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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; | |
faee47cd | 82 | peer->hb_sent = 0; |
a6465234 | 83 | peer->fast_recovery = 0; |
1da177e4 LT |
84 | |
85 | peer->last_time_heard = jiffies; | |
1da177e4 LT |
86 | peer->last_time_ecne_reduced = jiffies; |
87 | ||
3f7a87d2 FF |
88 | peer->init_sent_count = 0; |
89 | ||
52ccb8e9 FF |
90 | peer->param_flags = SPP_HB_DISABLE | |
91 | SPP_PMTUD_ENABLE | | |
92 | SPP_SACKDELAY_ENABLE; | |
93 | peer->hbinterval = 0; | |
1da177e4 LT |
94 | |
95 | /* Initialize the default path max_retrans. */ | |
52ccb8e9 | 96 | peer->pathmaxrxt = sctp_max_retrans_path; |
1da177e4 LT |
97 | peer->error_count = 0; |
98 | ||
99 | INIT_LIST_HEAD(&peer->transmitted); | |
100 | INIT_LIST_HEAD(&peer->send_ready); | |
101 | INIT_LIST_HEAD(&peer->transports); | |
102 | ||
6d0ccbac FW |
103 | peer->T3_rtx_timer.expires = 0; |
104 | peer->hb_timer.expires = 0; | |
105 | ||
b24b8a24 PE |
106 | setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event, |
107 | (unsigned long)peer); | |
108 | setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event, | |
109 | (unsigned long)peer); | |
1da177e4 | 110 | |
ad8fec17 SS |
111 | /* Initialize the 64-bit random nonce sent with heartbeat. */ |
112 | get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce)); | |
113 | ||
1da177e4 LT |
114 | atomic_set(&peer->refcnt, 1); |
115 | peer->dead = 0; | |
116 | ||
117 | peer->malloced = 0; | |
118 | ||
119 | /* Initialize the state information for SFR-CACC */ | |
120 | peer->cacc.changeover_active = 0; | |
121 | peer->cacc.cycling_changeover = 0; | |
122 | peer->cacc.next_tsn_at_change = 0; | |
123 | peer->cacc.cacc_saw_newack = 0; | |
124 | ||
125 | return peer; | |
126 | } | |
127 | ||
128 | /* Allocate and initialize a new transport. */ | |
3182cd84 | 129 | struct sctp_transport *sctp_transport_new(const union sctp_addr *addr, |
dd0fc66f | 130 | gfp_t gfp) |
1da177e4 | 131 | { |
d808ad9a | 132 | struct sctp_transport *transport; |
1da177e4 | 133 | |
d808ad9a | 134 | transport = t_new(struct sctp_transport, gfp); |
1da177e4 LT |
135 | if (!transport) |
136 | goto fail; | |
137 | ||
138 | if (!sctp_transport_init(transport, addr, gfp)) | |
139 | goto fail_init; | |
140 | ||
141 | transport->malloced = 1; | |
142 | SCTP_DBG_OBJCNT_INC(transport); | |
143 | ||
144 | return transport; | |
145 | ||
146 | fail_init: | |
147 | kfree(transport); | |
148 | ||
149 | fail: | |
150 | return NULL; | |
151 | } | |
152 | ||
153 | /* This transport is no longer needed. Free up if possible, or | |
154 | * delay until it last reference count. | |
155 | */ | |
156 | void sctp_transport_free(struct sctp_transport *transport) | |
157 | { | |
158 | transport->dead = 1; | |
159 | ||
160 | /* Try to delete the heartbeat timer. */ | |
161 | if (del_timer(&transport->hb_timer)) | |
162 | sctp_transport_put(transport); | |
163 | ||
164 | /* Delete the T3_rtx timer if it's active. | |
165 | * There is no point in not doing this now and letting | |
166 | * structure hang around in memory since we know | |
167 | * the tranport is going away. | |
168 | */ | |
169 | if (timer_pending(&transport->T3_rtx_timer) && | |
170 | del_timer(&transport->T3_rtx_timer)) | |
171 | sctp_transport_put(transport); | |
172 | ||
173 | ||
174 | sctp_transport_put(transport); | |
175 | } | |
176 | ||
177 | /* Destroy the transport data structure. | |
178 | * Assumes there are no more users of this structure. | |
179 | */ | |
180 | static void sctp_transport_destroy(struct sctp_transport *transport) | |
181 | { | |
