net/rxrpc/ar-output.c

   1 /* RxRPC packet transmission
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/net.h>
  13 #include <linux/gfp.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/circ_buf.h>
  16 #include <linux/export.h>
  17 #include <net/sock.h>
  18 #include <net/af_rxrpc.h>
  19 #include "ar-internal.h"
  20
  21 /*
  22  * Time till packet resend (in jiffies).
  23  */
  24 unsigned int rxrpc_resend_timeout = 4 * HZ;
  25
  26 static int rxrpc_send_data(struct rxrpc_sock *rx,
  27                            struct rxrpc_call *call,
  28                            struct msghdr *msg, size_t len);
  29
  30 /*
  31  * extract control messages from the sendmsg() control buffer
  32  */
  33 static int rxrpc_sendmsg_cmsg(struct rxrpc_sock *rx, struct msghdr *msg,
  34                               unsigned long *user_call_ID,
  35                               enum rxrpc_command *command,
  36                               u32 *abort_code,
  37                               bool server)
  38 {
  39         struct cmsghdr *cmsg;
  40         int len;
  41
  42         *command = RXRPC_CMD_SEND_DATA;
  43
  44         if (msg->msg_controllen == 0)
  45                 return -EINVAL;
  46
  47         for_each_cmsghdr(cmsg, msg) {
  48                 if (!CMSG_OK(msg, cmsg))
  49                         return -EINVAL;
  50
  51                 len = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
  52                 _debug("CMSG %d, %d, %d",
  53                        cmsg->cmsg_level, cmsg->cmsg_type, len);
  54
  55                 if (cmsg->cmsg_level != SOL_RXRPC)
  56                         continue;
  57
  58                 switch (cmsg->cmsg_type) {
  59                 case RXRPC_USER_CALL_ID:
  60                         if (msg->msg_flags & MSG_CMSG_COMPAT) {
  61                                 if (len != sizeof(u32))
  62                                         return -EINVAL;
  63                                 *user_call_ID = *(u32 *) CMSG_DATA(cmsg);
  64                         } else {
  65                                 if (len != sizeof(unsigned long))
  66                                         return -EINVAL;
  67                                 *user_call_ID = *(unsigned long *)
  68                                         CMSG_DATA(cmsg);
  69                         }
  70                         _debug("User Call ID %lx", *user_call_ID);
  71                         break;
  72
  73                 case RXRPC_ABORT:
  74                         if (*command != RXRPC_CMD_SEND_DATA)
  75                                 return -EINVAL;
  76                         *command = RXRPC_CMD_SEND_ABORT;
  77                         if (len != sizeof(*abort_code))
  78                                 return -EINVAL;
  79                         *abort_code = *(unsigned int *) CMSG_DATA(cmsg);
  80                         _debug("Abort %x", *abort_code);
  81                         if (*abort_code == 0)
  82                                 return -EINVAL;
  83                         break;
  84
  85                 case RXRPC_ACCEPT:
  86                         if (*command != RXRPC_CMD_SEND_DATA)
  87                                 return -EINVAL;
  88                         *command = RXRPC_CMD_ACCEPT;
  89                         if (len != 0)
  90                                 return -EINVAL;
  91                         if (!server)
  92                                 return -EISCONN;
  93                         break;
  94
  95                 default:
  96                         return -EINVAL;
  97                 }
  98         }
  99
 100         _leave(" = 0");
 101         return 0;
 102 }
 103
 104 /*
 105  * abort a call, sending an ABORT packet to the peer
 106  */
 107 static void rxrpc_send_abort(struct rxrpc_call *call, u32 abort_code)
 108 {
 109         write_lock_bh(&call->state_lock);
 110
 111         if (call->state <= RXRPC_CALL_COMPLETE) {
 112                 call->state = RXRPC_CALL_LOCALLY_ABORTED;
