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, write to 28 * the Free Software Foundation, 59 Temple Place - Suite 330, 29 * Boston, MA 02111-1307, USA. 30 * 31 * Please send any bug reports or fixes you make to the 32 * email address(es): 33 * lksctp developers <lksctp-developers@lists.sourceforge.net> 34 * 35 * Or submit a bug report through the following website: 36 * http://www.sf.net/projects/lksctp 37 * 38 * Written or modified by: 39 * La Monte H.P. Yarroll <piggy@acm.org> 40 * Karl Knutson <karl@athena.chicago.il.us> 41 * Jon Grimm <jgrimm@us.ibm.com> 42 * Xingang Guo <xingang.guo@intel.com> 43 * Hui Huang <hui.huang@nokia.com> 44 * Sridhar Samudrala <sri@us.ibm.com> 45 * Ardelle Fan <ardelle.fan@intel.com> 46 * 47 * Any bugs reported given to us we will try to fix... any fixes shared will 48 * be incorporated into the next SCTP release. 49 */ 50 51 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 52 53 #include <linux/slab.h> 54 #include <linux/types.h> 55 #include <linux/random.h> 56 #include <net/sctp/sctp.h> 57 #include <net/sctp/sm.h> 58 59 /* 1st Level Abstractions. */ 60 61 /* Initialize a new transport from provided memory. */ 62 static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer, 63 const union sctp_addr *addr, 64 gfp_t gfp) 65 { 66 /* Copy in the address. */ 67 peer->ipaddr = *addr; 68 peer->af_specific = sctp_get_af_specific(addr->sa.sa_family); 69 memset(&peer->saddr, 0, sizeof(union sctp_addr)); 70 71 peer->sack_generation = 0; 72 73 /* From 6.3.1 RTO Calculation: 74 * 75 * C1) Until an RTT measurement has been made for a packet sent to the 76 * given destination transport address, set RTO to the protocol 77 * parameter 'RTO.Initial'. 78 */ 79 peer->rto = msecs_to_jiffies(sctp_rto_initial); 80 81 peer->last_time_heard = jiffies; 82 peer->last_time_ecne_reduced = jiffies; 83 84 peer->param_flags = SPP_HB_DISABLE | 85 SPP_PMTUD_ENABLE | 86 SPP_SACKDELAY_ENABLE; 87 88 /* Initialize the default path max_retrans. */ 89 peer->pathmaxrxt = sctp_max_retrans_path; 90 peer->pf_retrans = sctp_pf_retrans; 91 92 INIT_LIST_HEAD(&peer->transmitted); 93 INIT_LIST_HEAD(&peer->send_ready); 94 INIT_LIST_HEAD(&peer->transports); 95 96 setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event, 97 (unsigned long)peer); 98 setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event, 99 (unsigned long)peer); 100 setup_timer(&peer->proto_unreach_timer, 101 sctp_generate_proto_unreach_event, (unsigned long)peer); 102 103 /* Initialize the 64-bit random nonce sent with heartbeat. */ 104 get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce)); 105 106 atomic_set(&peer->refcnt, 1); 107 108 return peer; 109 } 110 111 /* Allocate and initialize a new transport. */ 112 struct sctp_transport *sctp_transport_new(const union sctp_addr *addr, 113 gfp_t gfp) 114 { 115 struct sctp_transport *transport; 116 117 transport = t_new(struct sctp_transport, gfp); 118 if (!transport) 119 goto fail; 120 121 if (!sctp_transport_init(transport, addr, gfp)) 122 goto fail_init; 123 124 transport->malloced = 1; 125 SCTP_DBG_OBJCNT_INC(transport); 126 127 return transport; 128 129 fail_init: 130 kfree(transport); 131 132 fail: 133 return NULL; 134 } 135 136 /* This transport is no longer needed. Free up if possible, or 137 * delay until it last reference count. 138 */ 139 void sctp_transport_free(struct sctp_transport *transport) 140 { 141 transport->dead = 1; 142 143 /* Try to delete the heartbeat timer. */ 144 if (del_timer(&transport->hb_timer)) 145 sctp_transport_put(transport); 146 147 /* Delete the T3_rtx timer if it's active. 148 * There is no point in not doing this now and letting 149 * structure hang around in memory since we know 150 * the tranport is going away. 151 */ 152 if (timer_pending(&transport->T3_rtx_timer) && 153 del_timer(&transport->T3_rtx_timer)) 154 sctp_transport_put(transport); 155 156 /* Delete the ICMP proto unreachable timer if it's active. */ 157 if (timer_pending(&transport->proto_unreach_timer) && 158 del_timer(&transport->proto_unreach_timer)) 159 sctp_association_put(transport->asoc); 160 161 sctp_transport_put(transport); 162 } 163 164 /* Destroy the transport data structure. 