net/rxrpc/call_accept.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* incoming call handling
   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/module.h>
  11 #include <linux/net.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/errqueue.h>
  14 #include <linux/udp.h>
  15 #include <linux/in.h>
  16 #include <linux/in6.h>
  17 #include <linux/icmp.h>
  18 #include <linux/gfp.h>
  19 #include <linux/circ_buf.h>
  20 #include <net/sock.h>
  21 #include <net/af_rxrpc.h>
  22 #include <net/ip.h>
  23 #include "ar-internal.h"
  24
  25 /*
  26  * Preallocate a single service call, connection and peer and, if possible,
  27  * give them a user ID and attach the user's side of the ID to them.
  28  */
  29 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
  30                                       struct rxrpc_backlog *b,
  31                                       rxrpc_notify_rx_t notify_rx,
  32                                       rxrpc_user_attach_call_t user_attach_call,
  33                                       unsigned long user_call_ID, gfp_t gfp,
  34                                       unsigned int debug_id)
  35 {
  36         const void *here = __builtin_return_address(0);
  37         struct rxrpc_call *call;
  38         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
  39         int max, tmp;
  40         unsigned int size = RXRPC_BACKLOG_MAX;
  41         unsigned int head, tail, call_head, call_tail;
  42
  43         max = rx->sk.sk_max_ack_backlog;
  44         tmp = rx->sk.sk_ack_backlog;
  45         if (tmp >= max) {
  46                 _leave(" = -ENOBUFS [full %u]", max);
  47                 return -ENOBUFS;
  48         }
  49         max -= tmp;
  50
  51         /* We don't need more conns and peers than we have calls, but on the
  52          * other hand, we shouldn't ever use more peers than conns or conns
  53          * than calls.
  54          */
  55         call_head = b->call_backlog_head;
  56         call_tail = READ_ONCE(b->call_backlog_tail);
  57         tmp = CIRC_CNT(call_head, call_tail, size);
  58         if (tmp >= max) {
  59                 _leave(" = -ENOBUFS [enough %u]", tmp);
  60                 return -ENOBUFS;
  61         }
  62         max = tmp + 1;
  63
  64         head = b->peer_backlog_head;
  65         tail = READ_ONCE(b->peer_backlog_tail);
  66         if (CIRC_CNT(head, tail, size) < max) {
  67                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
  68                 if (!peer)
  69                         return -ENOMEM;
  70                 b->peer_backlog[head] = peer;
  71                 smp_store_release(&b->peer_backlog_head,
  72                                   (head + 1) & (size - 1));
  73         }
  74
  75         head = b->conn_backlog_head;
  76         tail = READ_ONCE(b->conn_backlog_tail);
  77         if (CIRC_CNT(head, tail, size) < max) {
  78                 struct rxrpc_connection *conn;
  79
  80                 conn = rxrpc_prealloc_service_connection(rxnet, gfp);
  81                 if (!conn)
  82                         return -ENOMEM;
  83                 b->conn_backlog[head] = conn;
  84                 smp_store_release(&b->conn_backlog_head,
  85                                   (head + 1) & (size - 1));
  86
  87                 trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_service,
  88                                  atomic_read(&conn->usage), here);
  89         }
  90
  91         /* Now it gets complicated, because calls get registered with the
  92          * socket here, particularly if a user ID is preassigned by the user.
  93          */
  94         call = rxrpc_alloc_call(rx, gfp, debug_id);
  95         if (!call)
  96                 return -ENOMEM;
  97         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
  98         call->state = RXRPC_CALL_SERVER_PREALLOC;
  99
 100         trace_rxrpc_call(call->debug_id, rxrpc_call_new_service,
 101                          atomic_read(&call->usage),
 102                          here, (const void *)user_call_ID);
 103
 104         write_lock(&rx->call_lock);
 105         if (user_attach_call) {
 106                 struct rxrpc_call *xcall;
 107                 struct rb_node *parent, **pp;
 108
 109                 /* Check the user ID isn't already in use */
 110                 pp = &rx->calls.rb_node;
 111                 parent = NULL;
 112                 while (*pp) {
 113                         parent = *pp;
 114                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 115                         if (user_call_ID < xcall->user_call_ID)
 116                                 pp = &(*pp)->rb_left;
 117                         else if (user_call_ID > xcall->user_call_ID)
 118                                 pp = &(*pp)->rb_right;
 119                         else
 120                                 goto id_in_use;
 121                 }
 122
 123                 call->user_call_ID = user_call_ID;
 124                 call->notify_rx = notify_rx;
 125                 rxrpc_get_call(call, rxrpc_call_got_kernel);
 126                 user_attach_call(call, user_call_ID);
 127                 rxrpc_get_call(call, rxrpc_call_got_userid);
 128                 rb_link_node(&call->sock_node, parent, pp);
 129                 rb_insert_color(&call->sock_node, &rx->calls);
 130                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 131         }
 132
 133         list_add(&call->sock_link, &rx->sock_calls);
 134
 135         write_unlock(&rx->call_lock);
 136
 137         rxnet = call->rxnet;
 138         write_lock(&rxnet->call_lock);
 139         list_add_tail(&call->link, &rxnet->calls);
 140         write_unlock(&rxnet->call_lock);
 141
 142         b->call_backlog[call_head] = call;
 143         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 144         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 145         return 0;
 146
 147 id_in_use:
 148         write_unlock(&rx->call_lock);
 149         rxrpc_cleanup_call(call);
 150         _leave(" = -EBADSLT");
 151         return -EBADSLT;
 152 }
 153
 154 /*
 155  * Preallocate sufficient service connections, calls and peers to cover the
 156  * entire backlog of a socket.  When a new call comes in, if we don't have
 157  * sufficient of each available, the call gets rejected as busy or ignored.
