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60c778b2 | 1 | /* SCTP kernel implementation |
1da177e4 LT |
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 | * | |
60c778b2 | 8 | * This file is part of the SCTP kernel implementation |
1da177e4 LT |
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 | * | |
60c778b2 | 14 | * This SCTP implementation is free software; |
1da177e4 LT |
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 | * | |
60c778b2 | 20 | * This SCTP implementation is distributed in the hope that it |
1da177e4 LT |
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 | #include <linux/types.h> | |
ad8fec17 | 52 | #include <linux/random.h> |
1da177e4 LT |
53 | #include <net/sctp/sctp.h> |
54 | #include <net/sctp/sm.h> | |
55 | ||
56 | /* 1st Level Abstractions. */ | |
57 | ||
58 | /* Initialize a new transport from provided memory. */ | |
59 | static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer, | |
60 | const union sctp_addr *addr, | |
dd0fc66f | 61 | gfp_t gfp) |
1da177e4 LT |
62 | { |
63 | /* Copy in the address. */ | |
64 | peer->ipaddr = *addr; | |
65 | peer->af_specific = sctp_get_af_specific(addr->sa.sa_family); | |
66 | peer->asoc = NULL; | |
67 | ||
68 | peer->dst = NULL; | |
69 | memset(&peer->saddr, 0, sizeof(union sctp_addr)); | |
70 | ||
71 | /* From 6.3.1 RTO Calculation: | |
72 | * | |
73 | * C1) Until an RTT measurement has been made for a packet sent to the | |
74 | * given destination transport address, set RTO to the protocol | |
75 | * parameter 'RTO.Initial'. | |
76 | */ | |
b6157d8e | 77 | peer->last_rto = peer->rto = msecs_to_jiffies(sctp_rto_initial); |
1da177e4 | 78 | peer->rtt = 0; |
1da177e4 LT |
79 | peer->rttvar = 0; |
80 | peer->srtt = 0; | |
81 | peer->rto_pending = 0; | |
82 | ||
83 | peer->last_time_heard = jiffies; | |
84 | peer->last_time_used = jiffies; | |
85 | peer->last_time_ecne_reduced = jiffies; | |
86 | ||
3f7a87d2 FF |
87 | peer->init_sent_count = 0; |
88 | ||
52ccb8e9 FF |
89 | peer->param_flags = SPP_HB_DISABLE | |
90 | SPP_PMTUD_ENABLE | | |
91 | SPP_SACKDELAY_ENABLE; | |
92 | peer->hbinterval = 0; | |
1da177e4 LT |
93 | |
94 | /* Initialize the default path max_retrans. */ | |
52ccb8e9 | 95 | peer->pathmaxrxt = sctp_max_retrans_path; |
1da177e4 LT |
96 | peer->error_count = 0; |
97 | ||
98 | INIT_LIST_HEAD(&peer->transmitted); | |
99 | INIT_LIST_HEAD(&peer->send_ready); | |
100 | INIT_LIST_HEAD(&peer->transports); | |
101 | ||
b24b8a24 PE |
102 | setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event, |
103 | (unsigned long)peer); | |
104 | setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event, | |
105 | (unsigned long)peer); | |
1da177e4 | 106 | |
ad8fec17 SS |
107 | /* Initialize the 64-bit random nonce sent with heartbeat. */ |
108 | get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce)); | |
109 | ||
1da177e4 LT |
110 | atomic_set(&peer->refcnt, 1); |
111 | peer->dead = 0; | |
112 | ||
113 | peer->malloced = 0; | |
114 | ||
115 | /* Initialize the state information for SFR-CACC */ | |
116 | peer->cacc.changeover_active = 0; | |
117 | peer->cacc.cycling_changeover = 0; | |
118 | peer->cacc.next_tsn_at_change = 0; | |
119 | peer->cacc.cacc_saw_newack = 0; | |
120 | ||
121 | return peer; | |
122 | } | |
123 | ||
124 | /* Allocate and initialize a new transport. */ | |
