net/sctp/ulpqueue.c

   1 /* SCTP kernel reference 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 Intel Corp.
   6  * Copyright (c) 2001 Nokia, Inc.
   7  * Copyright (c) 2001 La Monte H.P. Yarroll
   8  *
   9  * This abstraction carries sctp events to the ULP (sockets).
  10  *
  11  * The SCTP reference implementation is free software;
  12  * you can redistribute it and/or modify it under the terms of
  13  * the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2, or (at your option)
  15  * any later version.
  16  *
  17  * The SCTP reference implementation is distributed in the hope that it
  18  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  19  *                 ************************
  20  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  21  * See the GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with GNU CC; see the file COPYING.  If not, write to
  25  * the Free Software Foundation, 59 Temple Place - Suite 330,
  26  * Boston, MA 02111-1307, USA.
  27  *
  28  * Please send any bug reports or fixes you make to the
  29  * email address(es):
  30  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  31  *
  32  * Or submit a bug report through the following website:
  33  *    http://www.sf.net/projects/lksctp
  34  *
  35  * Written or modified by:
  36  *    Jon Grimm             <jgrimm@us.ibm.com>
  37  *    La Monte H.P. Yarroll <piggy@acm.org>
  38  *    Sridhar Samudrala     <sri@us.ibm.com>
  39  *
  40  * Any bugs reported given to us we will try to fix... any fixes shared will
  41  * be incorporated into the next SCTP release.
  42  */
  43
  44 #include <linux/types.h>
  45 #include <linux/skbuff.h>
  46 #include <net/sock.h>
  47 #include <net/sctp/structs.h>
  48 #include <net/sctp/sctp.h>
  49 #include <net/sctp/sm.h>
  50
  51 /* Forward declarations for internal helpers.  */
  52 static struct sctp_ulpevent * sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
  53                                               struct sctp_ulpevent *);
  54 static struct sctp_ulpevent * sctp_ulpq_order(struct sctp_ulpq *,
  55                                               struct sctp_ulpevent *);
  56
  57 /* 1st Level Abstractions */
  58
  59 /* Initialize a ULP queue from a block of memory.  */
  60 struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,
  61                                  struct sctp_association *asoc)
  62 {
  63         memset(ulpq, 0, sizeof(struct sctp_ulpq));
  64
  65         ulpq->asoc = asoc;
  66         skb_queue_head_init(&ulpq->reasm);
  67         skb_queue_head_init(&ulpq->lobby);
  68         ulpq->pd_mode  = 0;
  69         ulpq->malloced = 0;
  70
  71         return ulpq;
  72 }
  73
  74
  75 /* Flush the reassembly and ordering queues.  */
  76 static void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
  77 {
  78         struct sk_buff *skb;
  79         struct sctp_ulpevent *event;
  80
  81         while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) {
  82                 event = sctp_skb2event(skb);
  83                 sctp_ulpevent_free(event);
  84         }
  85
  86         while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) {
  87                 event = sctp_skb2event(skb);
  88                 sctp_ulpevent_free(event);
  89         }
  90
  91 }
  92
  93 /* Dispose of a ulpqueue.  */
  94 void sctp_ulpq_free(struct sctp_ulpq *ulpq)
  95 {
  96         sctp_ulpq_flush(ulpq);
  97         if (ulpq->malloced)
  98                 kfree(ulpq);
  99 }
 100
 101 /* Process an incoming DATA chunk.  */
 102 int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 103                         unsigned int __nocast gfp)
 104 {
 105         struct sk_buff_head temp;
 106         sctp_data_chunk_t *hdr;
 107         struct sctp_ulpevent *event;
 108
 109         hdr = (sctp_data_chunk_t *) chunk->chunk_hdr;
 110
 111         /* Create an event from the incoming chunk. */
 112         event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);
 113         if (!event)
 114                 return -ENOMEM;
 115
 116         /* Do reassembly if needed.  */
 117         event = sctp_ulpq_reasm(ulpq, event);
 118
 119         /* Do ordering if needed.  */
 120         if ((event) && (event->msg_flags & MSG_EOR)){
 121                 /* Create a temporary list to collect chunks on.  */
 122                 skb_queue_head_init(&temp);
 123                 __skb_queue_tail(&temp, sctp_event2skb(event));
 124
 125                 event = sctp_ulpq_order(ulpq, event);
 126         }
 127
 128         /* Send event to the ULP.  'event' is the sctp_ulpevent for
 129          * very first SKB on the 'temp' list.
