net/rxrpc/call_accept.c

   1 /* incoming call handling
   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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/errqueue.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/in6.h>
  21 #include <linux/icmp.h>
  22 #include <linux/gfp.h>
  23 #include <linux/circ_buf.h>
  24 #include <net/sock.h>
  25 #include <net/af_rxrpc.h>
  26 #include <net/ip.h>
  27 #include "ar-internal.h"
  28
  29 /*
  30  * Preallocate a single service call, connection and peer and, if possible,
  31  * give them a user ID and attach the user's side of the ID to them.
  32  */
  33 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
  34                                       struct rxrpc_backlog *b,
  35                                       rxrpc_notify_rx_t notify_rx,
  36                                       rxrpc_user_attach_call_t user_attach_call,
  37                                       unsigned long user_call_ID, gfp_t gfp)
  38 {
  39         const void *here = __builtin_return_address(0);
  40         struct rxrpc_call *call;
  41         int max, tmp;
  42         unsigned int size = RXRPC_BACKLOG_MAX;
  43         unsigned int head, tail, call_head, call_tail;
  44
  45         max = rx->sk.sk_max_ack_backlog;
  46         tmp = rx->sk.sk_ack_backlog;
  47         if (tmp >= max) {
  48                 _leave(" = -ENOBUFS [full %u]", max);
  49                 return -ENOBUFS;
  50         }
  51         max -= tmp;
  52
  53         /* We don't need more conns and peers than we have calls, but on the
  54          * other hand, we shouldn't ever use more peers than conns or conns
  55          * than calls.
  56          */
  57         call_head = b->call_backlog_head;
  58         call_tail = READ_ONCE(b->call_backlog_tail);
  59         tmp = CIRC_CNT(call_head, call_tail, size);
  60         if (tmp >= max) {
  61                 _leave(" = -ENOBUFS [enough %u]", tmp);
  62                 return -ENOBUFS;
  63         }
  64         max = tmp + 1;
  65
  66         head = b->peer_backlog_head;
  67         tail = READ_ONCE(b->peer_backlog_tail);
  68         if (CIRC_CNT(head, tail, size) < max) {
  69                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
  70                 if (!peer)
  71                         return -ENOMEM;
  72                 b->peer_backlog[head] = peer;
  73                 smp_store_release(&b->peer_backlog_head,
  74                                   (head + 1) & (size - 1));
  75         }
  76
  77         head = b->conn_backlog_head;
  78         tail = READ_ONCE(b->conn_backlog_tail);
  79         if (CIRC_CNT(head, tail, size) < max) {
  80                 struct rxrpc_connection *conn;
  81
  82                 conn = rxrpc_prealloc_service_connection(gfp);
  83                 if (!conn)
  84                         return -ENOMEM;
  85                 b->conn_backlog[head] = conn;
  86                 smp_store_release(&b->conn_backlog_head,
  87                                   (head + 1) & (size - 1));
  88
  89                 trace_rxrpc_conn(conn, rxrpc_conn_new_service,
  90                                  atomic_read(&conn->usage), here);
  91         }
  92
  93         /* Now it gets complicated, because calls get registered with the
  94          * socket here, particularly if a user ID is preassigned by the user.
  95          */
  96         call = rxrpc_alloc_call(gfp);
  97         if (!call)
  98                 return -ENOMEM;
  99         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
 100         call->state = RXRPC_CALL_SERVER_PREALLOC;
 101
 102         trace_rxrpc_call(call, rxrpc_call_new_service,
 103                          atomic_read(&call->usage),
 104                          here, (const void *)user_call_ID);
 105
 106         write_lock(&rx->call_lock);
 107         if (user_attach_call) {
 108                 struct rxrpc_call *xcall;
 109                 struct rb_node *parent, **pp;
 110
 111                 /* Check the user ID isn't already in use */
 112                 pp = &rx->calls.rb_node;
 113                 parent = NULL;
 114                 while (*pp) {
 115                         parent = *pp;
 116                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 117                         if (user_call_ID < call->user_call_ID)
 118                                 pp = &(*pp)->rb_left;
 119                         else if (user_call_ID > call->user_call_ID)
 120                                 pp = &(*pp)->rb_right;
 121                         else
 122                                 goto id_in_use;
 123                 }
 124
 125                 call->user_call_ID = user_call_ID;
 126                 call->notify_rx = notify_rx;
 127                 rxrpc_get_call(call, rxrpc_call_got_kernel);
 128                 user_attach_call(call, user_call_ID);
 129                 rxrpc_get_call(call, rxrpc_call_got_userid);
 130                 rb_link_node(&call->sock_node, parent, pp);
 131                 rb_insert_color(&call->sock_node, &rx->calls);
 132                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 133         }
 134
 135         list_add(&call->sock_link, &rx->sock_calls);
 136
 137         write_unlock(&rx->call_lock);
 138
 139         write_lock(&rxrpc_call_lock);
 140         list_add_tail(&call->link, &rxrpc_calls);
 141         write_unlock(&rxrpc_call_lock);
 142
 143         b->call_backlog[call_head] = call;
 144         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 145         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 146         return 0;
 147
 148 id_in_use:
 149         write_unlock(&rx->call_lock);
 150         rxrpc_cleanup_call(call);
 151         _leave(" = -EBADSLT");
 152         return -EBADSLT;
 153 }
 154
 155 /*
 156  * Preallocate sufficient service connections, calls and peers to cover the
 157  * entire backlog of a socket.  When a new call comes in, if we don't have
 158  * sufficient of each available, the call gets rejected as busy or ignored.
