net/rxrpc/output.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* RxRPC packet transmission
   3  *
   4  * Copyright (C) 2007 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 <linux/net.h>
  11 #include <linux/gfp.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/export.h>
  14 #include <net/sock.h>
  15 #include <net/af_rxrpc.h>
  16 #include <net/udp.h>
  17 #include "ar-internal.h"
  18
  19 extern int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
  20
  21 static ssize_t do_udp_sendmsg(struct socket *sk, struct msghdr *msg, size_t len)
  22 {
  23 #if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
  24         struct sockaddr *sa = msg->msg_name;
  25
  26         if (sa->sa_family == AF_INET6)
  27                 return udpv6_sendmsg(sk->sk, msg, len);
  28 #endif
  29         return udp_sendmsg(sk->sk, msg, len);
  30 }
  31
  32 struct rxrpc_abort_buffer {
  33         struct rxrpc_wire_header whdr;
  34         __be32 abort_code;
  35 };
  36
  37 static const char rxrpc_keepalive_string[] = "";
  38
  39 /*
  40  * Increase Tx backoff on transmission failure and clear it on success.
  41  */
  42 static void rxrpc_tx_backoff(struct rxrpc_call *call, int ret)
  43 {
  44         if (ret < 0) {
  45                 u16 tx_backoff = READ_ONCE(call->tx_backoff);
  46
  47                 if (tx_backoff < HZ)
  48                         WRITE_ONCE(call->tx_backoff, tx_backoff + 1);
  49         } else {
  50                 WRITE_ONCE(call->tx_backoff, 0);
  51         }
  52 }
  53
  54 /*
  55  * Arrange for a keepalive ping a certain time after we last transmitted.  This
  56  * lets the far side know we're still interested in this call and helps keep
  57  * the route through any intervening firewall open.
  58  *
  59  * Receiving a response to the ping will prevent the ->expect_rx_by timer from
  60  * expiring.
  61  */
  62 static void rxrpc_set_keepalive(struct rxrpc_call *call)
  63 {
  64         unsigned long now = jiffies, keepalive_at = call->next_rx_timo / 6;
  65
  66         keepalive_at += now;
  67         WRITE_ONCE(call->keepalive_at, keepalive_at);
  68         rxrpc_reduce_call_timer(call, keepalive_at, now,
  69                                 rxrpc_timer_set_for_keepalive);
  70 }
  71
  72 /*
  73  * Fill out an ACK packet.
  74  */
  75 static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn,
  76                                  struct rxrpc_call *call,
  77                                  struct rxrpc_txbuf *txb)
  78 {
  79         struct rxrpc_ackinfo ackinfo;
  80         unsigned int qsize;
  81         rxrpc_seq_t window, wtop, wrap_point, ix, first;
  82         int rsize;
  83         u64 wtmp;
  84         u32 mtu, jmax;
  85         u8 *ackp = txb->acks;
  86         u8 sack_buffer[sizeof(call->ackr_sack_table)] __aligned(8);
  87
  88         atomic_set(&call->ackr_nr_unacked, 0);
  89         atomic_set(&call->ackr_nr_consumed, 0);
  90         rxrpc_inc_stat(call->rxnet, stat_tx_ack_fill);
  91
  92         /* Barrier against rxrpc_input_data(). */
  93 retry:
  94         wtmp   = atomic64_read_acquire(&call->ackr_window);
  95         window = lower_32_bits(wtmp);
  96         wtop   = upper_32_bits(wtmp);
  97         txb->ack.firstPacket = htonl(window);
  98         txb->ack.nAcks = 0;
  99
 100         if (after(wtop, window)) {
 101                 /* Try to copy the SACK ring locklessly.  We can use the copy,
 102                  * only if the now-current top of the window didn't go past the
 103                  * previously read base - otherwise we can't know whether we
 104                  * have old data or new data.
 105                  */
 106                 memcpy(sack_buffer, call->ackr_sack_table, sizeof(sack_buffer));
 107                 wrap_point = window + RXRPC_SACK_SIZE - 1;
 108                 wtmp   = atomic64_read_acquire(&call->ackr_window);
 109                 window = lower_32_bits(wtmp);
 110                 wtop   = upper_32_bits(wtmp);
 111                 if (after(wtop, wrap_point)) {
 112                         cond_resched();
 113                         goto retry;
 114                 }
 115
 116                 /* The buffer is maintained as a ring with an invariant mapping
 117                  * between bit position and sequence number, so we'll probably
 118                  * need to rotate it.
