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         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
  42         int max, tmp;
  43         unsigned int size = RXRPC_BACKLOG_MAX;
  44         unsigned int head, tail, call_head, call_tail;
  45
  46         max = rx->sk.sk_max_ack_backlog;
  47         tmp = rx->sk.sk_ack_backlog;
  48         if (tmp >= max) {
  49                 _leave(" = -ENOBUFS [full %u]", max);
  50                 return -ENOBUFS;
  51         }
  52         max -= tmp;
  53
  54         /* We don't need more conns and peers than we have calls, but on the
  55          * other hand, we shouldn't ever use more peers than conns or conns
  56          * than calls.
  57          */
  58         call_head = b->call_backlog_head;
  59         call_tail = READ_ONCE(b->call_backlog_tail);
  60         tmp = CIRC_CNT(call_head, call_tail, size);
  61         if (tmp >= max) {
  62                 _leave(" = -ENOBUFS [enough %u]", tmp);
  63                 return -ENOBUFS;
  64         }
  65         max = tmp + 1;
  66
  67         head = b->peer_backlog_head;
  68         tail = READ_ONCE(b->peer_backlog_tail);
  69         if (CIRC_CNT(head, tail, size) < max) {
  70                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
  71                 if (!peer)
  72                         return -ENOMEM;
  73                 b->peer_backlog[head] = peer;
  74                 smp_store_release(&b->peer_backlog_head,
  75                                   (head + 1) & (size - 1));
  76         }
  77
  78         head = b->conn_backlog_head;
  79         tail = READ_ONCE(b->conn_backlog_tail);
  80         if (CIRC_CNT(head, tail, size) < max) {
  81                 struct rxrpc_connection *conn;
  82
  83                 conn = rxrpc_prealloc_service_connection(rxnet, gfp);
  84                 if (!conn)
  85                         return -ENOMEM;
  86                 b->conn_backlog[head] = conn;
  87                 smp_store_release(&b->conn_backlog_head,
  88                                   (head + 1) & (size - 1));
  89
  90                 trace_rxrpc_conn(conn, rxrpc_conn_new_service,
  91                                  atomic_read(&conn->usage), here);
  92         }
  93
  94         /* Now it gets complicated, because calls get registered with the
  95          * socket here, particularly if a user ID is preassigned by the user.
  96          */
  97         call = rxrpc_alloc_call(gfp);
  98         if (!call)
  99                 return -ENOMEM;
 100         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
 101         call->state = RXRPC_CALL_SERVER_PREALLOC;
 102
 103         trace_rxrpc_call(call, rxrpc_call_new_service,
 104                          atomic_read(&call->usage),
 105                          here, (const void *)user_call_ID);
 106
 107         write_lock(&rx->call_lock);
 108         if (user_attach_call) {
 109                 struct rxrpc_call *xcall;
 110                 struct rb_node *parent, **pp;
 111
 112                 /* Check the user ID isn't already in use */
 113                 pp = &rx->calls.rb_node;
 114                 parent = NULL;
 115                 while (*pp) {
 116                         parent = *pp;
 117                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 118                         if (user_call_ID < call->user_call_ID)
 119                                 pp = &(*pp)->rb_left;
 120                         else if (user_call_ID > call->user_call_ID)
 121                                 pp = &(*pp)->rb_right;
 122                         else
 123                                 goto id_in_use;
 124                 }
 125
 126                 call->user_call_ID = user_call_ID;
 127                 call->notify_rx = notify_rx;
 128                 rxrpc_get_call(call, rxrpc_call_got_kernel);
 129                 user_attach_call(call, user_call_ID);
 130                 rxrpc_get_call(call, rxrpc_call_got_userid);
 131                 rb_link_node(&call->sock_node, parent, pp);
 132                 rb_insert_color(&call->sock_node, &rx->calls);
 133                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 134         }
 135
 136         list_add(&call->sock_link, &rx->sock_calls);
 137
 138         write_unlock(&rx->call_lock);
 139
 140         write_lock(&rxnet->call_lock);
 141         list_add_tail(&call->link, &rxnet->calls);
 142         write_unlock(&rxnet->call_lock);
 143
 144         b->call_backlog[call_head] = call;
 145         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 146         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 147         return 0;
 148
 149 id_in_use:
 150         write_unlock(&rx->call_lock);
 151         rxrpc_cleanup_call(call);
 152         _leave(" = -EBADSLT");
 153         return -EBADSLT;
 154 }
 155
 156 /*
 157  * Preallocate sufficient service connections, calls and peers to cover the
 158  * entire backlog of a socket.  When a new call comes in, if we don't have
 159  * sufficient of each available, the call gets rejected as busy or ignored.
