sctp: Flush the queue only once during fast retransmit.
[linux-3.10.git] / net / sctp / outqueue.c
1 /* SCTP kernel implementation
2  * (C) Copyright IBM Corp. 2001, 2004
3  * Copyright (c) 1999-2000 Cisco, Inc.
4  * Copyright (c) 1999-2001 Motorola, Inc.
5  * Copyright (c) 2001-2003 Intel Corp.
6  *
7  * This file is part of the SCTP kernel implementation
8  *
9  * These functions implement the sctp_outq class.   The outqueue handles
10  * bundling and queueing of outgoing SCTP chunks.
11  *
12  * This SCTP implementation is free software;
13  * you can redistribute it and/or modify it under the terms of
14  * the GNU General Public License as published by
15  * the Free Software Foundation; either version 2, or (at your option)
16  * any later version.
17  *
18  * This SCTP implementation is distributed in the hope that it
19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
20  *                 ************************
21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22  * See the GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with GNU CC; see the file COPYING.  If not, write to
26  * the Free Software Foundation, 59 Temple Place - Suite 330,
27  * Boston, MA 02111-1307, USA.
28  *
29  * Please send any bug reports or fixes you make to the
30  * email address(es):
31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
32  *
33  * Or submit a bug report through the following website:
34  *    http://www.sf.net/projects/lksctp
35  *
36  * Written or modified by:
37  *    La Monte H.P. Yarroll <piggy@acm.org>
38  *    Karl Knutson          <karl@athena.chicago.il.us>
39  *    Perry Melange         <pmelange@null.cc.uic.edu>
40  *    Xingang Guo           <xingang.guo@intel.com>
41  *    Hui Huang             <hui.huang@nokia.com>
42  *    Sridhar Samudrala     <sri@us.ibm.com>
43  *    Jon Grimm             <jgrimm@us.ibm.com>
44  *
45  * Any bugs reported given to us we will try to fix... any fixes shared will
46  * be incorporated into the next SCTP release.
47  */
48
49 #include <linux/types.h>
50 #include <linux/list.h>   /* For struct list_head */
51 #include <linux/socket.h>
52 #include <linux/ip.h>
53 #include <net/sock.h>     /* For skb_set_owner_w */
54
55 #include <net/sctp/sctp.h>
56 #include <net/sctp/sm.h>
57
58 /* Declare internal functions here.  */
59 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
60 static void sctp_check_transmitted(struct sctp_outq *q,
61                                    struct list_head *transmitted_queue,
62                                    struct sctp_transport *transport,
63                                    struct sctp_sackhdr *sack,
64                                    __u32 highest_new_tsn);
65
66 static void sctp_mark_missing(struct sctp_outq *q,
67                               struct list_head *transmitted_queue,
68                               struct sctp_transport *transport,
69                               __u32 highest_new_tsn,
70                               int count_of_newacks);
71
72 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
73
74 /* Add data to the front of the queue. */
75 static inline void sctp_outq_head_data(struct sctp_outq *q,
76                                         struct sctp_chunk *ch)
77 {
78         list_add(&ch->list, &q->out_chunk_list);
79         q->out_qlen += ch->skb->len;
80         return;
81 }
82
83 /* Take data from the front of the queue. */
84 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
85 {
86         struct sctp_chunk *ch = NULL;
87
88         if (!list_empty(&q->out_chunk_list)) {
89                 struct list_head *entry = q->out_chunk_list.next;
90
91                 ch = list_entry(entry, struct sctp_chunk, list);
92                 list_del_init(entry);
93                 q->out_qlen -= ch->skb->len;
94         }
95         return ch;
96 }
97 /* Add data chunk to the end of the queue. */
98 static inline void sctp_outq_tail_data(struct sctp_outq *q,
99                                        struct sctp_chunk *ch)
100 {
101         list_add_tail(&ch->list, &q->out_chunk_list);
102         q->out_qlen += ch->skb->len;
103         return;
104 }
105
106 /*
107  * SFR-CACC algorithm:
108  * D) If count_of_newacks is greater than or equal to 2
109  * and t was not sent to the current primary then the
110  * sender MUST NOT increment missing report count for t.
111  */
112 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
113                                        struct sctp_transport *transport,
114                                        int count_of_newacks)
115 {
116         if (count_of_newacks >=2 && transport != primary)
117                 return 1;
118         return 0;
119 }
120
121 /*
122  * SFR-CACC algorithm:
123  * F) If count_of_newacks is less than 2, let d be the
124  * destination to which t was sent. If cacc_saw_newack
125  * is 0 for destination d, then the sender MUST NOT
126  * increment missing report count for t.
127  */
128 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
129                                        int count_of_newacks)
130 {
131         if (count_of_newacks < 2 && !transport->cacc.cacc_saw_newack)
132                 return 1;
133         return 0;
134 }
135
136 /*
137  * SFR-CACC algorithm:
138  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
139  * execute steps C, D, F.
140  *
141  * C has been implemented in sctp_outq_sack
142  */
143 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
144                                      struct sctp_transport *transport,
145                                      int count_of_newacks)
146 {
147         if (!primary->cacc.cycling_changeover) {
148                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
149                         return 1;
150                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
151                         return 1;
152                 return 0;
153         }
154         return 0;
155 }
156
157 /*
158  * SFR-CACC algorithm:
159  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
160  * than next_tsn_at_change of the current primary, then
161  * the sender MUST NOT increment missing report count
162  * for t.
163  */
164 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
165 {
166         if (primary->cacc.cycling_changeover &&
167             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
168                 return 1;
169         return 0;
170 }
171
172 /*
173  * SFR-CACC algorithm:
174  * 3) If the missing report count for TSN t is to be
175  * incremented according to [RFC2960] and
176  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
177  * then the sender MUST futher execute steps 3.1 and
178  * 3.2 to determine if the missing report count for
179  * TSN t SHOULD NOT be incremented.
180  *
181  * 3.3) If 3.1 and 3.2 do not dictate that the missing
182  * report count for t should not be incremented, then
183  * the sender SOULD increment missing report count for
184  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
185  */
186 static inline int sctp_cacc_skip(struct sctp_transport *primary,
187                                  struct sctp_transport *transport,
188                                  int count_of_newacks,
189                                  __u32 tsn)
190 {
191         if (primary->cacc.changeover_active &&
192             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks)
193              || sctp_cacc_skip_3_2(primary, tsn)))
194                 return 1;
195         return 0;
196 }
197
198 /* Initialize an existing sctp_outq.  This does the boring stuff.
199  * You still need to define handlers if you really want to DO
200  * something with this structure...
201  */
202 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
203 {
204         q->asoc = asoc;
205         INIT_LIST_HEAD(&q->out_chunk_list);
206         INIT_LIST_HEAD(&q->control_chunk_list);
207         INIT_LIST_HEAD(&q->retransmit);
208         INIT_LIST_HEAD(&q->sacked);
209         INIT_LIST_HEAD(&q->abandoned);
210
211         q->fast_rtx = 0;
212         q->outstanding_bytes = 0;
213         q->empty = 1;
214         q->cork  = 0;
215
216         q->malloced = 0;
217         q->out_qlen = 0;
218 }
219
220 /* Free the outqueue structure and any related pending chunks.