 119                  */
 120                 txb->ack.nAcks = wtop - window;
 121                 ix = window % RXRPC_SACK_SIZE;
 122                 first = sizeof(sack_buffer) - ix;
 123
 124                 if (ix + txb->ack.nAcks <= RXRPC_SACK_SIZE) {
 125                         memcpy(txb->acks, sack_buffer + ix, txb->ack.nAcks);
 126                 } else {
 127                         memcpy(txb->acks, sack_buffer + ix, first);
 128                         memcpy(txb->acks + first, sack_buffer,
 129                                txb->ack.nAcks - first);
 130                 }
 131
 132                 ackp += txb->ack.nAcks;
 133         } else if (before(wtop, window)) {
 134                 pr_warn("ack window backward %x %x", window, wtop);
 135         } else if (txb->ack.reason == RXRPC_ACK_DELAY) {
 136                 txb->ack.reason = RXRPC_ACK_IDLE;
 137         }
 138
 139         mtu = conn->params.peer->if_mtu;
 140         mtu -= conn->params.peer->hdrsize;
 141         jmax = rxrpc_rx_jumbo_max;
 142         qsize = (window - 1) - call->rx_consumed;
 143         rsize = max_t(int, call->rx_winsize - qsize, 0);
 144         ackinfo.rxMTU           = htonl(rxrpc_rx_mtu);
 145         ackinfo.maxMTU          = htonl(mtu);
 146         ackinfo.rwind           = htonl(rsize);
 147         ackinfo.jumbo_max       = htonl(jmax);
 148
 149         *ackp++ = 0;
 150         *ackp++ = 0;
 151         *ackp++ = 0;
 152         memcpy(ackp, &ackinfo, sizeof(ackinfo));
 153         return txb->ack.nAcks + 3 + sizeof(ackinfo);
 154 }
 155
 156 /*
 157  * Record the beginning of an RTT probe.
 158  */
 159 static int rxrpc_begin_rtt_probe(struct rxrpc_call *call, rxrpc_serial_t serial,
 160                                  enum rxrpc_rtt_tx_trace why)
 161 {
 162         unsigned long avail = call->rtt_avail;
 163         int rtt_slot = 9;
 164
 165         if (!(avail & RXRPC_CALL_RTT_AVAIL_MASK))
 166                 goto no_slot;
 167
 168         rtt_slot = __ffs(avail & RXRPC_CALL_RTT_AVAIL_MASK);
 169         if (!test_and_clear_bit(rtt_slot, &call->rtt_avail))
 170                 goto no_slot;
 171
 172         call->rtt_serial[rtt_slot] = serial;
 173         call->rtt_sent_at[rtt_slot] = ktime_get_real();
 174         smp_wmb(); /* Write data before avail bit */
 175         set_bit(rtt_slot + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
 176
 177         trace_rxrpc_rtt_tx(call, why, rtt_slot, serial);
 178         return rtt_slot;
 179
 180 no_slot:
 181         trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_no_slot, rtt_slot, serial);
 182         return -1;
 183 }
 184
 185 /*
 186  * Cancel an RTT probe.
 187  */
 188 static void rxrpc_cancel_rtt_probe(struct rxrpc_call *call,
 189                                    rxrpc_serial_t serial, int rtt_slot)
 190 {
 191         if (rtt_slot != -1) {
 192                 clear_bit(rtt_slot + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
 193                 smp_wmb(); /* Clear pending bit before setting slot */
 194                 set_bit(rtt_slot, &call->rtt_avail);
 195                 trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_cancel, rtt_slot, serial);
 196         }
 197 }
 198
 199 /*
 200  * Send an ACK call packet.
