net/rxrpc/input.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Processing of received RxRPC packets
   3  *
   4  * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include "ar-internal.h"
  11
  12 /* Override priority when generating ACKs for received DATA */
  13 static const u8 rxrpc_ack_priority[RXRPC_ACK__INVALID] = {
  14         [RXRPC_ACK_IDLE]                = 1,
  15         [RXRPC_ACK_DELAY]               = 2,
  16         [RXRPC_ACK_REQUESTED]           = 3,
  17         [RXRPC_ACK_DUPLICATE]           = 4,
  18         [RXRPC_ACK_EXCEEDS_WINDOW]      = 5,
  19         [RXRPC_ACK_NOSPACE]             = 6,
  20         [RXRPC_ACK_OUT_OF_SEQUENCE]     = 7,
  21 };
  22
  23 static void rxrpc_proto_abort(struct rxrpc_call *call, rxrpc_seq_t seq,
  24                               enum rxrpc_abort_reason why)
  25 {
  26         rxrpc_abort_call(call, seq, RX_PROTOCOL_ERROR, -EBADMSG, why);
  27 }
  28
  29 /*
  30  * Do TCP-style congestion management [RFC 5681].
  31  */
  32 static void rxrpc_congestion_management(struct rxrpc_call *call,
  33                                         struct sk_buff *skb,
  34                                         struct rxrpc_ack_summary *summary,
  35                                         rxrpc_serial_t acked_serial)
  36 {
  37         enum rxrpc_congest_change change = rxrpc_cong_no_change;
  38         unsigned int cumulative_acks = call->cong_cumul_acks;
  39         unsigned int cwnd = call->cong_cwnd;
  40         bool resend = false;
  41
  42         summary->flight_size =
  43                 (call->tx_top - call->acks_hard_ack) - summary->nr_acks;
  44
  45         if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
  46                 summary->retrans_timeo = true;
  47                 call->cong_ssthresh = max_t(unsigned int,
  48                                             summary->flight_size / 2, 2);
  49                 cwnd = 1;
  50                 if (cwnd >= call->cong_ssthresh &&
  51                     call->cong_mode == RXRPC_CALL_SLOW_START) {
  52                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  53                         call->cong_tstamp = skb->tstamp;
  54                         cumulative_acks = 0;
  55                 }
  56         }
  57
  58         cumulative_acks += summary->nr_new_acks;
  59         if (cumulative_acks > 255)
  60                 cumulative_acks = 255;
  61
  62         summary->cwnd = call->cong_cwnd;
  63         summary->ssthresh = call->cong_ssthresh;
  64         summary->cumulative_acks = cumulative_acks;
  65         summary->dup_acks = call->cong_dup_acks;
  66
  67         switch (call->cong_mode) {
  68         case RXRPC_CALL_SLOW_START:
  69                 if (summary->saw_nacks)
  70                         goto packet_loss_detected;
  71                 if (summary->cumulative_acks > 0)
  72                         cwnd += 1;
  73                 if (cwnd >= call->cong_ssthresh) {
  74                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  75                         call->cong_tstamp = skb->tstamp;
  76                 }
  77                 goto out;
  78
  79         case RXRPC_CALL_CONGEST_AVOIDANCE:
  80                 if (summary->saw_nacks)
  81                         goto packet_loss_detected;
  82
  83                 /* We analyse the number of packets that get ACK'd per RTT
  84                  * period and increase the window if we managed to fill it.
  85                  */
  86                 if (call->peer->rtt_count == 0)
  87                         goto out;
  88                 if (ktime_before(skb->tstamp,
  89                                  ktime_add_us(call->cong_tstamp,
  90                                               call->peer->srtt_us >> 3)))
  91                         goto out_no_clear_ca;
  92                 change = rxrpc_cong_rtt_window_end;
  93                 call->cong_tstamp = skb->tstamp;
  94                 if (cumulative_acks >= cwnd)
  95                         cwnd++;
  96                 goto out;
  97
  98         case RXRPC_CALL_PACKET_LOSS:
  99                 if (!summary->saw_nacks)
 100                         goto resume_normality;
 101
 102                 if (summary->new_low_nack) {
 103                         change = rxrpc_cong_new_low_nack;
 104                         call->cong_dup_acks = 1;
 105                         if (call->cong_extra > 1)
 106                                 call->cong_extra = 1;
 107                         goto send_extra_data;
 108                 }
 109
 110                 call->cong_dup_acks++;
 111                 if (call->cong_dup_acks < 3)
 112                         goto send_extra_data;
 113
 114                 change = rxrpc_cong_begin_retransmission;
 115                 call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
 116                 call->cong_ssthresh = max_t(unsigned int,
 117                                             summary->flight_size / 2, 2);
 118                 cwnd = call->cong_ssthresh + 3;
 119                 call->cong_extra = 0;
 120                 call->cong_dup_acks = 0;
 121                 resend = true;
 122                 goto out;
 123
 124         case RXRPC_CALL_FAST_RETRANSMIT:
 125                 if (!summary->new_low_nack) {
 126                         if (summary->nr_new_acks == 0)
 127                                 cwnd += 1;
 128                         call->cong_dup_acks++;
 129                         if (call->cong_dup_acks == 2) {
 130                                 change = rxrpc_cong_retransmit_again;
 131                                 call->cong_dup_acks = 0;
 132                                 resend = true;
 133                         }
 134                 } else {
 135                         change = rxrpc_cong_progress;
 136                         cwnd = call->cong_ssthresh;
 137                         if (!summary->saw_nacks)
 138                                 goto resume_normality;
 139                 }
 140                 goto out;
 141
 142         default:
 143                 BUG();