221  */
222 void sctp_outq_teardown(struct sctp_outq *q)
223 {
224         struct sctp_transport *transport;
225         struct list_head *lchunk, *temp;
226         struct sctp_chunk *chunk, *tmp;
227
228         /* Throw away unacknowledged chunks. */
229         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
230                         transports) {
231                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
232                         chunk = list_entry(lchunk, struct sctp_chunk,
233                                            transmitted_list);
234                         /* Mark as part of a failed message. */
235                         sctp_chunk_fail(chunk, q->error);
236                         sctp_chunk_free(chunk);
237                 }
238         }
239
240         /* Throw away chunks that have been gap ACKed.  */
241         list_for_each_safe(lchunk, temp, &q->sacked) {
242                 list_del_init(lchunk);
243                 chunk = list_entry(lchunk, struct sctp_chunk,
244                                    transmitted_list);
245                 sctp_chunk_fail(chunk, q->error);
246                 sctp_chunk_free(chunk);
247         }
248
249         /* Throw away any chunks in the retransmit queue. */
250         list_for_each_safe(lchunk, temp, &q->retransmit) {
251                 list_del_init(lchunk);
252                 chunk = list_entry(lchunk, struct sctp_chunk,
253                                    transmitted_list);
254                 sctp_chunk_fail(chunk, q->error);
255                 sctp_chunk_free(chunk);
256         }
257
258         /* Throw away any chunks that are in the abandoned queue. */
259         list_for_each_safe(lchunk, temp, &q->abandoned) {
260                 list_del_init(lchunk);
261                 chunk = list_entry(lchunk, struct sctp_chunk,
262                                    transmitted_list);
263                 sctp_chunk_fail(chunk, q->error);
264                 sctp_chunk_free(chunk);
265         }
266
267         /* Throw away any leftover data chunks. */
268         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
269
270                 /* Mark as send failure. */
271                 sctp_chunk_fail(chunk, q->error);
272                 sctp_chunk_free(chunk);
273         }
274
275         q->error = 0;
276
277         /* Throw away any leftover control chunks. */
278         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
279                 list_del_init(&chunk->list);
280                 sctp_chunk_free(chunk);
281         }
282 }
283
284 /* Free the outqueue structure and any related pending chunks.  */
285 void sctp_outq_free(struct sctp_outq *q)
286 {
287         /* Throw away leftover chunks. */
288         sctp_outq_teardown(q);
289
290         /* If we were kmalloc()'d, free the memory.  */
291         if (q->malloced)
292                 kfree(q);
293 }
294
295 /* Put a new chunk in an sctp_outq.  */
296 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
297 {
298         int error = 0;
299
300         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
301                           q, chunk, chunk && chunk->chunk_hdr ?
302                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
303                           : "Illegal Chunk");
304
305         /* If it is data, queue it up, otherwise, send it
306          * immediately.
307          */
308         if (SCTP_CID_DATA == chunk->chunk_hdr->type) {
309                 /* Is it OK to queue data chunks?  */
310                 /* From 9. Termination of Association
311                  *
312                  * When either endpoint performs a shutdown, the
313                  * association on each peer will stop accepting new
314                  * data from its user and only deliver data in queue
315                  * at the time of sending or receiving the SHUTDOWN
316                  * chunk.
317                  */
318                 switch (q->asoc->state) {
319                 case SCTP_STATE_EMPTY:
320                 case SCTP_STATE_CLOSED:
321                 case SCTP_STATE_SHUTDOWN_PENDING:
322                 case SCTP_STATE_SHUTDOWN_SENT:
323                 case SCTP_STATE_SHUTDOWN_RECEIVED:
324                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
325                         /* Cannot send after transport endpoint shutdown */
326                         error = -ESHUTDOWN;
327                         break;
328
329                 default:
330                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
331                           q, chunk, chunk && chunk->chunk_hdr ?
332                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
333                           : "Illegal Chunk");
334
335                         sctp_outq_tail_data(q, chunk);
336                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
337                                 SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
338                         else
339                                 SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
340                         q->empty = 0;
341                         break;
342                 }
343         } else {
344                 list_add_tail(&chunk->list, &q->control_chunk_list);
345                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
346         }
347
348         if (error < 0)
349                 return error;
350
351         if (!q->cork)
352                 error = sctp_outq_flush(q, 0);
353
354         return error;
355 }
356
357 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
358  * and the abandoned list are in ascending order.
359  */
360 static void sctp_insert_list(struct list_head *head, struct list_head *new)
361 {
362         struct list_head *pos;
363         struct sctp_chunk *nchunk, *lchunk;
364         __u32 ntsn, ltsn;
365         int done = 0;
366
367         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
368         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
369
370         list_for_each(pos, head) {
371                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
372                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
373                 if (TSN_lt(ntsn, ltsn)) {
374                         list_add(new, pos->prev);
375                         done = 1;
376                         break;
377                 }
378         }
379         if (!done)
380                 list_add_tail(new, head);
381 }
382
383 /* Mark all the eligible packets on a transport for retransmission.  */
384 void sctp_retransmit_mark(struct sctp_outq *q,
385                           struct sctp_transport *transport,
386                           __u8 reason)
387 {
388         struct list_head *lchunk, *ltemp;
389         struct sctp_chunk *chunk;
390
391         /* Walk through the specified transmitted queue.  */
392         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
393                 chunk = list_entry(lchunk, struct sctp_chunk,
394                                    transmitted_list);
395
396                 /* If the chunk is abandoned, move it to abandoned list. */
397                 if (sctp_chunk_abandoned(chunk)) {
398                         list_del_init(lchunk);
399                         sctp_insert_list(&q->abandoned, lchunk);
400
401                         /* If this chunk has not been previousely acked,
402                          * stop considering it 'outstanding'.  Our peer
403                          * will most likely never see it since it will
404                          * not be retransmitted
405                          */
406                         if (!chunk->tsn_gap_acked) {
407                                 chunk->transport->flight_size -=
408                                                 sctp_data_size(chunk);
409                                 q->outstanding_bytes -= sctp_data_size(chunk);
410                                 q->asoc->peer.rwnd += (sctp_data_size(chunk) +
411                                                         sizeof(struct sk_buff));
412                         }
413                         continue;
414                 }
415
416                 /* If we are doing  retransmission due to a timeout or pmtu
417                  * discovery, only the  chunks that are not yet acked should
418                  * be added to the retransmit queue.
419                  */
420                 if ((reason == SCTP_RTXR_FAST_RTX  &&
421                             (chunk->fast_retransmit > 0)) ||
422                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
423                         /* If this chunk was sent less then 1 rto ago, do not
424                          * retransmit this chunk, but give the peer time
425                          * to acknowlege it.  Do this only when
426                          * retransmitting due to T3 timeout.
427                          */
428                         if (reason == SCTP_RTXR_T3_RTX &&
429                             (jiffies - chunk->sent_at) < transport->last_rto)
430                                 continue;
431
432                         /* RFC 2960 6.2.1 Processing a Received SACK
433                          *
434                          * C) Any time a DATA chunk is marked for
435                          * retransmission (via either T3-rtx timer expiration
436                          * (Section 6.3.3) or via fast retransmit
437                          * (Section 7.2.4)), add the data size of those
438                          * chunks to the rwnd.
439                          */
440                         q->asoc->peer.rwnd += (sctp_data_size(chunk) +
441                                                 sizeof(struct sk_buff));
442                         q->outstanding_bytes -= sctp_data_size(chunk);
443                         transport->flight_size -= sctp_data_size(chunk);
444
445                         /* sctpimpguide-05 Section 2.8.2
446                          * M5) If a T3-rtx timer expires, the
447                          * 'TSN.Missing.Report' of all affected TSNs is set
448                          * to 0.
449                          */
450                         chunk->tsn_missing_report = 0;
451
452                         /* If a chunk that is being used for RTT measurement
453                          * has to be retransmitted, we cannot use this chunk
454                          * anymore for RTT measurements. Reset rto_pending so
455                          * that a new RTT measurement is started when a new
456                          * data chunk is sent.