182 | SCTP_ASSERT(transport->dead, "Transport is not dead", return); | |
183 | ||
184 | if (transport->asoc) | |
185 | sctp_association_put(transport->asoc); | |
186 | ||
d808ad9a | 187 | sctp_packet_free(&transport->packet); |
1da177e4 LT |
188 | |
189 | dst_release(transport->dst); | |
190 | kfree(transport); | |
191 | SCTP_DBG_OBJCNT_DEC(transport); | |
192 | } | |
193 | ||
194 | /* Start T3_rtx timer if it is not already running and update the heartbeat | |
195 | * timer. This routine is called every time a DATA chunk is sent. | |
196 | */ | |
62aeaff5 | 197 | void sctp_transport_reset_timers(struct sctp_transport *transport, int force) |
1da177e4 LT |
198 | { |
199 | /* RFC 2960 6.3.2 Retransmission Timer Rules | |
200 | * | |
201 | * R1) Every time a DATA chunk is sent to any address(including a | |
202 | * retransmission), if the T3-rtx timer of that address is not running | |
203 | * start it running so that it will expire after the RTO of that | |
204 | * address. | |
205 | */ | |
206 | ||
62aeaff5 | 207 | if (force || !timer_pending(&transport->T3_rtx_timer)) |
1da177e4 LT |
208 | if (!mod_timer(&transport->T3_rtx_timer, |
209 | jiffies + transport->rto)) | |
210 | sctp_transport_hold(transport); | |
211 | ||
212 | /* When a data chunk is sent, reset the heartbeat interval. */ | |
213 | if (!mod_timer(&transport->hb_timer, | |
214 | sctp_transport_timeout(transport))) | |
215 | sctp_transport_hold(transport); | |
216 | } | |
217 | ||
218 | /* This transport has been assigned to an association. | |
219 | * Initialize fields from the association or from the sock itself. | |
220 | * Register the reference count in the association. | |
221 | */ | |
222 | void sctp_transport_set_owner(struct sctp_transport *transport, | |
223 | struct sctp_association *asoc) | |
224 | { | |
225 | transport->asoc = asoc; | |
226 | sctp_association_hold(asoc); | |
227 | } | |
228 | ||
229 | /* Initialize the pmtu of a transport. */ | |
230 | void sctp_transport_pmtu(struct sctp_transport *transport) | |
231 | { | |
232 | struct dst_entry *dst; | |
233 | ||
234 | dst = transport->af_specific->get_dst(NULL, &transport->ipaddr, NULL); | |
235 | ||
236 | if (dst) { | |
52ccb8e9 | 237 | transport->pathmtu = dst_mtu(dst); |
1da177e4 LT |
238 | dst_release(dst); |
239 | } else | |
52ccb8e9 | 240 | transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; |
1da177e4 LT |
241 | } |
242 | ||
c910b47e VY |
243 | /* this is a complete rip-off from __sk_dst_check |
244 | * the cookie is always 0 since this is how it's used in the | |
245 | * pmtu code | |
246 | */ | |
247 | static struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t) | |
248 | { | |
249 | struct dst_entry *dst = t->dst; | |
250 | ||
251 | if (dst && dst->obsolete && dst->ops->check(dst, 0) == NULL) { | |
252 | dst_release(t->dst); | |
253 | t->dst = NULL; | |
254 | return NULL; | |
255 | } | |
256 | ||
257 | return dst; | |
258 | } | |
259 | ||
260 | void sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu) | |
261 | { | |
262 | struct dst_entry *dst; | |
263 | ||
264 | if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { | |
265 | printk(KERN_WARNING "%s: Reported pmtu %d too low, " | |
266 | "using default minimum of %d\n", | |
0dc47877 | 267 | __func__, pmtu, |
c910b47e VY |
268 | SCTP_DEFAULT_MINSEGMENT); |
269 | /* Use default minimum segment size and disable | |
270 | * pmtu discovery on this transport. | |
271 | */ | |
272 | t->pathmtu = SCTP_DEFAULT_MINSEGMENT; | |
c910b47e VY |
273 | } else { |
274 | t->pathmtu = pmtu; | |
275 | } | |
276 | ||
277 | dst = sctp_transport_dst_check(t); | |