 144                 goto out;
 145         }
 146
 147 resume_normality:
 148         change = rxrpc_cong_cleared_nacks;
 149         call->cong_dup_acks = 0;
 150         call->cong_extra = 0;
 151         call->cong_tstamp = skb->tstamp;
 152         if (cwnd < call->cong_ssthresh)
 153                 call->cong_mode = RXRPC_CALL_SLOW_START;
 154         else
 155                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 156 out:
 157         cumulative_acks = 0;
 158 out_no_clear_ca:
 159         if (cwnd >= RXRPC_TX_MAX_WINDOW)
 160                 cwnd = RXRPC_TX_MAX_WINDOW;
 161         call->cong_cwnd = cwnd;
 162         call->cong_cumul_acks = cumulative_acks;
 163         summary->mode = call->cong_mode;
 164         trace_rxrpc_congest(call, summary, acked_serial, change);
 165         if (resend)
 166                 rxrpc_resend(call, skb);
 167         return;
 168
 169 packet_loss_detected:
 170         change = rxrpc_cong_saw_nack;
 171         call->cong_mode = RXRPC_CALL_PACKET_LOSS;
 172         call->cong_dup_acks = 0;
 173         goto send_extra_data;
 174
 175 send_extra_data:
 176         /* Send some previously unsent DATA if we have some to advance the ACK
 177          * state.
 178          */
 179         if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ||
 180             summary->nr_acks != call->tx_top - call->acks_hard_ack) {
 181                 call->cong_extra++;
 182                 wake_up(&call->waitq);
 183         }
 184         goto out_no_clear_ca;
 185 }
 186
 187 /*
 188  * Degrade the congestion window if we haven't transmitted a packet for >1RTT.
 189  */
 190 void rxrpc_congestion_degrade(struct rxrpc_call *call)
 191 {
 192         ktime_t rtt, now;
 193
 194         if (call->cong_mode != RXRPC_CALL_SLOW_START &&
 195             call->cong_mode != RXRPC_CALL_CONGEST_AVOIDANCE)
 196                 return;
 197         if (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 198                 return;
 199
 200         rtt = ns_to_ktime(call->peer->srtt_us * (1000 / 8));
 201         now = ktime_get_real();
 202         if (!ktime_before(ktime_add(call->tx_last_sent, rtt), now))
 203                 return;
 204
 205         trace_rxrpc_reset_cwnd(call, now);
 206         rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);
 207         call->tx_last_sent = now;
 208         call->cong_mode = RXRPC_CALL_SLOW_START;
 209         call->cong_ssthresh = max_t(unsigned int, call->cong_ssthresh,
 210                                     call->cong_cwnd * 3 / 4);
 211         call->cong_cwnd = max_t(unsigned int, call->cong_cwnd / 2, RXRPC_MIN_CWND);
 212 }
 213
 214 /*
 215  * Apply a hard ACK by advancing the Tx window.
 216  */
 217 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
 218                                    struct rxrpc_ack_summary *summary)
 219 {
 220         struct rxrpc_txbuf *txb;
 221         bool rot_last = false;
 222
 223         list_for_each_entry_rcu(txb, &call->tx_buffer, call_link, false) {
 224                 if (before_eq(txb->seq, call->acks_hard_ack))
 225                         continue;
 226                 if (txb->flags & RXRPC_LAST_PACKET) {
 227                         set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 228                         rot_last = true;
 229                 }
 230                 if (txb->seq == to)
 231                         break;
 232         }
 233
 234         if (rot_last)
 235                 set_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags);
 236
 237         _enter("%x,%x,%x,%d", to, call->acks_hard_ack, call->tx_top, rot_last);
 238
 239         if (call->acks_lowest_nak == call->acks_hard_ack) {
 240                 call->acks_lowest_nak = to;
 241         } else if (after(to, call->acks_lowest_nak)) {
 242                 summary->new_low_nack = true;
 243                 call->acks_lowest_nak = to;
 244         }
 245
 246         smp_store_release(&call->acks_hard_ack, to);
 247
 248         trace_rxrpc_txqueue(call, (rot_last ?
 249                                    rxrpc_txqueue_rotate_last :
 250                                    rxrpc_txqueue_rotate));
 251         wake_up(&call->waitq);
 252         return rot_last;
 253 }
 254
 255 /*
 256  * End the transmission phase of a call.
 257  *
 258  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 259  * or a final ACK packet.
 260  */
 261 static void rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 262                                enum rxrpc_abort_reason abort_why)
 263 {
 264         ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 265
 266         call->resend_at = KTIME_MAX;
 267         trace_rxrpc_timer_can(call, rxrpc_timer_trace_resend);
 268
 269         if (unlikely(call->cong_last_nack)) {
 270                 rxrpc_free_skb(call->cong_last_nack, rxrpc_skb_put_last_nack);
 271                 call->cong_last_nack = NULL;
 272         }
 273
 274         switch (__rxrpc_call_state(call)) {
 275         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 276         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 277                 if (reply_begun) {
 278                         rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_RECV_REPLY);
 279                         trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
 280                         break;
 281                 }
 282
 283                 rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
 284                 trace_rxrpc_txqueue(call, rxrpc_txqueue_await_reply);
 285                 break;
 286
 287         case RXRPC_CALL_SERVER_AWAIT_ACK:
 288                 rxrpc_call_completed(call);
 289                 trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
 290                 break;
 291
 292         default:
 293                 kdebug("end_tx %s", rxrpc_call_states[__rxrpc_call_state(call)]);
 294                 rxrpc_proto_abort(call, call->tx_top, abort_why);
 295                 break;
 296         }
 297 }
 298
 299 /*
 300  * Begin the reply reception phase of a call.