457                          */
458                         if (chunk->rtt_in_progress) {
459                                 chunk->rtt_in_progress = 0;
460                                 transport->rto_pending = 0;
461                         }
462
463                         /* Move the chunk to the retransmit queue. The chunks
464                          * on the retransmit queue are always kept in order.
465                          */
466                         list_del_init(lchunk);
467                         sctp_insert_list(&q->retransmit, lchunk);
468                 }
469         }
470
471         SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "
472                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
473                           "pba: %d\n", __func__,
474                           transport, reason,
475                           transport->cwnd, transport->ssthresh,
476                           transport->flight_size,
477                           transport->partial_bytes_acked);
478
479 }
480
481 /* Mark all the eligible packets on a transport for retransmission and force
482  * one packet out.
483  */
484 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
485                      sctp_retransmit_reason_t reason)
486 {
487         int error = 0;
488
489         switch(reason) {
490         case SCTP_RTXR_T3_RTX:
491                 SCTP_INC_STATS(SCTP_MIB_T3_RETRANSMITS);
492                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
493                 /* Update the retran path if the T3-rtx timer has expired for
494                  * the current retran path.
495                  */
496                 if (transport == transport->asoc->peer.retran_path)
497                         sctp_assoc_update_retran_path(transport->asoc);
498                 transport->asoc->rtx_data_chunks +=
499                         transport->asoc->unack_data;
500                 break;
501         case SCTP_RTXR_FAST_RTX:
502                 SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);
503                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
504                 q->fast_rtx = 1;
505                 break;
506         case SCTP_RTXR_PMTUD:
507                 SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);
508                 break;
509         case SCTP_RTXR_T1_RTX:
510                 SCTP_INC_STATS(SCTP_MIB_T1_RETRANSMITS);
511                 transport->asoc->init_retries++;
512                 break;
513         default:
514                 BUG();
515         }
516
517         sctp_retransmit_mark(q, transport, reason);
518
519         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
520          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
521          * following the procedures outlined in C1 - C5.
522          */
523         if (reason == SCTP_RTXR_T3_RTX)
524                 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
525
526         /* Flush the queues only on timeout, since fast_rtx is only
527          * triggered during sack processing and the queue
528          * will be flushed at the end.
529          */
530         if (reason != SCTP_RTXR_FAST_RTX)
531                 error = sctp_outq_flush(q, /* rtx_timeout */ 1);
532
533         if (error)
534                 q->asoc->base.sk->sk_err = -error;
535 }
536
537 /*
538  * Transmit DATA chunks on the retransmit queue.  Upon return from
539  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
540  * need to be transmitted by the caller.
541  * We assume that pkt->transport has already been set.
542  *
543  * The return value is a normal kernel error return value.
544  */
545 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
546                                int rtx_timeout, int *start_timer)
547 {
548         struct list_head *lqueue;
549         struct sctp_transport *transport = pkt->transport;
550         sctp_xmit_t status;
551         struct sctp_chunk *chunk, *chunk1;
552         struct sctp_association *asoc;
553         int fast_rtx;
554         int error = 0;
555         int timer = 0;
556         int done = 0;
557
558         asoc = q->asoc;
559         lqueue = &q->retransmit;
560         fast_rtx = q->fast_rtx;
561
562         /* This loop handles time-out retransmissions, fast retransmissions,
563          * and retransmissions due to opening of whindow.
564          *
565          * RFC 2960 6.3.3 Handle T3-rtx Expiration
566          *
567          * E3) Determine how many of the earliest (i.e., lowest TSN)
568          * outstanding DATA chunks for the address for which the
569          * T3-rtx has expired will fit into a single packet, subject
570          * to the MTU constraint for the path corresponding to the
571          * destination transport address to which the retransmission
572          * is being sent (this may be different from the address for
573          * which the timer expires [see Section 6.4]). Call this value
574          * K. Bundle and retransmit those K DATA chunks in a single
575          * packet to the destination endpoint.
576          *
577          * [Just to be painfully clear, if we are retransmitting
578          * because a timeout just happened, we should send only ONE
579          * packet of retransmitted data.]
580          *
581          * For fast retransmissions we also send only ONE packet.  However,
582          * if we are just flushing the queue due to open window, we'll
583          * try to send as much as possible.
584          */
585         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
586
587                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
588                  * simple approach is just to move such TSNs out of the
589                  * way and into a 'transmitted' queue and skip to the
590                  * next chunk.
591                  */
592                 if (chunk->tsn_gap_acked) {
593                         list_del(&chunk->transmitted_list);
594                         list_add_tail(&chunk->transmitted_list,
595                                         &transport->transmitted);
596                         continue;
597                 }
598
599                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
600                  * chunks
601                  */
602                 if (fast_rtx && !chunk->fast_retransmit)
603                         continue;
604
605                 /* Attempt to append this chunk to the packet. */
606                 status = sctp_packet_append_chunk(pkt, chunk);
607
608                 switch (status) {
609                 case SCTP_XMIT_PMTU_FULL:
610                         /* Send this packet.  */
611                         error = sctp_packet_transmit(pkt);
612
613                         /* If we are retransmitting, we should only
614                          * send a single packet.
615                          */
616                         if (rtx_timeout || fast_rtx)
617                                 done = 1;
618
619                         /* Bundle next chunk in the next round.  */
620                         break;
621
622                 case SCTP_XMIT_RWND_FULL:
623                         /* Send this packet. */
624                         error = sctp_packet_transmit(pkt);
625
626                         /* Stop sending DATA as there is no more room
627                          * at the receiver.
628                          */
629                         done = 1;
630                         break;
631
632                 case SCTP_XMIT_NAGLE_DELAY:
633                         /* Send this packet. */
634                         error = sctp_packet_transmit(pkt);
635
636                         /* Stop sending DATA because of nagle delay. */
637                         done = 1;
638                         break;
639
640                 default:
641                         /* The append was successful, so add this chunk to
642                          * the transmitted list.
643                          */
644                         list_del(&chunk->transmitted_list);
645                         list_add_tail(&chunk->transmitted_list,
646                                         &transport->transmitted);
647
648                         /* Mark the chunk as ineligible for fast retransmit
649                          * after it is retransmitted.
650                          */
651                         if (chunk->fast_retransmit > 0)
652                                 chunk->fast_retransmit = -1;
653
654                         /* Force start T3-rtx timer when fast retransmitting
655                          * the earliest outstanding TSN
656                          */
657                         if (!timer && fast_rtx &&
658                             ntohl(chunk->subh.data_hdr->tsn) ==
659                                              asoc->ctsn_ack_point + 1)
660                                 timer = 2;
661
662                         q->empty = 0;
663                         break;
664                 }
665
666                 /* Set the timer if there were no errors */
667                 if (!error && !timer)
668                         timer = 1;
669
670                 if (done)
671                         break;
672         }
673
674         /* If we are here due to a retransmit timeout or a fast
675          * retransmit and if there are any chunks left in the retransmit
676          * queue that could not fit in the PMTU sized packet, they need
677          * to be marked as ineligible for a subsequent fast retransmit.
678          */
679         if (rtx_timeout || fast_rtx) {
680                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
681                         if (chunk1->fast_retransmit > 0)
682                                 chunk1->fast_retransmit = -1;
683                 }
684         }
685
686         *start_timer = timer;
687
688         /* Clear fast retransmit hint */
689         if (fast_rtx)
690                 q->fast_rtx = 0;
691
692         return error;
693 }
694
695 /* Cork the outqueue so queued chunks are really queued. */
696 int sctp_outq_uncork(struct sctp_outq *q)
697 {
698         int error = 0;
699         if (q->cork)
700                 q->cork = 0;
701         error = sctp_outq_flush(q, 0);
702         return error;
703 }
704
705 /*
706  * Try to flush an outqueue.