278 | if (dst) | |
279 | dst->ops->update_pmtu(dst, pmtu); | |
280 | } | |
281 | ||
1da177e4 LT |
282 | /* Caches the dst entry and source address for a transport's destination |
283 | * address. | |
284 | */ | |
285 | void sctp_transport_route(struct sctp_transport *transport, | |
286 | union sctp_addr *saddr, struct sctp_sock *opt) | |
287 | { | |
288 | struct sctp_association *asoc = transport->asoc; | |
289 | struct sctp_af *af = transport->af_specific; | |
290 | union sctp_addr *daddr = &transport->ipaddr; | |
291 | struct dst_entry *dst; | |
292 | ||
293 | dst = af->get_dst(asoc, daddr, saddr); | |
294 | ||
295 | if (saddr) | |
296 | memcpy(&transport->saddr, saddr, sizeof(union sctp_addr)); | |
297 | else | |
e5117101 | 298 | af->get_saddr(opt, asoc, dst, daddr, &transport->saddr); |
1da177e4 LT |
299 | |
300 | transport->dst = dst; | |
52ccb8e9 FF |
301 | if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) { |
302 | return; | |
303 | } | |
1da177e4 | 304 | if (dst) { |
52ccb8e9 | 305 | transport->pathmtu = dst_mtu(dst); |
1da177e4 LT |
306 | |
307 | /* Initialize sk->sk_rcv_saddr, if the transport is the | |
308 | * association's active path for getsockname(). | |
d808ad9a | 309 | */ |
a78102e7 VY |
310 | if (asoc && (!asoc->peer.primary_path || |
311 | (transport == asoc->peer.active_path))) | |
bf031fff NH |
312 | opt->pf->af->to_sk_saddr(&transport->saddr, |
313 | asoc->base.sk); | |
1da177e4 | 314 | } else |
52ccb8e9 | 315 | transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; |
1da177e4 LT |
316 | } |
317 | ||
318 | /* Hold a reference to a transport. */ | |
319 | void sctp_transport_hold(struct sctp_transport *transport) | |
320 | { | |
321 | atomic_inc(&transport->refcnt); | |
322 | } | |
323 | ||
324 | /* Release a reference to a transport and clean up | |
325 | * if there are no more references. | |
326 | */ | |
327 | void sctp_transport_put(struct sctp_transport *transport) | |
328 | { | |
329 | if (atomic_dec_and_test(&transport->refcnt)) | |
330 | sctp_transport_destroy(transport); | |
331 | } | |
332 | ||
333 | /* Update transport's RTO based on the newly calculated RTT. */ | |
334 | void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) | |
335 | { | |
336 | /* Check for valid transport. */ | |
337 | SCTP_ASSERT(tp, "NULL transport", return); | |
338 | ||
339 | /* We should not be doing any RTO updates unless rto_pending is set. */ | |
340 | SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return); | |
341 | ||
342 | if (tp->rttvar || tp->srtt) { | |
343 | /* 6.3.1 C3) When a new RTT measurement R' is made, set | |
344 | * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'| | |
345 | * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R' | |
346 | */ | |
347 | ||
348 | /* Note: The above algorithm has been rewritten to | |
349 | * express rto_beta and rto_alpha as inverse powers | |
350 | * of two. | |
351 | * For example, assuming the default value of RTO.Alpha of | |
352 | * 1/8, rto_alpha would be expressed as 3. | |
353 | */ | |
354 | tp->rttvar = tp->rttvar - (tp->rttvar >> sctp_rto_beta) | |
355 | + ((abs(tp->srtt - rtt)) >> sctp_rto_beta); | |
356 | tp->srtt = tp->srtt - (tp->srtt >> sctp_rto_alpha) | |
357 | + (rtt >> sctp_rto_alpha); | |
358 | } else { | |
359 | /* 6.3.1 C2) When the first RTT measurement R is made, set | |
360 | * SRTT <- R, RTTVAR <- R/2. | |
361 | */ | |
362 | tp->srtt = rtt; | |
363 | tp->rttvar = rtt >> 1; | |
364 | } | |
365 | ||
366 | /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then | |
367 | * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY. | |