 130          */
 131         if (event)
 132                 sctp_ulpq_tail_event(ulpq, event);
 133
 134         return 0;
 135 }
 136
 137 /* Add a new event for propagation to the ULP.  */
 138 /* Clear the partial delivery mode for this socket.   Note: This
 139  * assumes that no association is currently in partial delivery mode.
 140  */
 141 int sctp_clear_pd(struct sock *sk)
 142 {
 143         struct sctp_sock *sp = sctp_sk(sk);
 144
 145         sp->pd_mode = 0;
 146         if (!skb_queue_empty(&sp->pd_lobby)) {
 147                 struct list_head *list;
 148                 sctp_skb_list_tail(&sp->pd_lobby, &sk->sk_receive_queue);
 149                 list = (struct list_head *)&sctp_sk(sk)->pd_lobby;
 150                 INIT_LIST_HEAD(list);
 151                 return 1;
 152         }
 153         return 0;
 154 }
 155
 156 /* Clear the pd_mode and restart any pending messages waiting for delivery. */
 157 static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
 158 {
 159         ulpq->pd_mode = 0;
 160         return sctp_clear_pd(ulpq->asoc->base.sk);
 161 }
 162
 163 /* If the SKB of 'event' is on a list, it is the first such member
 164  * of that list.
 165  */
 166 int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
 167 {
 168         struct sock *sk = ulpq->asoc->base.sk;
 169         struct sk_buff_head *queue, *skb_list;
 170         struct sk_buff *skb = sctp_event2skb(event);
 171         int clear_pd = 0;
 172
 173         skb_list = (struct sk_buff_head *) skb->prev;
 174
 175         /* If the socket is just going to throw this away, do not
 176          * even try to deliver it.
 177          */
 178         if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))
 179                 goto out_free;
 180
 181         /* Check if the user wishes to receive this event.  */
 182         if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))
 183                 goto out_free;
 184
 185         /* If we are in partial delivery mode, post to the lobby until
 186          * partial delivery is cleared, unless, of course _this_ is
 187          * the association the cause of the partial delivery.
 188          */
 189
 190         if (!sctp_sk(sk)->pd_mode) {
 191                 queue = &sk->sk_receive_queue;
 192         } else if (ulpq->pd_mode) {
 193                 if (event->msg_flags & MSG_NOTIFICATION)
 194                         queue = &sctp_sk(sk)->pd_lobby;
 195                 else {
 196                         clear_pd = event->msg_flags & MSG_EOR;
 197                         queue = &sk->sk_receive_queue;
 198                 }
 199         } else
 200                 queue = &sctp_sk(sk)->pd_lobby;
 201
 202
 203         /* If we are harvesting multiple skbs they will be
 204          * collected on a list.
 205          */
 206         if (skb_list)
 207                 sctp_skb_list_tail(skb_list, queue);
 208         else
 209                 __skb_queue_tail(queue, skb);
 210
 211         /* Did we just complete partial delivery and need to get
 212          * rolling again?  Move pending data to the receive
 213          * queue.
 214          */
 215         if (clear_pd)
 216                 sctp_ulpq_clear_pd(ulpq);
 217
 218         if (queue == &sk->sk_receive_queue)
 219                 sk->sk_data_ready(sk, 0);
 220         return 1;
 221
 222 out_free:
 223         if (skb_list)
 224                 sctp_queue_purge_ulpevents(skb_list);
 225         else
 226                 sctp_ulpevent_free(event);
 227
 228         return 0;
 229 }
 230
 231 /* 2nd Level Abstractions */
 232
 233 /* Helper function to store chunks that need to be reassembled.  */
 234 static inline void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,
 235                                          struct sctp_ulpevent *event)
 236 {
 237         struct sk_buff *pos;
 238         struct sctp_ulpevent *cevent;
 239         __u32 tsn, ctsn;
 240
 241         tsn = event->tsn;
 242
 243         /* See if it belongs at the end. */
 244         pos = skb_peek_tail(&ulpq->reasm);
 245         if (!pos) {
 246                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
 247                 return;
 248         }
 249
 250         /* Short circuit just dropping it at the end. */
 251         cevent = sctp_skb2event(pos);
 252         ctsn = cevent->tsn;
 253         if (TSN_lt(ctsn, tsn)) {
 254                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
 255                 return;
 256         }
 257
 258         /* Find the right place in this list. We store them by TSN.  */
 259         skb_queue_walk(&ulpq->reasm, pos) {
 260                 cevent = sctp_skb2event(pos);
 261                 ctsn = cevent->tsn;
 262
 263                 if (TSN_lt(tsn, ctsn))
 264                         break;
 265         }
 266
 267         /* Insert before pos. */
 268         __skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->reasm);
 269
 270 }
 271
 272 /* Helper function to return an event corresponding to the reassembled
 273  * datagram.