 201  */
 202 static int rxrpc_send_ack_packet(struct rxrpc_local *local, struct rxrpc_txbuf *txb)
 203 {
 204         struct rxrpc_connection *conn;
 205         struct rxrpc_ack_buffer *pkt;
 206         struct rxrpc_call *call = txb->call;
 207         struct msghdr msg;
 208         struct kvec iov[1];
 209         rxrpc_serial_t serial;
 210         size_t len, n;
 211         int ret, rtt_slot = -1;
 212
 213         if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
 214                 return -ECONNRESET;
 215
 216         conn = call->conn;
 217
 218         msg.msg_name    = &call->peer->srx.transport;
 219         msg.msg_namelen = call->peer->srx.transport_len;
 220         msg.msg_control = NULL;
 221         msg.msg_controllen = 0;
 222         msg.msg_flags   = 0;
 223
 224         if (txb->ack.reason == RXRPC_ACK_PING)
 225                 txb->wire.flags |= RXRPC_REQUEST_ACK;
 226
 227         if (txb->ack.reason == RXRPC_ACK_DELAY)
 228                 clear_bit(RXRPC_CALL_DELAY_ACK_PENDING, &call->flags);
 229         if (txb->ack.reason == RXRPC_ACK_IDLE)
 230                 clear_bit(RXRPC_CALL_IDLE_ACK_PENDING, &call->flags);
 231
 232         n = rxrpc_fill_out_ack(conn, call, txb);
 233         if (n == 0)
 234                 return 0;
 235
 236         iov[0].iov_base = &txb->wire;
 237         iov[0].iov_len  = sizeof(txb->wire) + sizeof(txb->ack) + n;
 238         len = iov[0].iov_len;
 239
 240         serial = atomic_inc_return(&conn->serial);
 241         txb->wire.serial = htonl(serial);
 242         trace_rxrpc_tx_ack(call->debug_id, serial,
 243                            ntohl(txb->ack.firstPacket),
 244                            ntohl(txb->ack.serial), txb->ack.reason, txb->ack.nAcks);
 245         if (txb->ack_why == rxrpc_propose_ack_ping_for_lost_ack)
 246                 call->acks_lost_ping = serial;
 247
 248         if (txb->ack.reason == RXRPC_ACK_PING)
 249                 rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_ping);
 250
 251         rxrpc_inc_stat(call->rxnet, stat_tx_ack_send);
 252
 253         /* Grab the highest received seq as late as possible */
 254         txb->ack.previousPacket = htonl(call->rx_highest_seq);
 255
 256         iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
 257         ret = do_udp_sendmsg(conn->params.local->socket, &msg, len);
 258         call->peer->last_tx_at = ktime_get_seconds();
 259         if (ret < 0)
 260                 trace_rxrpc_tx_fail(call->debug_id, serial, ret,
 261                                     rxrpc_tx_point_call_ack);
 262         else
 263                 trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
 264                                       rxrpc_tx_point_call_ack);
 265         rxrpc_tx_backoff(call, ret);
 266
 267         if (call->state < RXRPC_CALL_COMPLETE) {
 268                 if (ret < 0)
 269                         rxrpc_cancel_rtt_probe(call, serial, rtt_slot);
 270                 rxrpc_set_keepalive(call);
 271         }
 272
 273         kfree(pkt);
 274         return ret;
 275 }
 276
 277 /*
 278  * ACK transmitter for a local endpoint.  The UDP socket locks around each
 279  * transmission, so we can only transmit one packet at a time, ACK, DATA or
 280  * otherwise.
 281  */
 282 void rxrpc_transmit_ack_packets(struct rxrpc_local *local)
 283 {
 284         LIST_HEAD(queue);
 285         int ret;
 286
 287         trace_rxrpc_local(local->debug_id, rxrpc_local_tx_ack,
 288                           refcount_read(&local->ref), NULL);
 289
 290         if (list_empty(&local->ack_tx_queue))
 291                 return;
 292
 293         spin_lock_bh(&local->ack_tx_lock);
 294         list_splice_tail_init(&local->ack_tx_queue, &queue);
 295         spin_unlock_bh(&local->ack_tx_lock);
 296
 297         while (!list_empty(&queue)) {
 298                 struct rxrpc_txbuf *txb =
 299                         list_entry(queue.next, struct rxrpc_txbuf, tx_link);
 300
 301                 ret = rxrpc_send_ack_packet(local, txb);
 302                 if (ret < 0 && ret != -ECONNRESET) {
 303                         spin_lock_bh(&local->ack_tx_lock);
 304                         list_splice_init(&queue, &local->ack_tx_queue);
 305                         spin_unlock_bh(&local->ack_tx_lock);
 306                         break;
 307                 }
 308
 309                 list_del_init(&txb->tx_link);
 310                 rxrpc_put_call(txb->call, rxrpc_call_put);
 311                 rxrpc_put_txbuf(txb, rxrpc_txbuf_put_ack_tx);
 312         }
 313 }
 314
 315 /*
 316  * Send an ABORT call packet.