 160  *
 161  * The backlog is replenished when a connection is accepted or rejected.
 162  */
 163 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 164 {
 165         struct rxrpc_backlog *b = rx->backlog;
 166
 167         if (!b) {
 168                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 169                 if (!b)
 170                         return -ENOMEM;
 171                 rx->backlog = b;
 172         }
 173
 174         if (rx->discard_new_call)
 175                 return 0;
 176
 177         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp) == 0)
 178                 ;
 179
 180         return 0;
 181 }
 182
 183 /*
 184  * Discard the preallocation on a service.
 185  */
 186 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 187 {
 188         struct rxrpc_backlog *b = rx->backlog;
 189         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
 190         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 191
 192         if (!b)
 193                 return;
 194         rx->backlog = NULL;
 195
 196         /* Make sure that there aren't any incoming calls in progress before we
 197          * clear the preallocation buffers.
 198          */
 199         spin_lock_bh(&rx->incoming_lock);
 200         spin_unlock_bh(&rx->incoming_lock);
 201
 202         head = b->peer_backlog_head;
 203         tail = b->peer_backlog_tail;
 204         while (CIRC_CNT(head, tail, size) > 0) {
 205                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 206                 kfree(peer);
 207                 tail = (tail + 1) & (size - 1);
 208         }
 209
 210         head = b->conn_backlog_head;
 211         tail = b->conn_backlog_tail;
 212         while (CIRC_CNT(head, tail, size) > 0) {
 213                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 214                 write_lock(&rxnet->conn_lock);
 215                 list_del(&conn->link);
 216                 list_del(&conn->proc_link);
 217                 write_unlock(&rxnet->conn_lock);
 218                 kfree(conn);
 219                 tail = (tail + 1) & (size - 1);
 220         }
 221
 222         head = b->call_backlog_head;
 223         tail = b->call_backlog_tail;
 224         while (CIRC_CNT(head, tail, size) > 0) {
 225                 struct rxrpc_call *call = b->call_backlog[tail];
 226                 if (rx->discard_new_call) {
 227                         _debug("discard %lx", call->user_call_ID);
 228                         rx->discard_new_call(call, call->user_call_ID);
 229                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 230                 }
 231                 rxrpc_call_completed(call);
 232                 rxrpc_release_call(rx, call);
 233                 rxrpc_put_call(call, rxrpc_call_put);
 234                 tail = (tail + 1) & (size - 1);
 235         }
 236
 237         kfree(b);
 238 }
 239
 240 /*
 241  * Allocate a new incoming call from the prealloc pool, along with a connection
 242  * and a peer as necessary.
 243  */
 244 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 245                                                     struct rxrpc_local *local,
 246                                                     struct rxrpc_connection *conn,
 247                                                     struct sk_buff *skb)
 248 {
 249         struct rxrpc_backlog *b = rx->backlog;
 250         struct rxrpc_peer *peer, *xpeer;
 251         struct rxrpc_call *call;
 252         unsigned short call_head, conn_head, peer_head;
 253         unsigned short call_tail, conn_tail, peer_tail;
 254         unsigned short call_count, conn_count;
 255
 256         /* #calls >= #conns >= #peers must hold true. */
 257         call_head = smp_load_acquire(&b->call_backlog_head);
 258         call_tail = b->call_backlog_tail;
 259         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 260         conn_head = smp_load_acquire(&b->conn_backlog_head);
 261         conn_tail = b->conn_backlog_tail;
 262         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 263         ASSERTCMP(conn_count, >=, call_count);
 264         peer_head = smp_load_acquire(&b->peer_backlog_head);
 265         peer_tail = b->peer_backlog_tail;
 266         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 267                   conn_count);
 268
 269         if (call_count == 0)
 270                 return NULL;
 271
 272         if (!conn) {
 273                 /* No connection.  We're going to need a peer to start off
 274                  * with.  If one doesn't yet exist, use a spare from the
 275                  * preallocation set.  We dump the address into the spare in
 276                  * anticipation - and to save on stack space.