 274  * This routine creates a re-assembled skb given the first and last skb's
 275  * as stored in the reassembly queue. The skb's may be non-linear if the sctp
 276  * payload was fragmented on the way and ip had to reassemble them.
 277  * We add the rest of skb's to the first skb's fraglist.
 278  */
 279 static struct sctp_ulpevent *sctp_make_reassembled_event(struct sk_buff_head *queue, struct sk_buff *f_frag, struct sk_buff *l_frag)
 280 {
 281         struct sk_buff *pos;
 282         struct sctp_ulpevent *event;
 283         struct sk_buff *pnext, *last;
 284         struct sk_buff *list = skb_shinfo(f_frag)->frag_list;
 285
 286         /* Store the pointer to the 2nd skb */
 287         if (f_frag == l_frag)
 288                 pos = NULL;
 289         else
 290                 pos = f_frag->next;
 291
 292         /* Get the last skb in the f_frag's frag_list if present. */
 293         for (last = list; list; last = list, list = list->next);
 294
 295         /* Add the list of remaining fragments to the first fragments
 296          * frag_list.
 297          */
 298         if (last)
 299                 last->next = pos;
 300         else
 301                 skb_shinfo(f_frag)->frag_list = pos;
 302
 303         /* Remove the first fragment from the reassembly queue.  */
 304         __skb_unlink(f_frag, queue);
 305         while (pos) {
 306
 307                 pnext = pos->next;
 308
 309                 /* Update the len and data_len fields of the first fragment. */
 310                 f_frag->len += pos->len;
 311                 f_frag->data_len += pos->len;
 312
 313                 /* Remove the fragment from the reassembly queue.  */
 314                 __skb_unlink(pos, queue);
 315
 316                 /* Break if we have reached the last fragment.  */
 317                 if (pos == l_frag)
 318                         break;
 319                 pos->next = pnext;
 320                 pos = pnext;
 321         };
 322
 323         event = sctp_skb2event(f_frag);
 324         SCTP_INC_STATS(SCTP_MIB_REASMUSRMSGS);
 325
 326         return event;
 327 }
 328
 329
 330 /* Helper function to check if an incoming chunk has filled up the last
 331  * missing fragment in a SCTP datagram and return the corresponding event.
 332  */
 333 static inline struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq)
 334 {
 335         struct sk_buff *pos;
 336         struct sctp_ulpevent *cevent;
 337         struct sk_buff *first_frag = NULL;
 338         __u32 ctsn, next_tsn;
 339         struct sctp_ulpevent *retval = NULL;
 340
 341         /* Initialized to 0 just to avoid compiler warning message.  Will
 342          * never be used with this value. It is referenced only after it
 343          * is set when we find the first fragment of a message.
 344          */
 345         next_tsn = 0;
 346
 347         /* The chunks are held in the reasm queue sorted by TSN.
 348          * Walk through the queue sequentially and look for a sequence of
 349          * fragmented chunks that complete a datagram.
 350          * 'first_frag' and next_tsn are reset when we find a chunk which
 351          * is the first fragment of a datagram. Once these 2 fields are set
 352          * we expect to find the remaining middle fragments and the last
 353          * fragment in order. If not, first_frag is reset to NULL and we
 354          * start the next pass when we find another first fragment.