 317  */
 318 int rxrpc_send_abort_packet(struct rxrpc_call *call)
 319 {
 320         struct rxrpc_connection *conn;
 321         struct rxrpc_abort_buffer pkt;
 322         struct msghdr msg;
 323         struct kvec iov[1];
 324         rxrpc_serial_t serial;
 325         int ret;
 326
 327         /* Don't bother sending aborts for a client call once the server has
 328          * hard-ACK'd all of its request data.  After that point, we're not
 329          * going to stop the operation proceeding, and whilst we might limit
 330          * the reply, it's not worth it if we can send a new call on the same
 331          * channel instead, thereby closing off this call.
 332          */
 333         if (rxrpc_is_client_call(call) &&
 334             test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
 335                 return 0;
 336
 337         if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
 338                 return -ECONNRESET;
 339
 340         conn = call->conn;
 341
 342         msg.msg_name    = &call->peer->srx.transport;
 343         msg.msg_namelen = call->peer->srx.transport_len;
 344         msg.msg_control = NULL;
 345         msg.msg_controllen = 0;
 346         msg.msg_flags   = 0;
 347
 348         pkt.whdr.epoch          = htonl(conn->proto.epoch);
 349         pkt.whdr.cid            = htonl(call->cid);
 350         pkt.whdr.callNumber     = htonl(call->call_id);
 351         pkt.whdr.seq            = 0;
 352         pkt.whdr.type           = RXRPC_PACKET_TYPE_ABORT;
 353         pkt.whdr.flags          = conn->out_clientflag;
 354         pkt.whdr.userStatus     = 0;
 355         pkt.whdr.securityIndex  = call->security_ix;
 356         pkt.whdr._rsvd          = 0;
 357         pkt.whdr.serviceId      = htons(call->service_id);
 358         pkt.abort_code          = htonl(call->abort_code);
 359
 360         iov[0].iov_base = &pkt;
 361         iov[0].iov_len  = sizeof(pkt);
 362
 363         serial = atomic_inc_return(&conn->serial);
 364         pkt.whdr.serial = htonl(serial);
 365
 366         iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, sizeof(pkt));
 367         ret = do_udp_sendmsg(conn->params.local->socket, &msg, sizeof(pkt));
 368         conn->params.peer->last_tx_at = ktime_get_seconds();
 369         if (ret < 0)
 370                 trace_rxrpc_tx_fail(call->debug_id, serial, ret,
 371                                     rxrpc_tx_point_call_abort);
 372         else
 373                 trace_rxrpc_tx_packet(call->debug_id, &pkt.whdr,
 374                                       rxrpc_tx_point_call_abort);
 375         rxrpc_tx_backoff(call, ret);
 376         return ret;
 377 }
 378
 379 /*
 380  * send a packet through the transport endpoint
 381  */
 382 int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 383 {
 384         enum rxrpc_req_ack_trace why;
 385         struct rxrpc_connection *conn = call->conn;
 386         struct msghdr msg;
 387         struct kvec iov[1];
 388         rxrpc_serial_t serial;
 389         size_t len;
 390         int ret, rtt_slot = -1;
 391
 392         _enter("%x,{%d}", txb->seq, txb->len);
 393
 394         if (hlist_unhashed(&call->error_link)) {
 395                 spin_lock_bh(&call->peer->lock);
 396                 hlist_add_head_rcu(&call->error_link, &call->peer->error_targets);
 397                 spin_unlock_bh(&call->peer->lock);
 398         }
 399
 400         /* Each transmission of a Tx packet needs a new serial number */
 401         serial = atomic_inc_return(&conn->serial);
 402         txb->wire.serial = htonl(serial);
 403
 404         if (test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags) &&
 405             txb->seq == 1)
 406                 txb->wire.userStatus = RXRPC_USERSTATUS_SERVICE_UPGRADE;
 407
 408         iov[0].iov_base = &txb->wire;
 409         iov[0].iov_len = sizeof(txb->wire) + txb->len;
 410         len = iov[0].iov_len;
 411         iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
 412
 413         msg.msg_name = &call->peer->srx.transport;
 414         msg.msg_namelen = call->peer->srx.transport_len;
 415         msg.msg_control = NULL;
 416         msg.msg_controllen = 0;
 417         msg.msg_flags = 0;
 418
 419         /* If our RTT cache needs working on, request an ACK.  Also request
 420          * ACKs if a DATA packet appears to have been lost.