 159  *
 160  * The backlog is replenished when a connection is accepted or rejected.
 161  */
 162 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 163 {
 164         struct rxrpc_backlog *b = rx->backlog;
 165
 166         if (!b) {
 167                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 168                 if (!b)
 169                         return -ENOMEM;
 170                 rx->backlog = b;
 171         }
 172
 173         if (rx->discard_new_call)
 174                 return 0;
 175
 176         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp) == 0)
 177                 ;
 178
 179         return 0;
 180 }
 181
 182 /*
 183  * Discard the preallocation on a service.
 184  */
 185 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 186 {
 187         struct rxrpc_backlog *b = rx->backlog;
 188         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 189
 190         if (!b)
 191                 return;
 192         rx->backlog = NULL;
 193
 194         /* Make sure that there aren't any incoming calls in progress before we
 195          * clear the preallocation buffers.
 196          */
 197         spin_lock_bh(&rx->incoming_lock);
 198         spin_unlock_bh(&rx->incoming_lock);
 199
 200         head = b->peer_backlog_head;
 201         tail = b->peer_backlog_tail;
 202         while (CIRC_CNT(head, tail, size) > 0) {
 203                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 204                 kfree(peer);
 205                 tail = (tail + 1) & (size - 1);
 206         }
 207
 208         head = b->conn_backlog_head;
 209         tail = b->conn_backlog_tail;
 210         while (CIRC_CNT(head, tail, size) > 0) {
 211                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 212                 write_lock(&rxrpc_connection_lock);
 213                 list_del(&conn->link);
 214                 list_del(&conn->proc_link);
 215                 write_unlock(&rxrpc_connection_lock);
 216                 kfree(conn);
 217                 tail = (tail + 1) & (size - 1);
 218         }
 219
 220         head = b->call_backlog_head;
 221         tail = b->call_backlog_tail;
 222         while (CIRC_CNT(head, tail, size) > 0) {
 223                 struct rxrpc_call *call = b->call_backlog[tail];
 224                 if (rx->discard_new_call) {
 225                         _debug("discard %lx", call->user_call_ID);
 226                         rx->discard_new_call(call, call->user_call_ID);
 227                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 228                 }
 229                 rxrpc_call_completed(call);
 230                 rxrpc_release_call(rx, call);
 231                 rxrpc_put_call(call, rxrpc_call_put);
 232                 tail = (tail + 1) & (size - 1);
 233         }
 234
 235         kfree(b);
 236 }
 237
 238 /*
 239  * Allocate a new incoming call from the prealloc pool, along with a connection
 240  * and a peer as necessary.
 241  */
 242 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 243                                                     struct rxrpc_local *local,
 244                                                     struct rxrpc_connection *conn,
 245                                                     struct sk_buff *skb)
 246 {
 247         struct rxrpc_backlog *b = rx->backlog;
 248         struct rxrpc_peer *peer, *xpeer;
 249         struct rxrpc_call *call;
 250         unsigned short call_head, conn_head, peer_head;
 251         unsigned short call_tail, conn_tail, peer_tail;
 252         unsigned short call_count, conn_count;
 253
 254         /* #calls >= #conns >= #peers must hold true. */
 255         call_head = smp_load_acquire(&b->call_backlog_head);
 256         call_tail = b->call_backlog_tail;
 257         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 258         conn_head = smp_load_acquire(&b->conn_backlog_head);
 259         conn_tail = b->conn_backlog_tail;
 260         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 261         ASSERTCMP(conn_count, >=, call_count);
 262         peer_head = smp_load_acquire(&b->peer_backlog_head);
 263         peer_tail = b->peer_backlog_tail;
 264         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 265                   conn_count);
 266
 267         if (call_count == 0)
 268                 return NULL;
 269
 270         if (!conn) {
 271                 /* No connection.  We're going to need a peer to start off
 272                  * with.  If one doesn't yet exist, use a spare from the
 273                  * preallocation set.  We dump the address into the spare in
 274                  * anticipation - and to save on stack space.