 113                 call->local_abort = abort_code;
 114                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 115                 del_timer_sync(&call->resend_timer);
 116                 del_timer_sync(&call->ack_timer);
 117                 clear_bit(RXRPC_CALL_EV_RESEND_TIMER, &call->events);
 118                 clear_bit(RXRPC_CALL_EV_ACK, &call->events);
 119                 clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 120                 rxrpc_queue_call(call);
 121         }
 122
 123         write_unlock_bh(&call->state_lock);
 124 }
 125
 126 /*
 127  * send a message forming part of a client call through an RxRPC socket
 128  * - caller holds the socket locked
 129  * - the socket may be either a client socket or a server socket
 130  */
 131 int rxrpc_client_sendmsg(struct rxrpc_sock *rx, struct rxrpc_transport *trans,
 132                          struct msghdr *msg, size_t len)
 133 {
 134         struct rxrpc_conn_bundle *bundle;
 135         enum rxrpc_command cmd;
 136         struct rxrpc_call *call;
 137         unsigned long user_call_ID = 0;
 138         struct key *key;
 139         u16 service_id;
 140         u32 abort_code = 0;
 141         int ret;
 142
 143         _enter("");
 144
 145         ASSERT(trans != NULL);
 146
 147         ret = rxrpc_sendmsg_cmsg(rx, msg, &user_call_ID, &cmd, &abort_code,
 148                                  false);
 149         if (ret < 0)
 150                 return ret;
 151
 152         bundle = NULL;
 153         if (trans) {
 154                 service_id = rx->srx.srx_service;
 155                 if (msg->msg_name) {
 156                         DECLARE_SOCKADDR(struct sockaddr_rxrpc *, srx,
 157                                          msg->msg_name);
 158                         service_id = srx->srx_service;
 159                 }
 160                 key = rx->key;
 161                 if (key && !rx->key->payload.data[0])
 162                         key = NULL;
 163                 bundle = rxrpc_get_bundle(rx, trans, key, service_id,
 164                                           GFP_KERNEL);
 165                 if (IS_ERR(bundle))
 166                         return PTR_ERR(bundle);
 167         }
 168
 169         call = rxrpc_get_client_call(rx, trans, bundle, user_call_ID,
 170                                      abort_code == 0, GFP_KERNEL);
 171         if (trans)
 172                 rxrpc_put_bundle(trans, bundle);
 173         if (IS_ERR(call)) {
 174                 _leave(" = %ld", PTR_ERR(call));
 175                 return PTR_ERR(call);
 176         }
 177
 178         _debug("CALL %d USR %lx ST %d on CONN %p",
 179                call->debug_id, call->user_call_ID, call->state, call->conn);
 180
 181         if (call->state >= RXRPC_CALL_COMPLETE) {
 182                 /* it's too late for this call */
 183                 ret = -ESHUTDOWN;
 184         } else if (cmd == RXRPC_CMD_SEND_ABORT) {
 185                 rxrpc_send_abort(call, abort_code);
 186         } else if (cmd != RXRPC_CMD_SEND_DATA) {
 187                 ret = -EINVAL;
 188         } else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
 189                 /* request phase complete for this client call */
 190                 ret = -EPROTO;
 191         } else {
 192                 ret = rxrpc_send_data(rx, call, msg, len);
 193         }
 194
 195         rxrpc_put_call(call);
 196         _leave(" = %d", ret);
 197         return ret;
 198 }
 199
 200 /**
 201  * rxrpc_kernel_send_data - Allow a kernel service to send data on a call
 202  * @call: The call to send data through
 203  * @msg: The data to send
 204  * @len: The amount of data to send
 205  *
 206  * Allow a kernel service to send data on a call.  The call must be in an state
 207  * appropriate to sending data.  No control data should be supplied in @msg,
 208  * nor should an address be supplied.  MSG_MORE should be flagged if there's
 209  * more data to come, otherwise this data will end the transmission phase.