 421          *
 422          * However, we mustn't request an ACK on the last reply packet of a
 423          * service call, lest OpenAFS incorrectly send us an ACK with some
 424          * soft-ACKs in it and then never follow up with a proper hard ACK.
 425          */
 426         if (txb->wire.flags & RXRPC_REQUEST_ACK)
 427                 why = rxrpc_reqack_already_on;
 428         else if (test_bit(RXRPC_TXBUF_LAST, &txb->flags) && rxrpc_sending_to_client(txb))
 429                 why = rxrpc_reqack_no_srv_last;
 430         else if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
 431                 why = rxrpc_reqack_ack_lost;
 432         else if (test_bit(RXRPC_TXBUF_RESENT, &txb->flags))
 433                 why = rxrpc_reqack_retrans;
 434         else if (call->cong_mode == RXRPC_CALL_SLOW_START && call->cong_cwnd <= 2)
 435                 why = rxrpc_reqack_slow_start;
 436         else if (call->tx_winsize <= 2)
 437                 why = rxrpc_reqack_small_txwin;
 438         else if (call->peer->rtt_count < 3 && txb->seq & 1)
 439                 why = rxrpc_reqack_more_rtt;
 440         else if (ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), ktime_get_real()))
 441                 why = rxrpc_reqack_old_rtt;
 442         else
 443                 goto dont_set_request_ack;
 444
 445         rxrpc_inc_stat(call->rxnet, stat_why_req_ack[why]);
 446         trace_rxrpc_req_ack(call->debug_id, txb->seq, why);
 447         if (why != rxrpc_reqack_no_srv_last)
 448                 txb->wire.flags |= RXRPC_REQUEST_ACK;
 449 dont_set_request_ack:
 450
 451         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
 452                 static int lose;
 453                 if ((lose++ & 7) == 7) {
 454                         ret = 0;
 455                         trace_rxrpc_tx_data(call, txb->seq, serial,
 456                                             txb->wire.flags,
 457                                             test_bit(RXRPC_TXBUF_RESENT, &txb->flags),
 458                                             true);
 459                         goto done;
 460                 }
 461         }
 462
 463         trace_rxrpc_tx_data(call, txb->seq, serial, txb->wire.flags,
 464                             test_bit(RXRPC_TXBUF_RESENT, &txb->flags), false);
 465         cmpxchg(&call->tx_transmitted, txb->seq - 1, txb->seq);
 466
 467         /* send the packet with the don't fragment bit set if we currently
 468          * think it's small enough */
 469         if (txb->len >= call->peer->maxdata)
 470                 goto send_fragmentable;
 471
 472         down_read(&conn->params.local->defrag_sem);
 473
 474         txb->last_sent = ktime_get_real();
 475         if (txb->wire.flags & RXRPC_REQUEST_ACK)
 476                 rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_data);
 477
 478         /* send the packet by UDP
 479          * - returns -EMSGSIZE if UDP would have to fragment the packet
 480          *   to go out of the interface
 481          *   - in which case, we'll have processed the ICMP error
 482          *     message and update the peer record
 483          */
 484         rxrpc_inc_stat(call->rxnet, stat_tx_data_send);
 485         ret = do_udp_sendmsg(conn->params.local->socket, &msg, len);
 486         conn->params.peer->last_tx_at = ktime_get_seconds();
 487
 488         up_read(&conn->params.local->defrag_sem);
 489         if (ret < 0) {
 490                 rxrpc_cancel_rtt_probe(call, serial, rtt_slot);
 491                 trace_rxrpc_tx_fail(call->debug_id, serial, ret,
 492                                     rxrpc_tx_point_call_data_nofrag);
 493         } else {
 494                 trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
 495                                       rxrpc_tx_point_call_data_nofrag);
 496         }
 497
 498         rxrpc_tx_backoff(call, ret);
 499         if (ret == -EMSGSIZE)
 500                 goto send_fragmentable;
 501
 502 done:
 503         if (ret >= 0) {
 504                 call->tx_last_sent = txb->last_sent;
 505                 if (txb->wire.flags & RXRPC_REQUEST_ACK) {
 506                         call->peer->rtt_last_req = txb->last_sent;
 507                         if (call->peer->rtt_count > 1) {