3182cd84 | 125 | struct sctp_transport *sctp_transport_new(const union sctp_addr *addr, |
dd0fc66f | 126 | gfp_t gfp) |
1da177e4 | 127 | { |
d808ad9a | 128 | struct sctp_transport *transport; |
1da177e4 | 129 | |
d808ad9a | 130 | transport = t_new(struct sctp_transport, gfp); |
1da177e4 LT |
131 | if (!transport) |
132 | goto fail; | |
133 | ||
134 | if (!sctp_transport_init(transport, addr, gfp)) | |
135 | goto fail_init; | |
136 | ||
137 | transport->malloced = 1; | |
138 | SCTP_DBG_OBJCNT_INC(transport); | |
139 | ||
140 | return transport; | |
141 | ||
142 | fail_init: | |
143 | kfree(transport); | |
144 | ||
145 | fail: | |
146 | return NULL; | |
147 | } | |
148 | ||
149 | /* This transport is no longer needed. Free up if possible, or | |
150 | * delay until it last reference count. | |
151 | */ | |
152 | void sctp_transport_free(struct sctp_transport *transport) | |
153 | { | |
154 | transport->dead = 1; | |
155 | ||
156 | /* Try to delete the heartbeat timer. */ | |
157 | if (del_timer(&transport->hb_timer)) | |
158 | sctp_transport_put(transport); | |
159 | ||
160 | /* Delete the T3_rtx timer if it's active. | |
161 | * There is no point in not doing this now and letting | |
162 | * structure hang around in memory since we know | |
163 | * the tranport is going away. | |
164 | */ | |
165 | if (timer_pending(&transport->T3_rtx_timer) && | |
166 | del_timer(&transport->T3_rtx_timer)) | |
167 | sctp_transport_put(transport); | |
168 | ||
169 | ||
170 | sctp_transport_put(transport); | |
171 | } | |
172 | ||
173 | /* Destroy the transport data structure. | |
174 | * Assumes there are no more users of this structure. | |
175 | */ | |
176 | static void sctp_transport_destroy(struct sctp_transport *transport) | |
177 | { | |
178 | SCTP_ASSERT(transport->dead, "Transport is not dead", return); | |
179 | ||
180 | if (transport->asoc) | |
181 | sctp_association_put(transport->asoc); | |
182 | ||
d808ad9a | 183 | sctp_packet_free(&transport->packet); |
1da177e4 LT |
184 | |
185 | dst_release(transport->dst); | |
186 | kfree(transport); | |
187 | SCTP_DBG_OBJCNT_DEC(transport); | |
188 | } | |
189 | ||
190 | /* Start T3_rtx timer if it is not already running and update the heartbeat | |
191 | * timer. This routine is called every time a DATA chunk is sent. | |
192 | */ | |
193 | void sctp_transport_reset_timers(struct sctp_transport *transport) | |
194 | { | |
195 | /* RFC 2960 6.3.2 Retransmission Timer Rules | |
196 | * | |
197 | * R1) Every time a DATA chunk is sent to any address(including a | |
198 | * retransmission), if the T3-rtx timer of that address is not running | |
199 | * start it running so that it will expire after the RTO of that | |
200 | * address. | |
201 | */ | |
202 | ||
203 | if (!timer_pending(&transport->T3_rtx_timer)) | |
204 | if (!mod_timer(&transport->T3_rtx_timer, | |
205 | jiffies + transport->rto)) | |
206 | sctp_transport_hold(transport); | |
207 | ||
208 | /* When a data chunk is sent, reset the heartbeat interval. */ | |
209 | if (!mod_timer(&transport->hb_timer, | |
210 | sctp_transport_timeout(transport))) | |
211 | sctp_transport_hold(transport); | |
212 | } | |
213 | ||
214 | /* This transport has been assigned to an association. | |
215 | * Initialize fields from the association or from the sock itself. | |
