kernel/net/rxrpc/ar-ack.c

   1 /* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/circ_buf.h>
  14 #include <linux/net.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/slab.h>
  17 #include <linux/udp.h>
  18 #include <net/sock.h>
  19 #include <net/af_rxrpc.h>
  20 #include "ar-internal.h"
  21
  22 /*
  23  * How long to wait before scheduling ACK generation after seeing a
  24  * packet with RXRPC_REQUEST_ACK set (in jiffies).
  25  */
  26 unsigned rxrpc_requested_ack_delay = 1;
  27
  28 /*
  29  * How long to wait before scheduling an ACK with subtype DELAY (in jiffies).
  30  *
  31  * We use this when we've received new data packets.  If those packets aren't
  32  * all consumed within this time we will send a DELAY ACK if an ACK was not
  33  * requested to let the sender know it doesn't need to resend.
  34  */
  35 unsigned rxrpc_soft_ack_delay = 1 * HZ;
  36
  37 /*
  38  * How long to wait before scheduling an ACK with subtype IDLE (in jiffies).
  39  *
  40  * We use this when we've consumed some previously soft-ACK'd packets when
  41  * further packets aren't immediately received to decide when to send an IDLE
  42  * ACK let the other end know that it can free up its Tx buffer space.
  43  */
  44 unsigned rxrpc_idle_ack_delay = 0.5 * HZ;
  45
  46 /*
  47  * Receive window size in packets.  This indicates the maximum number of
  48  * unconsumed received packets we're willing to retain in memory.  Once this
  49  * limit is hit, we should generate an EXCEEDS_WINDOW ACK and discard further
  50  * packets.
  51  */
  52 unsigned rxrpc_rx_window_size = 32;
  53
  54 /*
  55  * Maximum Rx MTU size.  This indicates to the sender the size of jumbo packet
  56  * made by gluing normal packets together that we're willing to handle.
  57  */
  58 unsigned rxrpc_rx_mtu = 5692;
  59
  60 /*
  61  * The maximum number of fragments in a received jumbo packet that we tell the
  62  * sender that we're willing to handle.
  63  */
  64 unsigned rxrpc_rx_jumbo_max = 4;
  65
  66 static const char *rxrpc_acks(u8 reason)
  67 {
  68         static const char *const str[] = {
  69                 "---", "REQ", "DUP", "OOS", "WIN", "MEM", "PNG", "PNR", "DLY",
  70                 "IDL", "-?-"
  71         };
  72
  73         if (reason >= ARRAY_SIZE(str))
  74                 reason = ARRAY_SIZE(str) - 1;
  75         return str[reason];
  76 }
  77
  78 static const s8 rxrpc_ack_priority[] = {
  79         [0]                             = 0,
  80         [RXRPC_ACK_DELAY]               = 1,
  81         [RXRPC_ACK_REQUESTED]           = 2,
  82         [RXRPC_ACK_IDLE]                = 3,
  83         [RXRPC_ACK_PING_RESPONSE]       = 4,
  84         [RXRPC_ACK_DUPLICATE]           = 5,
  85         [RXRPC_ACK_OUT_OF_SEQUENCE]     = 6,
  86         [RXRPC_ACK_EXCEEDS_WINDOW]      = 7,
  87         [RXRPC_ACK_NOSPACE]             = 8,
  88 };
  89
  90 /*
  91  * propose an ACK be sent
  92  */
  93 void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
  94                          __be32 serial, bool immediate)
  95 {
  96         unsigned long expiry;
  97         s8 prior = rxrpc_ack_priority[ack_reason];
  98
  99         ASSERTCMP(prior, >, 0);
 100
 101         _enter("{%d},%s,%%%x,%u",
 102                call->debug_id, rxrpc_acks(ack_reason), ntohl(serial),
 103                immediate);
 104
 105         if (prior < rxrpc_ack_priority[call->ackr_reason]) {
 106                 if (immediate)
 107                         goto cancel_timer;
 108                 return;
 109         }
 110
 111         /* update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
 112          * numbers */
 113         if (prior == rxrpc_ack_priority[call->ackr_reason]) {
 114                 if (prior <= 4)
 115                         call->ackr_serial = serial;
 116                 if (immediate)
 117                         goto cancel_timer;
 118                 return;
 119         }
 120
 121         call->ackr_reason = ack_reason;
 122         call->ackr_serial = serial;
 123
 124         switch (ack_reason) {
 125         case RXRPC_ACK_DELAY:
 126                 _debug("run delay timer");
 127                 expiry = rxrpc_soft_ack_delay;
 128                 goto run_timer;
 129
 130         case RXRPC_ACK_IDLE:
 131                 if (!immediate) {
 132                         _debug("run defer timer");
 133                         expiry = rxrpc_idle_ack_delay;
 134                         goto run_timer;
 135                 }
 136                 goto cancel_timer;
 137
 138         case RXRPC_ACK_REQUESTED:
 139                 expiry = rxrpc_requested_ack_delay;
 140                 if (!expiry)
 141                         goto cancel_timer;
 142                 if (!immediate || serial == cpu_to_be32(1)) {
 143                         _debug("run defer timer");
 144                         goto run_timer;
 145                 }
 146
 147         default:
 148                 _debug("immediate ACK");
 149                 goto cancel_timer;
 150         }
 151
 152 run_timer:
 153         expiry += jiffies;
 154         if (!timer_pending(&call->ack_timer) ||
 155             time_after(call->ack_timer.expires, expiry))
 156                 mod_timer(&call->ack_timer, expiry);
 157         return;
 158
 159 cancel_timer:
 160         _debug("cancel timer %%%u", ntohl(serial));
 161         try_to_del_timer_sync(&call->ack_timer);
 162         read_lock_bh(&call->state_lock);
 163         if (call->state <= RXRPC_CALL_COMPLETE &&
 164             !test_and_set_bit(RXRPC_CALL_ACK, &call->events))
 165                 rxrpc_queue_call(call);
 166         read_unlock_bh(&call->state_lock);
 167 }
 168
 169 /*
 170  * propose an ACK be sent, locking the call structure
 171  */
 172 void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 173                        __be32 serial, bool immediate)
 174 {
 175         s8 prior = rxrpc_ack_priority[ack_reason];
 176
 177         if (prior > rxrpc_ack_priority[call->ackr_reason]) {
 178                 spin_lock_bh(&call->lock);
 179                 __rxrpc_propose_ACK(call, ack_reason, serial, immediate);
 180                 spin_unlock_bh(&call->lock);
 181         }
 182 }
 183
 184 /*
 185  * set the resend timer
 186  */
 187 static void rxrpc_set_resend(struct rxrpc_call *call, u8 resend,
 188                              unsigned long resend_at)
 189 {
 190         read_lock_bh(&call->state_lock);
 191         if (call->state >= RXRPC_CALL_COMPLETE)
 192                 resend = 0;
 193
 194         if (resend & 1) {
 195                 _debug("SET RESEND");
 196                 set_bit(RXRPC_CALL_RESEND, &call->events);
 197         }
 198
 199         if (resend & 2) {