 508                                 unsigned long nowj = jiffies, ack_lost_at;
 509
 510                                 ack_lost_at = rxrpc_get_rto_backoff(call->peer, false);
 511                                 ack_lost_at += nowj;
 512                                 WRITE_ONCE(call->ack_lost_at, ack_lost_at);
 513                                 rxrpc_reduce_call_timer(call, ack_lost_at, nowj,
 514                                                         rxrpc_timer_set_for_lost_ack);
 515                         }
 516                 }
 517
 518                 if (txb->seq == 1 &&
 519                     !test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER,
 520                                       &call->flags)) {
 521                         unsigned long nowj = jiffies, expect_rx_by;
 522
 523                         expect_rx_by = nowj + call->next_rx_timo;
 524                         WRITE_ONCE(call->expect_rx_by, expect_rx_by);
 525                         rxrpc_reduce_call_timer(call, expect_rx_by, nowj,
 526                                                 rxrpc_timer_set_for_normal);
 527                 }
 528
 529                 rxrpc_set_keepalive(call);
 530         } else {
 531                 /* Cancel the call if the initial transmission fails,
 532                  * particularly if that's due to network routing issues that
 533                  * aren't going away anytime soon.  The layer above can arrange
 534                  * the retransmission.
 535                  */
 536                 if (!test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags))
 537                         rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
 538                                                   RX_USER_ABORT, ret);
 539         }
 540
 541         _leave(" = %d [%u]", ret, call->peer->maxdata);
 542         return ret;
 543
 544 send_fragmentable:
 545         /* attempt to send this message with fragmentation enabled */
 546         _debug("send fragment");
 547
 548         down_write(&conn->params.local->defrag_sem);
 549
 550         txb->last_sent = ktime_get_real();
 551         if (txb->wire.flags & RXRPC_REQUEST_ACK)
 552                 rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_data);
 553
 554         switch (conn->params.local->srx.transport.family) {
 555         case AF_INET6:
 556         case AF_INET:
 557                 ip_sock_set_mtu_discover(conn->params.local->socket->sk,
 558                                          IP_PMTUDISC_DONT);
 559                 rxrpc_inc_stat(call->rxnet, stat_tx_data_send_frag);
 560                 ret = do_udp_sendmsg(conn->params.local->socket, &msg, len);
 561                 conn->params.peer->last_tx_at = ktime_get_seconds();
 562
 563                 ip_sock_set_mtu_discover(conn->params.local->socket->sk,
 564                                          IP_PMTUDISC_DO);
 565                 break;
 566
 567         default:
 568                 BUG();
 569         }
 570
 571         if (ret < 0) {
 572                 rxrpc_cancel_rtt_probe(call, serial, rtt_slot);
 573                 trace_rxrpc_tx_fail(call->debug_id, serial, ret,
 574                                     rxrpc_tx_point_call_data_frag);
 575         } else {
 576                 trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
 577                                       rxrpc_tx_point_call_data_frag);
 578         }
 579         rxrpc_tx_backoff(call, ret);
 580
 581         up_write(&conn->params.local->defrag_sem);
 582         goto done;
 583 }
 584
 585 /*
 586  * reject packets through the local endpoint
 587  */
 588 void rxrpc_reject_packets(struct rxrpc_local *local)
 589 {
 590         struct sockaddr_rxrpc srx;
 591         struct rxrpc_skb_priv *sp;
 592         struct rxrpc_wire_header whdr;
 593         struct sk_buff *skb;
 594         struct msghdr msg;
 595         struct kvec iov[2];
 596         size_t size;
 597         __be32 code;
 598         int ret, ioc;
 599
 600         _enter("%d", local->debug_id);
 601
 602         iov[0].iov_base = &whdr;
 603         iov[0].iov_len = sizeof(whdr);
 604         iov[1].iov_base = &code;
 605         iov[1].iov_len = sizeof(code);
 606
 607         msg.msg_name = &srx.transport;
 608         msg.msg_control = NULL;