216 | * Register the reference count in the association. | |
217 | */ | |
218 | void sctp_transport_set_owner(struct sctp_transport *transport, | |
219 | struct sctp_association *asoc) | |
220 | { | |
221 | transport->asoc = asoc; | |
222 | sctp_association_hold(asoc); | |
223 | } | |
224 | ||
225 | /* Initialize the pmtu of a transport. */ | |
226 | void sctp_transport_pmtu(struct sctp_transport *transport) | |
227 | { | |
228 | struct dst_entry *dst; | |
229 | ||
230 | dst = transport->af_specific->get_dst(NULL, &transport->ipaddr, NULL); | |
231 | ||
232 | if (dst) { | |
52ccb8e9 | 233 | transport->pathmtu = dst_mtu(dst); |
1da177e4 LT |
234 | dst_release(dst); |
235 | } else | |
52ccb8e9 | 236 | transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; |
1da177e4 LT |
237 | } |
238 | ||
c910b47e VY |
239 | /* this is a complete rip-off from __sk_dst_check |
240 | * the cookie is always 0 since this is how it's used in the | |
241 | * pmtu code | |
242 | */ | |
243 | static struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t) | |
244 | { | |
245 | struct dst_entry *dst = t->dst; | |
246 | ||
247 | if (dst && dst->obsolete && dst->ops->check(dst, 0) == NULL) { | |
248 | dst_release(t->dst); | |
249 | t->dst = NULL; | |
250 | return NULL; | |
251 | } | |
252 | ||
253 | return dst; | |
254 | } | |
255 | ||
256 | void sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu) | |
257 | { | |
258 | struct dst_entry *dst; | |
259 | ||
260 | if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { | |
261 | printk(KERN_WARNING "%s: Reported pmtu %d too low, " | |
262 | "using default minimum of %d\n", | |
263 | __FUNCTION__, pmtu, | |
264 | SCTP_DEFAULT_MINSEGMENT); | |
265 | /* Use default minimum segment size and disable | |
266 | * pmtu discovery on this transport. | |
267 | */ | |
268 | t->pathmtu = SCTP_DEFAULT_MINSEGMENT; | |
c910b47e VY |
269 | } else { |
270 | t->pathmtu = pmtu; | |
271 | } | |
272 | ||
273 | dst = sctp_transport_dst_check(t); | |
274 | if (dst) | |
275 | dst->ops->update_pmtu(dst, pmtu); | |
276 | } | |
277 | ||
1da177e4 LT |
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 | union sctp_addr *daddr = &transport->ipaddr; | |
287 | struct dst_entry *dst; | |
288 | ||
289 | dst = af->get_dst(asoc, daddr, saddr); | |
290 | ||
291 | if (saddr) | |
292 | memcpy(&transport->saddr, saddr, sizeof(union sctp_addr)); | |
293 | else | |
294 | af->get_saddr(asoc, dst, daddr, &transport->saddr); | |
295 | ||
296 | transport->dst = dst; | |
52ccb8e9 FF |
297 | if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) { |
298 | return; | |
299 | } | |
1da177e4 | 300 | if (dst) { |
52ccb8e9 | 301 | transport->pathmtu = dst_mtu(dst); |
1da177e4 LT |
302 | |
303 | /* Initialize sk->sk_rcv_saddr, if the transport is the | |
304 | * association's active path for getsockname(). | |
d808ad9a | 305 | */ |
1da177e4 | 306 | if (asoc && (transport == asoc->peer.active_path)) |
bf031fff NH |
307 | opt->pf->af->to_sk_saddr(&transport->saddr, |
308 | asoc->base.sk); | |
1da177e4 | 309 | } else |
52ccb8e9 | 310 | transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; |
1da177e4 LT |
311 | } |
312 | ||
313 | /* Hold a reference to a transport. */ | |
314 | void sctp_transport_hold(struct sctp_transport *transport) | |
315 | { | |
316 | atomic_inc(&transport->refcnt); | |
317 | } | |
318 | ||