 210  */
 211 int rxrpc_kernel_send_data(struct rxrpc_call *call, struct msghdr *msg,
 212                            size_t len)
 213 {
 214         int ret;
 215
 216         _enter("{%d,%s},", call->debug_id, rxrpc_call_states[call->state]);
 217
 218         ASSERTCMP(msg->msg_name, ==, NULL);
 219         ASSERTCMP(msg->msg_control, ==, NULL);
 220
 221         lock_sock(&call->socket->sk);
 222
 223         _debug("CALL %d USR %lx ST %d on CONN %p",
 224                call->debug_id, call->user_call_ID, call->state, call->conn);
 225
 226         if (call->state >= RXRPC_CALL_COMPLETE) {
 227                 ret = -ESHUTDOWN; /* it's too late for this call */
 228         } else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
 229                    call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
 230                    call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
 231                 ret = -EPROTO; /* request phase complete for this client call */
 232         } else {
 233                 ret = rxrpc_send_data(call->socket, call, msg, len);
 234         }
 235
 236         release_sock(&call->socket->sk);
 237         _leave(" = %d", ret);
 238         return ret;
 239 }
 240
 241 EXPORT_SYMBOL(rxrpc_kernel_send_data);
 242
 243 /**
 244  * rxrpc_kernel_abort_call - Allow a kernel service to abort a call
 245  * @call: The call to be aborted
 246  * @abort_code: The abort code to stick into the ABORT packet
 247  *
 248  * Allow a kernel service to abort a call, if it's still in an abortable state.
 249  */
 250 void rxrpc_kernel_abort_call(struct rxrpc_call *call, u32 abort_code)
 251 {
 252         _enter("{%d},%d", call->debug_id, abort_code);
 253
 254         lock_sock(&call->socket->sk);
 255
 256         _debug("CALL %d USR %lx ST %d on CONN %p",
 257                call->debug_id, call->user_call_ID, call->state, call->conn);
 258
 259         if (call->state < RXRPC_CALL_COMPLETE)
 260                 rxrpc_send_abort(call, abort_code);
 261
 262         release_sock(&call->socket->sk);
 263         _leave("");
 264 }
 265
 266 EXPORT_SYMBOL(rxrpc_kernel_abort_call);
 267
 268 /*
 269  * send a message through a server socket
 270  * - caller holds the socket locked
 271  */
 272 int rxrpc_server_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
 273 {
 274         enum rxrpc_command cmd;
 275         struct rxrpc_call *call;
 276         unsigned long user_call_ID = 0;
 277         u32 abort_code = 0;
 278         int ret;
 279
 280         _enter("");
 281
 282         ret = rxrpc_sendmsg_cmsg(rx, msg, &user_call_ID, &cmd, &abort_code,
 283                                  true);
 284         if (ret < 0)
 285                 return ret;
 286
 287         if (cmd == RXRPC_CMD_ACCEPT) {
 288                 call = rxrpc_accept_call(rx, user_call_ID);
 289                 if (IS_ERR(call))
 290                         return PTR_ERR(call);
 291                 rxrpc_put_call(call);
 292                 return 0;
 293         }
 294
 295         call = rxrpc_find_server_call(rx, user_call_ID);
 296         if (!call)
 297                 return -EBADSLT;
 298         if (call->state >= RXRPC_CALL_COMPLETE) {
 299                 ret = -ESHUTDOWN;
 300                 goto out;
 301         }
 302
 303         switch (cmd) {
 304         case RXRPC_CMD_SEND_DATA:
 305                 if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
 306                     call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
 307                     call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
 308                         /* Tx phase not yet begun for this call */
 309                         ret = -EPROTO;
 310                         break;
 311                 }
 312
 313                 ret = rxrpc_send_data(rx, call, msg, len);
 314                 break;
 315
 316         case RXRPC_CMD_SEND_ABORT:
 317                 rxrpc_send_abort(call, abort_code);
 318                 break;
 319         default:
 320                 BUG();
 321         }
 322
 323         out:
 324         rxrpc_put_call(call);
 325         _leave(" = %d", ret);
 326         return ret;
 327 }
 328
 329 /*
 330  * send a packet through the transport endpoint
 331  */
 332 int rxrpc_send_packet(struct rxrpc_transport *trans, struct sk_buff *skb)
 333 {
 334         struct kvec iov[1];
 335         struct msghdr msg;
 336         int ret, opt;
 337
 338         _enter(",{%d}", skb->len);
 339
 340         iov[0].iov_base = skb->head;
 341         iov[0].iov_len = skb->len;
 342
 343         msg.msg_name = &trans->peer->srx.transport.sin;
 344         msg.msg_namelen = sizeof(trans->peer->srx.transport.sin);
 345         msg.msg_control = NULL;
 346         msg.msg_controllen = 0;
 347         msg.msg_flags = 0;
 348
 349         /* send the packet with the don't fragment bit set if we currently
 350          * think it's small enough */
 351         if (skb->len - sizeof(struct rxrpc_wire_header) < trans->peer->maxdata) {
 352                 down_read(&trans->local->defrag_sem);
 353                 /* send the packet by UDP
 354                  * - returns -EMSGSIZE if UDP would have to fragment the packet
 355                  *   to go out of the interface
 356                  *   - in which case, we'll have processed the ICMP error
 357                  *     message and update the peer record
 358                  */
 359                 ret = kernel_sendmsg(trans->local->socket, &msg, iov, 1,
 360                                      iov[0].iov_len);
 361
 362                 up_read(&trans->local->defrag_sem);
 363                 if (ret == -EMSGSIZE)
 364                         goto send_fragmentable;
 365
 366                 _leave(" = %d [%u]", ret, trans->peer->maxdata);
 367                 return ret;
 368         }
 369
 370 send_fragmentable:
 371         /* attempt to send this message with fragmentation enabled */
 372         _debug("send fragment");
 373
 374         down_write(&trans->local->defrag_sem);
 375         opt = IP_PMTUDISC_DONT;
 376         ret = kernel_setsockopt(trans->local->socket, SOL_IP, IP_MTU_DISCOVER,
 377                                 (char *) &opt, sizeof(opt));
 378         if (ret == 0) {
 379                 ret = kernel_sendmsg(trans->local->socket, &msg, iov, 1,
 380                                      iov[0].iov_len);
 381
 382                 opt = IP_PMTUDISC_DO;
 383                 kernel_setsockopt(trans->local->socket, SOL_IP,
 384                                   IP_MTU_DISCOVER, (char *) &opt, sizeof(opt));
 385         }
 386
 387         up_write(&trans->local->defrag_sem);
 388         _leave(" = %d [frag %u]", ret, trans->peer->maxdata);
 389         return ret;
 390 }
 391
 392 /*
 393  * wait for space to appear in the transmit/ACK window
 394  * - caller holds the socket locked
 395  */
 396 static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
 397                                     struct rxrpc_call *call,
 398                                     long *timeo)
 399 {
 400         DECLARE_WAITQUEUE(myself, current);
 401         int ret;
 402
 403         _enter(",{%d},%ld",
 404                CIRC_SPACE(call->acks_head, ACCESS_ONCE(call->acks_tail),
 405                           call->acks_winsz),
 406                *timeo);
 407
 408         add_wait_queue(&call->tx_waitq, &myself);
 409
 410         for (;;) {
 411                 set_current_state(TASK_INTERRUPTIBLE);
 412                 ret = 0;
 413                 if (CIRC_SPACE(call->acks_head, ACCESS_ONCE(call->acks_tail),
 414                                call->acks_winsz) > 0)
 415                         break;
 416                 if (signal_pending(current)) {
 417                         ret = sock_intr_errno(*timeo);