165 * Assumes there are no more users of this structure. 166 */ 167 static void sctp_transport_destroy(struct sctp_transport *transport) 168 { 169 SCTP_ASSERT(transport->dead, "Transport is not dead", return); 170 171 if (transport->asoc) 172 sctp_association_put(transport->asoc); 173 174 sctp_packet_free(&transport->packet); 175 176 dst_release(transport->dst); 177 kfree(transport); 178 SCTP_DBG_OBJCNT_DEC(transport); 179 } 180 181 /* Start T3_rtx timer if it is not already running and update the heartbeat 182 * timer. This routine is called every time a DATA chunk is sent. 183 */ 184 void sctp_transport_reset_timers(struct sctp_transport *transport) 185 { 186 /* RFC 2960 6.3.2 Retransmission Timer Rules 187 * 188 * R1) Every time a DATA chunk is sent to any address(including a 189 * retransmission), if the T3-rtx timer of that address is not running 190 * start it running so that it will expire after the RTO of that 191 * address. 192 */ 193 194 if (!timer_pending(&transport->T3_rtx_timer)) 195 if (!mod_timer(&transport->T3_rtx_timer, 196 jiffies + transport->rto)) 197 sctp_transport_hold(transport); 198 199 /* When a data chunk is sent, reset the heartbeat interval. */ 200 if (!mod_timer(&transport->hb_timer, 201 sctp_transport_timeout(transport))) 202 sctp_transport_hold(transport); 203 } 204 205 /* This transport has been assigned to an association. 206 * Initialize fields from the association or from the sock itself. 207 * Register the reference count in the association. 208 */ 209 void sctp_transport_set_owner(struct sctp_transport *transport, 210 struct sctp_association *asoc) 211 { 212 transport->asoc = asoc; 213 sctp_association_hold(asoc); 214 } 215 216 /* Initialize the pmtu of a transport. */ 217 void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk) 218 { 219 /* If we don't have a fresh route, look one up */ 220 if (!transport->dst || transport->dst->obsolete) { 221 dst_release(transport->dst); 222 transport->af_specific->get_dst(transport, &transport->saddr, 223 &transport->fl, sk); 224 } 225 226 if (transport->dst) { 227 transport->pathmtu = dst_mtu(transport->dst); 228 } else 229 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; 230 } 231 232 void sctp_transport_update_pmtu(struct sock *sk, struct sctp_transport *t, u32 pmtu) 233 { 234 struct dst_entry *dst; 235 236 if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { 237 pr_warn("%s: Reported pmtu %d too low, using default minimum of %d\n", 238 __func__, pmtu, 239 SCTP_DEFAULT_MINSEGMENT); 240 /* Use default minimum segment size and disable 241 * pmtu discovery on this transport. 242 */ 243 t->pathmtu = SCTP_DEFAULT_MINSEGMENT; 244 } else { 245 t->pathmtu = pmtu; 246 } 247 248 dst = sctp_transport_dst_check(t); 249 if (!dst) 250 t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); 251 252 if (dst) { 253 dst->ops->update_pmtu(dst, sk, NULL, pmtu); 254 255 dst = sctp_transport_dst_check(t); 256 if (!dst) 257 t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); 258 } 259 } 260 261 /* Caches the dst entry and source address for a transport's destination 262 * address. 263 */ 264 void sctp_transport_route(struct sctp_transport *transport, 265 union sctp_addr *saddr, struct sctp_sock *opt) 266 { 267 struct sctp_association *asoc = transport->asoc; 268 struct sctp_af *af = transport->af_specific; 269 270 af->get_dst(transport, saddr, &transport->fl, sctp_opt2sk(opt)); 271 272 if (saddr) 273 memcpy(&transport->saddr, saddr, sizeof(union sctp_addr)); 274 else 275 af->get_saddr(opt, transport, &transport->fl); 276 277 if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) { 278 return; 279 } 280 if (transport->dst) { 281 transport->pathmtu = dst_mtu(transport->dst); 282 283 /* Initialize sk->sk_rcv_saddr, if the transport is the 284 * association's active path for getsockname(). 