 355          */
 356         skb_queue_walk(&ulpq->reasm, pos) {
 357                 cevent = sctp_skb2event(pos);
 358                 ctsn = cevent->tsn;
 359
 360                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 361                 case SCTP_DATA_FIRST_FRAG:
 362                         first_frag = pos;
 363                         next_tsn = ctsn + 1;
 364                         break;
 365
 366                 case SCTP_DATA_MIDDLE_FRAG:
 367                         if ((first_frag) && (ctsn == next_tsn))
 368                                 next_tsn++;
 369                         else
 370                                 first_frag = NULL;
 371                         break;
 372
 373                 case SCTP_DATA_LAST_FRAG:
 374                         if (first_frag && (ctsn == next_tsn))
 375                                 goto found;
 376                         else
 377                                 first_frag = NULL;
 378                         break;
 379                 };
 380
 381         }
 382 done:
 383         return retval;
 384 found:
 385         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, pos);
 386         if (retval)
 387                 retval->msg_flags |= MSG_EOR;
 388         goto done;
 389 }
 390
 391 /* Retrieve the next set of fragments of a partial message. */
 392 static inline struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq)
 393 {
 394         struct sk_buff *pos, *last_frag, *first_frag;
 395         struct sctp_ulpevent *cevent;
 396         __u32 ctsn, next_tsn;
 397         int is_last;
 398         struct sctp_ulpevent *retval;
 399
 400         /* The chunks are held in the reasm queue sorted by TSN.
 401          * Walk through the queue sequentially and look for the first
 402          * sequence of fragmented chunks.
 403          */
 404
 405         if (skb_queue_empty(&ulpq->reasm))
 406                 return NULL;
 407
 408         last_frag = first_frag = NULL;
 409         retval = NULL;
 410         next_tsn = 0;
 411         is_last = 0;
 412
 413         skb_queue_walk(&ulpq->reasm, pos) {
 414                 cevent = sctp_skb2event(pos);
 415                 ctsn = cevent->tsn;
 416
 417                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 418                 case SCTP_DATA_MIDDLE_FRAG:
 419                         if (!first_frag) {
 420                                 first_frag = pos;
 421                                 next_tsn = ctsn + 1;
 422                                 last_frag = pos;
 423                         } else if (next_tsn == ctsn)
 424                                 next_tsn++;
 425                         else
 426                                 goto done;
 427                         break;
 428                 case SCTP_DATA_LAST_FRAG:
 429                         if (!first_frag)
 430                                 first_frag = pos;
 431                         else if (ctsn != next_tsn)
 432                                 goto done;
 433                         last_frag = pos;
 434                         is_last = 1;
 435                         goto done;
 436                 default:
 437                         return NULL;
 438                 };
 439         }
 440
 441         /* We have the reassembled event. There is no need to look
 442          * further.
 443          */
 444 done:
 445         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);
 446         if (retval && is_last)
 447                 retval->msg_flags |= MSG_EOR;
 448
 449         return retval;
 450 }
 451
 452
 453 /* Helper function to reassemble chunks.  Hold chunks on the reasm queue that
 454  * need reassembling.
 455  */
 456 static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
 457                                                 struct sctp_ulpevent *event)
 458 {
 459         struct sctp_ulpevent *retval = NULL;
 460
 461         /* Check if this is part of a fragmented message.  */
 462         if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {
 463                 event->msg_flags |= MSG_EOR;
 464                 return event;
 465         }
 466
 467         sctp_ulpq_store_reasm(ulpq, event);
 468         if (!ulpq->pd_mode)
 469                 retval = sctp_ulpq_retrieve_reassembled(ulpq);
 470         else {
 471                 __u32 ctsn, ctsnap;
 472
 473                 /* Do not even bother unless this is the next tsn to
 474                  * be delivered.
 475                  */
 476                 ctsn = event->tsn;
 477                 ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);
 478                 if (TSN_lte(ctsn, ctsnap))
 479                         retval = sctp_ulpq_retrieve_partial(ulpq);
 480         }
 481
 482         return retval;
 483 }
 484
 485 /* Retrieve the first part (sequential fragments) for partial delivery.  */
 486 static inline struct sctp_ulpevent *sctp_ulpq_retrieve_first(struct sctp_ulpq *ulpq)
 487 {
 488         struct sk_buff *pos, *last_frag, *first_frag;
 489         struct sctp_ulpevent *cevent;
 490         __u32 ctsn, next_tsn;
 491         struct sctp_ulpevent *retval;
 492
 493         /* The chunks are held in the reasm queue sorted by TSN.
 494          * Walk through the queue sequentially and look for a sequence of
 495          * fragmented chunks that start a datagram.