319 | /* Release a reference to a transport and clean up | |
320 | * if there are no more references. | |
321 | */ | |
322 | void sctp_transport_put(struct sctp_transport *transport) | |
323 | { | |
324 | if (atomic_dec_and_test(&transport->refcnt)) | |
325 | sctp_transport_destroy(transport); | |
326 | } | |
327 | ||
328 | /* Update transport's RTO based on the newly calculated RTT. */ | |
329 | void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) | |
330 | { | |
331 | /* Check for valid transport. */ | |
332 | SCTP_ASSERT(tp, "NULL transport", return); | |
333 | ||
334 | /* We should not be doing any RTO updates unless rto_pending is set. */ | |
335 | SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return); | |
336 | ||
337 | if (tp->rttvar || tp->srtt) { | |
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 >> sctp_rto_beta) | |
350 | + ((abs(tp->srtt - rtt)) >> sctp_rto_beta); | |
351 | tp->srtt = tp->srtt - (tp->srtt >> sctp_rto_alpha) | |
352 | + (rtt >> 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 | tp->rtt = rtt; | |
b6157d8e | 383 | tp->last_rto = tp->rto; |
1da177e4 LT |
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 | SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d " | |
8116ffad | 391 | "rttvar: %d, rto: %ld\n", __FUNCTION__, |
1da177e4 LT |
392 | tp, rtt, tp->srtt, tp->rttvar, tp->rto); |
393 | } | |
394 | ||
395 | /* This routine updates the transport's cwnd and partial_bytes_acked | |
396 | * parameters based on the bytes acked in the received SACK. | |
397 | */ | |
398 | void sctp_transport_raise_cwnd(struct sctp_transport *transport, | |
399 | __u32 sack_ctsn, __u32 bytes_acked) | |
400 | { | |
401 | __u32 cwnd, ssthresh, flight_size, pba, pmtu; | |
402 | ||
403 | cwnd = transport->cwnd; | |
404 | flight_size = transport->flight_size; | |
405 | ||
406 | /* The appropriate cwnd increase algorithm is performed if, and only | |
407 | * if the cumulative TSN has advanced and the congestion window is | |
408 | * being fully utilized. | |
409 | */ | |
410 | if ((transport->asoc->ctsn_ack_point >= sack_ctsn) || | |
411 | (flight_size < cwnd)) | |
412 | return; | |
413 | ||
414 | ssthresh = transport->ssthresh; | |
415 | pba = transport->partial_bytes_acked; | |
52ccb8e9 | 416 | pmtu = transport->asoc->pathmtu; |
1da177e4 LT |
417 | |
418 | if (cwnd <= ssthresh) { | |
419 | /* RFC 2960 7.2.1, sctpimpguide-05 2.14.2 When cwnd is less | |
420 | * than or equal to ssthresh an SCTP endpoint MUST use the | |
421 | * slow start algorithm to increase cwnd only if the current | |
422 | * congestion window is being fully utilized and an incoming | |
423 | * SACK advances the Cumulative TSN Ack Point. Only when these | |
424 | * two conditions are met can the cwnd be increased otherwise | |
425 | * the cwnd MUST not be increased. If these conditions are met | |
426 | * then cwnd MUST be increased by at most the lesser of | |
427 | * 1) the total size of the previously outstanding DATA | |
428 | * chunk(s) acknowledged, and 2) the destination's path MTU. | |
429 | */ | |
430 | if (bytes_acked > pmtu) | |
431 | cwnd += pmtu; | |
432 | else | |
433 | cwnd += bytes_acked; | |
434 | SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, " | |
435 | "bytes_acked: %d, cwnd: %d, ssthresh: %d, " | |
436 | "flight_size: %d, pba: %d\n", | |
