 * congestion loss in non-ECN Capable TCP. That is, the TCP 549 * source halves the congestion window "cwnd" and reduces the 550 * slow start threshold "ssthresh". 551 * A critical condition is that TCP does not react to 552 * congestion indications more than once every window of 553 * data (or more loosely more than once every round-trip time). 554 */ 555 if (time_after(jiffies, transport->last_time_ecne_reduced + 556 transport->rtt)) { 557 transport->ssthresh = max(transport->cwnd/2, 558 4*asoc->pathmtu); 559 transport->cwnd = transport->ssthresh; 560 transport->last_time_ecne_reduced = jiffies; 561 } 562 break; 563 564 case SCTP_LOWER_CWND_INACTIVE: 565 /* RFC 2960 Section 7.2.1, sctpimpguide 566 * When the endpoint does not transmit data on a given 567 * transport address, the cwnd of the transport address 568 * should be adjusted to max(cwnd/2, 4*MTU) per RTO. 569 * NOTE: Although the draft recommends that this check needs 570 * to be done every RTO interval, we do it every hearbeat 571 * interval. 572 */ 573 transport->cwnd = max(transport->cwnd/2, 574 4*asoc->pathmtu); 575 /* RFC 4960 Errata 3.27.2: also adjust sshthresh */ 576 transport->ssthresh = transport->cwnd; 577 break; 578 } 579 580 transport->partial_bytes_acked = 0; 581 582 pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d\n", 583 __func__, transport, reason, transport->cwnd, 584 transport->ssthresh); 585 } 586 587 /* Apply Max.Burst limit to the congestion window: 588 * sctpimpguide-05 2.14.2 589 * D) When the time comes for the sender to 590 * transmit new DATA chunks, the protocol parameter Max.Burst MUST 591 * first be applied to limit how many new DATA chunks may be sent. 592 * The limit is applied by adjusting cwnd as follows: 593 * if ((flightsize+ Max.Burst * MTU) < cwnd) 594 * cwnd = flightsize + Max.Burst * MTU 595 */ 596 597 void sctp_transport_burst_limited(struct sctp_transport *t) 598 { 599 struct sctp_association *asoc = t->asoc; 600 u32 old_cwnd = t->cwnd; 601 u32 max_burst_bytes; 602 603 if (t->burst_limited || asoc->max_burst == 0) 604 return; 605 606 max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu); 607 if (max_burst_bytes < old_cwnd) { 608 t->cwnd = max_burst_bytes; 609 t->burst_limited = old_cwnd; 610 } 611 } 612 613 /* Restore the old cwnd congestion window, after the burst had it's 614 * desired effect. 615 */ 616 void sctp_transport_burst_reset(struct sctp_transport *t) 617 { 618 if (t->burst_limited) { 619 t->cwnd = t->burst_limited; 620 t->burst_limited = 0; 621 } 622 } 623 624 /* What is the next timeout value for this transport? */ 625 unsigned long sctp_transport_timeout(struct sctp_transport *trans) 626 { 627 /* RTO + timer slack +/- 50% of RTO */ 628 unsigned long timeout = trans->rto >> 1; 629 630 if (trans->state != SCTP_UNCONFIRMED && 631 trans->state != SCTP_PF) 632 timeout += trans->hbinterval; 633 634 return max_t(unsigned long, timeout, HZ / 5); 635 } 636 637 /* Reset transport variables to their initial values */ 638 void sctp_transport_reset(struct sctp_transport *t) 639 { 640 struct sctp_association *asoc = t->asoc; 641 642 /* RFC 2960 (bis), Section 5.2.4 643 * All the congestion control parameters (e.g., cwnd, ssthresh) 644 * related to this peer MUST be reset to their initial values 645 * (see Section 6.2.1) 646 */ 647 t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380)); 648 t->burst_limited = 0; 649 t->ssthresh = asoc->peer.i.a_rwnd; 650 t->rto = asoc->rto_initial; 651 sctp_max_rto(asoc, t); 652 t->rtt = 0; 653 t->srtt = 0; 654 t->rttvar = 0; 655 656 /* Reset these additional variables so that we have a clean slate. */ 657 t->partial_bytes_acked = 0; 658 t->flight_size = 0; 659 t->error_count = 0; 660 t->rto_pending = 0; 661 t->hb_sent = 0; 662 663 /* Initialize the state information for SFR-CACC */ 664 t->cacc.changeover_active = 0; 665 t->cacc.cycling_changeover = 0; 666 t->cacc.next_tsn_at_change = 0; 667 t->cacc.cacc_saw_newack = 0; 668 } 669 670 /* Schedule retransmission on the given transport */ 671 void sctp_transport_immediate_rtx(struct sctp_transport *t) 672 { 673 /* Stop pending T3_rtx_timer */ 674 if (del_timer(&t->T3_rtx_timer)) 675 sctp_transport_put(t); 676 677 sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX); 678 if (!timer_pending(&t->T3_rtx_timer)) { 679 if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto)) 680 sctp_transport_hold(t); 681 } 682 } 683 684 /* Drop dst */ 685 void sctp_transport_dst_release(struct sctp_transport *t) 686 { 687 dst_release(t->dst); 688 t->dst = NULL; 689 t->dst_pending_confirm = 0; 690 } 691 692 /* Schedule neighbour confirm */ 693 void sctp_transport_dst_confirm(struct sctp_transport *t) 694 { 695 t->dst_pending_confirm = 1; 696 } 697