368 | */ | |
369 | if (tp->rttvar == 0) | |
370 | tp->rttvar = SCTP_CLOCK_GRANULARITY; | |
371 | ||
372 | /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */ | |
373 | tp->rto = tp->srtt + (tp->rttvar << 2); | |
374 | ||
375 | /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min | |
376 | * seconds then it is rounded up to RTO.Min seconds. | |
377 | */ | |
378 | if (tp->rto < tp->asoc->rto_min) | |
379 | tp->rto = tp->asoc->rto_min; | |
380 | ||
381 | /* 6.3.1 C7) A maximum value may be placed on RTO provided it is | |
382 | * at least RTO.max seconds. | |
383 | */ | |
384 | if (tp->rto > tp->asoc->rto_max) | |
385 | tp->rto = tp->asoc->rto_max; | |
386 | ||
387 | tp->rtt = rtt; | |
b6157d8e | 388 | tp->last_rto = tp->rto; |
1da177e4 LT |
389 | |
390 | /* Reset rto_pending so that a new RTT measurement is started when a | |
391 | * new data chunk is sent. | |
392 | */ | |
393 | tp->rto_pending = 0; | |
394 | ||
395 | SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d " | |
0dc47877 | 396 | "rttvar: %d, rto: %ld\n", __func__, |
1da177e4 LT |
397 | tp, rtt, tp->srtt, tp->rttvar, tp->rto); |
398 | } | |
399 | ||
400 | /* This routine updates the transport's cwnd and partial_bytes_acked | |
401 | * parameters based on the bytes acked in the received SACK. | |
402 | */ | |
403 | void sctp_transport_raise_cwnd(struct sctp_transport *transport, | |
404 | __u32 sack_ctsn, __u32 bytes_acked) | |
405 | { | |
406 | __u32 cwnd, ssthresh, flight_size, pba, pmtu; | |
407 | ||
408 | cwnd = transport->cwnd; | |
409 | flight_size = transport->flight_size; | |
410 | ||
a6465234 VY |
411 | /* See if we need to exit Fast Recovery first */ |
412 | if (transport->fast_recovery && | |
413 | TSN_lte(transport->fast_recovery_exit, sack_ctsn)) | |
414 | transport->fast_recovery = 0; | |
415 | ||
1da177e4 | 416 | /* The appropriate cwnd increase algorithm is performed if, and only |
a6465234 | 417 | * if the cumulative TSN whould advanced and the congestion window is |
1da177e4 LT |
418 | * being fully utilized. |
419 | */ | |
a6465234 | 420 | if (TSN_lte(sack_ctsn, transport->asoc->ctsn_ack_point) || |
1da177e4 LT |
421 | (flight_size < cwnd)) |
422 | return; | |
423 | ||
424 | ssthresh = transport->ssthresh; | |
425 | pba = transport->partial_bytes_acked; | |
52ccb8e9 | 426 | pmtu = transport->asoc->pathmtu; |
1da177e4 LT |
427 | |
428 | if (cwnd <= ssthresh) { | |
a6465234 VY |
429 | /* RFC 4960 7.2.1 |
430 | * o When cwnd is less than or equal to ssthresh, an SCTP | |
431 | * endpoint MUST use the slow-start algorithm to increase | |
432 | * cwnd only if the current congestion window is being fully | |
433 | * utilized, an incoming SACK advances the Cumulative TSN | |
434 | * Ack Point, and the data sender is not in Fast Recovery. | |
435 | * Only when these three conditions are met can the cwnd be | |
436 | * increased; otherwise, the cwnd MUST not be increased. | |
437 | * If these conditions are met, then cwnd MUST be increased | |
438 | * by, at most, the lesser of 1) the total size of the | |
439 | * previously outstanding DATA chunk(s) acknowledged, and | |
440 | * 2) the destination's path MTU. This upper bound protects | |
441 | * against the ACK-Splitting attack outlined in [SAVAGE99]. | |
1da177e4 | 442 | */ |
a6465234 VY |
443 | if (transport->fast_recovery) |
444 | return; | |
445 | ||
1da177e4 LT |
446 | if (bytes_acked > pmtu) |
447 | cwnd += pmtu; | |
448 | else | |
449 | cwnd += bytes_acked; | |
450 | SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, " | |
451 | "bytes_acked: %d, cwnd: %d, ssthresh: %d, " | |