 418                         break;
 419                 }
 420
 421                 release_sock(&rx->sk);
 422                 *timeo = schedule_timeout(*timeo);
 423                 lock_sock(&rx->sk);
 424         }
 425
 426         remove_wait_queue(&call->tx_waitq, &myself);
 427         set_current_state(TASK_RUNNING);
 428         _leave(" = %d", ret);
 429         return ret;
 430 }
 431
 432 /*
 433  * attempt to schedule an instant Tx resend
 434  */
 435 static inline void rxrpc_instant_resend(struct rxrpc_call *call)
 436 {
 437         read_lock_bh(&call->state_lock);
 438         if (try_to_del_timer_sync(&call->resend_timer) >= 0) {
 439                 clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 440                 if (call->state < RXRPC_CALL_COMPLETE &&
 441                     !test_and_set_bit(RXRPC_CALL_EV_RESEND_TIMER, &call->events))
 442                         rxrpc_queue_call(call);
 443         }
 444         read_unlock_bh(&call->state_lock);
 445 }
 446
 447 /*
 448  * queue a packet for transmission, set the resend timer and attempt
 449  * to send the packet immediately
 450  */
 451 static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
 452                                bool last)
 453 {
 454         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 455         int ret;
 456
 457         _net("queue skb %p [%d]", skb, call->acks_head);
 458
 459         ASSERT(call->acks_window != NULL);
 460         call->acks_window[call->acks_head] = (unsigned long) skb;
 461         smp_wmb();
 462         call->acks_head = (call->acks_head + 1) & (call->acks_winsz - 1);
 463
 464         if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
 465                 _debug("________awaiting reply/ACK__________");
 466                 write_lock_bh(&call->state_lock);
 467                 switch (call->state) {
 468                 case RXRPC_CALL_CLIENT_SEND_REQUEST:
 469                         call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 470                         break;
 471                 case RXRPC_CALL_SERVER_ACK_REQUEST:
 472                         call->state = RXRPC_CALL_SERVER_SEND_REPLY;
 473                         if (!last)
 474                                 break;
 475                 case RXRPC_CALL_SERVER_SEND_REPLY:
 476                         call->state = RXRPC_CALL_SERVER_AWAIT_ACK;
 477                         break;
 478                 default:
 479                         break;
 480                 }
 481                 write_unlock_bh(&call->state_lock);
 482         }
 483
 484         _proto("Tx DATA %%%u { #%u }", sp->hdr.serial, sp->hdr.seq);
 485
 486         sp->need_resend = false;
 487         sp->resend_at = jiffies + rxrpc_resend_timeout;
 488         if (!test_and_set_bit(RXRPC_CALL_RUN_RTIMER, &call->flags)) {
 489                 _debug("run timer");
 490                 call->resend_timer.expires = sp->resend_at;
 491                 add_timer(&call->resend_timer);
 492         }
 493
 494         /* attempt to cancel the rx-ACK timer, deferring reply transmission if
 495          * we're ACK'ing the request phase of an incoming call */
 496         ret = -EAGAIN;
 497         if (try_to_del_timer_sync(&call->ack_timer) >= 0) {
 498                 /* the packet may be freed by rxrpc_process_call() before this
 499                  * returns */
 500                 ret = rxrpc_send_packet(call->conn->trans, skb);
 501                 _net("sent skb %p", skb);
 502         } else {
 503                 _debug("failed to delete ACK timer");
 504         }
 505
 506         if (ret < 0) {
 507                 _debug("need instant resend %d", ret);
 508                 sp->need_resend = true;
 509                 rxrpc_instant_resend(call);
 510         }
 511
 512         _leave("");
 513 }
 514
 515 /*
 516  * Convert a host-endian header into a network-endian header.