 275                  */
 276                 xpeer = b->peer_backlog[peer_tail];
 277                 if (rxrpc_extract_addr_from_skb(&xpeer->srx, skb) < 0)
 278                         return NULL;
 279
 280                 peer = rxrpc_lookup_incoming_peer(local, xpeer);
 281                 if (peer == xpeer) {
 282                         b->peer_backlog[peer_tail] = NULL;
 283                         smp_store_release(&b->peer_backlog_tail,
 284                                           (peer_tail + 1) &
 285                                           (RXRPC_BACKLOG_MAX - 1));
 286                 }
 287
 288                 /* Now allocate and set up the connection */
 289                 conn = b->conn_backlog[conn_tail];
 290                 b->conn_backlog[conn_tail] = NULL;
 291                 smp_store_release(&b->conn_backlog_tail,
 292                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 293                 rxrpc_get_local(local);
 294                 conn->params.local = local;
 295                 conn->params.peer = peer;
 296                 rxrpc_see_connection(conn);
 297                 rxrpc_new_incoming_connection(conn, skb);
 298         } else {
 299                 rxrpc_get_connection(conn);
 300         }
 301
 302         /* And now we can allocate and set up a new call */
 303         call = b->call_backlog[call_tail];
 304         b->call_backlog[call_tail] = NULL;
 305         smp_store_release(&b->call_backlog_tail,
 306                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 307
 308         rxrpc_see_call(call);
 309         call->conn = conn;
 310         call->peer = rxrpc_get_peer(conn->params.peer);
 311         return call;
 312 }
 313
 314 /*
 315  * Set up a new incoming call.  Called in BH context with the RCU read lock
 316  * held.
 317  *
 318  * If this is for a kernel service, when we allocate the call, it will have
 319  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 320  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 321  * services only have the ref from the backlog buffer.  We want to pass this
 322  * ref to non-BH context to dispose of.
 323  *
 324  * If we want to report an error, we mark the skb with the packet type and
 325  * abort code and return NULL.
 326  *
 327  * The call is returned with the user access mutex held.
 328  */
 329 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 330                                            struct rxrpc_connection *conn,
 331                                            struct sk_buff *skb)
 332 {
 333         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 334         struct rxrpc_sock *rx;
 335         struct rxrpc_call *call;
 336         u16 service_id = sp->hdr.serviceId;
 337
 338         _enter("");
 339
 340         /* Get the socket providing the service */
 341         rx = rcu_dereference(local->service);
 342         if (rx && service_id == rx->srx.srx_service)
 343                 goto found_service;
 344
 345         trace_rxrpc_abort("INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
 346                           RX_INVALID_OPERATION, EOPNOTSUPP);
 347         skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 348         skb->priority = RX_INVALID_OPERATION;
 349         _leave(" = NULL [service]");
 350         return NULL;
 351
 352 found_service:
 353         spin_lock(&rx->incoming_lock);
 354         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
 355             rx->sk.sk_state == RXRPC_CLOSE) {
 356                 trace_rxrpc_abort("CLS", sp->hdr.cid, sp->hdr.callNumber,
 357                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 358                 skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 359                 skb->priority = RX_INVALID_OPERATION;
 360                 _leave(" = NULL [close]");
 361                 call = NULL;
 362                 goto out;
 363         }
 364
 365         call = rxrpc_alloc_incoming_call(rx, local, conn, skb);
 366         if (!call) {
 367                 skb->mark = RXRPC_SKB_MARK_BUSY;
 368                 _leave(" = NULL [busy]");
 369                 call = NULL;
 370                 goto out;
 371         }
 372
 373         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 374                             sp->hdr.serial, sp->hdr.seq);
 375
 376         /* Lock the call to prevent rxrpc_kernel_send/recv_data() and
 377          * sendmsg()/recvmsg() inconveniently stealing the mutex once the
 378          * notification is generated.
 379          *
 380          * The BUG should never happen because the kernel should be well
 381          * behaved enough not to access the call before the first notification
 382          * event and userspace is prevented from doing so until the state is
 383          * appropriate.