 277                  */
 278                 xpeer = b->peer_backlog[peer_tail];
 279                 if (rxrpc_extract_addr_from_skb(&xpeer->srx, skb) < 0)
 280                         return NULL;
 281
 282                 peer = rxrpc_lookup_incoming_peer(local, xpeer);
 283                 if (peer == xpeer) {
 284                         b->peer_backlog[peer_tail] = NULL;
 285                         smp_store_release(&b->peer_backlog_tail,
 286                                           (peer_tail + 1) &
 287                                           (RXRPC_BACKLOG_MAX - 1));
 288                 }
 289
 290                 /* Now allocate and set up the connection */
 291                 conn = b->conn_backlog[conn_tail];
 292                 b->conn_backlog[conn_tail] = NULL;
 293                 smp_store_release(&b->conn_backlog_tail,
 294                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 295                 rxrpc_get_local(local);
 296                 conn->params.local = local;
 297                 conn->params.peer = peer;
 298                 rxrpc_see_connection(conn);
 299                 rxrpc_new_incoming_connection(rx, conn, skb);
 300         } else {
 301                 rxrpc_get_connection(conn);
 302         }
 303
 304         /* And now we can allocate and set up a new call */
 305         call = b->call_backlog[call_tail];
 306         b->call_backlog[call_tail] = NULL;
 307         smp_store_release(&b->call_backlog_tail,
 308                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 309
 310         rxrpc_see_call(call);
 311         call->conn = conn;
 312         call->peer = rxrpc_get_peer(conn->params.peer);
 313         call->cong_cwnd = call->peer->cong_cwnd;
 314         return call;
 315 }
 316
 317 /*
 318  * Set up a new incoming call.  Called in BH context with the RCU read lock
 319  * held.
 320  *
 321  * If this is for a kernel service, when we allocate the call, it will have
 322  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 323  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 324  * services only have the ref from the backlog buffer.  We want to pass this
 325  * ref to non-BH context to dispose of.
 326  *
 327  * If we want to report an error, we mark the skb with the packet type and
 328  * abort code and return NULL.
 329  *
 330  * The call is returned with the user access mutex held.
 331  */
 332 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 333                                            struct rxrpc_connection *conn,
 334                                            struct sk_buff *skb)
 335 {
 336         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 337         struct rxrpc_sock *rx;
 338         struct rxrpc_call *call;
 339         u16 service_id = sp->hdr.serviceId;
 340
 341         _enter("");
 342
 343         /* Get the socket providing the service */
 344         rx = rcu_dereference(local->service);
 345         if (rx && (service_id == rx->srx.srx_service ||
 346                    service_id == rx->second_service))
 347                 goto found_service;
 348
 349         trace_rxrpc_abort("INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
 350                           RX_INVALID_OPERATION, EOPNOTSUPP);
 351         skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 352         skb->priority = RX_INVALID_OPERATION;
 353         _leave(" = NULL [service]");
 354         return NULL;
 355
 356 found_service:
 357         spin_lock(&rx->incoming_lock);
 358         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
 359             rx->sk.sk_state == RXRPC_CLOSE) {
 360                 trace_rxrpc_abort("CLS", sp->hdr.cid, sp->hdr.callNumber,
 361                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 362                 skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 363                 skb->priority = RX_INVALID_OPERATION;
 364                 _leave(" = NULL [close]");
 365                 call = NULL;
 366                 goto out;
 367         }
 368
 369         call = rxrpc_alloc_incoming_call(rx, local, conn, skb);
 370         if (!call) {
 371                 skb->mark = RXRPC_SKB_MARK_BUSY;
 372                 _leave(" = NULL [busy]");
 373                 call = NULL;
 374                 goto out;
 375         }
 376
 377         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 378                             sp->hdr.serial, sp->hdr.seq);
 379
 380         /* Lock the call to prevent rxrpc_kernel_send/recv_data() and
 381          * sendmsg()/recvmsg() inconveniently stealing the mutex once the
 382          * notification is generated.
 383          *
 384          * The BUG should never happen because the kernel should be well
 385          * behaved enough not to access the call before the first notification
 386          * event and userspace is prevented from doing so until the state is
 387          * appropriate.