 517  */
 518 static void rxrpc_insert_header(struct sk_buff *skb)
 519 {
 520         struct rxrpc_wire_header whdr;
 521         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 522
 523         whdr.epoch      = htonl(sp->hdr.epoch);
 524         whdr.cid        = htonl(sp->hdr.cid);
 525         whdr.callNumber = htonl(sp->hdr.callNumber);
 526         whdr.seq        = htonl(sp->hdr.seq);
 527         whdr.serial     = htonl(sp->hdr.serial);
 528         whdr.type       = sp->hdr.type;
 529         whdr.flags      = sp->hdr.flags;
 530         whdr.userStatus = sp->hdr.userStatus;
 531         whdr.securityIndex = sp->hdr.securityIndex;
 532         whdr._rsvd      = htons(sp->hdr._rsvd);
 533         whdr.serviceId  = htons(sp->hdr.serviceId);
 534
 535         memcpy(skb->head, &whdr, sizeof(whdr));
 536 }
 537
 538 /*
 539  * send data through a socket
 540  * - must be called in process context
 541  * - caller holds the socket locked
 542  */
 543 static int rxrpc_send_data(struct rxrpc_sock *rx,
 544                            struct rxrpc_call *call,
 545                            struct msghdr *msg, size_t len)
 546 {
 547         struct rxrpc_skb_priv *sp;
 548         struct sk_buff *skb;
 549         struct sock *sk = &rx->sk;
 550         long timeo;
 551         bool more;
 552         int ret, copied;
 553
 554         timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 555
 556         /* this should be in poll */
 557         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 558
 559         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 560                 return -EPIPE;
 561
 562         more = msg->msg_flags & MSG_MORE;
 563
 564         skb = call->tx_pending;
 565         call->tx_pending = NULL;
 566
 567         copied = 0;
 568         do {
 569                 if (!skb) {
 570                         size_t size, chunk, max, space;
 571
 572                         _debug("alloc");
 573
 574                         if (CIRC_SPACE(call->acks_head,
 575                                        ACCESS_ONCE(call->acks_tail),
 576                                        call->acks_winsz) <= 0) {
 577                                 ret = -EAGAIN;
 578                                 if (msg->msg_flags & MSG_DONTWAIT)
 579                                         goto maybe_error;
 580                                 ret = rxrpc_wait_for_tx_window(rx, call,
 581                                                                &timeo);
 582                                 if (ret < 0)
 583                                         goto maybe_error;
 584                         }
 585
 586                         max = call->conn->trans->peer->maxdata;
 587                         max -= call->conn->security_size;
 588                         max &= ~(call->conn->size_align - 1UL);
 589
 590                         chunk = max;
 591                         if (chunk > msg_data_left(msg) && !more)
 592                                 chunk = msg_data_left(msg);
 593
 594                         space = chunk + call->conn->size_align;
 595                         space &= ~(call->conn->size_align - 1UL);
 596
 597                         size = space + call->conn->header_size;
 598
 599                         _debug("SIZE: %zu/%zu/%zu", chunk, space, size);
 600
 601                         /* create a buffer that we can retain until it's ACK'd */
 602                         skb = sock_alloc_send_skb(
 603                                 sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
 604                         if (!skb)
 605                                 goto maybe_error;
 606
 607                         rxrpc_new_skb(skb);
 608
 609                         _debug("ALLOC SEND %p", skb);
 610
 611                         ASSERTCMP(skb->mark, ==, 0);
 612
 613                         _debug("HS: %u", call->conn->header_size);
 614                         skb_reserve(skb, call->conn->header_size);
 615                         skb->len += call->conn->header_size;
 616
 617                         sp = rxrpc_skb(skb);
 618                         sp->remain = chunk;
 619                         if (sp->remain > skb_tailroom(skb))
 620                                 sp->remain = skb_tailroom(skb);
 621
 622                         _net("skb: hr %d, tr %d, hl %d, rm %d",
 623                                skb_headroom(skb),
 624                                skb_tailroom(skb),
 625                                skb_headlen(skb),
 626                                sp->remain);
 627
 628                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 629                 }