 384          */
 385         if (!mutex_trylock(&call->user_mutex))
 386                 BUG();
 387
 388         /* Make the call live. */
 389         rxrpc_incoming_call(rx, call, skb);
 390         conn = call->conn;
 391
 392         if (rx->notify_new_call)
 393                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 394         else
 395                 sk_acceptq_added(&rx->sk);
 396
 397         spin_lock(&conn->state_lock);
 398         switch (conn->state) {
 399         case RXRPC_CONN_SERVICE_UNSECURED:
 400                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 401                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 402                 rxrpc_queue_conn(call->conn);
 403                 break;
 404
 405         case RXRPC_CONN_SERVICE:
 406                 write_lock(&call->state_lock);
 407                 if (rx->discard_new_call)
 408                         call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 409                 else
 410                         call->state = RXRPC_CALL_SERVER_ACCEPTING;
 411                 write_unlock(&call->state_lock);
 412                 break;
 413
 414         case RXRPC_CONN_REMOTELY_ABORTED:
 415                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 416                                           conn->remote_abort, ECONNABORTED);
 417                 break;
 418         case RXRPC_CONN_LOCALLY_ABORTED:
 419                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 420                                  conn->local_abort, ECONNABORTED);
 421                 break;
 422         default:
 423                 BUG();
 424         }
 425         spin_unlock(&conn->state_lock);
 426
 427         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 428                 rxrpc_notify_socket(call);
 429
 430         /* We have to discard the prealloc queue's ref here and rely on a
 431          * combination of the RCU read lock and refs held either by the socket
 432          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
 433          * service to prevent the call from being deallocated too early.
 434          */
 435         rxrpc_put_call(call, rxrpc_call_put);
 436
 437         _leave(" = %p{%d}", call, call->debug_id);
 438 out:
 439         spin_unlock(&rx->incoming_lock);
 440         return call;
 441 }
 442
 443 /*
 444  * handle acceptance of a call by userspace
 445  * - assign the user call ID to the call at the front of the queue
 446  * - called with the socket locked.
 447  */
 448 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 449                                      unsigned long user_call_ID,
 450                                      rxrpc_notify_rx_t notify_rx)
 451         __releases(&rx->sk.sk_lock.slock)
 452 {
 453         struct rxrpc_call *call;
 454         struct rb_node *parent, **pp;
 455         int ret;
 456
 457         _enter(",%lx", user_call_ID);
 458
 459         ASSERT(!irqs_disabled());
 460
 461         write_lock(&rx->call_lock);
 462
 463         if (list_empty(&rx->to_be_accepted)) {
 464                 write_unlock(&rx->call_lock);
 465                 release_sock(&rx->sk);
 466                 kleave(" = -ENODATA [empty]");
 467                 return ERR_PTR(-ENODATA);
 468         }
 469
 470         /* check the user ID isn't already in use */
 471         pp = &rx->calls.rb_node;
 472         parent = NULL;
 473         while (*pp) {
 474                 parent = *pp;
 475                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 476
 477                 if (user_call_ID < call->user_call_ID)
 478                         pp = &(*pp)->rb_left;
 479                 else if (user_call_ID > call->user_call_ID)
 480                         pp = &(*pp)->rb_right;
 481                 else
 482                         goto id_in_use;
 483         }
 484
 485         /* Dequeue the first call and check it's still valid.  We gain
 486          * responsibility for the queue's reference.
 487          */
 488         call = list_entry(rx->to_be_accepted.next,
 489                           struct rxrpc_call, accept_link);
 490         write_unlock(&rx->call_lock);
 491
 492         /* We need to gain the mutex from the interrupt handler without
 493          * upsetting lockdep, so we have to release it there and take it here.
 494          * We are, however, still holding the socket lock, so other accepts
 495          * must wait for us and no one can add the user ID behind our backs.