285 */ 286 if (asoc && (!asoc->peer.primary_path || 287 (transport == asoc->peer.active_path))) 288 opt->pf->af->to_sk_saddr(&transport->saddr, 289 asoc->base.sk); 290 } else 291 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; 292 } 293 294 /* Hold a reference to a transport. */ 295 void sctp_transport_hold(struct sctp_transport *transport) 296 { 297 atomic_inc(&transport->refcnt); 298 } 299 300 /* Release a reference to a transport and clean up 301 * if there are no more references. 302 */ 303 void sctp_transport_put(struct sctp_transport *transport) 304 { 305 if (atomic_dec_and_test(&transport->refcnt)) 306 sctp_transport_destroy(transport); 307 } 308 309 /* Update transport's RTO based on the newly calculated RTT. */ 310 void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) 311 { 312 /* Check for valid transport. */ 313 SCTP_ASSERT(tp, "NULL transport", return); 314 315 /* We should not be doing any RTO updates unless rto_pending is set. */ 316 SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return); 317 318 if (tp->rttvar || tp->srtt) { 319 /* 6.3.1 C3) When a new RTT measurement R' is made, set 320 * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'| 321 * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R' 322 */ 323 324 /* Note: The above algorithm has been rewritten to 325 * express rto_beta and rto_alpha as inverse powers 326 * of two. 327 * For example, assuming the default value of RTO.Alpha of 328 * 1/8, rto_alpha would be expressed as 3. 329 */ 330 tp->rttvar = tp->rttvar - (tp->rttvar >> sctp_rto_beta) 331 + ((abs(tp->srtt - rtt)) >> sctp_rto_beta); 332 tp->srtt = tp->srtt - (tp->srtt >> sctp_rto_alpha) 333 + (rtt >> sctp_rto_alpha); 334 } else { 335 /* 6.3.1 C2) When the first RTT measurement R is made, set 336 * SRTT <- R, RTTVAR <- R/2. 337 */ 338 tp->srtt = rtt; 339 tp->rttvar = rtt >> 1; 340 } 341 342 /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then 343 * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY. 344 */ 345 if (tp->rttvar == 0) 346 tp->rttvar = SCTP_CLOCK_GRANULARITY; 347 348 /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */ 349 tp->rto = tp->srtt + (tp->rttvar << 2); 350 351 /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min 352 * seconds then it is rounded up to RTO.Min seconds. 353 */ 354 if (tp->rto < tp->asoc->rto_min) 355 tp->rto = tp->asoc->rto_min; 356 357 /* 6.3.1 C7) A maximum value may be placed on RTO provided it is 358 * at least RTO.max seconds. 359 */ 360 if (tp->rto > tp->asoc->rto_max) 361 tp->rto = tp->asoc->rto_max; 362 363 tp->rtt = rtt; 364 365 /* Reset rto_pending so that a new RTT measurement is started when a 366 * new data chunk is sent. 367 */ 368 tp->rto_pending = 0; 369 370 SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d " 371 "rttvar: %d, rto: %ld\n", __func__, 372 tp, rtt, tp->srtt, tp->rttvar, tp->rto); 373 } 374 375 /* This routine updates the transport's cwnd and partial_bytes_acked 376 * parameters based on the bytes acked in the received SACK. 377 */ 378 void sctp_transport_raise_cwnd(struct sctp_transport *transport, 379 __u32 sack_ctsn, __u32 bytes_acked) 380 { 381 struct sctp_association *asoc = transport->asoc; 382 __u32 cwnd, ssthresh, flight_size, pba, pmtu; 383 384 cwnd = transport->cwnd; 385 flight_size = transport->flight_size; 386 387 /* See if we need to exit Fast Recovery first */ 388 if (asoc->fast_recovery && 389 TSN_lte(asoc->fast_recovery_exit, sack_ctsn)) 390 asoc->fast_recovery = 0; 391 392 /* The appropriate cwnd increase algorithm is performed if, and only 393 * if the cumulative TSN whould advanced and the congestion window is 394 * being fully utilized. 395 */ 396 if (TSN_lte(sack_ctsn, transport->asoc->ctsn_ack_point) || 397 (flight_size < cwnd)) 398 return; 399 400 ssthresh = transport->ssthresh; 401 pba = transport->partial_bytes_acked; 402 pmtu = transport->asoc->pathmtu; 403 404 if (cwnd <= ssthresh) { 405 /* RFC 4960 7.2.1 406 * o When cwnd is less than or equal to ssthresh, an SCTP 407 * endpoint MUST use the slow-start algorithm to increase 408 * cwnd only if the current congestion window is being fully 409 * utilized, an incoming SACK advances the Cumulative TSN 410 * Ack Point, and the data sender is not in Fast Recovery. 