437 | __FUNCTION__, | |
438 | transport, bytes_acked, cwnd, | |
439 | ssthresh, flight_size, pba); | |
440 | } else { | |
441 | /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh, | |
442 | * upon each SACK arrival that advances the Cumulative TSN Ack | |
443 | * Point, increase partial_bytes_acked by the total number of | |
444 | * bytes of all new chunks acknowledged in that SACK including | |
445 | * chunks acknowledged by the new Cumulative TSN Ack and by | |
446 | * Gap Ack Blocks. | |
447 | * | |
448 | * When partial_bytes_acked is equal to or greater than cwnd | |
449 | * and before the arrival of the SACK the sender had cwnd or | |
450 | * more bytes of data outstanding (i.e., before arrival of the | |
451 | * SACK, flightsize was greater than or equal to cwnd), | |
452 | * increase cwnd by MTU, and reset partial_bytes_acked to | |
453 | * (partial_bytes_acked - cwnd). | |
454 | */ | |
455 | pba += bytes_acked; | |
456 | if (pba >= cwnd) { | |
457 | cwnd += pmtu; | |
458 | pba = ((cwnd < pba) ? (pba - cwnd) : 0); | |
459 | } | |
460 | SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: " | |
461 | "transport: %p, bytes_acked: %d, cwnd: %d, " | |
462 | "ssthresh: %d, flight_size: %d, pba: %d\n", | |
463 | __FUNCTION__, | |
464 | transport, bytes_acked, cwnd, | |
465 | ssthresh, flight_size, pba); | |
466 | } | |
467 | ||
468 | transport->cwnd = cwnd; | |
469 | transport->partial_bytes_acked = pba; | |
470 | } | |
471 | ||
472 | /* This routine is used to lower the transport's cwnd when congestion is | |
473 | * detected. | |
474 | */ | |
475 | void sctp_transport_lower_cwnd(struct sctp_transport *transport, | |
476 | sctp_lower_cwnd_t reason) | |
477 | { | |
478 | switch (reason) { | |
479 | case SCTP_LOWER_CWND_T3_RTX: | |
480 | /* RFC 2960 Section 7.2.3, sctpimpguide | |
481 | * When the T3-rtx timer expires on an address, SCTP should | |
482 | * perform slow start by: | |
483 | * ssthresh = max(cwnd/2, 4*MTU) | |
484 | * cwnd = 1*MTU | |
485 | * partial_bytes_acked = 0 | |
486 | */ | |
487 | transport->ssthresh = max(transport->cwnd/2, | |
52ccb8e9 FF |
488 | 4*transport->asoc->pathmtu); |
489 | transport->cwnd = transport->asoc->pathmtu; | |
1da177e4 LT |
490 | break; |
491 | ||
492 | case SCTP_LOWER_CWND_FAST_RTX: | |
493 | /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the | |
494 | * destination address(es) to which the missing DATA chunks | |
495 | * were last sent, according to the formula described in | |
496 | * Section 7.2.3. | |
d808ad9a YH |
497 | * |
498 | * RFC 2960 7.2.3, sctpimpguide Upon detection of packet | |
1da177e4 LT |
499 | * losses from SACK (see Section 7.2.4), An endpoint |
500 | * should do the following: | |
501 | * ssthresh = max(cwnd/2, 4*MTU) | |
502 | * cwnd = ssthresh | |
503 | * partial_bytes_acked = 0 | |
504 | */ | |
505 | transport->ssthresh = max(transport->cwnd/2, | |
52ccb8e9 | 506 | 4*transport->asoc->pathmtu); |
1da177e4 LT |
507 | transport->cwnd = transport->ssthresh; |
508 | break; | |
509 | ||
510 | case SCTP_LOWER_CWND_ECNE: | |
511 | /* RFC 2481 Section 6.1.2. | |
512 | * If the sender receives an ECN-Echo ACK packet | |
513 | * then the sender knows that congestion was encountered in the | |
514 | * network on the path from the sender to the receiver. The | |
515 | * indication of congestion should be treated just as a | |