 200                 _debug("MODIFY RESEND TIMER");
 201                 set_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 202                 mod_timer(&call->resend_timer, resend_at);
 203         } else {
 204                 _debug("KILL RESEND TIMER");
 205                 del_timer_sync(&call->resend_timer);
 206                 clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
 207                 clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 208         }
 209         read_unlock_bh(&call->state_lock);
 210 }
 211
 212 /*
 213  * resend packets
 214  */
 215 static void rxrpc_resend(struct rxrpc_call *call)
 216 {
 217         struct rxrpc_skb_priv *sp;
 218         struct rxrpc_header *hdr;
 219         struct sk_buff *txb;
 220         unsigned long *p_txb, resend_at;
 221         bool stop;
 222         int loop;
 223         u8 resend;
 224
 225         _enter("{%d,%d,%d,%d},",
 226                call->acks_hard, call->acks_unacked,
 227                atomic_read(&call->sequence),
 228                CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));
 229
 230         stop = false;
 231         resend = 0;
 232         resend_at = 0;
 233
 234         for (loop = call->acks_tail;
 235              loop != call->acks_head || stop;
 236              loop = (loop + 1) &  (call->acks_winsz - 1)
 237              ) {
 238                 p_txb = call->acks_window + loop;
 239                 smp_read_barrier_depends();
 240                 if (*p_txb & 1)
 241                         continue;
 242
 243                 txb = (struct sk_buff *) *p_txb;
 244                 sp = rxrpc_skb(txb);
 245
 246                 if (sp->need_resend) {
 247                         sp->need_resend = false;
 248
 249                         /* each Tx packet has a new serial number */
 250                         sp->hdr.serial =
 251                                 htonl(atomic_inc_return(&call->conn->serial));
 252
 253                         hdr = (struct rxrpc_header *) txb->head;
 254                         hdr->serial = sp->hdr.serial;
 255
 256                         _proto("Tx DATA %%%u { #%d }",
 257                                ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
 258                         if (rxrpc_send_packet(call->conn->trans, txb) < 0) {
 259                                 stop = true;
 260                                 sp->resend_at = jiffies + 3;
 261                         } else {
 262                                 sp->resend_at =
 263                                         jiffies + rxrpc_resend_timeout;
 264                         }
 265                 }
 266
 267                 if (time_after_eq(jiffies + 1, sp->resend_at)) {
 268                         sp->need_resend = true;
 269                         resend |= 1;
 270                 } else if (resend & 2) {
 271                         if (time_before(sp->resend_at, resend_at))
 272                                 resend_at = sp->resend_at;
 273                 } else {
 274                         resend_at = sp->resend_at;
 275                         resend |= 2;
 276                 }
 277         }
 278
 279         rxrpc_set_resend(call, resend, resend_at);
 280         _leave("");
 281 }
 282
 283 /*
 284  * handle resend timer expiry
 285  */
 286 static void rxrpc_resend_timer(struct rxrpc_call *call)
 287 {
 288         struct rxrpc_skb_priv *sp;
 289         struct sk_buff *txb;
 290         unsigned long *p_txb, resend_at;
 291         int loop;
 292         u8 resend;
 293
 294         _enter("%d,%d,%d",
 295                call->acks_tail, call->acks_unacked, call->acks_head);
 296
 297         if (call->state >= RXRPC_CALL_COMPLETE)
 298                 return;
 299
 300         resend = 0;
 301         resend_at = 0;
 302
 303         for (loop = call->acks_unacked;
 304              loop != call->acks_head;
 305              loop = (loop + 1) &  (call->acks_winsz - 1)
 306              ) {
 307                 p_txb = call->acks_window + loop;
 308                 smp_read_barrier_depends();
 309                 txb = (struct sk_buff *) (*p_txb & ~1);
 310                 sp = rxrpc_skb(txb);
 311
 312                 ASSERT(!(*p_txb & 1));
 313
 314                 if (sp->need_resend) {
 315                         ;
 316                 } else if (time_after_eq(jiffies + 1, sp->resend_at)) {
 317                         sp->need_resend = true;
 318                         resend |= 1;
 319                 } else if (resend & 2) {
 320                         if (time_before(sp->resend_at, resend_at))
 321                                 resend_at = sp->resend_at;
 322                 } else {
 323                         resend_at = sp->resend_at;
 324                         resend |= 2;
 325                 }
 326         }
 327
 328         rxrpc_set_resend(call, resend, resend_at);
 329         _leave("");
 330 }
 331
 332 /*
 333  * process soft ACKs of our transmitted packets
 334  * - these indicate packets the peer has or has not received, but hasn't yet
 335  *   given to the consumer, and so can still be discarded and re-requested
 336  */
 337 static int rxrpc_process_soft_ACKs(struct rxrpc_call *call,
 338                                    struct rxrpc_ackpacket *ack,
 339                                    struct sk_buff *skb)
 340 {
 341         struct rxrpc_skb_priv *sp;
 342         struct sk_buff *txb;
 343         unsigned long *p_txb, resend_at;
 344         int loop;
 345         u8 sacks[RXRPC_MAXACKS], resend;
 346
 347         _enter("{%d,%d},{%d},",
 348                call->acks_hard,
 349                CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz),
 350                ack->nAcks);
 351
 352         if (skb_copy_bits(skb, 0, sacks, ack->nAcks) < 0)
 353                 goto protocol_error;
 354
 355         resend = 0;
 356         resend_at = 0;
 357         for (loop = 0; loop < ack->nAcks; loop++) {
 358                 p_txb = call->acks_window;
 359                 p_txb += (call->acks_tail + loop) & (call->acks_winsz - 1);
 360                 smp_read_barrier_depends();
 361                 txb = (struct sk_buff *) (*p_txb & ~1);
 362                 sp = rxrpc_skb(txb);
 363
 364                 switch (sacks[loop]) {
 365                 case RXRPC_ACK_TYPE_ACK:
 366                         sp->need_resend = false;
 367                         *p_txb |= 1;
 368                         break;
 369                 case RXRPC_ACK_TYPE_NACK:
 370                         sp->need_resend = true;
 371                         *p_txb &= ~1;
 372                         resend = 1;
 373                         break;
 374                 default:
 375                         _debug("Unsupported ACK type %d", sacks[loop]);
 376                         goto protocol_error;
 377                 }
 378         }
 379
 380         smp_mb();
 381         call->acks_unacked = (call->acks_tail + loop) & (call->acks_winsz - 1);
 382
 383         /* anything not explicitly ACK'd is implicitly NACK'd, but may just not
 384          * have been received or processed yet by the far end */
 385         for (loop = call->acks_unacked;
 386              loop != call->acks_head;
 387              loop = (loop + 1) &  (call->acks_winsz - 1)
 388              ) {
 389                 p_txb = call->acks_window + loop;
 390                 smp_read_barrier_depends();
 391                 txb = (struct sk_buff *) (*p_txb & ~1);
 392                 sp = rxrpc_skb(txb);
 393
 394                 if (*p_txb & 1) {
 395                         /* packet must have been discarded */
 396                         sp->need_resend = true;
 397                         *p_txb &= ~1;
 398                         resend |= 1;
 399                 } else if (sp->need_resend) {
 400                         ;
 401                 } else if (time_after_eq(jiffies + 1, sp->resend_at)) {
 402                         sp->need_resend = true;
 403                         resend |= 1;
 404                 } else if (resend & 2) {
 405                         if (time_before(sp->resend_at, resend_at))
 406                                 resend_at = sp->resend_at;
 407                 } else {
 408                         resend_at = sp->resend_at;
 409                         resend |= 2;
 410                 }
 411         }
 412
 413         rxrpc_set_resend(call, resend, resend_at);
 414         _leave(" = 0");
 415         return 0;
 416
 417 protocol_error:
 418         _leave(" = -EPROTO");
 419         return -EPROTO;
 420 }
 421
 422 /*
 423  * discard hard-ACK'd packets from the Tx window
 424  */
 425 static void rxrpc_rotate_tx_window(struct rxrpc_call *call, u32 hard)
 426 {
 427         unsigned long _skb;
 428         int tail = call->acks_tail, old_tail;
 429         int win = CIRC_CNT(call->acks_head, tail, call->acks_winsz);
 430
 431         _enter("{%u,%u},%u", call->acks_hard, win, hard);
 432
 433         ASSERTCMP(hard - call->acks_hard, <=, win);
 434
 435         while (call->acks_hard < hard) {
 436                 smp_read_barrier_depends();
 437                 _skb = call->acks_window[tail] & ~1;
 438                 rxrpc_free_skb((struct sk_buff *) _skb);
 439                 old_tail = tail;
 440                 tail = (tail + 1) & (call->acks_winsz - 1);
 441                 call->acks_tail = tail;
 442                 if (call->acks_unacked == old_tail)
 443                         call->acks_unacked = tail;
 444                 call->acks_hard++;
 445         }
 446
 447         wake_up(&call->tx_waitq);
 448 }
 449
 450 /*
 451  * clear the Tx window in the event of a failure
 452  */
 453 static void rxrpc_clear_tx_window(struct rxrpc_call *call)
 454 {
 455         rxrpc_rotate_tx_window(call, atomic_read(&call->sequence));
 456 }
 457
 458 /*
 459  * drain the out of sequence received packet queue into the packet Rx queue
 460  */
 461 static int rxrpc_drain_rx_oos_queue(struct rxrpc_call *call)
 462 {
 463         struct rxrpc_skb_priv *sp;
 464         struct sk_buff *skb;
 465         bool terminal;
 466         int ret;
 467
 468         _enter("{%d,%d}", call->rx_data_post, call->rx_first_oos);
 469
 470         spin_lock_bh(&call->lock);
 471
 472         ret = -ECONNRESET;
 473         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 474                 goto socket_unavailable;
 475
 476         skb = skb_dequeue(&call->rx_oos_queue);
 477         if (skb) {
 478                 sp = rxrpc_skb(skb);
 479
 480                 _debug("drain OOS packet %d [%d]",
 481                        ntohl(sp->hdr.seq), call->rx_first_oos);
 482
 483                 if (ntohl(sp->hdr.seq) != call->rx_first_oos) {
 484                         skb_queue_head(&call->rx_oos_queue, skb);
 485                         call->rx_first_oos = ntohl(rxrpc_skb(skb)->hdr.seq);
 486                         _debug("requeue %p {%u}", skb, call->rx_first_oos);
 487                 } else {
 488                         skb->mark = RXRPC_SKB_MARK_DATA;
 489                         terminal = ((sp->hdr.flags & RXRPC_LAST_PACKET) &&
 490                                 !(sp->hdr.flags & RXRPC_CLIENT_INITIATED));
 491                         ret = rxrpc_queue_rcv_skb(call, skb, true, terminal);
 492                         BUG_ON(ret < 0);
 493                         _debug("drain #%u", call->rx_data_post);
 494                         call->rx_data_post++;
 495
 496                         /* find out what the next packet is */
 497                         skb = skb_peek(&call->rx_oos_queue);
 498                         if (skb)
 499                                 call->rx_first_oos =
 500                                         ntohl(rxrpc_skb(skb)->hdr.seq);
 501                         else
 502                                 call->rx_first_oos = 0;
 503                         _debug("peek %p {%u}", skb, call->rx_first_oos);
 504                 }
 505         }
 506
 507         ret = 0;
 508 socket_unavailable:
 509         spin_unlock_bh(&call->lock);
 510         _leave(" = %d", ret);
 511         return ret;
 512 }
 513
 514 /*
 515  * insert an out of sequence packet into the buffer
 516  */
 517 static void rxrpc_insert_oos_packet(struct rxrpc_call *call,
 518                                     struct sk_buff *skb)
 519 {
 520         struct rxrpc_skb_priv *sp, *psp;
 521         struct sk_buff *p;
 522         u32 seq;
 523
 524         sp = rxrpc_skb(skb);
 525         seq = ntohl(sp->hdr.seq);
 526         _enter(",,{%u}", seq);
 527
 528         skb->destructor = rxrpc_packet_destructor;
 529         ASSERTCMP(sp->call, ==, NULL);
 530         sp->call = call;
 531         rxrpc_get_call(call);
 532
 533         /* insert into the buffer in sequence order */
 534         spin_lock_bh(&call->lock);
 535
 536         skb_queue_walk(&call->rx_oos_queue, p) {
 537                 psp = rxrpc_skb(p);
 538                 if (ntohl(psp->hdr.seq) > seq) {
 539                         _debug("insert oos #%u before #%u",
 540                                seq, ntohl(psp->hdr.seq));
 541                         skb_insert(p, skb, &call->rx_oos_queue);
 542                         goto inserted;
 543                 }
 544         }
 545
 546         _debug("append oos #%u", seq);
 547         skb_queue_tail(&call->rx_oos_queue, skb);
 548 inserted:
 549
 550         /* we might now have a new front to the queue */