411 * Only when these three conditions are met can the cwnd be 412 * increased; otherwise, the cwnd MUST not be increased. 413 * If these conditions are met, then cwnd MUST be increased 414 * by, at most, the lesser of 1) the total size of the 415 * previously outstanding DATA chunk(s) acknowledged, and 416 * 2) the destination's path MTU. This upper bound protects 417 * against the ACK-Splitting attack outlined in [SAVAGE99]. 418 */ 419 if (asoc->fast_recovery) 420 return; 421 422 if (bytes_acked > pmtu) 423 cwnd += pmtu; 424 else 425 cwnd += bytes_acked; 426 SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, " 427 "bytes_acked: %d, cwnd: %d, ssthresh: %d, " 428 "flight_size: %d, pba: %d\n", 429 __func__, 430 transport, bytes_acked, cwnd, 431 ssthresh, flight_size, pba); 432 } else { 433 /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh, 434 * upon each SACK arrival that advances the Cumulative TSN Ack 435 * Point, increase partial_bytes_acked by the total number of 436 * bytes of all new chunks acknowledged in that SACK including 437 * chunks acknowledged by the new Cumulative TSN Ack and by 438 * Gap Ack Blocks. 439 * 440 * When partial_bytes_acked is equal to or greater than cwnd 441 * and before the arrival of the SACK the sender had cwnd or 442 * more bytes of data outstanding (i.e., before arrival of the 443 * SACK, flightsize was greater than or equal to cwnd), 444 * increase cwnd by MTU, and reset partial_bytes_acked to 445 * (partial_bytes_acked - cwnd). 446 */ 447 pba += bytes_acked; 448 if (pba >= cwnd) { 449 cwnd += pmtu; 450 pba = ((cwnd < pba) ? (pba - cwnd) : 0); 451 } 452 SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: " 453 "transport: %p, bytes_acked: %d, cwnd: %d, " 454 "ssthresh: %d, flight_size: %d, pba: %d\n", 455 __func__, 456 transport, bytes_acked, cwnd, 457 ssthresh, flight_size, pba); 458 } 459 460 transport->cwnd = cwnd; 461 transport->partial_bytes_acked = pba; 462 } 463 464 /* This routine is used to lower the transport's cwnd when congestion is 465 * detected. 466 */ 467 void sctp_transport_lower_cwnd(struct sctp_transport *transport, 468 sctp_lower_cwnd_t reason) 469 { 470 struct sctp_association *asoc = transport->asoc; 471 472 switch (reason) { 473 case SCTP_LOWER_CWND_T3_RTX: 474 /* RFC 2960 Section 7.2.3, sctpimpguide 475 * When the T3-rtx timer expires on an address, SCTP should 476 * perform slow start by: 477 * ssthresh = max(cwnd/2, 4*MTU) 478 * cwnd = 1*MTU 479 * partial_bytes_acked = 0 480 */ 481 transport->ssthresh = max(transport->cwnd/2, 482 4*asoc->pathmtu); 483 transport->cwnd = asoc->pathmtu; 484 485 /* T3-rtx also clears fast recovery */ 486 asoc->fast_recovery = 0; 487 break; 488 489 case SCTP_LOWER_CWND_FAST_RTX: 490 /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the 491 * destination address(es) to which the missing DATA chunks 492 * were last sent, according to the formula described in 493 * Section 7.2.3. 494 * 495 * RFC 2960 7.2.3, sctpimpguide Upon detection of packet 496 * losses from SACK (see Section 7.2.4), An endpoint 497 * should do the following: 498 * ssthresh = max(cwnd/2, 4*MTU) 499 * cwnd = ssthresh 500 * partial_bytes_acked = 0 501 */ 502 if (asoc->fast_recovery) 503 return; 504 505 /* Mark Fast recovery */ 506 asoc->fast_recovery = 1; 507 asoc->fast_recovery_exit = asoc->next_tsn - 1; 508 509 transport->ssthresh = max(transport->cwnd/2, 510 4*asoc->pathmtu); 511 transport->cwnd = transport->ssthresh; 512 break; 513 514 case SCTP_LOWER_CWND_ECNE: 515 /* RFC 2481 Section 6.1.2. 516 * If the sender receives an ECN-Echo ACK packet 517 * then the sender knows that congestion was encountered in the 518 * network on the path from the sender to the receiver. The 519 * indication of congestion should be treated just as a 520 * congestion loss in non-ECN Capable TCP. That is, the TCP 521 * source halves the congestion window "cwnd" and reduces the 522 * slow start threshold "ssthresh". 