452 | "flight_size: %d, pba: %d\n", | |
0dc47877 | 453 | __func__, |
1da177e4 LT |
454 | transport, bytes_acked, cwnd, |
455 | ssthresh, flight_size, pba); | |
456 | } else { | |
457 | /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh, | |
458 | * upon each SACK arrival that advances the Cumulative TSN Ack | |
459 | * Point, increase partial_bytes_acked by the total number of | |
460 | * bytes of all new chunks acknowledged in that SACK including | |
461 | * chunks acknowledged by the new Cumulative TSN Ack and by | |
462 | * Gap Ack Blocks. | |
463 | * | |
464 | * When partial_bytes_acked is equal to or greater than cwnd | |
465 | * and before the arrival of the SACK the sender had cwnd or | |
466 | * more bytes of data outstanding (i.e., before arrival of the | |
467 | * SACK, flightsize was greater than or equal to cwnd), | |
468 | * increase cwnd by MTU, and reset partial_bytes_acked to | |
469 | * (partial_bytes_acked - cwnd). | |
470 | */ | |
471 | pba += bytes_acked; | |
472 | if (pba >= cwnd) { | |
473 | cwnd += pmtu; | |
474 | pba = ((cwnd < pba) ? (pba - cwnd) : 0); | |
475 | } | |
476 | SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: " | |
477 | "transport: %p, bytes_acked: %d, cwnd: %d, " | |
478 | "ssthresh: %d, flight_size: %d, pba: %d\n", | |
0dc47877 | 479 | __func__, |
1da177e4 LT |
480 | transport, bytes_acked, cwnd, |
481 | ssthresh, flight_size, pba); | |
482 | } | |
483 | ||
484 | transport->cwnd = cwnd; | |
485 | transport->partial_bytes_acked = pba; | |
486 | } | |
487 | ||
488 | /* This routine is used to lower the transport's cwnd when congestion is | |
489 | * detected. | |
490 | */ | |
491 | void sctp_transport_lower_cwnd(struct sctp_transport *transport, | |
492 | sctp_lower_cwnd_t reason) | |
493 | { | |
494 | switch (reason) { | |
495 | case SCTP_LOWER_CWND_T3_RTX: | |
496 | /* RFC 2960 Section 7.2.3, sctpimpguide | |
497 | * When the T3-rtx timer expires on an address, SCTP should | |
498 | * perform slow start by: | |
499 | * ssthresh = max(cwnd/2, 4*MTU) | |
500 | * cwnd = 1*MTU | |
501 | * partial_bytes_acked = 0 | |
502 | */ | |
503 | transport->ssthresh = max(transport->cwnd/2, | |
52ccb8e9 FF |
504 | 4*transport->asoc->pathmtu); |
505 | transport->cwnd = transport->asoc->pathmtu; | |
33ce8281 VY |
506 | |
507 | /* T3-rtx also clears fast recovery on the transport */ | |
508 | transport->fast_recovery = 0; | |
1da177e4 LT |
509 | break; |
510 | ||
511 | case SCTP_LOWER_CWND_FAST_RTX: | |
512 | /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the | |
513 | * destination address(es) to which the missing DATA chunks | |
514 | * were last sent, according to the formula described in | |
515 | * Section 7.2.3. | |
d808ad9a YH |
516 | * |
517 | * RFC 2960 7.2.3, sctpimpguide Upon detection of packet | |
1da177e4 LT |
518 | * losses from SACK (see Section 7.2.4), An endpoint |
519 | * should do the following: | |
520 | * ssthresh = max(cwnd/2, 4*MTU) | |
521 | * cwnd = ssthresh | |
522 | * partial_bytes_acked = 0 | |
523 | */ | |
a6465234 VY |
524 | if (transport->fast_recovery) |
525 | return; | |
526 | ||
527 | /* Mark Fast recovery */ | |
528 | transport->fast_recovery = 1; | |
529 | transport->fast_recovery_exit = transport->asoc->next_tsn - 1; | |
530 | ||
1da177e4 | 531 | transport->ssthresh = max(transport->cwnd/2, |
52ccb8e9 | 532 | 4*transport->asoc->pathmtu); |
1da177e4 LT |
533 | transport->cwnd = transport->ssthresh; |
534 | break; | |
535 | ||
536 | case SCTP_LOWER_CWND_ECNE: | |
537 | /* RFC 2481 Section 6.1.2. | |
538 | * If the sender receives an ECN-Echo ACK packet | |