 551         if (call->rx_first_oos == 0 || seq < call->rx_first_oos)
 552                 call->rx_first_oos = seq;
 553
 554         read_lock(&call->state_lock);
 555         if (call->state < RXRPC_CALL_COMPLETE &&
 556             call->rx_data_post == call->rx_first_oos) {
 557                 _debug("drain rx oos now");
 558                 set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
 559         }
 560         read_unlock(&call->state_lock);
 561
 562         spin_unlock_bh(&call->lock);
 563         _leave(" [stored #%u]", call->rx_first_oos);
 564 }
 565
 566 /*
 567  * clear the Tx window on final ACK reception
 568  */
 569 static void rxrpc_zap_tx_window(struct rxrpc_call *call)
 570 {
 571         struct rxrpc_skb_priv *sp;
 572         struct sk_buff *skb;
 573         unsigned long _skb, *acks_window;
 574         u8 winsz = call->acks_winsz;
 575         int tail;
 576
 577         acks_window = call->acks_window;
 578         call->acks_window = NULL;
 579
 580         while (CIRC_CNT(call->acks_head, call->acks_tail, winsz) > 0) {
 581                 tail = call->acks_tail;
 582                 smp_read_barrier_depends();
 583                 _skb = acks_window[tail] & ~1;
 584                 smp_mb();
 585                 call->acks_tail = (call->acks_tail + 1) & (winsz - 1);
 586
 587                 skb = (struct sk_buff *) _skb;
 588                 sp = rxrpc_skb(skb);
 589                 _debug("+++ clear Tx %u", ntohl(sp->hdr.seq));
 590                 rxrpc_free_skb(skb);
 591         }
 592
 593         kfree(acks_window);
 594 }
 595
 596 /*
 597  * process the extra information that may be appended to an ACK packet
 598  */
 599 static void rxrpc_extract_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 600                                   unsigned int latest, int nAcks)
 601 {
 602         struct rxrpc_ackinfo ackinfo;
 603         struct rxrpc_peer *peer;
 604         unsigned int mtu;
 605
 606         if (skb_copy_bits(skb, nAcks + 3, &ackinfo, sizeof(ackinfo)) < 0) {
 607                 _leave(" [no ackinfo]");
 608                 return;
 609         }
 610
 611         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 612                latest,
 613                ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU),
 614                ntohl(ackinfo.rwind), ntohl(ackinfo.jumbo_max));
 615
 616         mtu = min(ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU));
 617
 618         peer = call->conn->trans->peer;
 619         if (mtu < peer->maxdata) {
 620                 spin_lock_bh(&peer->lock);
 621                 peer->maxdata = mtu;
 622                 peer->mtu = mtu + peer->hdrsize;
 623                 spin_unlock_bh(&peer->lock);
 624                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 625         }
 626 }
 627
 628 /*
 629  * process packets in the reception queue
 630  */
 631 static int rxrpc_process_rx_queue(struct rxrpc_call *call,
 632                                   u32 *_abort_code)
 633 {
 634         struct rxrpc_ackpacket ack;
 635         struct rxrpc_skb_priv *sp;
 636         struct sk_buff *skb;
 637         bool post_ACK;
 638         int latest;
 639         u32 hard, tx;
 640
 641         _enter("");
 642
 643 process_further:
 644         skb = skb_dequeue(&call->rx_queue);
 645         if (!skb)
 646                 return -EAGAIN;
 647
 648         _net("deferred skb %p", skb);
 649
 650         sp = rxrpc_skb(skb);
 651
 652         _debug("process %s [st %d]", rxrpc_pkts[sp->hdr.type], call->state);
 653
 654         post_ACK = false;
 655
 656         switch (sp->hdr.type) {
 657                 /* data packets that wind up here have been received out of
 658                  * order, need security processing or are jumbo packets */
 659         case RXRPC_PACKET_TYPE_DATA:
 660                 _proto("OOSQ DATA %%%u { #%u }",
 661                        ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
 662
 663                 /* secured packets must be verified and possibly decrypted */
 664                 if (rxrpc_verify_packet(call, skb, _abort_code) < 0)
 665                         goto protocol_error;
 666
 667                 rxrpc_insert_oos_packet(call, skb);
 668                 goto process_further;
 669
 670                 /* partial ACK to process */
 671         case RXRPC_PACKET_TYPE_ACK:
 672                 if (skb_copy_bits(skb, 0, &ack, sizeof(ack)) < 0) {
 673                         _debug("extraction failure");
 674                         goto protocol_error;
 675                 }
 676                 if (!skb_pull(skb, sizeof(ack)))
 677                         BUG();
 678
 679                 latest = ntohl(sp->hdr.serial);
 680                 hard = ntohl(ack.firstPacket);
 681                 tx = atomic_read(&call->sequence);
 682
 683                 _proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
 684                        latest,
 685                        ntohs(ack.maxSkew),
 686                        hard,
 687                        ntohl(ack.previousPacket),
 688                        ntohl(ack.serial),
 689                        rxrpc_acks(ack.reason),
 690                        ack.nAcks);
 691
 692                 rxrpc_extract_ackinfo(call, skb, latest, ack.nAcks);
 693
 694                 if (ack.reason == RXRPC_ACK_PING) {
 695                         _proto("Rx ACK %%%u PING Request", latest);
 696                         rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 697                                           sp->hdr.serial, true);
 698                 }
 699
 700                 /* discard any out-of-order or duplicate ACKs */
 701                 if (latest - call->acks_latest <= 0) {
 702                         _debug("discard ACK %d <= %d",
 703                                latest, call->acks_latest);
 704                         goto discard;
 705                 }
 706                 call->acks_latest = latest;
 707
 708                 if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
 709                     call->state != RXRPC_CALL_CLIENT_AWAIT_REPLY &&
 710                     call->state != RXRPC_CALL_SERVER_SEND_REPLY &&
 711                     call->state != RXRPC_CALL_SERVER_AWAIT_ACK)
 712                         goto discard;
 713
 714                 _debug("Tx=%d H=%u S=%d", tx, call->acks_hard, call->state);
 715
 716                 if (hard > 0) {
 717                         if (hard - 1 > tx) {
 718                                 _debug("hard-ACK'd packet %d not transmitted"
 719                                        " (%d top)",
 720                                        hard - 1, tx);