 496          */
 497
 498         if (skb_queue_empty(&ulpq->reasm))
 499                 return NULL;
 500
 501         last_frag = first_frag = NULL;
 502         retval = NULL;
 503         next_tsn = 0;
 504
 505         skb_queue_walk(&ulpq->reasm, pos) {
 506                 cevent = sctp_skb2event(pos);
 507                 ctsn = cevent->tsn;
 508
 509                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 510                 case SCTP_DATA_FIRST_FRAG:
 511                         if (!first_frag) {
 512                                 first_frag = pos;
 513                                 next_tsn = ctsn + 1;
 514                                 last_frag = pos;
 515                         } else
 516                                 goto done;
 517                         break;
 518
 519                 case SCTP_DATA_MIDDLE_FRAG:
 520                         if (!first_frag)
 521                                 return NULL;
 522                         if (ctsn == next_tsn) {
 523                                 next_tsn++;
 524                                 last_frag = pos;
 525                         } else
 526                                 goto done;
 527                         break;
 528                 default:
 529                         return NULL;
 530                 };
 531         }
 532
 533         /* We have the reassembled event. There is no need to look
 534          * further.
 535          */
 536 done:
 537         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);
 538         return retval;
 539 }
 540
 541 /* Helper function to gather skbs that have possibly become
 542  * ordered by an an incoming chunk.
 543  */
 544 static inline void sctp_ulpq_retrieve_ordered(struct sctp_ulpq *ulpq,
 545                                               struct sctp_ulpevent *event)
 546 {
 547         struct sk_buff_head *event_list;
 548         struct sk_buff *pos, *tmp;
 549         struct sctp_ulpevent *cevent;
 550         struct sctp_stream *in;
 551         __u16 sid, csid;
 552         __u16 ssn, cssn;
 553
 554         sid = event->stream;
 555         ssn = event->ssn;
 556         in  = &ulpq->asoc->ssnmap->in;
 557
 558         event_list = (struct sk_buff_head *) sctp_event2skb(event)->prev;
 559
 560         /* We are holding the chunks by stream, by SSN.  */
 561         sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
 562                 cevent = (struct sctp_ulpevent *) pos->cb;
 563                 csid = cevent->stream;
 564                 cssn = cevent->ssn;
 565
 566                 /* Have we gone too far?  */
 567                 if (csid > sid)
 568                         break;
 569
 570                 /* Have we not gone far enough?  */
 571                 if (csid < sid)
 572                         continue;
 573
 574                 if (cssn != sctp_ssn_peek(in, sid))
 575                         break;
 576
 577                 /* Found it, so mark in the ssnmap. */
 578                 sctp_ssn_next(in, sid);
 579
 580                 __skb_unlink(pos, &ulpq->lobby);
 581
 582                 /* Attach all gathered skbs to the event.  */
 583                 __skb_queue_tail(event_list, pos);
 584         }
 585 }
 586
 587 /* Helper function to store chunks needing ordering.  */
 588 static inline void sctp_ulpq_store_ordered(struct sctp_ulpq *ulpq,
 589                                            struct sctp_ulpevent *event)
 590 {
 591         struct sk_buff *pos;
 592         struct sctp_ulpevent *cevent;
 593         __u16 sid, csid;
 594         __u16 ssn, cssn;
 595
 596         pos = skb_peek_tail(&ulpq->lobby);
 597         if (!pos) {
 598                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 599                 return;
 600         }
 601
 602         sid = event->stream;
 603         ssn = event->ssn;
 604
 605         cevent = (struct sctp_ulpevent *) pos->cb;
 606         csid = cevent->stream;
 607         cssn = cevent->ssn;
 608         if (sid > csid) {
 609                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 610                 return;
 611         }
 612
 613         if ((sid == csid) && SSN_lt(cssn, ssn)) {
 614                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 615                 return;
 616         }
 617
 618         /* Find the right place in this list.  We store them by
 619          * stream ID and then by SSN.
 620          */
 621         skb_queue_walk(&ulpq->lobby, pos) {
 622                 cevent = (struct sctp_ulpevent *) pos->cb;
 623                 csid = cevent->stream;
 624                 cssn = cevent->ssn;
 625
 626                 if (csid > sid)
 627                         break;
 628                 if (csid == sid && SSN_lt(ssn, cssn))
 629                         break;
 630         }
 631
 632
 633         /* Insert before pos. */
 634         __skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->lobby);
 635
 636 }
 637
 638 static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
 639                                              struct sctp_ulpevent *event)
 640 {
 641         __u16 sid, ssn;
 642         struct sctp_stream *in;
 643
 644         /* Check if this message needs ordering.  */
 645         if (SCTP_DATA_UNORDERED & event->msg_flags)
 646                 return event;
 647
 648         /* Note: The stream ID must be verified before this routine.  */
 649         sid = event->stream;
 650         ssn = event->ssn;
 651         in  = &ulpq->asoc->ssnmap->in;
 652
 653         /* Is this the expected SSN for this stream ID?  */
 654         if (ssn != sctp_ssn_peek(in, sid)) {
 655                 /* We've received something out of order, so find where it
 656                  * needs to be placed.  We order by stream and then by SSN.