707  *
708  * Description: Send everything in q which we legally can, subject to
709  * congestion limitations.
710  * * Note: This function can be called from multiple contexts so appropriate
711  * locking concerns must be made.  Today we use the sock lock to protect
712  * this function.
713  */
714 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
715 {
716         struct sctp_packet *packet;
717         struct sctp_packet singleton;
718         struct sctp_association *asoc = q->asoc;
719         __u16 sport = asoc->base.bind_addr.port;
720         __u16 dport = asoc->peer.port;
721         __u32 vtag = asoc->peer.i.init_tag;
722         struct sctp_transport *transport = NULL;
723         struct sctp_transport *new_transport;
724         struct sctp_chunk *chunk, *tmp;
725         sctp_xmit_t status;
726         int error = 0;
727         int start_timer = 0;
728
729         /* These transports have chunks to send. */
730         struct list_head transport_list;
731         struct list_head *ltransport;
732
733         INIT_LIST_HEAD(&transport_list);
734         packet = NULL;
735
736         /*
737          * 6.10 Bundling
738          *   ...
739          *   When bundling control chunks with DATA chunks, an
740          *   endpoint MUST place control chunks first in the outbound
741          *   SCTP packet.  The transmitter MUST transmit DATA chunks
742          *   within a SCTP packet in increasing order of TSN.
743          *   ...
744          */
745
746         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
747                 list_del_init(&chunk->list);
748
749                 /* Pick the right transport to use. */
750                 new_transport = chunk->transport;
751
752                 if (!new_transport) {
753                         /*
754                          * If we have a prior transport pointer, see if
755                          * the destination address of the chunk
756                          * matches the destination address of the
757                          * current transport.  If not a match, then
758                          * try to look up the transport with a given
759                          * destination address.  We do this because
760                          * after processing ASCONFs, we may have new
761                          * transports created.
762                          */
763                         if (transport &&
764                             sctp_cmp_addr_exact(&chunk->dest,
765                                                 &transport->ipaddr))
766                                         new_transport = transport;
767                         else
768                                 new_transport = sctp_assoc_lookup_paddr(asoc,
769                                                                 &chunk->dest);
770
771                         /* if we still don't have a new transport, then
772                          * use the current active path.
773                          */
774                         if (!new_transport)
775                                 new_transport = asoc->peer.active_path;
776                 } else if ((new_transport->state == SCTP_INACTIVE) ||
777                            (new_transport->state == SCTP_UNCONFIRMED)) {
778                         /* If the chunk is Heartbeat or Heartbeat Ack,
779                          * send it to chunk->transport, even if it's
780                          * inactive.
781                          *
782                          * 3.3.6 Heartbeat Acknowledgement:
783                          * ...
784                          * A HEARTBEAT ACK is always sent to the source IP
785                          * address of the IP datagram containing the
786                          * HEARTBEAT chunk to which this ack is responding.
787                          * ...
788                          *
789                          * ASCONF_ACKs also must be sent to the source.
790                          */
791                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
792                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
793                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
794                                 new_transport = asoc->peer.active_path;
795                 }
796
797                 /* Are we switching transports?
798                  * Take care of transport locks.
799                  */
800                 if (new_transport != transport) {
801                         transport = new_transport;
802                         if (list_empty(&transport->send_ready)) {
803                                 list_add_tail(&transport->send_ready,
804                                               &transport_list);
805                         }
806                         packet = &transport->packet;
807                         sctp_packet_config(packet, vtag,
808                                            asoc->peer.ecn_capable);
809                 }
810
811                 switch (chunk->chunk_hdr->type) {
812                 /*
813                  * 6.10 Bundling
814                  *   ...
815                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
816                  *   COMPLETE with any other chunks.  [Send them immediately.]
817                  */
818                 case SCTP_CID_INIT:
819                 case SCTP_CID_INIT_ACK:
820                 case SCTP_CID_SHUTDOWN_COMPLETE:
821                         sctp_packet_init(&singleton, transport, sport, dport);
822                         sctp_packet_config(&singleton, vtag, 0);
823                         sctp_packet_append_chunk(&singleton, chunk);
824                         error = sctp_packet_transmit(&singleton);
825                         if (error < 0)
826                                 return error;
827                         break;
828
829                 case SCTP_CID_ABORT:
830                         if (sctp_test_T_bit(chunk)) {
831                                 packet->vtag = asoc->c.my_vtag;
832                         }
833                 case SCTP_CID_SACK:
834                 case SCTP_CID_HEARTBEAT:
835                 case SCTP_CID_HEARTBEAT_ACK:
836                 case SCTP_CID_SHUTDOWN:
837                 case SCTP_CID_SHUTDOWN_ACK:
838                 case SCTP_CID_ERROR:
839                 case SCTP_CID_COOKIE_ECHO:
840                 case SCTP_CID_COOKIE_ACK:
841                 case SCTP_CID_ECN_ECNE:
842                 case SCTP_CID_ECN_CWR:
843                 case SCTP_CID_ASCONF:
844                 case SCTP_CID_ASCONF_ACK:
845                 case SCTP_CID_FWD_TSN:
846                         sctp_packet_transmit_chunk(packet, chunk);
847                         break;
848
849                 default:
850                         /* We built a chunk with an illegal type! */
851                         BUG();
852                 }
853         }
854
855         /* Is it OK to send data chunks?  */
856         switch (asoc->state) {
857         case SCTP_STATE_COOKIE_ECHOED:
858                 /* Only allow bundling when this packet has a COOKIE-ECHO
859                  * chunk.
860                  */
861                 if (!packet || !packet->has_cookie_echo)
862                         break;
863
864                 /* fallthru */
865         case SCTP_STATE_ESTABLISHED:
866         case SCTP_STATE_SHUTDOWN_PENDING:
867         case SCTP_STATE_SHUTDOWN_RECEIVED:
868                 /*
869                  * RFC 2960 6.1  Transmission of DATA Chunks
870                  *
871                  * C) When the time comes for the sender to transmit,
872                  * before sending new DATA chunks, the sender MUST
873                  * first transmit any outstanding DATA chunks which
874                  * are marked for retransmission (limited by the
875                  * current cwnd).
876                  */
877                 if (!list_empty(&q->retransmit)) {
878                         if (transport == asoc->peer.retran_path)
879                                 goto retran;
880
881                         /* Switch transports & prepare the packet.  */
882
883                         transport = asoc->peer.retran_path;
884
885                         if (list_empty(&transport->send_ready)) {
886                                 list_add_tail(&transport->send_ready,
887                                               &transport_list);
888                         }
889
890                         packet = &transport->packet;
891                         sctp_packet_config(packet, vtag,
892                                            asoc->peer.ecn_capable);
893                 retran:
894                         error = sctp_outq_flush_rtx(q, packet,
895                                                     rtx_timeout, &start_timer);
896
897                         if (start_timer)
898                                 sctp_transport_reset_timers(transport,
899                                                             start_timer-1);
900
901                         /* This can happen on COOKIE-ECHO resend.  Only
902                          * one chunk can get bundled with a COOKIE-ECHO.
903                          */
904                         if (packet->has_cookie_echo)
905                                 goto sctp_flush_out;
906
907                         /* Don't send new data if there is still data
908                          * waiting to retransmit.
909                          */
910                         if (!list_empty(&q->retransmit))
911                                 goto sctp_flush_out;
912                 }
913
914                 /* Finally, transmit new packets.  */
915                 start_timer = 0;
916                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
917                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
918                          * stream identifier.