523 * A critical condition is that TCP does not react to 524 * congestion indications more than once every window of 525 * data (or more loosely more than once every round-trip time). 526 */ 527 if (time_after(jiffies, transport->last_time_ecne_reduced + 528 transport->rtt)) { 529 transport->ssthresh = max(transport->cwnd/2, 530 4*asoc->pathmtu); 531 transport->cwnd = transport->ssthresh; 532 transport->last_time_ecne_reduced = jiffies; 533 } 534 break; 535 536 case SCTP_LOWER_CWND_INACTIVE: 537 /* RFC 2960 Section 7.2.1, sctpimpguide 538 * When the endpoint does not transmit data on a given 539 * transport address, the cwnd of the transport address 540 * should be adjusted to max(cwnd/2, 4*MTU) per RTO. 541 * NOTE: Although the draft recommends that this check needs 542 * to be done every RTO interval, we do it every hearbeat 543 * interval. 544 */ 545 transport->cwnd = max(transport->cwnd/2, 546 4*asoc->pathmtu); 547 break; 548 } 549 550 transport->partial_bytes_acked = 0; 551 SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: " 552 "%d ssthresh: %d\n", __func__, 553 transport, reason, 554 transport->cwnd, transport->ssthresh); 555 } 556 557 /* Apply Max.Burst limit to the congestion window: 558 * sctpimpguide-05 2.14.2 559 * D) When the time comes for the sender to 560 * transmit new DATA chunks, the protocol parameter Max.Burst MUST 561 * first be applied to limit how many new DATA chunks may be sent. 562 * The limit is applied by adjusting cwnd as follows: 563 * if ((flightsize+ Max.Burst * MTU) < cwnd) 564 * cwnd = flightsize + Max.Burst * MTU 565 */ 566 567 void sctp_transport_burst_limited(struct sctp_transport *t) 568 { 569 struct sctp_association *asoc = t->asoc; 570 u32 old_cwnd = t->cwnd; 571 u32 max_burst_bytes; 572 573 if (t->burst_limited) 574 return; 575 576 max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu); 577 if (max_burst_bytes < old_cwnd) { 578 t->cwnd = max_burst_bytes; 579 t->burst_limited = old_cwnd; 580 } 581 } 582 583 /* Restore the old cwnd congestion window, after the burst had it's 584 * desired effect. 585 */ 586 void sctp_transport_burst_reset(struct sctp_transport *t) 587 { 588 if (t->burst_limited) { 589 t->cwnd = t->burst_limited; 590 t->burst_limited = 0; 591 } 592 } 593 594 /* What is the next timeout value for this transport? */ 595 unsigned long sctp_transport_timeout(struct sctp_transport *t) 596 { 597 unsigned long timeout; 598 timeout = t->rto + sctp_jitter(t->rto); 599 if ((t->state != SCTP_UNCONFIRMED) && 600 (t->state != SCTP_PF)) 601 timeout += t->hbinterval; 602 timeout += jiffies; 603 return timeout; 604 } 605 606 /* Reset transport variables to their initial values */ 607 void sctp_transport_reset(struct sctp_transport *t) 608 { 609 struct sctp_association *asoc = t->asoc; 610 611 /* RFC 2960 (bis), Section 5.2.4 612 * All the congestion control parameters (e.g., cwnd, ssthresh) 613 * related to this peer MUST be reset to their initial values 614 * (see Section 6.2.1) 615 */ 616 t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380)); 617 t->burst_limited = 0; 618 t->ssthresh = asoc->peer.i.a_rwnd; 619 t->rto = asoc->rto_initial; 620 t->rtt = 0; 621 t->srtt = 0; 622 t->rttvar = 0; 623 624 /* Reset these additional varibles so that we have a clean 625 * slate. 626 */ 627 t->partial_bytes_acked = 0; 628 t->flight_size = 0; 629 t->error_count = 0; 630 t->rto_pending = 0; 631 t->hb_sent = 0; 632 633 /* Initialize the state information for SFR-CACC */ 634 t->cacc.changeover_active = 0; 635 t->cacc.cycling_changeover = 0; 636 t->cacc.next_tsn_at_change = 0; 637 t->cacc.cacc_saw_newack = 0; 638 } 639 640 /* Schedule retransmission on the given transport */ 641 void sctp_transport_immediate_rtx(struct sctp_transport *t) 642 { 643 /* Stop pending T3_rtx_timer */ 644 if (timer_pending(&t->T3_rtx_timer)) { 645 (void)del_timer(&t->T3_rtx_timer); 646 sctp_transport_put(t); 647 } 648 sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX); 649 if (!timer_pending(&t->T3_rtx_timer)) { 650 if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto)) 651 sctp_transport_hold(t); 652 } 653 return; 654 } 655