539 | * then the sender knows that congestion was encountered in the | |
540 | * network on the path from the sender to the receiver. The | |
541 | * indication of congestion should be treated just as a | |
542 | * congestion loss in non-ECN Capable TCP. That is, the TCP | |
543 | * source halves the congestion window "cwnd" and reduces the | |
544 | * slow start threshold "ssthresh". | |
545 | * A critical condition is that TCP does not react to | |
546 | * congestion indications more than once every window of | |
547 | * data (or more loosely more than once every round-trip time). | |
548 | */ | |
f61f6f82 WY |
549 | if (time_after(jiffies, transport->last_time_ecne_reduced + |
550 | transport->rtt)) { | |
1da177e4 | 551 | transport->ssthresh = max(transport->cwnd/2, |
d808ad9a | 552 | 4*transport->asoc->pathmtu); |
1da177e4 LT |
553 | transport->cwnd = transport->ssthresh; |
554 | transport->last_time_ecne_reduced = jiffies; | |
555 | } | |
556 | break; | |
557 | ||
558 | case SCTP_LOWER_CWND_INACTIVE: | |
559 | /* RFC 2960 Section 7.2.1, sctpimpguide | |
560 | * When the endpoint does not transmit data on a given | |
561 | * transport address, the cwnd of the transport address | |
562 | * should be adjusted to max(cwnd/2, 4*MTU) per RTO. | |
563 | * NOTE: Although the draft recommends that this check needs | |
564 | * to be done every RTO interval, we do it every hearbeat | |
565 | * interval. | |
566 | */ | |
245cba7e VY |
567 | transport->cwnd = max(transport->cwnd/2, |
568 | 4*transport->asoc->pathmtu); | |
1da177e4 | 569 | break; |
3ff50b79 | 570 | } |
1da177e4 LT |
571 | |
572 | transport->partial_bytes_acked = 0; | |
573 | SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: " | |
0dc47877 | 574 | "%d ssthresh: %d\n", __func__, |
1da177e4 LT |
575 | transport, reason, |
576 | transport->cwnd, transport->ssthresh); | |
577 | } | |
578 | ||
579 | /* What is the next timeout value for this transport? */ | |
580 | unsigned long sctp_transport_timeout(struct sctp_transport *t) | |
581 | { | |
582 | unsigned long timeout; | |
ad8fec17 SS |
583 | timeout = t->rto + sctp_jitter(t->rto); |
584 | if (t->state != SCTP_UNCONFIRMED) | |
585 | timeout += t->hbinterval; | |
1da177e4 LT |
586 | timeout += jiffies; |
587 | return timeout; | |
588 | } | |
749bf921 VY |
589 | |
590 | /* Reset transport variables to their initial values */ | |
591 | void sctp_transport_reset(struct sctp_transport *t) | |
592 | { | |
593 | struct sctp_association *asoc = t->asoc; | |
594 | ||
595 | /* RFC 2960 (bis), Section 5.2.4 | |
596 | * All the congestion control parameters (e.g., cwnd, ssthresh) | |
597 | * related to this peer MUST be reset to their initial values | |
598 | * (see Section 6.2.1) | |
599 | */ | |
600 | t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380)); | |
289f4249 | 601 | t->ssthresh = asoc->peer.i.a_rwnd; |
b6157d8e | 602 | t->last_rto = t->rto = asoc->rto_initial; |
749bf921 VY |
603 | t->rtt = 0; |
604 | t->srtt = 0; | |
605 | t->rttvar = 0; | |
606 | ||
607 | /* Reset these additional varibles so that we have a clean | |
608 | * slate. | |
609 | */ | |
610 | t->partial_bytes_acked = 0; | |
611 | t->flight_size = 0; | |
612 | t->error_count = 0; | |
613 | t->rto_pending = 0; | |
faee47cd | 614 | t->hb_sent = 0; |
a6465234 | 615 | t->fast_recovery = 0; |
749bf921 VY |
616 | |
617 | /* Initialize the state information for SFR-CACC */ | |
618 | t->cacc.changeover_active = 0; | |
619 | t->cacc.cycling_changeover = 0; | |
620 | t->cacc.next_tsn_at_change = 0; | |
621 | t->cacc.cacc_saw_newack = 0; | |
622 | } |