 721                                 goto protocol_error;
 722                         }
 723
 724                         if ((call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY ||
 725                              call->state == RXRPC_CALL_SERVER_AWAIT_ACK) &&
 726                             hard > tx) {
 727                                 call->acks_hard = tx;
 728                                 goto all_acked;
 729                         }
 730
 731                         smp_rmb();
 732                         rxrpc_rotate_tx_window(call, hard - 1);
 733                 }
 734
 735                 if (ack.nAcks > 0) {
 736                         if (hard - 1 + ack.nAcks > tx) {
 737                                 _debug("soft-ACK'd packet %d+%d not"
 738                                        " transmitted (%d top)",
 739                                        hard - 1, ack.nAcks, tx);
 740                                 goto protocol_error;
 741                         }
 742
 743                         if (rxrpc_process_soft_ACKs(call, &ack, skb) < 0)
 744                                 goto protocol_error;
 745                 }
 746                 goto discard;
 747
 748                 /* complete ACK to process */
 749         case RXRPC_PACKET_TYPE_ACKALL:
 750                 goto all_acked;
 751
 752                 /* abort and busy are handled elsewhere */
 753         case RXRPC_PACKET_TYPE_BUSY:
 754         case RXRPC_PACKET_TYPE_ABORT:
 755                 BUG();
 756
 757                 /* connection level events - also handled elsewhere */
 758         case RXRPC_PACKET_TYPE_CHALLENGE:
 759         case RXRPC_PACKET_TYPE_RESPONSE:
 760         case RXRPC_PACKET_TYPE_DEBUG:
 761                 BUG();
 762         }
 763
 764         /* if we've had a hard ACK that covers all the packets we've sent, then
 765          * that ends that phase of the operation */
 766 all_acked:
 767         write_lock_bh(&call->state_lock);
 768         _debug("ack all %d", call->state);
 769
 770         switch (call->state) {
 771         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 772                 call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
 773                 break;
 774         case RXRPC_CALL_SERVER_AWAIT_ACK:
 775                 _debug("srv complete");
 776                 call->state = RXRPC_CALL_COMPLETE;
 777                 post_ACK = true;
 778                 break;
 779         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 780         case RXRPC_CALL_SERVER_RECV_REQUEST:
 781                 goto protocol_error_unlock; /* can't occur yet */
 782         default:
 783                 write_unlock_bh(&call->state_lock);
 784                 goto discard; /* assume packet left over from earlier phase */
 785         }
 786
 787         write_unlock_bh(&call->state_lock);
 788
 789         /* if all the packets we sent are hard-ACK'd, then we can discard
 790          * whatever we've got left */
 791         _debug("clear Tx %d",
 792                CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));
 793
 794         del_timer_sync(&call->resend_timer);
 795         clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 796         clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
 797
 798         if (call->acks_window)
 799                 rxrpc_zap_tx_window(call);
 800
 801         if (post_ACK) {
 802                 /* post the final ACK message for userspace to pick up */
 803                 _debug("post ACK");
 804                 skb->mark = RXRPC_SKB_MARK_FINAL_ACK;
 805                 sp->call = call;
 806                 rxrpc_get_call(call);
 807                 spin_lock_bh(&call->lock);
 808                 if (rxrpc_queue_rcv_skb(call, skb, true, true) < 0)
 809                         BUG();
 810                 spin_unlock_bh(&call->lock);
 811                 goto process_further;
 812         }
 813
 814 discard:
 815         rxrpc_free_skb(skb);
 816         goto process_further;
 817
 818 protocol_error_unlock:
 819         write_unlock_bh(&call->state_lock);
 820 protocol_error:
 821         rxrpc_free_skb(skb);
 822         _leave(" = -EPROTO");
 823         return -EPROTO;
 824 }
 825
 826 /*
 827  * post a message to the socket Rx queue for recvmsg() to pick up
 828  */
 829 static int rxrpc_post_message(struct rxrpc_call *call, u32 mark, u32 error,
 830                               bool fatal)
 831 {
 832         struct rxrpc_skb_priv *sp;
 833         struct sk_buff *skb;
 834         int ret;
 835
 836         _enter("{%d,%lx},%u,%u,%d",
 837                call->debug_id, call->flags, mark, error, fatal);
 838
 839         /* remove timers and things for fatal messages */
 840         if (fatal) {
 841                 del_timer_sync(&call->resend_timer);
 842                 del_timer_sync(&call->ack_timer);
 843                 clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 844         }
 845
 846         if (mark != RXRPC_SKB_MARK_NEW_CALL &&
 847             !test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 848                 _leave("[no userid]");
 849                 return 0;
 850         }
 851
 852         if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
 853                 skb = alloc_skb(0, GFP_NOFS);
 854                 if (!skb)
 855                         return -ENOMEM;
 856
 857                 rxrpc_new_skb(skb);
 858
 859                 skb->mark = mark;
 860
 861                 sp = rxrpc_skb(skb);
 862                 memset(sp, 0, sizeof(*sp));
 863                 sp->error = error;
 864                 sp->call = call;
 865                 rxrpc_get_call(call);
 866
 867                 spin_lock_bh(&call->lock);
 868                 ret = rxrpc_queue_rcv_skb(call, skb, true, fatal);
 869                 spin_unlock_bh(&call->lock);
 870                 BUG_ON(ret < 0);
 871         }
 872
 873         return 0;
 874 }
 875
 876 /*
 877  * handle background processing of incoming call packets and ACK / abort
 878  * generation
 879  */
 880 void rxrpc_process_call(struct work_struct *work)
 881 {
 882         struct rxrpc_call *call =
 883                 container_of(work, struct rxrpc_call, processor);
 884         struct rxrpc_ackpacket ack;
 885         struct rxrpc_ackinfo ackinfo;
 886         struct rxrpc_header hdr;
 887         struct msghdr msg;
 888         struct kvec iov[5];
 889         unsigned long bits;
 890         __be32 data, pad;
 891         size_t len;
 892         int genbit, loop, nbit, ioc, ret, mtu;
 893         u32 abort_code = RX_PROTOCOL_ERROR;
 894         u8 *acks = NULL;
 895
 896         //printk("\n--------------------\n");