 657                  */
 658                 sctp_ulpq_store_ordered(ulpq, event);
 659                 return NULL;
 660         }
 661
 662         /* Mark that the next chunk has been found.  */
 663         sctp_ssn_next(in, sid);
 664
 665         /* Go find any other chunks that were waiting for
 666          * ordering.
 667          */
 668         sctp_ulpq_retrieve_ordered(ulpq, event);
 669
 670         return event;
 671 }
 672
 673 /* Helper function to gather skbs that have possibly become
 674  * ordered by forward tsn skipping their dependencies.
 675  */
 676 static inline void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq)
 677 {
 678         struct sk_buff *pos, *tmp;
 679         struct sctp_ulpevent *cevent;
 680         struct sctp_ulpevent *event;
 681         struct sctp_stream *in;
 682         struct sk_buff_head temp;
 683         __u16 csid, cssn;
 684
 685         in  = &ulpq->asoc->ssnmap->in;
 686
 687         /* We are holding the chunks by stream, by SSN.  */
 688         skb_queue_head_init(&temp);
 689         event = NULL;
 690         sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
 691                 cevent = (struct sctp_ulpevent *) pos->cb;
 692                 csid = cevent->stream;
 693                 cssn = cevent->ssn;
 694
 695                 if (cssn != sctp_ssn_peek(in, csid))
 696                         break;
 697
 698                 /* Found it, so mark in the ssnmap. */
 699                 sctp_ssn_next(in, csid);
 700
 701                 __skb_unlink(pos, &ulpq->lobby);
 702                 if (!event) {
 703                         /* Create a temporary list to collect chunks on.  */
 704                         event = sctp_skb2event(pos);
 705                         __skb_queue_tail(&temp, sctp_event2skb(event));
 706                 } else {
 707                         /* Attach all gathered skbs to the event.  */
 708                         __skb_queue_tail(&temp, pos);
 709                 }
 710         }
 711
 712         /* Send event to the ULP.  'event' is the sctp_ulpevent for
 713          * very first SKB on the 'temp' list.
 714          */
 715         if (event)
 716                 sctp_ulpq_tail_event(ulpq, event);
 717 }
 718
 719 /* Skip over an SSN. */
 720 void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
 721 {
 722         struct sctp_stream *in;
 723
 724         /* Note: The stream ID must be verified before this routine.  */
 725         in  = &ulpq->asoc->ssnmap->in;
 726
 727         /* Is this an old SSN?  If so ignore. */
 728         if (SSN_lt(ssn, sctp_ssn_peek(in, sid)))
 729                 return;
 730
 731         /* Mark that we are no longer expecting this SSN or lower. */
 732         sctp_ssn_skip(in, sid, ssn);
 733
 734         /* Go find any other chunks that were waiting for
 735          * ordering and deliver them if needed.