919                          */
920                         if (chunk->sinfo.sinfo_stream >=
921                             asoc->c.sinit_num_ostreams) {
922
923                                 /* Mark as failed send. */
924                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
925                                 sctp_chunk_free(chunk);
926                                 continue;
927                         }
928
929                         /* Has this chunk expired? */
930                         if (sctp_chunk_abandoned(chunk)) {
931                                 sctp_chunk_fail(chunk, 0);
932                                 sctp_chunk_free(chunk);
933                                 continue;
934                         }
935
936                         /* If there is a specified transport, use it.
937                          * Otherwise, we want to use the active path.
938                          */
939                         new_transport = chunk->transport;
940                         if (!new_transport ||
941                             ((new_transport->state == SCTP_INACTIVE) ||
942                              (new_transport->state == SCTP_UNCONFIRMED)))
943                                 new_transport = asoc->peer.active_path;
944
945                         /* Change packets if necessary.  */
946                         if (new_transport != transport) {
947                                 transport = new_transport;
948
949                                 /* Schedule to have this transport's
950                                  * packet flushed.
951                                  */
952                                 if (list_empty(&transport->send_ready)) {
953                                         list_add_tail(&transport->send_ready,
954                                                       &transport_list);
955                                 }
956
957                                 packet = &transport->packet;
958                                 sctp_packet_config(packet, vtag,
959                                                    asoc->peer.ecn_capable);
960                         }
961
962                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
963                                           q, chunk,
964                                           chunk && chunk->chunk_hdr ?
965                                           sctp_cname(SCTP_ST_CHUNK(
966                                                   chunk->chunk_hdr->type))
967                                           : "Illegal Chunk");
968
969                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
970                                         "%p skb->users %d.\n",
971                                         ntohl(chunk->subh.data_hdr->tsn),
972                                         chunk->skb ?chunk->skb->head : NULL,
973                                         chunk->skb ?
974                                         atomic_read(&chunk->skb->users) : -1);
975
976                         /* Add the chunk to the packet.  */
977                         status = sctp_packet_transmit_chunk(packet, chunk);
978
979                         switch (status) {
980                         case SCTP_XMIT_PMTU_FULL:
981                         case SCTP_XMIT_RWND_FULL:
982                         case SCTP_XMIT_NAGLE_DELAY:
983                                 /* We could not append this chunk, so put
984                                  * the chunk back on the output queue.
985                                  */
986                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
987                                         "not transmit TSN: 0x%x, status: %d\n",
988                                         ntohl(chunk->subh.data_hdr->tsn),
989                                         status);
990                                 sctp_outq_head_data(q, chunk);
991                                 goto sctp_flush_out;
992                                 break;
993
994                         case SCTP_XMIT_OK:
995                                 break;
996
997                         default:
998                                 BUG();
999                         }
1000
1001                         /* BUG: We assume that the sctp_packet_transmit()
1002                          * call below will succeed all the time and add the
1003                          * chunk to the transmitted list and restart the
1004                          * timers.
1005                          * It is possible that the call can fail under OOM
1006                          * conditions.
1007                          *
1008                          * Is this really a problem?  Won't this behave
1009                          * like a lost TSN?
1010                          */
1011                         list_add_tail(&chunk->transmitted_list,
1012                                       &transport->transmitted);
1013
1014                         sctp_transport_reset_timers(transport, start_timer-1);
1015
1016                         q->empty = 0;
1017
1018                         /* Only let one DATA chunk get bundled with a
1019                          * COOKIE-ECHO chunk.
1020                          */
1021                         if (packet->has_cookie_echo)
1022                                 goto sctp_flush_out;
1023                 }
1024                 break;
1025
1026         default:
1027                 /* Do nothing.  */
1028                 break;
1029         }
1030
1031 sctp_flush_out:
1032
1033         /* Before returning, examine all the transports touched in
1034          * this call.  Right now, we bluntly force clear all the
1035          * transports.  Things might change after we implement Nagle.
1036          * But such an examination is still required.
1037          *
1038          * --xguo
1039          */
1040         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
1041                 struct sctp_transport *t = list_entry(ltransport,
1042                                                       struct sctp_transport,
1043                                                       send_ready);
1044                 packet = &t->packet;
1045                 if (!sctp_packet_empty(packet))
1046                         error = sctp_packet_transmit(packet);
1047         }
1048
1049         return error;
1050 }
1051
1052 /* Update unack_data based on the incoming SACK chunk */
1053 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1054                                         struct sctp_sackhdr *sack)
1055 {
1056         sctp_sack_variable_t *frags;
1057         __u16 unack_data;
1058         int i;
1059
1060         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1061
1062         frags = sack->variable;
1063         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1064                 unack_data -= ((ntohs(frags[i].gab.end) -
1065                                 ntohs(frags[i].gab.start) + 1));
1066         }
1067
1068         assoc->unack_data = unack_data;
1069 }
1070
1071 /* Return the highest new tsn that is acknowledged by the given SACK chunk. */
1072 static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
1073                                   struct sctp_association *asoc)
1074 {
1075         struct sctp_transport *transport;
1076         struct sctp_chunk *chunk;
1077         __u32 highest_new_tsn, tsn;
1078         struct list_head *transport_list = &asoc->peer.transport_addr_list;
1079
1080         highest_new_tsn = ntohl(sack->cum_tsn_ack);
1081
1082         list_for_each_entry(transport, transport_list, transports) {
1083                 list_for_each_entry(chunk, &transport->transmitted,
1084                                 transmitted_list) {
1085                         tsn = ntohl(chunk->subh.data_hdr->tsn);
1086
1087                         if (!chunk->tsn_gap_acked &&
1088                             TSN_lt(highest_new_tsn, tsn) &&
1089                             sctp_acked(sack, tsn))
1090                                 highest_new_tsn = tsn;
1091                 }
1092         }
1093
1094         return highest_new_tsn;
1095 }
1096
1097 /* This is where we REALLY process a SACK.
1098  *
1099  * Process the SACK against the outqueue.  Mostly, this just frees
1100  * things off the transmitted queue.
1101  */
1102 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1103 {
1104         struct sctp_association *asoc = q->asoc;
1105         struct sctp_transport *transport;
1106         struct sctp_chunk *tchunk = NULL;
1107         struct list_head *lchunk, *transport_list, *temp;
1108         sctp_sack_variable_t *frags = sack->variable;
1109         __u32 sack_ctsn, ctsn, tsn;
1110         __u32 highest_tsn, highest_new_tsn;
1111         __u32 sack_a_rwnd;
1112         unsigned outstanding;
1113         struct sctp_transport *primary = asoc->peer.primary_path;
1114         int count_of_newacks = 0;
1115
1116         /* Grab the association's destination address list. */
1117         transport_list = &asoc->peer.transport_addr_list;
1118
1119         sack_ctsn = ntohl(sack->cum_tsn_ack);
1120
1121         /*
1122          * SFR-CACC algorithm:
1123          * On receipt of a SACK the sender SHOULD execute the
1124          * following statements.
1125          *
1126          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1127          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1128          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1129          * all destinations.
1130          */
1131         if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1132                 primary->cacc.changeover_active = 0;
1133                 list_for_each_entry(transport, transport_list,
1134                                 transports) {
1135                         transport->cacc.cycling_changeover = 0;
1136                 }
1137         }
1138
1139         /*
1140          * SFR-CACC algorithm:
1141          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1142          * is set the receiver of the SACK MUST take the following actions:
1143          *
1144          * A) Initialize the cacc_saw_newack to 0 for all destination
1145          * addresses.