 897         _enter("{%d,%s,%lx} [%lu]",
 898                call->debug_id, rxrpc_call_states[call->state], call->events,
 899                (jiffies - call->creation_jif) / (HZ / 10));
 900
 901         if (test_and_set_bit(RXRPC_CALL_PROC_BUSY, &call->flags)) {
 902                 _debug("XXXXXXXXXXXXX RUNNING ON MULTIPLE CPUS XXXXXXXXXXXXX");
 903                 return;
 904         }
 905
 906         /* there's a good chance we're going to have to send a message, so set
 907          * one up in advance */
 908         msg.msg_name    = &call->conn->trans->peer->srx.transport.sin;
 909         msg.msg_namelen = sizeof(call->conn->trans->peer->srx.transport.sin);
 910         msg.msg_control = NULL;
 911         msg.msg_controllen = 0;
 912         msg.msg_flags   = 0;
 913
 914         hdr.epoch       = call->conn->epoch;
 915         hdr.cid         = call->cid;
 916         hdr.callNumber  = call->call_id;
 917         hdr.seq         = 0;
 918         hdr.type        = RXRPC_PACKET_TYPE_ACK;
 919         hdr.flags       = call->conn->out_clientflag;
 920         hdr.userStatus  = 0;
 921         hdr.securityIndex = call->conn->security_ix;
 922         hdr._rsvd       = 0;
 923         hdr.serviceId   = call->conn->service_id;
 924
 925         memset(iov, 0, sizeof(iov));
 926         iov[0].iov_base = &hdr;
 927         iov[0].iov_len  = sizeof(hdr);
 928
 929         /* deal with events of a final nature */
 930         if (test_bit(RXRPC_CALL_RELEASE, &call->events)) {
 931                 rxrpc_release_call(call);
 932                 clear_bit(RXRPC_CALL_RELEASE, &call->events);
 933         }
 934
 935         if (test_bit(RXRPC_CALL_RCVD_ERROR, &call->events)) {
 936                 int error;
 937
 938                 clear_bit(RXRPC_CALL_CONN_ABORT, &call->events);
 939                 clear_bit(RXRPC_CALL_REJECT_BUSY, &call->events);
 940                 clear_bit(RXRPC_CALL_ABORT, &call->events);
 941
 942                 error = call->conn->trans->peer->net_error;
 943                 _debug("post net error %d", error);
 944
 945                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_NET_ERROR,
 946                                        error, true) < 0)
 947                         goto no_mem;
 948                 clear_bit(RXRPC_CALL_RCVD_ERROR, &call->events);
 949                 goto kill_ACKs;
 950         }
 951
 952         if (test_bit(RXRPC_CALL_CONN_ABORT, &call->events)) {
 953                 ASSERTCMP(call->state, >, RXRPC_CALL_COMPLETE);
 954
 955                 clear_bit(RXRPC_CALL_REJECT_BUSY, &call->events);
 956                 clear_bit(RXRPC_CALL_ABORT, &call->events);
 957
 958                 _debug("post conn abort");
 959
 960                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
 961                                        call->conn->error, true) < 0)
 962                         goto no_mem;
 963                 clear_bit(RXRPC_CALL_CONN_ABORT, &call->events);
 964                 goto kill_ACKs;
 965         }
 966
 967         if (test_bit(RXRPC_CALL_REJECT_BUSY, &call->events)) {
 968                 hdr.type = RXRPC_PACKET_TYPE_BUSY;
 969                 genbit = RXRPC_CALL_REJECT_BUSY;
 970                 goto send_message;
 971         }
 972
 973         if (test_bit(RXRPC_CALL_ABORT, &call->events)) {
 974                 ASSERTCMP(call->state, >, RXRPC_CALL_COMPLETE);
 975
 976                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
 977                                        ECONNABORTED, true) < 0)
 978                         goto no_mem;
 979                 hdr.type = RXRPC_PACKET_TYPE_ABORT;
 980                 data = htonl(call->abort_code);
 981                 iov[1].iov_base = &data;
 982                 iov[1].iov_len = sizeof(data);
 983                 genbit = RXRPC_CALL_ABORT;
 984                 goto send_message;
 985         }
 986
 987         if (test_bit(RXRPC_CALL_ACK_FINAL, &call->events)) {
 988                 genbit = RXRPC_CALL_ACK_FINAL;
 989
 990                 ack.bufferSpace = htons(8);
 991                 ack.maxSkew     = 0;
 992                 ack.serial      = 0;
 993                 ack.reason      = RXRPC_ACK_IDLE;
 994                 ack.nAcks       = 0;
 995                 call->ackr_reason = 0;
 996
 997                 spin_lock_bh(&call->lock);
 998                 ack.serial = call->ackr_serial;
 999                 ack.previousPacket = call->ackr_prev_seq;
1000                 ack.firstPacket = htonl(call->rx_data_eaten + 1);
1001                 spin_unlock_bh(&call->lock);
1002
1003                 pad = 0;
1004
1005                 iov[1].iov_base = &ack;
1006                 iov[1].iov_len  = sizeof(ack);
1007                 iov[2].iov_base = &pad;
1008                 iov[2].iov_len  = 3;
1009                 iov[3].iov_base = &ackinfo;
1010                 iov[3].iov_len  = sizeof(ackinfo);
1011                 goto send_ACK;
1012         }
1013
1014         if (call->events & ((1 << RXRPC_CALL_RCVD_BUSY) |
1015                             (1 << RXRPC_CALL_RCVD_ABORT))
1016             ) {
1017                 u32 mark;
1018
1019                 if (test_bit(RXRPC_CALL_RCVD_ABORT, &call->events))
1020                         mark = RXRPC_SKB_MARK_REMOTE_ABORT;
1021                 else
1022                         mark = RXRPC_SKB_MARK_BUSY;
1023
1024                 _debug("post abort/busy");
1025                 rxrpc_clear_tx_window(call);
1026                 if (rxrpc_post_message(call, mark, ECONNABORTED, true) < 0)
1027                         goto no_mem;
1028
1029                 clear_bit(RXRPC_CALL_RCVD_BUSY, &call->events);
1030                 clear_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
1031                 goto kill_ACKs;
1032         }
1033
1034         if (test_and_clear_bit(RXRPC_CALL_RCVD_ACKALL, &call->events)) {
1035                 _debug("do implicit ackall");
1036                 rxrpc_clear_tx_window(call);
1037         }
1038
1039         if (test_bit(RXRPC_CALL_LIFE_TIMER, &call->events)) {
1040                 write_lock_bh(&call->state_lock);
1041                 if (call->state <= RXRPC_CALL_COMPLETE) {
1042                         call->state = RXRPC_CALL_LOCALLY_ABORTED;
1043                         call->abort_code = RX_CALL_TIMEOUT;
1044                         set_bit(RXRPC_CALL_ABORT, &call->events);
1045                 }
1046                 write_unlock_bh(&call->state_lock);
1047
1048                 _debug("post timeout");
1049                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
1050                                        ETIME, true) < 0)
1051                         goto no_mem;
1052