516 | * congestion loss in non-ECN Capable TCP. That is, the TCP | |
517 | * source halves the congestion window "cwnd" and reduces the | |
518 | * slow start threshold "ssthresh". | |
519 | * A critical condition is that TCP does not react to | |
520 | * congestion indications more than once every window of | |
521 | * data (or more loosely more than once every round-trip time). | |
522 | */ | |
523 | if ((jiffies - transport->last_time_ecne_reduced) > | |
524 | transport->rtt) { | |
525 | transport->ssthresh = max(transport->cwnd/2, | |
d808ad9a | 526 | 4*transport->asoc->pathmtu); |
1da177e4 LT |
527 | transport->cwnd = transport->ssthresh; |
528 | transport->last_time_ecne_reduced = jiffies; | |
529 | } | |
530 | break; | |
531 | ||
532 | case SCTP_LOWER_CWND_INACTIVE: | |
533 | /* RFC 2960 Section 7.2.1, sctpimpguide | |
534 | * When the endpoint does not transmit data on a given | |
535 | * transport address, the cwnd of the transport address | |
536 | * should be adjusted to max(cwnd/2, 4*MTU) per RTO. | |
537 | * NOTE: Although the draft recommends that this check needs | |
538 | * to be done every RTO interval, we do it every hearbeat | |
539 | * interval. | |
540 | */ | |
541 | if ((jiffies - transport->last_time_used) > transport->rto) | |
542 | transport->cwnd = max(transport->cwnd/2, | |
52ccb8e9 | 543 | 4*transport->asoc->pathmtu); |
1da177e4 | 544 | break; |
3ff50b79 | 545 | } |
1da177e4 LT |
546 | |
547 | transport->partial_bytes_acked = 0; | |
548 | SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: " | |
549 | "%d ssthresh: %d\n", __FUNCTION__, | |
550 | transport, reason, | |
551 | transport->cwnd, transport->ssthresh); | |
552 | } | |
553 | ||
554 | /* What is the next timeout value for this transport? */ | |
555 | unsigned long sctp_transport_timeout(struct sctp_transport *t) | |
556 | { | |
557 | unsigned long timeout; | |
ad8fec17 SS |
558 | timeout = t->rto + sctp_jitter(t->rto); |
559 | if (t->state != SCTP_UNCONFIRMED) | |
560 | timeout += t->hbinterval; | |
1da177e4 LT |
561 | timeout += jiffies; |
562 | return timeout; | |
563 | } | |
749bf921 VY |
564 | |
565 | /* Reset transport variables to their initial values */ | |
566 | void sctp_transport_reset(struct sctp_transport *t) | |
567 | { | |
568 | struct sctp_association *asoc = t->asoc; | |
569 | ||
570 | /* RFC 2960 (bis), Section 5.2.4 | |
571 | * All the congestion control parameters (e.g., cwnd, ssthresh) | |
572 | * related to this peer MUST be reset to their initial values | |
573 | * (see Section 6.2.1) | |
574 | */ | |
575 | t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380)); | |
289f4249 | 576 | t->ssthresh = asoc->peer.i.a_rwnd; |
b6157d8e | 577 | t->last_rto = t->rto = asoc->rto_initial; |
749bf921 VY |
578 | t->rtt = 0; |
579 | t->srtt = 0; | |
580 | t->rttvar = 0; | |
581 | ||
582 | /* Reset these additional varibles so that we have a clean | |
583 | * slate. | |
584 | */ | |
585 | t->partial_bytes_acked = 0; | |
586 | t->flight_size = 0; | |
587 | t->error_count = 0; | |
588 | t->rto_pending = 0; | |
589 | ||
590 | /* Initialize the state information for SFR-CACC */ | |
591 | t->cacc.changeover_active = 0; | |
592 | t->cacc.cycling_changeover = 0; | |
593 | t->cacc.next_tsn_at_change = 0; | |
594 | t->cacc.cacc_saw_newack = 0; | |
595 | } |