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