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