 301  */
 302 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 303 {
 304         struct rxrpc_ack_summary summary = { 0 };
 305         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 306
 307         if (call->ackr_reason) {
 308                 call->delay_ack_at = KTIME_MAX;
 309                 trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
 310         }
 311
 312         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 313                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 314                         rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);
 315                         return false;
 316                 }
 317         }
 318
 319         rxrpc_end_tx_phase(call, true, rxrpc_eproto_unexpected_reply);
 320         return true;
 321 }
 322
 323 /*
 324  * End the packet reception phase.
 325  */
 326 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
 327 {
 328         rxrpc_seq_t whigh = READ_ONCE(call->rx_highest_seq);
 329
 330         _enter("%d,%s", call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)]);
 331
 332         trace_rxrpc_receive(call, rxrpc_receive_end, 0, whigh);
 333
 334         switch (__rxrpc_call_state(call)) {
 335         case RXRPC_CALL_CLIENT_RECV_REPLY:
 336                 rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_terminal_ack);
 337                 rxrpc_call_completed(call);
 338                 break;
 339
 340         case RXRPC_CALL_SERVER_RECV_REQUEST:
 341                 rxrpc_set_call_state(call, RXRPC_CALL_SERVER_ACK_REQUEST);
 342                 call->expect_req_by = KTIME_MAX;
 343                 rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_processing_op);
 344                 break;
 345
 346         default:
 347                 break;
 348         }
 349 }
 350
 351 static void rxrpc_input_update_ack_window(struct rxrpc_call *call,
 352                                           rxrpc_seq_t window, rxrpc_seq_t wtop)
 353 {
 354         call->ackr_window = window;
 355         call->ackr_wtop = wtop;
 356 }
 357
 358 /*
 359  * Push a DATA packet onto the Rx queue.
 360  */
 361 static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb,
 362                                    rxrpc_seq_t window, rxrpc_seq_t wtop,
 363                                    enum rxrpc_receive_trace why)
 364 {
 365         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 366         bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
 367
 368         __skb_queue_tail(&call->recvmsg_queue, skb);
 369         rxrpc_input_update_ack_window(call, window, wtop);
 370         trace_rxrpc_receive(call, last ? why + 1 : why, sp->hdr.serial, sp->hdr.seq);
 371         if (last)
 372                 rxrpc_end_rx_phase(call, sp->hdr.serial);
 373 }
 374
 375 /*
 376  * Process a DATA packet.
 377  */
 378 static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb,
 379                                  bool *_notify, rxrpc_serial_t *_ack_serial, int *_ack_reason)
 380 {
 381         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 382         struct sk_buff *oos;
 383         rxrpc_serial_t serial = sp->hdr.serial;
 384         unsigned int sack = call->ackr_sack_base;
 385         rxrpc_seq_t window = call->ackr_window;
 386         rxrpc_seq_t wtop = call->ackr_wtop;
 387         rxrpc_seq_t wlimit = window + call->rx_winsize - 1;
 388         rxrpc_seq_t seq = sp->hdr.seq;
 389         bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
 390         int ack_reason = -1;
 391
 392         rxrpc_inc_stat(call->rxnet, stat_rx_data);
 393         if (sp->hdr.flags & RXRPC_REQUEST_ACK)
 394                 rxrpc_inc_stat(call->rxnet, stat_rx_data_reqack);
 395         if (sp->hdr.flags & RXRPC_JUMBO_PACKET)
 396                 rxrpc_inc_stat(call->rxnet, stat_rx_data_jumbo);
 397
 398         if (last) {
 399                 if (test_and_set_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 400                     seq + 1 != wtop)
 401                         return rxrpc_proto_abort(call, seq, rxrpc_eproto_different_last);
 402         } else {
 403                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 404                     after_eq(seq, wtop)) {
 405                         pr_warn("Packet beyond last: c=%x q=%x window=%x-%x wlimit=%x\n",
 406                                 call->debug_id, seq, window, wtop, wlimit);
 407                         return rxrpc_proto_abort(call, seq, rxrpc_eproto_data_after_last);
 408                 }
 409         }
 410
 411         if (after(seq, call->rx_highest_seq))
 412                 call->rx_highest_seq = seq;
 413
 414         trace_rxrpc_rx_data(call->debug_id, seq, serial, sp->hdr.flags);