1053                 clear_bit(RXRPC_CALL_LIFE_TIMER, &call->events);
1054                 goto kill_ACKs;
1055         }
1056
1057         /* deal with assorted inbound messages */
1058         if (!skb_queue_empty(&call->rx_queue)) {
1059                 switch (rxrpc_process_rx_queue(call, &abort_code)) {
1060                 case 0:
1061                 case -EAGAIN:
1062                         break;
1063                 case -ENOMEM:
1064                         goto no_mem;
1065                 case -EKEYEXPIRED:
1066                 case -EKEYREJECTED:
1067                 case -EPROTO:
1068                         rxrpc_abort_call(call, abort_code);
1069                         goto kill_ACKs;
1070                 }
1071         }
1072
1073         /* handle resending */
1074         if (test_and_clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events))
1075                 rxrpc_resend_timer(call);
1076         if (test_and_clear_bit(RXRPC_CALL_RESEND, &call->events))
1077                 rxrpc_resend(call);
1078
1079         /* consider sending an ordinary ACK */
1080         if (test_bit(RXRPC_CALL_ACK, &call->events)) {
1081                 _debug("send ACK: window: %d - %d { %lx }",
1082                        call->rx_data_eaten, call->ackr_win_top,
1083                        call->ackr_window[0]);
1084
1085                 if (call->state > RXRPC_CALL_SERVER_ACK_REQUEST &&
1086                     call->ackr_reason != RXRPC_ACK_PING_RESPONSE) {
1087                         /* ACK by sending reply DATA packet in this state */
1088                         clear_bit(RXRPC_CALL_ACK, &call->events);
1089                         goto maybe_reschedule;
1090                 }
1091
1092                 genbit = RXRPC_CALL_ACK;
1093
1094                 acks = kzalloc(call->ackr_win_top - call->rx_data_eaten,
1095                                GFP_NOFS);
1096                 if (!acks)
1097                         goto no_mem;
1098
1099                 //hdr.flags     = RXRPC_SLOW_START_OK;
1100                 ack.bufferSpace = htons(8);
1101                 ack.maxSkew     = 0;
1102                 ack.serial      = 0;
1103                 ack.reason      = 0;
1104
1105                 spin_lock_bh(&call->lock);
1106                 ack.reason = call->ackr_reason;
1107                 ack.serial = call->ackr_serial;
1108                 ack.previousPacket = call->ackr_prev_seq;
1109                 ack.firstPacket = htonl(call->rx_data_eaten + 1);
1110
1111                 ack.nAcks = 0;
1112                 for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
1113                         nbit = loop * BITS_PER_LONG;
1114                         for (bits = call->ackr_window[loop]; bits; bits >>= 1
1115                              ) {
1116                                 _debug("- l=%d n=%d b=%lx", loop, nbit, bits);
1117                                 if (bits & 1) {
1118                                         acks[nbit] = RXRPC_ACK_TYPE_ACK;
1119                                         ack.nAcks = nbit + 1;
1120                                 }
1121                                 nbit++;
1122                         }
1123                 }
1124                 call->ackr_reason = 0;
1125                 spin_unlock_bh(&call->lock);
1126
1127                 pad = 0;
1128
1129                 iov[1].iov_base = &ack;
1130                 iov[1].iov_len  = sizeof(ack);
1131                 iov[2].iov_base = acks;
1132                 iov[2].iov_len  = ack.nAcks;
1133                 iov[3].iov_base = &pad;
1134                 iov[3].iov_len  = 3;
1135                 iov[4].iov_base = &ackinfo;
1136                 iov[4].iov_len  = sizeof(ackinfo);
1137
1138                 switch (ack.reason) {
1139                 case RXRPC_ACK_REQUESTED:
1140                 case RXRPC_ACK_DUPLICATE:
1141                 case RXRPC_ACK_OUT_OF_SEQUENCE:
1142                 case RXRPC_ACK_EXCEEDS_WINDOW:
1143                 case RXRPC_ACK_NOSPACE:
1144                 case RXRPC_ACK_PING:
1145                 case RXRPC_ACK_PING_RESPONSE:
1146                         goto send_ACK_with_skew;
1147                 case RXRPC_ACK_DELAY:
1148                 case RXRPC_ACK_IDLE:
1149                         goto send_ACK;
1150                 }
1151         }
1152
1153         /* handle completion of security negotiations on an incoming
1154          * connection */
1155         if (test_and_clear_bit(RXRPC_CALL_SECURED, &call->events)) {
1156                 _debug("secured");
1157                 spin_lock_bh(&call->lock);
1158
1159                 if (call->state == RXRPC_CALL_SERVER_SECURING) {
1160                         _debug("securing");
1161                         write_lock(&call->conn->lock);
1162                         if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
1163                             !test_bit(RXRPC_CALL_RELEASE, &call->events)) {
1164                                 _debug("not released");
1165                                 call->state = RXRPC_CALL_SERVER_ACCEPTING;
1166                                 list_move_tail(&call->accept_link,
1167                                                &call->socket->acceptq);
1168                         }
1169                         write_unlock(&call->conn->lock);
1170                         read_lock(&call->state_lock);
1171                         if (call->state < RXRPC_CALL_COMPLETE)
1172                                 set_bit(RXRPC_CALL_POST_ACCEPT, &call->events);
1173                         read_unlock(&call->state_lock);
1174                 }
1175
1176                 spin_unlock_bh(&call->lock);
1177                 if (!test_bit(RXRPC_CALL_POST_ACCEPT, &call->events))
1178                         goto maybe_reschedule;
1179         }
1180
1181         /* post a notification of an acceptable connection to the app */
1182         if (test_bit(RXRPC_CALL_POST_ACCEPT, &call->events)) {
1183                 _debug("post accept");
1184                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_NEW_CALL,
1185                                        0, false) < 0)
1186                         goto no_mem;
1187                 clear_bit(RXRPC_CALL_POST_ACCEPT, &call->events);
1188                 goto maybe_reschedule;
1189         }
1190
1191         /* handle incoming call acceptance */
1192         if (test_and_clear_bit(RXRPC_CALL_ACCEPTED, &call->events)) {
1193                 _debug("accepted");
1194                 ASSERTCMP(call->rx_data_post, ==, 0);
1195                 call->rx_data_post = 1;
1196                 read_lock_bh(&call->state_lock);
1197                 if (call->state < RXRPC_CALL_COMPLETE)