1146          */
1147         if (sack->num_gap_ack_blocks &&
1148             primary->cacc.changeover_active) {
1149                 list_for_each_entry(transport, transport_list, transports) {
1150                         transport->cacc.cacc_saw_newack = 0;
1151                 }
1152         }
1153
1154         /* Get the highest TSN in the sack. */
1155         highest_tsn = sack_ctsn;
1156         if (sack->num_gap_ack_blocks)
1157                 highest_tsn +=
1158                     ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
1159
1160         if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
1161                 highest_new_tsn = highest_tsn;
1162                 asoc->highest_sacked = highest_tsn;
1163         } else {
1164                 highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
1165         }
1166
1167         /* Run through the retransmit queue.  Credit bytes received
1168          * and free those chunks that we can.
1169          */
1170         sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
1171         sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
1172
1173         /* Run through the transmitted queue.
1174          * Credit bytes received and free those chunks which we can.
1175          *
1176          * This is a MASSIVE candidate for optimization.
1177          */
1178         list_for_each_entry(transport, transport_list, transports) {
1179                 sctp_check_transmitted(q, &transport->transmitted,
1180                                        transport, sack, highest_new_tsn);
1181                 /*
1182                  * SFR-CACC algorithm:
1183                  * C) Let count_of_newacks be the number of
1184                  * destinations for which cacc_saw_newack is set.
1185                  */
1186                 if (transport->cacc.cacc_saw_newack)
1187                         count_of_newacks ++;
1188         }
1189
1190         list_for_each_entry(transport, transport_list, transports) {
1191                 sctp_mark_missing(q, &transport->transmitted, transport,
1192                                   highest_new_tsn, count_of_newacks);
1193         }
1194
1195         /* Move the Cumulative TSN Ack Point if appropriate.  */
1196         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn))
1197                 asoc->ctsn_ack_point = sack_ctsn;
1198
1199         /* Update unack_data field in the assoc. */
1200         sctp_sack_update_unack_data(asoc, sack);
1201
1202         ctsn = asoc->ctsn_ack_point;
1203
1204         /* Throw away stuff rotting on the sack queue.  */
1205         list_for_each_safe(lchunk, temp, &q->sacked) {
1206                 tchunk = list_entry(lchunk, struct sctp_chunk,
1207                                     transmitted_list);
1208                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1209                 if (TSN_lte(tsn, ctsn)) {
1210                         list_del_init(&tchunk->transmitted_list);
1211                         sctp_chunk_free(tchunk);
1212                 }
1213         }
1214
1215         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1216          *     number of bytes still outstanding after processing the
1217          *     Cumulative TSN Ack and the Gap Ack Blocks.
1218          */
1219
1220         sack_a_rwnd = ntohl(sack->a_rwnd);
1221         outstanding = q->outstanding_bytes;
1222
1223         if (outstanding < sack_a_rwnd)
1224                 sack_a_rwnd -= outstanding;
1225         else
1226                 sack_a_rwnd = 0;
1227
1228         asoc->peer.rwnd = sack_a_rwnd;
1229
1230         sctp_generate_fwdtsn(q, sack_ctsn);
1231
1232         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1233                           __func__, sack_ctsn);
1234         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1235                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1236                           __func__, asoc, ctsn, asoc->adv_peer_ack_point);
1237
1238         /* See if all chunks are acked.
1239          * Make sure the empty queue handler will get run later.
1240          */
1241         q->empty = (list_empty(&q->out_chunk_list) &&
1242                     list_empty(&q->control_chunk_list) &&
1243                     list_empty(&q->retransmit));
1244         if (!q->empty)
1245                 goto finish;
1246
1247         list_for_each_entry(transport, transport_list, transports) {
1248                 q->empty = q->empty && list_empty(&transport->transmitted);
1249                 if (!q->empty)
1250                         goto finish;
1251         }
1252
1253         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1254 finish:
1255         return q->empty;
1256 }
1257
1258 /* Is the outqueue empty?  */
1259 int sctp_outq_is_empty(const struct sctp_outq *q)
1260 {
1261         return q->empty;
1262 }
1263
1264 /********************************************************************
1265  * 2nd Level Abstractions
1266  ********************************************************************/
1267
1268 /* Go through a transport's transmitted list or the association's retransmit
1269  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1270  * The retransmit list will not have an associated transport.
1271  *
1272  * I added coherent debug information output.   --xguo
1273  *
1274  * Instead of printing 'sacked' or 'kept' for each TSN on the
1275  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1276  * KEPT TSN6-TSN7, etc.
1277  */
1278 static void sctp_check_transmitted(struct sctp_outq *q,
1279                                    struct list_head *transmitted_queue,
1280                                    struct sctp_transport *transport,
1281                                    struct sctp_sackhdr *sack,
1282                                    __u32 highest_new_tsn_in_sack)
1283 {
1284         struct list_head *lchunk;
1285         struct sctp_chunk *tchunk;
1286         struct list_head tlist;
1287         __u32 tsn;
1288         __u32 sack_ctsn;
1289         __u32 rtt;
1290         __u8 restart_timer = 0;
1291         int bytes_acked = 0;
1292
1293         /* These state variables are for coherent debug output. --xguo */
1294
1295 #if SCTP_DEBUG
1296         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1297         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1298         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1299         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1300
1301         /* 0 : The last TSN was ACKed.
1302          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1303          * -1: We need to initialize.
1304          */
1305         int dbg_prt_state = -1;
1306 #endif /* SCTP_DEBUG */
1307
1308         sack_ctsn = ntohl(sack->cum_tsn_ack);
1309
1310         INIT_LIST_HEAD(&tlist);
1311
1312         /* The while loop will skip empty transmitted queues. */
1313         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1314                 tchunk = list_entry(lchunk, struct sctp_chunk,
1315                                     transmitted_list);
1316
1317                 if (sctp_chunk_abandoned(tchunk)) {
1318                         /* Move the chunk to abandoned list. */
1319                         sctp_insert_list(&q->abandoned, lchunk);
1320
1321                         /* If this chunk has not been acked, stop
1322                          * considering it as 'outstanding'.
1323                          */
1324                         if (!tchunk->tsn_gap_acked) {
1325                                 tchunk->transport->flight_size -=
1326                                                 sctp_data_size(tchunk);
1327                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1328                         }
1329                         continue;
1330                 }
1331
1332                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1333                 if (sctp_acked(sack, tsn)) {
1334                         /* If this queue is the retransmit queue, the
1335                          * retransmit timer has already reclaimed
1336                          * the outstanding bytes for this chunk, so only
1337                          * count bytes associated with a transport.
1338                          */
1339                         if (transport) {
1340                                 /* If this chunk is being used for RTT
1341                                  * measurement, calculate the RTT and update
1342                                  * the RTO using this value.
1343                                  *
1344                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1345                                  * MUST NOT be made using packets that were
1346                                  * retransmitted (and thus for which it is
1347                                  * ambiguous whether the reply was for the
1348                                  * first instance of the packet or a later
1349                                  * instance).
1350                                  */
1351                                 if (!tchunk->tsn_gap_acked &&
1352                                     !tchunk->resent &&
1353                                     tchunk->rtt_in_progress) {
1354                                         tchunk->rtt_in_progress = 0;
1355                                         rtt = jiffies - tchunk->sent_at;
1356                                         sctp_transport_update_rto(transport,
1357                                                                   rtt);
1358                                 }
1359                         }
1360                         if (TSN_lte(tsn, sack_ctsn)) {
1361                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1362                                  *
1363                                  * R3) Whenever a SACK is received
1364                                  * that acknowledges the DATA chunk
1365                                  * with the earliest outstanding TSN
1366                                  * for that address, restart T3-rtx
1367                                  * timer for that address with its
1368                                  * current RTO.