 736          */
 737         sctp_ulpq_reap_ordered(ulpq);
 738         return;
 739 }
 740
 741 /* Renege 'needed' bytes from the ordering queue. */
 742 static __u16 sctp_ulpq_renege_order(struct sctp_ulpq *ulpq, __u16 needed)
 743 {
 744         __u16 freed = 0;
 745         __u32 tsn;
 746         struct sk_buff *skb;
 747         struct sctp_ulpevent *event;
 748         struct sctp_tsnmap *tsnmap;
 749
 750         tsnmap = &ulpq->asoc->peer.tsn_map;
 751
 752         while ((skb = __skb_dequeue_tail(&ulpq->lobby)) != NULL) {
 753                 freed += skb_headlen(skb);
 754                 event = sctp_skb2event(skb);
 755                 tsn = event->tsn;
 756
 757                 sctp_ulpevent_free(event);
 758                 sctp_tsnmap_renege(tsnmap, tsn);
 759                 if (freed >= needed)
 760                         return freed;
 761         }
 762
 763         return freed;
 764 }
 765
 766 /* Renege 'needed' bytes from the reassembly queue. */
 767 static __u16 sctp_ulpq_renege_frags(struct sctp_ulpq *ulpq, __u16 needed)
 768 {
 769         __u16 freed = 0;
 770         __u32 tsn;
 771         struct sk_buff *skb;
 772         struct sctp_ulpevent *event;
 773         struct sctp_tsnmap *tsnmap;
 774
 775         tsnmap = &ulpq->asoc->peer.tsn_map;
 776
 777         /* Walk backwards through the list, reneges the newest tsns. */
 778         while ((skb = __skb_dequeue_tail(&ulpq->reasm)) != NULL) {
 779                 freed += skb_headlen(skb);
 780                 event = sctp_skb2event(skb);
 781                 tsn = event->tsn;
 782
 783                 sctp_ulpevent_free(event);
 784                 sctp_tsnmap_renege(tsnmap, tsn);
 785                 if (freed >= needed)
 786                         return freed;
 787         }
 788
 789         return freed;
 790 }
 791
 792 /* Partial deliver the first message as there is pressure on rwnd. */
 793 void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
 794                                 struct sctp_chunk *chunk,
 795                                 unsigned int __nocast gfp)
 796 {
 797         struct sctp_ulpevent *event;
 798         struct sctp_association *asoc;
 799
 800         asoc = ulpq->asoc;
 801
 802         /* Are we already in partial delivery mode?  */
 803         if (!sctp_sk(asoc->base.sk)->pd_mode) {
 804
 805                 /* Is partial delivery possible?  */
 806                 event = sctp_ulpq_retrieve_first(ulpq);
 807                 /* Send event to the ULP.   */
 808                 if (event) {
 809                         sctp_ulpq_tail_event(ulpq, event);
 810                         sctp_sk(asoc->base.sk)->pd_mode = 1;
 811                         ulpq->pd_mode = 1;
 812                         return;
 813                 }
 814         }
 815 }
 816
 817 /* Renege some packets to make room for an incoming chunk.  */
 818 void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 819                       unsigned int __nocast gfp)
 820 {
 821         struct sctp_association *asoc;
 822         __u16 needed, freed;
 823
 824         asoc = ulpq->asoc;
 825
 826         if (chunk) {
 827                 needed = ntohs(chunk->chunk_hdr->length);
 828                 needed -= sizeof(sctp_data_chunk_t);
 829         } else
 830                 needed = SCTP_DEFAULT_MAXWINDOW;
 831
 832         freed = 0;
 833
 834         if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
 835                 freed = sctp_ulpq_renege_order(ulpq, needed);
 836                 if (freed < needed) {
 837                         freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
 838                 }
 839         }
 840         /* If able to free enough room, accept this chunk. */
 841         if (chunk && (freed >= needed)) {
 842                 __u32 tsn;
 843                 tsn = ntohl(chunk->subh.data_hdr->tsn);
 844                 sctp_tsnmap_mark(&asoc->peer.tsn_map, tsn);
 845                 sctp_ulpq_tail_data(ulpq, chunk, gfp);
 846
 847                 sctp_ulpq_partial_delivery(ulpq, chunk, gfp);
 848         }
 849
 850         return;
 851 }
 852
 853
 854
 855 /* Notify the application if an association is aborted and in
 856  * partial delivery mode.  Send up any pending received messages.
 857  */
 858 void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, unsigned int __nocast gfp)
 859 {
 860         struct sctp_ulpevent *ev = NULL;
 861         struct sock *sk;
 862
 863         if (!ulpq->pd_mode)
 864                 return;
 865
 866         sk = ulpq->asoc->base.sk;
 867         if (sctp_ulpevent_type_enabled(SCTP_PARTIAL_DELIVERY_EVENT,
 868                                        &sctp_sk(sk)->subscribe))
 869                 ev = sctp_ulpevent_make_pdapi(ulpq->asoc,
 870                                               SCTP_PARTIAL_DELIVERY_ABORTED,
 871                                               gfp);
 872         if (ev)
 873                 __skb_queue_tail(&sk->sk_receive_queue, sctp_event2skb(ev));
 874
 875         /* If there is data waiting, send it up the socket now. */
 876         if (sctp_ulpq_clear_pd(ulpq) || ev)
 877                 sk->sk_data_ready(sk, 0);
 878 }