 496          */
 497         if (mutex_lock_interruptible(&call->user_mutex) < 0) {
 498                 release_sock(&rx->sk);
 499                 kleave(" = -ERESTARTSYS");
 500                 return ERR_PTR(-ERESTARTSYS);
 501         }
 502
 503         write_lock(&rx->call_lock);
 504         list_del_init(&call->accept_link);
 505         sk_acceptq_removed(&rx->sk);
 506         rxrpc_see_call(call);
 507
 508         /* Find the user ID insertion point. */
 509         pp = &rx->calls.rb_node;
 510         parent = NULL;
 511         while (*pp) {
 512                 parent = *pp;
 513                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 514
 515                 if (user_call_ID < call->user_call_ID)
 516                         pp = &(*pp)->rb_left;
 517                 else if (user_call_ID > call->user_call_ID)
 518                         pp = &(*pp)->rb_right;
 519                 else
 520                         BUG();
 521         }
 522
 523         write_lock_bh(&call->state_lock);
 524         switch (call->state) {
 525         case RXRPC_CALL_SERVER_ACCEPTING:
 526                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 527                 break;
 528         case RXRPC_CALL_COMPLETE:
 529                 ret = call->error;
 530                 goto out_release;
 531         default:
 532                 BUG();
 533         }
 534
 535         /* formalise the acceptance */
 536         call->notify_rx = notify_rx;
 537         call->user_call_ID = user_call_ID;
 538         rxrpc_get_call(call, rxrpc_call_got_userid);
 539         rb_link_node(&call->sock_node, parent, pp);
 540         rb_insert_color(&call->sock_node, &rx->calls);
 541         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 542                 BUG();
 543
 544         write_unlock_bh(&call->state_lock);
 545         write_unlock(&rx->call_lock);
 546         rxrpc_notify_socket(call);
 547         rxrpc_service_prealloc(rx, GFP_KERNEL);
 548         release_sock(&rx->sk);
 549         _leave(" = %p{%d}", call, call->debug_id);
 550         return call;
 551
 552 out_release:
 553         _debug("release %p", call);
 554         write_unlock_bh(&call->state_lock);
 555         write_unlock(&rx->call_lock);
 556         rxrpc_release_call(rx, call);
 557         rxrpc_put_call(call, rxrpc_call_put);
 558         goto out;
 559
 560 id_in_use:
 561         ret = -EBADSLT;
 562         write_unlock(&rx->call_lock);
 563 out:
 564         rxrpc_service_prealloc(rx, GFP_KERNEL);
 565         release_sock(&rx->sk);
 566         _leave(" = %d", ret);
 567         return ERR_PTR(ret);
 568 }
 569
 570 /*
 571  * Handle rejection of a call by userspace
 572  * - reject the call at the front of the queue
 573  */
 574 int rxrpc_reject_call(struct rxrpc_sock *rx)
 575 {
 576         struct rxrpc_call *call;
 577         bool abort = false;
 578         int ret;
 579
 580         _enter("");
 581
 582         ASSERT(!irqs_disabled());
 583
 584         write_lock(&rx->call_lock);
 585
 586         if (list_empty(&rx->to_be_accepted)) {
 587                 write_unlock(&rx->call_lock);
 588                 return -ENODATA;
 589         }
 590
 591         /* Dequeue the first call and check it's still valid.  We gain
 592          * responsibility for the queue's reference.
 593          */
 594         call = list_entry(rx->to_be_accepted.next,
 595                           struct rxrpc_call, accept_link);
 596         list_del_init(&call->accept_link);
 597         sk_acceptq_removed(&rx->sk);
 598         rxrpc_see_call(call);
 599
 600         write_lock_bh(&call->state_lock);
 601         switch (call->state) {
 602         case RXRPC_CALL_SERVER_ACCEPTING:
 603                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, ECONNABORTED);
 604                 abort = true;
 605                 /* fall through */
 606         case RXRPC_CALL_COMPLETE:
 607                 ret = call->error;
 608                 goto out_discard;
 609         default:
 610                 BUG();
 611         }
 612
 613 out_discard:
 614         write_unlock_bh(&call->state_lock);
 615         write_unlock(&rx->call_lock);
 616         if (abort) {
 617                 rxrpc_send_abort_packet(call);
 618                 rxrpc_release_call(rx, call);
 619                 rxrpc_put_call(call, rxrpc_call_put);
 620         }
 621         rxrpc_service_prealloc(rx, GFP_KERNEL);
 622         _leave(" = %d", ret);
 623         return ret;
 624 }
 625
 626 /*
 627  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 628  * @sock: The socket on which to preallocate
 629  * @notify_rx: Event notification function for the call
 630  * @user_attach_call: Func to attach call to user_call_ID
 631  * @user_call_ID: The tag to attach to the preallocated call
 632  * @gfp: The allocation conditions.
 633  *
 634  * Charge up the socket with preallocated calls, each with a user ID.  A
 635  * function should be provided to effect the attachment from the user's side.
 636  * The user is given a ref to hold on the call.
 637  *
 638  * Note that the call may be come connected before this function returns.
 639  */
 640 int rxrpc_kernel_charge_accept(struct socket *sock,
 641                                rxrpc_notify_rx_t notify_rx,
 642                                rxrpc_user_attach_call_t user_attach_call,
 643                                unsigned long user_call_ID, gfp_t gfp)
 644 {
 645         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 646         struct rxrpc_backlog *b = rx->backlog;
 647
 648         if (sock->sk->sk_state == RXRPC_CLOSE)
 649                 return -ESHUTDOWN;
 650
 651         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 652                                           user_attach_call, user_call_ID,
 653                                           gfp);
 654 }
 655 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);