1369                                  */
1370                                 restart_timer = 1;
1371
1372                                 if (!tchunk->tsn_gap_acked) {
1373                                         tchunk->tsn_gap_acked = 1;
1374                                         bytes_acked += sctp_data_size(tchunk);
1375                                         /*
1376                                          * SFR-CACC algorithm:
1377                                          * 2) If the SACK contains gap acks
1378                                          * and the flag CHANGEOVER_ACTIVE is
1379                                          * set the receiver of the SACK MUST
1380                                          * take the following action:
1381                                          *
1382                                          * B) For each TSN t being acked that
1383                                          * has not been acked in any SACK so
1384                                          * far, set cacc_saw_newack to 1 for
1385                                          * the destination that the TSN was
1386                                          * sent to.
1387                                          */
1388                                         if (transport &&
1389                                             sack->num_gap_ack_blocks &&
1390                                             q->asoc->peer.primary_path->cacc.
1391                                             changeover_active)
1392                                                 transport->cacc.cacc_saw_newack
1393                                                         = 1;
1394                                 }
1395
1396                                 list_add_tail(&tchunk->transmitted_list,
1397                                               &q->sacked);
1398                         } else {
1399                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1400                                  * M2) Each time a SACK arrives reporting
1401                                  * 'Stray DATA chunk(s)' record the highest TSN
1402                                  * reported as newly acknowledged, call this
1403                                  * value 'HighestTSNinSack'. A newly
1404                                  * acknowledged DATA chunk is one not
1405                                  * previously acknowledged in a SACK.
1406                                  *
1407                                  * When the SCTP sender of data receives a SACK
1408                                  * chunk that acknowledges, for the first time,
1409                                  * the receipt of a DATA chunk, all the still
1410                                  * unacknowledged DATA chunks whose TSN is
1411                                  * older than that newly acknowledged DATA
1412                                  * chunk, are qualified as 'Stray DATA chunks'.
1413                                  */
1414                                 if (!tchunk->tsn_gap_acked) {
1415                                         tchunk->tsn_gap_acked = 1;
1416                                         bytes_acked += sctp_data_size(tchunk);
1417                                 }
1418                                 list_add_tail(lchunk, &tlist);
1419                         }
1420
1421 #if SCTP_DEBUG
1422                         switch (dbg_prt_state) {
1423                         case 0: /* last TSN was ACKed */
1424                                 if (dbg_last_ack_tsn + 1 == tsn) {
1425                                         /* This TSN belongs to the
1426                                          * current ACK range.
1427                                          */
1428                                         break;
1429                                 }
1430
1431                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1432                                         /* Display the end of the
1433                                          * current range.
1434                                          */
1435                                         SCTP_DEBUG_PRINTK("-%08x",
1436                                                           dbg_last_ack_tsn);
1437                                 }
1438
1439                                 /* Start a new range.  */
1440                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1441                                 dbg_ack_tsn = tsn;
1442                                 break;
1443
1444                         case 1: /* The last TSN was NOT ACKed. */
1445                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1446                                         /* Display the end of current range. */
1447                                         SCTP_DEBUG_PRINTK("-%08x",
1448                                                           dbg_last_kept_tsn);
1449                                 }
1450
1451                                 SCTP_DEBUG_PRINTK("\n");
1452
1453                                 /* FALL THROUGH... */
1454                         default:
1455                                 /* This is the first-ever TSN we examined.  */
1456                                 /* Start a new range of ACK-ed TSNs.  */
1457                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1458                                 dbg_prt_state = 0;
1459                                 dbg_ack_tsn = tsn;
1460                         }
1461
1462                         dbg_last_ack_tsn = tsn;
1463 #endif /* SCTP_DEBUG */
1464
1465                 } else {
1466                         if (tchunk->tsn_gap_acked) {
1467                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1468                                                   "data TSN: 0x%x\n",
1469                                                   __func__,
1470                                                   tsn);
1471                                 tchunk->tsn_gap_acked = 0;
1472
1473                                 bytes_acked -= sctp_data_size(tchunk);
1474
1475                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1476                                  *
1477                                  * R4) Whenever a SACK is received missing a
1478                                  * TSN that was previously acknowledged via a
1479                                  * Gap Ack Block, start T3-rtx for the
1480                                  * destination address to which the DATA
1481                                  * chunk was originally
1482                                  * transmitted if it is not already running.
1483                                  */
1484                                 restart_timer = 1;
1485                         }
1486
1487                         list_add_tail(lchunk, &tlist);
1488
1489 #if SCTP_DEBUG
1490                         /* See the above comments on ACK-ed TSNs. */
1491                         switch (dbg_prt_state) {
1492                         case 1:
1493                                 if (dbg_last_kept_tsn + 1 == tsn)
1494                                         break;
1495
1496                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1497                                         SCTP_DEBUG_PRINTK("-%08x",
1498                                                           dbg_last_kept_tsn);
1499
1500                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1501                                 dbg_kept_tsn = tsn;
1502                                 break;
1503
1504                         case 0:
1505                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1506                                         SCTP_DEBUG_PRINTK("-%08x",
1507                                                           dbg_last_ack_tsn);
1508                                 SCTP_DEBUG_PRINTK("\n");
1509
1510                                 /* FALL THROUGH... */
1511                         default:
1512                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1513                                 dbg_prt_state = 1;
1514                                 dbg_kept_tsn = tsn;
1515                         }
1516
1517                         dbg_last_kept_tsn = tsn;
1518 #endif /* SCTP_DEBUG */
1519                 }
1520         }
1521
1522 #if SCTP_DEBUG
1523         /* Finish off the last range, displaying its ending TSN.  */
1524         switch (dbg_prt_state) {
1525         case 0:
1526                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1527                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
1528                 } else {
1529                         SCTP_DEBUG_PRINTK("\n");
1530                 }
1531         break;
1532
1533         case 1:
1534                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1535                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
1536                 } else {
1537                         SCTP_DEBUG_PRINTK("\n");
1538                 }
1539         }
1540 #endif /* SCTP_DEBUG */
1541         if (transport) {
1542                 if (bytes_acked) {
1543                         /* 8.2. When an outstanding TSN is acknowledged,
1544                          * the endpoint shall clear the error counter of
1545                          * the destination transport address to which the
1546                          * DATA chunk was last sent.
1547                          * The association's overall error counter is
1548                          * also cleared.
1549                          */
1550                         transport->error_count = 0;
1551                         transport->asoc->overall_error_count = 0;
1552
1553                         /* Mark the destination transport address as
1554                          * active if it is not so marked.
1555                          */
1556                         if ((transport->state == SCTP_INACTIVE) ||
1557                             (transport->state == SCTP_UNCONFIRMED)) {
1558                                 sctp_assoc_control_transport(
1559                                         transport->asoc,
1560                                         transport,
1561                                         SCTP_TRANSPORT_UP,
1562                                         SCTP_RECEIVED_SACK);
1563                         }
1564
1565                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1566                                                   bytes_acked);
1567
1568                         transport->flight_size -= bytes_acked;
1569                         if (transport->flight_size == 0)
1570                                 transport->partial_bytes_acked = 0;
1571                         q->outstanding_bytes -= bytes_acked;
1572                 } else {
1573                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1574                          * When a sender is doing zero window probing, it
1575                          * should not timeout the association if it continues
1576                          * to receive new packets from the receiver. The
1577                          * reason is that the receiver MAY keep its window
1578                          * closed for an indefinite time.
1579                          * A sender is doing zero window probing when the
1580                          * receiver's advertised window is zero, and there is
1581                          * only one data chunk in flight to the receiver.