 630
 631                 _debug("append");
 632                 sp = rxrpc_skb(skb);
 633
 634                 /* append next segment of data to the current buffer */
 635                 if (msg_data_left(msg) > 0) {
 636                         int copy = skb_tailroom(skb);
 637                         ASSERTCMP(copy, >, 0);
 638                         if (copy > msg_data_left(msg))
 639                                 copy = msg_data_left(msg);
 640                         if (copy > sp->remain)
 641                                 copy = sp->remain;
 642
 643                         _debug("add");
 644                         ret = skb_add_data(skb, &msg->msg_iter, copy);
 645                         _debug("added");
 646                         if (ret < 0)
 647                                 goto efault;
 648                         sp->remain -= copy;
 649                         skb->mark += copy;
 650                         copied += copy;
 651                 }
 652
 653                 /* check for the far side aborting the call or a network error
 654                  * occurring */
 655                 if (call->state > RXRPC_CALL_COMPLETE)
 656                         goto call_aborted;
 657
 658                 /* add the packet to the send queue if it's now full */
 659                 if (sp->remain <= 0 ||
 660                     (msg_data_left(msg) == 0 && !more)) {
 661                         struct rxrpc_connection *conn = call->conn;
 662                         uint32_t seq;
 663                         size_t pad;
 664
 665                         /* pad out if we're using security */
 666                         if (conn->security_ix) {
 667                                 pad = conn->security_size + skb->mark;
 668                                 pad = conn->size_align - pad;
 669                                 pad &= conn->size_align - 1;
 670                                 _debug("pad %zu", pad);
 671                                 if (pad)
 672                                         memset(skb_put(skb, pad), 0, pad);
 673                         }
 674
 675                         seq = atomic_inc_return(&call->sequence);
 676
 677                         sp->hdr.epoch   = conn->epoch;
 678                         sp->hdr.cid     = call->cid;
 679                         sp->hdr.callNumber = call->call_id;
 680                         sp->hdr.seq     = seq;
 681                         sp->hdr.serial  = atomic_inc_return(&conn->serial);
 682                         sp->hdr.type    = RXRPC_PACKET_TYPE_DATA;
 683                         sp->hdr.userStatus = 0;
 684                         sp->hdr.securityIndex = conn->security_ix;
 685                         sp->hdr._rsvd   = 0;
 686                         sp->hdr.serviceId = call->service_id;
 687
 688                         sp->hdr.flags = conn->out_clientflag;
 689                         if (msg_data_left(msg) == 0 && !more)
 690                                 sp->hdr.flags |= RXRPC_LAST_PACKET;
 691                         else if (CIRC_SPACE(call->acks_head,
 692                                             ACCESS_ONCE(call->acks_tail),
 693                                             call->acks_winsz) > 1)
 694                                 sp->hdr.flags |= RXRPC_MORE_PACKETS;
 695                         if (more && seq & 1)
 696                                 sp->hdr.flags |= RXRPC_REQUEST_ACK;
 697
 698                         ret = conn->security->secure_packet(
 699                                 call, skb, skb->mark,
 700                                 skb->head + sizeof(struct rxrpc_wire_header));
 701                         if (ret < 0)
 702                                 goto out;
 703
 704                         rxrpc_insert_header(skb);
 705                         rxrpc_queue_packet(call, skb, !msg_data_left(msg) && !more);
 706                         skb = NULL;
 707                 }
 708         } while (msg_data_left(msg) > 0);
 709
 710 success:
 711         ret = copied;
 712 out:
 713         call->tx_pending = skb;
 714         _leave(" = %d", ret);
 715         return ret;
 716
 717 call_aborted:
 718         rxrpc_free_skb(skb);
 719         if (call->state == RXRPC_CALL_NETWORK_ERROR)
 720                 ret = call->conn->trans->peer->net_error;
 721         else
 722                 ret = -ECONNABORTED;
 723         _leave(" = %d", ret);
 724         return ret;
 725
 726 maybe_error:
 727         if (copied)
 728                 goto success;
 729         goto out;
 730
 731 efault:
 732         ret = -EFAULT;
 733         goto out;
 734 }