 388          */
 389         if (!mutex_trylock(&call->user_mutex))
 390                 BUG();
 391
 392         /* Make the call live. */
 393         rxrpc_incoming_call(rx, call, skb);
 394         conn = call->conn;
 395
 396         if (rx->notify_new_call)
 397                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 398         else
 399                 sk_acceptq_added(&rx->sk);
 400
 401         spin_lock(&conn->state_lock);
 402         switch (conn->state) {
 403         case RXRPC_CONN_SERVICE_UNSECURED:
 404                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 405                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 406                 rxrpc_queue_conn(call->conn);
 407                 break;
 408
 409         case RXRPC_CONN_SERVICE:
 410                 write_lock(&call->state_lock);
 411                 if (rx->discard_new_call)
 412                         call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 413                 else
 414                         call->state = RXRPC_CALL_SERVER_ACCEPTING;
 415                 write_unlock(&call->state_lock);
 416                 break;
 417
 418         case RXRPC_CONN_REMOTELY_ABORTED:
 419                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 420                                           conn->remote_abort, -ECONNABORTED);
 421                 break;
 422         case RXRPC_CONN_LOCALLY_ABORTED:
 423                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 424                                  conn->local_abort, -ECONNABORTED);
 425                 break;
 426         default:
 427                 BUG();
 428         }
 429         spin_unlock(&conn->state_lock);
 430
 431         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 432                 rxrpc_notify_socket(call);
 433
 434         /* We have to discard the prealloc queue's ref here and rely on a
 435          * combination of the RCU read lock and refs held either by the socket
 436          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
 437          * service to prevent the call from being deallocated too early.
 438          */
 439         rxrpc_put_call(call, rxrpc_call_put);
 440
 441         _leave(" = %p{%d}", call, call->debug_id);
 442 out:
 443         spin_unlock(&rx->incoming_lock);
 444         return call;
 445 }
 446
 447 /*
 448  * handle acceptance of a call by userspace
 449  * - assign the user call ID to the call at the front of the queue
 450  * - called with the socket locked.
 451  */
 452 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 453                                      unsigned long user_call_ID,
 454                                      rxrpc_notify_rx_t notify_rx)
 455         __releases(&rx->sk.sk_lock.slock)
 456 {
 457         struct rxrpc_call *call;
 458         struct rb_node *parent, **pp;
 459         int ret;
 460
 461         _enter(",%lx", user_call_ID);
 462
 463         ASSERT(!irqs_disabled());
 464
 465         write_lock(&rx->call_lock);
 466
 467         if (list_empty(&rx->to_be_accepted)) {
 468                 write_unlock(&rx->call_lock);
 469                 release_sock(&rx->sk);
 470                 kleave(" = -ENODATA [empty]");
 471                 return ERR_PTR(-ENODATA);
 472         }
 473
 474         /* check the user ID isn't already in use */
 475         pp = &rx->calls.rb_node;
 476         parent = NULL;
 477         while (*pp) {
 478                 parent = *pp;
 479                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 480
 481                 if (user_call_ID < call->user_call_ID)
 482                         pp = &(*pp)->rb_left;
 483                 else if (user_call_ID > call->user_call_ID)
 484                         pp = &(*pp)->rb_right;
 485                 else
 486                         goto id_in_use;
 487         }
 488
 489         /* Dequeue the first call and check it's still valid.  We gain
 490          * responsibility for the queue's reference.
 491          */
 492         call = list_entry(rx->to_be_accepted.next,
 493                           struct rxrpc_call, accept_link);
 494         write_unlock(&rx->call_lock);
 495
 496         /* We need to gain the mutex from the interrupt handler without
 497          * upsetting lockdep, so we have to release it there and take it here.
 498          * We are, however, still holding the socket lock, so other accepts
 499          * must wait for us and no one can add the user ID behind our backs.