 415
 416         if (before(seq, window)) {
 417                 ack_reason = RXRPC_ACK_DUPLICATE;
 418                 goto send_ack;
 419         }
 420         if (after(seq, wlimit)) {
 421                 ack_reason = RXRPC_ACK_EXCEEDS_WINDOW;
 422                 goto send_ack;
 423         }
 424
 425         /* Queue the packet. */
 426         if (seq == window) {
 427                 if (sp->hdr.flags & RXRPC_REQUEST_ACK)
 428                         ack_reason = RXRPC_ACK_REQUESTED;
 429                 /* Send an immediate ACK if we fill in a hole */
 430                 else if (!skb_queue_empty(&call->rx_oos_queue))
 431                         ack_reason = RXRPC_ACK_DELAY;
 432
 433                 window++;
 434                 if (after(window, wtop)) {
 435                         trace_rxrpc_sack(call, seq, sack, rxrpc_sack_none);
 436                         wtop = window;
 437                 } else {
 438                         trace_rxrpc_sack(call, seq, sack, rxrpc_sack_advance);
 439                         sack = (sack + 1) % RXRPC_SACK_SIZE;
 440                 }
 441
 442
 443                 rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg);
 444
 445                 spin_lock(&call->recvmsg_queue.lock);
 446                 rxrpc_input_queue_data(call, skb, window, wtop, rxrpc_receive_queue);
 447                 *_notify = true;
 448
 449                 while ((oos = skb_peek(&call->rx_oos_queue))) {
 450                         struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
 451
 452                         if (after(osp->hdr.seq, window))
 453                                 break;
 454
 455                         __skb_unlink(oos, &call->rx_oos_queue);
 456                         last = osp->hdr.flags & RXRPC_LAST_PACKET;
 457                         seq = osp->hdr.seq;
 458                         call->ackr_sack_table[sack] = 0;
 459                         trace_rxrpc_sack(call, seq, sack, rxrpc_sack_fill);
 460                         sack = (sack + 1) % RXRPC_SACK_SIZE;
 461
 462                         window++;
 463                         rxrpc_input_queue_data(call, oos, window, wtop,
 464                                                rxrpc_receive_queue_oos);
 465                 }
 466
 467                 spin_unlock(&call->recvmsg_queue.lock);
 468
 469                 call->ackr_sack_base = sack;
 470         } else {
 471                 unsigned int slot;
 472
 473                 ack_reason = RXRPC_ACK_OUT_OF_SEQUENCE;
 474
 475                 slot = seq - window;
 476                 sack = (sack + slot) % RXRPC_SACK_SIZE;
 477
 478                 if (call->ackr_sack_table[sack % RXRPC_SACK_SIZE]) {
 479                         ack_reason = RXRPC_ACK_DUPLICATE;
 480                         goto send_ack;
 481                 }
 482
 483                 call->ackr_sack_table[sack % RXRPC_SACK_SIZE] |= 1;
 484                 trace_rxrpc_sack(call, seq, sack, rxrpc_sack_oos);
 485
 486                 if (after(seq + 1, wtop)) {
 487                         wtop = seq + 1;
 488                         rxrpc_input_update_ack_window(call, window, wtop);
 489                 }
 490
 491                 skb_queue_walk(&call->rx_oos_queue, oos) {
 492                         struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
 493
 494                         if (after(osp->hdr.seq, seq)) {
 495                                 rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
 496                                 __skb_queue_before(&call->rx_oos_queue, oos, skb);
 497                                 goto oos_queued;
 498                         }
 499                 }
 500
 501                 rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
 502                 __skb_queue_tail(&call->rx_oos_queue, skb);
 503         oos_queued:
 504                 trace_rxrpc_receive(call, last ? rxrpc_receive_oos_last : rxrpc_receive_oos,
 505                                     sp->hdr.serial, sp->hdr.seq);
 506         }
 507
 508 send_ack:
 509         if (ack_reason >= 0) {
 510                 if (rxrpc_ack_priority[ack_reason] > rxrpc_ack_priority[*_ack_reason]) {
 511                         *_ack_serial = serial;
 512                         *_ack_reason = ack_reason;
 513                 } else if (rxrpc_ack_priority[ack_reason] == rxrpc_ack_priority[*_ack_reason] &&
 514                            ack_reason == RXRPC_ACK_REQUESTED) {
 515                         *_ack_serial = serial;
 516                         *_ack_reason = ack_reason;
 517                 }
 518         }
 519 }
 520
 521 /*
 522  * Split a jumbo packet and file the bits separately.