 609         msg.msg_controllen = 0;
 610         msg.msg_flags = 0;
 611
 612         memset(&whdr, 0, sizeof(whdr));
 613
 614         while ((skb = skb_dequeue(&local->reject_queue))) {
 615                 rxrpc_see_skb(skb, rxrpc_skb_seen);
 616                 sp = rxrpc_skb(skb);
 617
 618                 switch (skb->mark) {
 619                 case RXRPC_SKB_MARK_REJECT_BUSY:
 620                         whdr.type = RXRPC_PACKET_TYPE_BUSY;
 621                         size = sizeof(whdr);
 622                         ioc = 1;
 623                         break;
 624                 case RXRPC_SKB_MARK_REJECT_ABORT:
 625                         whdr.type = RXRPC_PACKET_TYPE_ABORT;
 626                         code = htonl(skb->priority);
 627                         size = sizeof(whdr) + sizeof(code);
 628                         ioc = 2;
 629                         break;
 630                 default:
 631                         rxrpc_free_skb(skb, rxrpc_skb_freed);
 632                         continue;
 633                 }
 634
 635                 if (rxrpc_extract_addr_from_skb(&srx, skb) == 0) {
 636                         msg.msg_namelen = srx.transport_len;
 637
 638                         whdr.epoch      = htonl(sp->hdr.epoch);
 639                         whdr.cid        = htonl(sp->hdr.cid);
 640                         whdr.callNumber = htonl(sp->hdr.callNumber);
 641                         whdr.serviceId  = htons(sp->hdr.serviceId);
 642                         whdr.flags      = sp->hdr.flags;
 643                         whdr.flags      ^= RXRPC_CLIENT_INITIATED;
 644                         whdr.flags      &= RXRPC_CLIENT_INITIATED;
 645
 646                         iov_iter_kvec(&msg.msg_iter, WRITE, iov, ioc, size);
 647                         ret = do_udp_sendmsg(local->socket, &msg, size);
 648                         if (ret < 0)
 649                                 trace_rxrpc_tx_fail(local->debug_id, 0, ret,
 650                                                     rxrpc_tx_point_reject);
 651                         else
 652                                 trace_rxrpc_tx_packet(local->debug_id, &whdr,
 653                                                       rxrpc_tx_point_reject);
 654                 }
 655
 656                 rxrpc_free_skb(skb, rxrpc_skb_freed);
 657         }
 658
 659         _leave("");
 660 }
 661
 662 /*
 663  * Send a VERSION reply to a peer as a keepalive.
 664  */
 665 void rxrpc_send_keepalive(struct rxrpc_peer *peer)
 666 {
 667         struct rxrpc_wire_header whdr;
 668         struct msghdr msg;
 669         struct kvec iov[2];
 670         size_t len;
 671         int ret;
 672
 673         _enter("");
 674
 675         msg.msg_name    = &peer->srx.transport;
 676         msg.msg_namelen = peer->srx.transport_len;
 677         msg.msg_control = NULL;
 678         msg.msg_controllen = 0;
 679         msg.msg_flags   = 0;
 680
 681         whdr.epoch      = htonl(peer->local->rxnet->epoch);
 682         whdr.cid        = 0;
 683         whdr.callNumber = 0;
 684         whdr.seq        = 0;
 685         whdr.serial     = 0;
 686         whdr.type       = RXRPC_PACKET_TYPE_VERSION; /* Not client-initiated */
 687         whdr.flags      = RXRPC_LAST_PACKET;
 688         whdr.userStatus = 0;
 689         whdr.securityIndex = 0;
 690         whdr._rsvd      = 0;
 691         whdr.serviceId  = 0;
 692
 693         iov[0].iov_base = &whdr;
 694         iov[0].iov_len  = sizeof(whdr);
 695         iov[1].iov_base = (char *)rxrpc_keepalive_string;
 696         iov[1].iov_len  = sizeof(rxrpc_keepalive_string);
 697
 698         len = iov[0].iov_len + iov[1].iov_len;
 699
 700         _proto("Tx VERSION (keepalive)");
 701
 702         iov_iter_kvec(&msg.msg_iter, WRITE, iov, 2, len);
 703         ret = do_udp_sendmsg(peer->local->socket, &msg, len);
 704         if (ret < 0)
 705                 trace_rxrpc_tx_fail(peer->debug_id, 0, ret,
 706                                     rxrpc_tx_point_version_keepalive);
 707         else
 708                 trace_rxrpc_tx_packet(peer->debug_id, &whdr,
 709                                       rxrpc_tx_point_version_keepalive);
 710
 711         peer->last_tx_at = ktime_get_seconds();
 712         _leave("");
 713 }