 500          */
 501         if (mutex_lock_interruptible(&call->user_mutex) < 0) {
 502                 release_sock(&rx->sk);
 503                 kleave(" = -ERESTARTSYS");
 504                 return ERR_PTR(-ERESTARTSYS);
 505         }
 506
 507         write_lock(&rx->call_lock);
 508         list_del_init(&call->accept_link);
 509         sk_acceptq_removed(&rx->sk);
 510         rxrpc_see_call(call);
 511
 512         /* Find the user ID insertion point. */
 513         pp = &rx->calls.rb_node;
 514         parent = NULL;
 515         while (*pp) {
 516                 parent = *pp;
 517                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 518
 519                 if (user_call_ID < call->user_call_ID)
 520                         pp = &(*pp)->rb_left;
 521                 else if (user_call_ID > call->user_call_ID)
 522                         pp = &(*pp)->rb_right;
 523                 else
 524                         BUG();
 525         }
 526
 527         write_lock_bh(&call->state_lock);
 528         switch (call->state) {
 529         case RXRPC_CALL_SERVER_ACCEPTING:
 530                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 531                 break;
 532         case RXRPC_CALL_COMPLETE:
 533                 ret = call->error;
 534                 goto out_release;
 535         default:
 536                 BUG();
 537         }
 538
 539         /* formalise the acceptance */
 540         call->notify_rx = notify_rx;
 541         call->user_call_ID = user_call_ID;
 542         rxrpc_get_call(call, rxrpc_call_got_userid);
 543         rb_link_node(&call->sock_node, parent, pp);
 544         rb_insert_color(&call->sock_node, &rx->calls);
 545         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 546                 BUG();
 547
 548         write_unlock_bh(&call->state_lock);
 549         write_unlock(&rx->call_lock);
 550         rxrpc_notify_socket(call);
 551         rxrpc_service_prealloc(rx, GFP_KERNEL);
 552         release_sock(&rx->sk);
 553         _leave(" = %p{%d}", call, call->debug_id);
 554         return call;
 555
 556 out_release:
 557         _debug("release %p", call);
 558         write_unlock_bh(&call->state_lock);
 559         write_unlock(&rx->call_lock);
 560         rxrpc_release_call(rx, call);
 561         rxrpc_put_call(call, rxrpc_call_put);
 562         goto out;
 563
 564 id_in_use:
 565         ret = -EBADSLT;
 566         write_unlock(&rx->call_lock);
 567 out:
 568         rxrpc_service_prealloc(rx, GFP_KERNEL);
 569         release_sock(&rx->sk);
 570         _leave(" = %d", ret);
 571         return ERR_PTR(ret);
 572 }
 573
 574 /*
 575  * Handle rejection of a call by userspace
 576  * - reject the call at the front of the queue
 577  */
 578 int rxrpc_reject_call(struct rxrpc_sock *rx)
 579 {
 580         struct rxrpc_call *call;
 581         bool abort = false;
 582         int ret;
 583
 584         _enter("");
 585
 586         ASSERT(!irqs_disabled());
 587
 588         write_lock(&rx->call_lock);
 589
 590         if (list_empty(&rx->to_be_accepted)) {
 591                 write_unlock(&rx->call_lock);
 592                 return -ENODATA;
 593         }
 594
 595         /* Dequeue the first call and check it's still valid.  We gain
 596          * responsibility for the queue's reference.
 597          */
 598         call = list_entry(rx->to_be_accepted.next,
 599                           struct rxrpc_call, accept_link);
 600         list_del_init(&call->accept_link);
 601         sk_acceptq_removed(&rx->sk);
 602         rxrpc_see_call(call);
 603
 604         write_lock_bh(&call->state_lock);
 605         switch (call->state) {
 606         case RXRPC_CALL_SERVER_ACCEPTING:
 607                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, -ECONNABORTED);
 608                 abort = true;
 609                 /* fall through */
 610         case RXRPC_CALL_COMPLETE:
 611                 ret = call->error;
 612                 goto out_discard;
 613         default:
 614                 BUG();
 615         }
 616
 617 out_discard:
 618         write_unlock_bh(&call->state_lock);
 619         write_unlock(&rx->call_lock);
 620         if (abort) {
 621                 rxrpc_send_abort_packet(call);
 622                 rxrpc_release_call(rx, call);
 623                 rxrpc_put_call(call, rxrpc_call_put);
 624         }
 625         rxrpc_service_prealloc(rx, GFP_KERNEL);
 626         _leave(" = %d", ret);
 627         return ret;
 628 }
 629
 630 /*
 631  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 632  * @sock: The socket on which to preallocate
 633  * @notify_rx: Event notification function for the call
 634  * @user_attach_call: Func to attach call to user_call_ID
 635  * @user_call_ID: The tag to attach to the preallocated call
 636  * @gfp: The allocation conditions.
 637  *
 638  * Charge up the socket with preallocated calls, each with a user ID.  A
 639  * function should be provided to effect the attachment from the user's side.
 640  * The user is given a ref to hold on the call.
 641  *
 642  * Note that the call may be come connected before this function returns.
 643  */
 644 int rxrpc_kernel_charge_accept(struct socket *sock,
 645                                rxrpc_notify_rx_t notify_rx,
 646                                rxrpc_user_attach_call_t user_attach_call,
 647                                unsigned long user_call_ID, gfp_t gfp)
 648 {
 649         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 650         struct rxrpc_backlog *b = rx->backlog;
 651
 652         if (sock->sk->sk_state == RXRPC_CLOSE)
 653                 return -ESHUTDOWN;
 654
 655         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 656                                           user_attach_call, user_call_ID,
 657                                           gfp);
 658 }
 659 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);