 523  */
 524 static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb)
 525 {
 526         struct rxrpc_jumbo_header jhdr;
 527         struct rxrpc_skb_priv *sp = rxrpc_skb(skb), *jsp;
 528         struct sk_buff *jskb;
 529         rxrpc_serial_t ack_serial = 0;
 530         unsigned int offset = sizeof(struct rxrpc_wire_header);
 531         unsigned int len = skb->len - offset;
 532         bool notify = false;
 533         int ack_reason = 0;
 534
 535         while (sp->hdr.flags & RXRPC_JUMBO_PACKET) {
 536                 if (len < RXRPC_JUMBO_SUBPKTLEN)
 537                         goto protocol_error;
 538                 if (sp->hdr.flags & RXRPC_LAST_PACKET)
 539                         goto protocol_error;
 540                 if (skb_copy_bits(skb, offset + RXRPC_JUMBO_DATALEN,
 541                                   &jhdr, sizeof(jhdr)) < 0)
 542                         goto protocol_error;
 543
 544                 jskb = skb_clone(skb, GFP_NOFS);
 545                 if (!jskb) {
 546                         kdebug("couldn't clone");
 547                         return false;
 548                 }
 549                 rxrpc_new_skb(jskb, rxrpc_skb_new_jumbo_subpacket);
 550                 jsp = rxrpc_skb(jskb);
 551                 jsp->offset = offset;
 552                 jsp->len = RXRPC_JUMBO_DATALEN;
 553                 rxrpc_input_data_one(call, jskb, &notify, &ack_serial, &ack_reason);
 554                 rxrpc_free_skb(jskb, rxrpc_skb_put_jumbo_subpacket);
 555
 556                 sp->hdr.flags = jhdr.flags;
 557                 sp->hdr._rsvd = ntohs(jhdr._rsvd);
 558                 sp->hdr.seq++;
 559                 sp->hdr.serial++;
 560                 offset += RXRPC_JUMBO_SUBPKTLEN;
 561                 len -= RXRPC_JUMBO_SUBPKTLEN;
 562         }
 563
 564         sp->offset = offset;
 565         sp->len    = len;
 566         rxrpc_input_data_one(call, skb, &notify, &ack_serial, &ack_reason);
 567
 568         if (ack_reason > 0) {
 569                 rxrpc_send_ACK(call, ack_reason, ack_serial,
 570                                rxrpc_propose_ack_input_data);
 571         } else {
 572                 call->ackr_nr_unacked++;
 573                 rxrpc_propose_delay_ACK(call, sp->hdr.serial,
 574                                         rxrpc_propose_ack_input_data);
 575         }
 576         if (notify) {
 577                 trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial);
 578                 rxrpc_notify_socket(call);
 579         }
 580         return true;
 581
 582 protocol_error:
 583         return false;
 584 }
 585
 586 /*
 587  * Process a DATA packet, adding the packet to the Rx ring.  The caller's
 588  * packet ref must be passed on or discarded.
 589  */
 590 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 591 {
 592         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 593         rxrpc_serial_t serial = sp->hdr.serial;
 594         rxrpc_seq_t seq0 = sp->hdr.seq;
 595
 596         _enter("{%x,%x,%x},{%u,%x}",
 597                call->ackr_window, call->ackr_wtop, call->rx_highest_seq,
 598                skb->len, seq0);
 599
 600         if (__rxrpc_call_is_complete(call))
 601                 return;
 602
 603         switch (__rxrpc_call_state(call)) {
 604         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 605         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 606                 /* Received data implicitly ACKs all of the request
 607                  * packets we sent when we're acting as a client.
 608                  */
 609                 if (!rxrpc_receiving_reply(call))
 610                         goto out_notify;
 611                 break;
 612
 613         case RXRPC_CALL_SERVER_RECV_REQUEST: {
 614                 unsigned long timo = READ_ONCE(call->next_req_timo);
 615
 616                 if (timo) {
 617                         ktime_t delay = ms_to_ktime(timo);
 618
 619                         call->expect_req_by = ktime_add(ktime_get_real(), delay);
 620                         trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_idle);
 621                 }
 622                 break;
 623         }
 624
 625         default:
 626                 break;
 627         }
 628
 629         if (!rxrpc_input_split_jumbo(call, skb)) {
 630                 rxrpc_proto_abort(call, sp->hdr.seq, rxrpc_badmsg_bad_jumbo);
 631                 goto out_notify;
 632         }
 633         return;
 634
 635 out_notify:
 636         trace_rxrpc_notify_socket(call->debug_id, serial);
 637         rxrpc_notify_socket(call);
 638         _leave(" [queued]");
 639 }
 640
 641 /*
 642  * See if there's a cached RTT probe to complete.
 643  */
 644 static void rxrpc_complete_rtt_probe(struct rxrpc_call *call,
 645                                      ktime_t resp_time,
 646                                      rxrpc_serial_t acked_serial,
 647                                      rxrpc_serial_t ack_serial,
 648                                      enum rxrpc_rtt_rx_trace type)
 649 {
 650         rxrpc_serial_t orig_serial;
 651         unsigned long avail;
 652         ktime_t sent_at;
 653         bool matched = false;
 654         int i;
 655
 656         avail = READ_ONCE(call->rtt_avail);
 657         smp_rmb(); /* Read avail bits before accessing data. */
 658
 659         for (i = 0; i < ARRAY_SIZE(call->rtt_serial); i++) {
 660                 if (!test_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &avail))
 661                         continue;
 662
 663                 sent_at = call->rtt_sent_at[i];
 664                 orig_serial = call->rtt_serial[i];
 665
 666                 if (orig_serial == acked_serial) {
 667                         clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
 668                         smp_mb(); /* Read data before setting avail bit */
 669                         set_bit(i, &call->rtt_avail);
 670                         rxrpc_peer_add_rtt(call, type, i, acked_serial, ack_serial,
 671                                            sent_at, resp_time);
 672                         matched = true;
 673                 }
 674
 675                 /* If a later serial is being acked, then mark this slot as
 676                  * being available.