1198                         set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
1199                 read_unlock_bh(&call->state_lock);
1200         }
1201
1202         /* drain the out of sequence received packet queue into the packet Rx
1203          * queue */
1204         if (test_and_clear_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events)) {
1205                 while (call->rx_data_post == call->rx_first_oos)
1206                         if (rxrpc_drain_rx_oos_queue(call) < 0)
1207                                 break;
1208                 goto maybe_reschedule;
1209         }
1210
1211         /* other events may have been raised since we started checking */
1212         goto maybe_reschedule;
1213
1214 send_ACK_with_skew:
1215         ack.maxSkew = htons(atomic_read(&call->conn->hi_serial) -
1216                             ntohl(ack.serial));
1217 send_ACK:
1218         mtu = call->conn->trans->peer->if_mtu;
1219         mtu -= call->conn->trans->peer->hdrsize;
1220         ackinfo.maxMTU  = htonl(mtu);
1221         ackinfo.rwind   = htonl(rxrpc_rx_window_size);
1222
1223         /* permit the peer to send us jumbo packets if it wants to */
1224         ackinfo.rxMTU   = htonl(rxrpc_rx_mtu);
1225         ackinfo.jumbo_max = htonl(rxrpc_rx_jumbo_max);
1226
1227         hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
1228         _proto("Tx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
1229                ntohl(hdr.serial),
1230                ntohs(ack.maxSkew),
1231                ntohl(ack.firstPacket),
1232                ntohl(ack.previousPacket),
1233                ntohl(ack.serial),
1234                rxrpc_acks(ack.reason),
1235                ack.nAcks);
1236
1237         del_timer_sync(&call->ack_timer);
1238         if (ack.nAcks > 0)
1239                 set_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags);
1240         goto send_message_2;
1241
1242 send_message:
1243         _debug("send message");
1244
1245         hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
1246         _proto("Tx %s %%%u", rxrpc_pkts[hdr.type], ntohl(hdr.serial));
1247 send_message_2:
1248
1249         len = iov[0].iov_len;
1250         ioc = 1;
1251         if (iov[4].iov_len) {
1252                 ioc = 5;
1253                 len += iov[4].iov_len;
1254                 len += iov[3].iov_len;
1255                 len += iov[2].iov_len;
1256                 len += iov[1].iov_len;
1257         } else if (iov[3].iov_len) {
1258                 ioc = 4;
1259                 len += iov[3].iov_len;
1260                 len += iov[2].iov_len;
1261                 len += iov[1].iov_len;
1262         } else if (iov[2].iov_len) {
1263                 ioc = 3;
1264                 len += iov[2].iov_len;
1265                 len += iov[1].iov_len;
1266         } else if (iov[1].iov_len) {
1267                 ioc = 2;
1268                 len += iov[1].iov_len;
1269         }
1270
1271         ret = kernel_sendmsg(call->conn->trans->local->socket,
1272                              &msg, iov, ioc, len);
1273         if (ret < 0) {
1274                 _debug("sendmsg failed: %d", ret);
1275                 read_lock_bh(&call->state_lock);
1276                 if (call->state < RXRPC_CALL_DEAD)
1277                         rxrpc_queue_call(call);
1278                 read_unlock_bh(&call->state_lock);
1279                 goto error;
1280         }
1281
1282         switch (genbit) {
1283         case RXRPC_CALL_ABORT:
1284                 clear_bit(genbit, &call->events);
1285                 clear_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
1286                 goto kill_ACKs;
1287
1288         case RXRPC_CALL_ACK_FINAL:
1289                 write_lock_bh(&call->state_lock);
1290                 if (call->state == RXRPC_CALL_CLIENT_FINAL_ACK)
1291                         call->state = RXRPC_CALL_COMPLETE;
1292                 write_unlock_bh(&call->state_lock);
1293                 goto kill_ACKs;
1294
1295         default:
1296                 clear_bit(genbit, &call->events);
1297                 switch (call->state) {
1298                 case RXRPC_CALL_CLIENT_AWAIT_REPLY:
1299                 case RXRPC_CALL_CLIENT_RECV_REPLY:
1300                 case RXRPC_CALL_SERVER_RECV_REQUEST:
1301                 case RXRPC_CALL_SERVER_ACK_REQUEST:
1302                         _debug("start ACK timer");
1303                         rxrpc_propose_ACK(call, RXRPC_ACK_DELAY,
1304                                           call->ackr_serial, false);
1305                 default:
1306                         break;
1307                 }
1308                 goto maybe_reschedule;
1309         }
1310
1311 kill_ACKs:
1312         del_timer_sync(&call->ack_timer);
1313         if (test_and_clear_bit(RXRPC_CALL_ACK_FINAL, &call->events))
1314                 rxrpc_put_call(call);
1315         clear_bit(RXRPC_CALL_ACK, &call->events);
1316
1317 maybe_reschedule:
1318         if (call->events || !skb_queue_empty(&call->rx_queue)) {
1319                 read_lock_bh(&call->state_lock);
1320                 if (call->state < RXRPC_CALL_DEAD)
1321                         rxrpc_queue_call(call);
1322                 read_unlock_bh(&call->state_lock);
1323         }
1324
1325         /* don't leave aborted connections on the accept queue */
1326         if (call->state >= RXRPC_CALL_COMPLETE &&
1327             !list_empty(&call->accept_link)) {
1328                 _debug("X unlinking once-pending call %p { e=%lx f=%lx c=%x }",
1329                        call, call->events, call->flags,
1330                        ntohl(call->conn->cid));
1331
1332                 read_lock_bh(&call->state_lock);
1333                 if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
1334                     !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
1335                         rxrpc_queue_call(call);
1336                 read_unlock_bh(&call->state_lock);
1337         }
1338
1339 error:
1340         clear_bit(RXRPC_CALL_PROC_BUSY, &call->flags);
1341         kfree(acks);
1342
1343         /* because we don't want two CPUs both processing the work item for one
1344          * call at the same time, we use a flag to note when it's busy; however
1345          * this means there's a race between clearing the flag and setting the
1346          * work pending bit and the work item being processed again */
1347         if (call->events && !work_pending(&call->processor)) {
1348                 _debug("jumpstart %x", ntohl(call->conn->cid));
1349                 rxrpc_queue_call(call);
1350         }
1351
1352         _leave("");
1353         return;
1354
1355 no_mem:
1356         _debug("out of memory");
1357         goto maybe_reschedule;
1358 }