1582                          */
1583                         if (!q->asoc->peer.rwnd &&
1584                             !list_empty(&tlist) &&
1585                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1586                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1587                                                   "window probe: %u\n",
1588                                                   __func__, sack_ctsn);
1589                                 q->asoc->overall_error_count = 0;
1590                                 transport->error_count = 0;
1591                         }
1592                 }
1593
1594                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1595                  *
1596                  * R2) Whenever all outstanding data sent to an address have
1597                  * been acknowledged, turn off the T3-rtx timer of that
1598                  * address.
1599                  */
1600                 if (!transport->flight_size) {
1601                         if (timer_pending(&transport->T3_rtx_timer) &&
1602                             del_timer(&transport->T3_rtx_timer)) {
1603                                 sctp_transport_put(transport);
1604                         }
1605                 } else if (restart_timer) {
1606                         if (!mod_timer(&transport->T3_rtx_timer,
1607                                        jiffies + transport->rto))
1608                                 sctp_transport_hold(transport);
1609                 }
1610         }
1611
1612         list_splice(&tlist, transmitted_queue);
1613 }
1614
1615 /* Mark chunks as missing and consequently may get retransmitted. */
1616 static void sctp_mark_missing(struct sctp_outq *q,
1617                               struct list_head *transmitted_queue,
1618                               struct sctp_transport *transport,
1619                               __u32 highest_new_tsn_in_sack,
1620                               int count_of_newacks)
1621 {
1622         struct sctp_chunk *chunk;
1623         __u32 tsn;
1624         char do_fast_retransmit = 0;
1625         struct sctp_transport *primary = q->asoc->peer.primary_path;
1626
1627         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1628
1629                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1630
1631                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1632                  * 'Unacknowledged TSN's', if the TSN number of an
1633                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1634                  * value, increment the 'TSN.Missing.Report' count on that
1635                  * chunk if it has NOT been fast retransmitted or marked for
1636                  * fast retransmit already.
1637                  */
1638                 if (!chunk->fast_retransmit &&
1639                     !chunk->tsn_gap_acked &&
1640                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1641
1642                         /* SFR-CACC may require us to skip marking
1643                          * this chunk as missing.
1644                          */
1645                         if (!transport || !sctp_cacc_skip(primary, transport,
1646                                             count_of_newacks, tsn)) {
1647                                 chunk->tsn_missing_report++;
1648
1649                                 SCTP_DEBUG_PRINTK(
1650                                         "%s: TSN 0x%x missing counter: %d\n",
1651                                         __func__, tsn,
1652                                         chunk->tsn_missing_report);
1653                         }
1654                 }
1655                 /*
1656                  * M4) If any DATA chunk is found to have a
1657                  * 'TSN.Missing.Report'
1658                  * value larger than or equal to 3, mark that chunk for
1659                  * retransmission and start the fast retransmit procedure.
1660                  */
1661
1662                 if (chunk->tsn_missing_report >= 3) {
1663                         chunk->fast_retransmit = 1;
1664                         do_fast_retransmit = 1;
1665                 }
1666         }
1667
1668         if (transport) {
1669                 if (do_fast_retransmit)
1670                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1671
1672                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1673                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1674                                   __func__, transport, transport->cwnd,
1675                                   transport->ssthresh, transport->flight_size,
1676                                   transport->partial_bytes_acked);
1677         }
1678 }
1679
1680 /* Is the given TSN acked by this packet?  */
1681 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1682 {
1683         int i;
1684         sctp_sack_variable_t *frags;
1685         __u16 gap;
1686         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1687
1688         if (TSN_lte(tsn, ctsn))
1689                 goto pass;
1690
1691         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1692          *
1693          * Gap Ack Blocks:
1694          *  These fields contain the Gap Ack Blocks. They are repeated
1695          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1696          *  defined in the Number of Gap Ack Blocks field. All DATA
1697          *  chunks with TSNs greater than or equal to (Cumulative TSN
1698          *  Ack + Gap Ack Block Start) and less than or equal to
1699          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1700          *  Block are assumed to have been received correctly.
1701          */
1702
1703         frags = sack->variable;
1704         gap = tsn - ctsn;
1705         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1706                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1707                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1708                         goto pass;
1709         }
1710
1711         return 0;
1712 pass:
1713         return 1;
1714 }
1715
1716 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1717                                     int nskips, __be16 stream)
1718 {
1719         int i;
1720
1721         for (i = 0; i < nskips; i++) {
1722                 if (skiplist[i].stream == stream)
1723                         return i;
1724         }
1725         return i;
1726 }
1727
1728 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1729 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1730 {
1731         struct sctp_association *asoc = q->asoc;
1732         struct sctp_chunk *ftsn_chunk = NULL;
1733         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1734         int nskips = 0;
1735         int skip_pos = 0;
1736         __u32 tsn;
1737         struct sctp_chunk *chunk;
1738         struct list_head *lchunk, *temp;
1739
1740         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1741          * received SACK.
1742          *
1743          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1744          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1745          */
1746         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1747                 asoc->adv_peer_ack_point = ctsn;
1748
1749         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1750          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1751          * the chunk next in the out-queue space is marked as "abandoned" as
1752          * shown in the following example:
1753          *
1754          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1755          * and the Advanced.Peer.Ack.Point is updated to this value:
1756          *
1757          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1758          *   normal SACK processing           local advancement
1759          *                ...                           ...
1760          *   Adv.Ack.Pt-> 102 acked                     102 acked
1761          *                103 abandoned                 103 abandoned
1762          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1763          *                105                           105
1764          *                106 acked                     106 acked
1765          *                ...                           ...
1766          *
1767          * In this example, the data sender successfully advanced the
1768          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1769          */
1770         list_for_each_safe(lchunk, temp, &q->abandoned) {
1771                 chunk = list_entry(lchunk, struct sctp_chunk,
1772                                         transmitted_list);
1773                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1774
1775                 /* Remove any chunks in the abandoned queue that are acked by
1776                  * the ctsn.
1777                  */
1778                 if (TSN_lte(tsn, ctsn)) {
1779                         list_del_init(lchunk);
1780                         sctp_chunk_free(chunk);
1781                 } else {
1782                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1783                                 asoc->adv_peer_ack_point = tsn;
1784                                 if (chunk->chunk_hdr->flags &
1785                                          SCTP_DATA_UNORDERED)
1786                                         continue;
1787                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1788                                                 nskips,
1789                                                 chunk->subh.data_hdr->stream);
1790                                 ftsn_skip_arr[skip_pos].stream =
1791                                         chunk->subh.data_hdr->stream;
1792                                 ftsn_skip_arr[skip_pos].ssn =
1793                                          chunk->subh.data_hdr->ssn;
1794                                 if (skip_pos == nskips)
1795                                         nskips++;
1796                                 if (nskips == 10)
1797                                         break;
1798                         } else
1799                                 break;
1800                 }
1801         }
1802
1803         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1804          * is greater than the Cumulative TSN ACK carried in the received
1805          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1806          * chunk containing the latest value of the
1807          * "Advanced.Peer.Ack.Point".
1808          *
1809          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1810          * list each stream and sequence number in the forwarded TSN. This
1811          * information will enable the receiver to easily find any
1812          * stranded TSN's waiting on stream reorder queues. Each stream
1813          * SHOULD only be reported once; this means that if multiple
1814          * abandoned messages occur in the same stream then only the
1815          * highest abandoned stream sequence number is reported. If the
1816          * total size of the FORWARD TSN does NOT fit in a single MTU then
1817          * the sender of the FORWARD TSN SHOULD lower the
1818          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1819          * single MTU.
1820          */
1821         if (asoc->adv_peer_ack_point > ctsn)
1822                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1823                                               nskips, &ftsn_skip_arr[0]);
1824
1825         if (ftsn_chunk) {
1826                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1827                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1828         }
1829 }