 677                  */
 678                 if (after(acked_serial, orig_serial)) {
 679                         trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_obsolete, i,
 680                                            orig_serial, acked_serial, 0, 0);
 681                         clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
 682                         smp_wmb();
 683                         set_bit(i, &call->rtt_avail);
 684                 }
 685         }
 686
 687         if (!matched)
 688                 trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_lost, 9, 0, acked_serial, 0, 0);
 689 }
 690
 691 /*
 692  * Process the extra information that may be appended to an ACK packet
 693  */
 694 static void rxrpc_input_ack_trailer(struct rxrpc_call *call, struct sk_buff *skb,
 695                                     struct rxrpc_acktrailer *trailer)
 696 {
 697         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 698         struct rxrpc_peer *peer;
 699         unsigned int mtu;
 700         bool wake = false;
 701         u32 rwind = ntohl(trailer->rwind);
 702
 703         if (rwind > RXRPC_TX_MAX_WINDOW)
 704                 rwind = RXRPC_TX_MAX_WINDOW;
 705         if (call->tx_winsize != rwind) {
 706                 if (rwind > call->tx_winsize)
 707                         wake = true;
 708                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
 709                 call->tx_winsize = rwind;
 710         }
 711
 712         mtu = min(ntohl(trailer->maxMTU), ntohl(trailer->ifMTU));
 713
 714         peer = call->peer;
 715         if (mtu < peer->maxdata) {
 716                 spin_lock(&peer->lock);
 717                 peer->maxdata = mtu;
 718                 peer->mtu = mtu + peer->hdrsize;
 719                 spin_unlock(&peer->lock);
 720         }
 721
 722         if (wake)
 723                 wake_up(&call->waitq);
 724 }
 725
 726 /*
 727  * Determine how many nacks from the previous ACK have now been satisfied.
 728  */
 729 static rxrpc_seq_t rxrpc_input_check_prev_ack(struct rxrpc_call *call,
 730                                               struct rxrpc_ack_summary *summary,
 731                                               rxrpc_seq_t seq)
 732 {
 733         struct sk_buff *skb = call->cong_last_nack;
 734         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 735         unsigned int i, new_acks = 0, retained_nacks = 0;
 736         rxrpc_seq_t old_seq = sp->ack.first_ack;
 737         u8 *acks = skb->data + sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
 738
 739         if (after_eq(seq, old_seq + sp->ack.nr_acks)) {
 740                 summary->nr_new_acks += sp->ack.nr_nacks;
 741                 summary->nr_new_acks += seq - (old_seq + sp->ack.nr_acks);
 742                 summary->nr_retained_nacks = 0;
 743         } else if (seq == old_seq) {
 744                 summary->nr_retained_nacks = sp->ack.nr_nacks;
 745         } else {
 746                 for (i = 0; i < sp->ack.nr_acks; i++) {
 747                         if (acks[i] == RXRPC_ACK_TYPE_NACK) {
 748                                 if (before(old_seq + i, seq))
 749                                         new_acks++;
 750                                 else
 751                                         retained_nacks++;
 752                         }
 753                 }
 754
 755                 summary->nr_new_acks += new_acks;
 756                 summary->nr_retained_nacks = retained_nacks;
 757         }
 758
 759         return old_seq + sp->ack.nr_acks;
 760 }
 761
 762 /*
 763  * Process individual soft ACKs.
 764  *
 765  * Each ACK in the array corresponds to one packet and can be either an ACK or
 766  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 767  * packets that lie beyond the end of the ACK list are scheduled for resend by
 768  * the timer on the basis that the peer might just not have processed them at
 769  * the time the ACK was sent.
 770  */
 771 static void rxrpc_input_soft_acks(struct rxrpc_call *call,
 772                                   struct rxrpc_ack_summary *summary,
 773                                   struct sk_buff *skb,
 774                                   rxrpc_seq_t seq,
 775                                   rxrpc_seq_t since)
 776 {
 777         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 778         unsigned int i, old_nacks = 0;
 779         rxrpc_seq_t lowest_nak = seq + sp->ack.nr_acks;
 780         u8 *acks = skb->data + sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
 781
 782         for (i = 0; i < sp->ack.nr_acks; i++) {
 783                 if (acks[i] == RXRPC_ACK_TYPE_ACK) {
 784                         summary->nr_acks++;
 785                         if (after_eq(seq, since))
 786                                 summary->nr_new_acks++;
 787                 } else {
 788                         summary->saw_nacks = true;
 789                         if (before(seq, since)) {
 790                                 /* Overlap with previous ACK */
 791                                 old_nacks++;
 792                         } else {
 793                                 summary->nr_new_nacks++;
 794                                 sp->ack.nr_nacks++;
 795                         }
 796
 797                         if (before(seq, lowest_nak))
 798                                 lowest_nak = seq;
 799                 }
 800                 seq++;
 801         }
 802
 803         if (lowest_nak != call->acks_lowest_nak) {
 804                 call->acks_lowest_nak = lowest_nak;
 805                 summary->new_low_nack = true;
 806         }
 807
 808         /* We *can* have more nacks than we did - the peer is permitted to drop
 809          * packets it has soft-acked and re-request them.  Further, it is
 810          * possible for the nack distribution to change whilst the number of
 811          * nacks stays the same or goes down.
 812          */
 813         if (old_nacks < summary->nr_retained_nacks)
 814                 summary->nr_new_acks += summary->nr_retained_nacks - old_nacks;
 815         summary->nr_retained_nacks = old_nacks;
 816 }
 817
 818 /*
 819  * Return true if the ACK is valid - ie. it doesn't appear to have regressed
 820  * with respect to the ack state conveyed by preceding ACKs.
 821  */
 822 static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 823                                rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
 824 {
 825         rxrpc_seq_t base = READ_ONCE(call->acks_first_seq);
 826
 827         if (after(first_pkt, base))
 828                 return true; /* The window advanced */
 829
 830         if (before(first_pkt, base))
 831                 return false; /* firstPacket regressed */
 832
 833         if (after_eq(prev_pkt, call->acks_prev_seq))
 834                 return true; /* previousPacket hasn't regressed. */
 835
 836         /* Some rx implementations put a serial number in previousPacket. */
 837         if (after_eq(prev_pkt, base + call->tx_winsize))
 838                 return false;
 839         return true;
 840 }
 841
 842 /*
 843  * Process an ACK packet.
 844  *
 845  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 846  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 847  *
 848  * A hard-ACK means that a packet has been processed and may be discarded; a
 849  * soft-ACK means that the packet may be discarded and retransmission
 850  * requested.  A phase is complete when all packets are hard-ACK'd.
 851  */
 852 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 853 {
 854         struct rxrpc_ack_summary summary = { 0 };
 855         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 856         struct rxrpc_acktrailer trailer;
 857         rxrpc_serial_t ack_serial, acked_serial;
 858         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt, since;
 859         int nr_acks, offset, ioffset;
 860
 861         _enter("");
 862
 863         offset = sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
 864
 865         ack_serial      = sp->hdr.serial;
 866         acked_serial    = sp->ack.acked_serial;
 867         first_soft_ack  = sp->ack.first_ack;
 868         prev_pkt        = sp->ack.prev_ack;
 869         nr_acks         = sp->ack.nr_acks;
 870         hard_ack        = first_soft_ack - 1;
 871         summary.ack_reason = (sp->ack.reason < RXRPC_ACK__INVALID ?
 872                               sp->ack.reason : RXRPC_ACK__INVALID);
 873
 874         trace_rxrpc_rx_ack(call, ack_serial, acked_serial,
 875                            first_soft_ack, prev_pkt,
 876                            summary.ack_reason, nr_acks);
 877         rxrpc_inc_stat(call->rxnet, stat_rx_acks[summary.ack_reason]);
 878
 879         if (acked_serial != 0) {
 880                 switch (summary.ack_reason) {
 881                 case RXRPC_ACK_PING_RESPONSE:
 882                         rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 883                                                  rxrpc_rtt_rx_ping_response);
 884                         break;
 885                 case RXRPC_ACK_REQUESTED:
 886                         rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 887                                                  rxrpc_rtt_rx_requested_ack);
 888                         break;
 889                 default:
 890                         rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 891                                                  rxrpc_rtt_rx_other_ack);
 892                         break;
 893                 }
 894         }
 895
 896         /* If we get an EXCEEDS_WINDOW ACK from the server, it probably
 897          * indicates that the client address changed due to NAT.  The server
 898          * lost the call because it switched to a different peer.
 899          */
 900         if (unlikely(summary.ack_reason == RXRPC_ACK_EXCEEDS_WINDOW) &&
 901             first_soft_ack == 1 &&
 902             prev_pkt == 0 &&
 903             rxrpc_is_client_call(call)) {
 904                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 905                                           0, -ENETRESET);
 906                 goto send_response;
 907         }
 908
 909         /* If we get an OUT_OF_SEQUENCE ACK from the server, that can also
 910          * indicate a change of address.  However, we can retransmit the call
 911          * if we still have it buffered to the beginning.
 912          */
 913         if (unlikely(summary.ack_reason == RXRPC_ACK_OUT_OF_SEQUENCE) &&
 914             first_soft_ack == 1 &&
 915             prev_pkt == 0 &&
 916             call->acks_hard_ack == 0 &&
 917             rxrpc_is_client_call(call)) {
 918                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 919                                           0, -ENETRESET);
 920                 goto send_response;
 921         }
 922
 923         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 924         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 925                 trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
 926                                            first_soft_ack, call->acks_first_seq,
 927                                            prev_pkt, call->acks_prev_seq);
 928                 goto send_response;
 929         }
 930
 931         trailer.maxMTU = 0;
 932         ioffset = offset + nr_acks + 3;
 933         if (skb->len >= ioffset + sizeof(trailer) &&
 934             skb_copy_bits(skb, ioffset, &trailer, sizeof(trailer)) < 0)
 935                 return rxrpc_proto_abort(call, 0, rxrpc_badmsg_short_ack_trailer);
 936
 937         if (nr_acks > 0)
 938                 skb_condense(skb);
 939
 940         if (call->cong_last_nack) {
 941                 since = rxrpc_input_check_prev_ack(call, &summary, first_soft_ack);
 942                 rxrpc_free_skb(call->cong_last_nack, rxrpc_skb_put_last_nack);
 943                 call->cong_last_nack = NULL;
 944         } else {
 945                 summary.nr_new_acks = first_soft_ack - call->acks_first_seq;
 946                 call->acks_lowest_nak = first_soft_ack + nr_acks;
 947                 since = first_soft_ack;
 948         }
 949
 950         call->acks_latest_ts = skb->tstamp;
 951         call->acks_first_seq = first_soft_ack;
 952         call->acks_prev_seq = prev_pkt;
 953
 954         switch (summary.ack_reason) {
 955         case RXRPC_ACK_PING:
 956                 break;
 957         default:
 958                 if (acked_serial && after(acked_serial, call->acks_highest_serial))
 959                         call->acks_highest_serial = acked_serial;
 960                 break;
 961         }
 962
 963         /* Parse rwind and mtu sizes if provided. */
 964         if (trailer.maxMTU)
 965                 rxrpc_input_ack_trailer(call, skb, &trailer);
 966
 967         if (first_soft_ack == 0)
 968                 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_zero);
 969
 970         /* Ignore ACKs unless we are or have just been transmitting. */
 971         switch (__rxrpc_call_state(call)) {
 972         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 973         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 974         case RXRPC_CALL_SERVER_SEND_REPLY:
 975         case RXRPC_CALL_SERVER_AWAIT_ACK:
 976                 break;
 977         default:
 978                 goto send_response;
 979         }
 980
 981         if (before(hard_ack, call->acks_hard_ack) ||
 982             after(hard_ack, call->tx_top))
 983                 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_outside_window);
 984         if (nr_acks > call->tx_top - hard_ack)
 985                 return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_sack_overflow);
 986
 987         if (after(hard_ack, call->acks_hard_ack)) {
 988                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 989                         rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ack);
 990                         goto send_response;
 991                 }
 992         }
 993
 994         if (nr_acks > 0) {
 995                 if (offset > (int)skb->len - nr_acks)
 996                         return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_short_sack);
 997                 rxrpc_input_soft_acks(call, &summary, skb, first_soft_ack, since);
 998                 rxrpc_get_skb(skb, rxrpc_skb_get_last_nack);
 999                 call->cong_last_nack = skb;
1000         }
1001
1002         if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) &&
1003             summary.nr_acks == call->tx_top - hard_ack &&
1004             rxrpc_is_client_call(call))
1005                 rxrpc_propose_ping(call, ack_serial,
1006                                    rxrpc_propose_ack_ping_for_lost_reply);
1007
1008         rxrpc_congestion_management(call, skb, &summary, acked_serial);
1009
1010 send_response:
1011         if (summary.ack_reason == RXRPC_ACK_PING)
1012                 rxrpc_send_ACK(call, RXRPC_ACK_PING_RESPONSE, ack_serial,
1013                                rxrpc_propose_ack_respond_to_ping);
1014         else if (sp->hdr.flags & RXRPC_REQUEST_ACK)
1015                 rxrpc_send_ACK(call, RXRPC_ACK_REQUESTED, ack_serial,
1016                                rxrpc_propose_ack_respond_to_ack);
1017 }
1018
1019 /*
1020  * Process an ACKALL packet.
1021  */
1022 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
1023 {
1024         struct rxrpc_ack_summary summary = { 0 };
1025
1026         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
1027                 rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ackall);
1028 }
1029
1030 /*
1031  * Process an ABORT packet directed at a call.
1032  */
1033 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
1034 {
1035         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1036
1037         trace_rxrpc_rx_abort(call, sp->hdr.serial, skb->priority);
1038
1039         rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1040                                   skb->priority, -ECONNABORTED);
1041 }
1042
1043 /*
1044  * Process an incoming call packet.
1045  */
1046 void rxrpc_input_call_packet(struct rxrpc_call *call, struct sk_buff *skb)
1047 {
1048         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1049         unsigned long timo;
1050
1051         _enter("%p,%p", call, skb);
1052
1053         if (sp->hdr.serviceId != call->dest_srx.srx_service)
1054                 call->dest_srx.srx_service = sp->hdr.serviceId;
1055         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1056                 call->rx_serial = sp->hdr.serial;
1057         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1058                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1059
1060         timo = READ_ONCE(call->next_rx_timo);
1061         if (timo) {
1062                 ktime_t delay = ms_to_ktime(timo);
1063
1064                 call->expect_rx_by = ktime_add(ktime_get_real(), delay);
1065                 trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_expect_rx);
1066         }
1067
1068         switch (sp->hdr.type) {
1069         case RXRPC_PACKET_TYPE_DATA:
1070                 return rxrpc_input_data(call, skb);
1071
1072         case RXRPC_PACKET_TYPE_ACK:
1073                 return rxrpc_input_ack(call, skb);
1074
1075         case RXRPC_PACKET_TYPE_BUSY:
1076                 /* Just ignore BUSY packets from the server; the retry and
1077                  * lifespan timers will take care of business.  BUSY packets
1078                  * from the client don't make sense.
1079                  */
1080                 return;
1081
1082         case RXRPC_PACKET_TYPE_ABORT:
1083                 return rxrpc_input_abort(call, skb);
1084
1085         case RXRPC_PACKET_TYPE_ACKALL:
1086                 return rxrpc_input_ackall(call, skb);
1087
1088         default:
1089                 break;
1090         }
1091 }
1092
1093 /*
1094  * Handle a new service call on a channel implicitly completing the preceding
1095  * call on that channel.  This does not apply to client conns.
1096  *
1097  * TODO: If callNumber > call_id + 1, renegotiate security.
1098  */
1099 void rxrpc_implicit_end_call(struct rxrpc_call *call, struct sk_buff *skb)
1100 {
1101         switch (__rxrpc_call_state(call)) {
1102         case RXRPC_CALL_SERVER_AWAIT_ACK:
1103                 rxrpc_call_completed(call);
1104                 fallthrough;
1105         case RXRPC_CALL_COMPLETE:
1106                 break;
1107         default:
1108                 rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ESHUTDOWN,
1109                                  rxrpc_eproto_improper_term);
1110                 trace_rxrpc_improper_term(call);
1111                 break;
1112         }
1113
1114         rxrpc_input_call_event(call, skb);
1115 }