 158  *
 159  * The backlog is replenished when a connection is accepted or rejected.
 160  */
 161 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 162 {
 163         struct rxrpc_backlog *b = rx->backlog;
 164
 165         if (!b) {
 166                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 167                 if (!b)
 168                         return -ENOMEM;
 169                 rx->backlog = b;
 170         }
 171
 172         if (rx->discard_new_call)
 173                 return 0;
 174
 175         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp,
 176                                           atomic_inc_return(&rxrpc_debug_id)) == 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         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
 189         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 190
 191         if (!b)
 192                 return;
 193         rx->backlog = NULL;
 194
 195         /* Make sure that there aren't any incoming calls in progress before we
 196          * clear the preallocation buffers.
 197          */
 198         spin_lock_bh(&rx->incoming_lock);
 199         spin_unlock_bh(&rx->incoming_lock);
 200
 201         head = b->peer_backlog_head;
 202         tail = b->peer_backlog_tail;
 203         while (CIRC_CNT(head, tail, size) > 0) {
 204                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 205                 kfree(peer);
 206                 tail = (tail + 1) & (size - 1);
 207         }
 208
 209         head = b->conn_backlog_head;
 210         tail = b->conn_backlog_tail;
 211         while (CIRC_CNT(head, tail, size) > 0) {
 212                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 213                 write_lock(&rxnet->conn_lock);
 214                 list_del(&conn->link);
 215                 list_del(&conn->proc_link);
 216                 write_unlock(&rxnet->conn_lock);
 217                 kfree(conn);
 218                 if (atomic_dec_and_test(&rxnet->nr_conns))
 219                         wake_up_var(&rxnet->nr_conns);
 220                 tail = (tail + 1) & (size - 1);
 221         }
 222
 223         head = b->call_backlog_head;
 224         tail = b->call_backlog_tail;
 225         while (CIRC_CNT(head, tail, size) > 0) {
 226                 struct rxrpc_call *call = b->call_backlog[tail];
 227                 rcu_assign_pointer(call->socket, rx);
 228                 if (rx->discard_new_call) {
 229                         _debug("discard %lx", call->user_call_ID);
 230                         rx->discard_new_call(call, call->user_call_ID);
 231                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 232                 }
 233                 rxrpc_call_completed(call);
 234                 rxrpc_release_call(rx, call);
 235                 rxrpc_put_call(call, rxrpc_call_put);
 236                 tail = (tail + 1) & (size - 1);
 237         }
 238
 239         kfree(b);
 240 }
 241
 242 /*
 243  * Ping the other end to fill our RTT cache and to retrieve the rwind
 244  * and MTU parameters.
 245  */
 246 static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
 247 {
 248         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 249         ktime_t now = skb->tstamp;
 250
 251         if (call->peer->rtt_count < 3 ||
 252             ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
 253                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 254                                   true, true,
 255                                   rxrpc_propose_ack_ping_for_params);
 256 }
 257
 258 /*
 259  * Allocate a new incoming call from the prealloc pool, along with a connection
 260  * and a peer as necessary.
 261  */
 262 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 263                                                     struct rxrpc_local *local,
 264                                                     struct rxrpc_peer *peer,
 265                                                     struct rxrpc_connection *conn,
 266                                                     const struct rxrpc_security *sec,
 267                                                     struct key *key,
 268                                                     struct sk_buff *skb)
 269 {
 270         struct rxrpc_backlog *b = rx->backlog;
 271         struct rxrpc_call *call;
 272         unsigned short call_head, conn_head, peer_head;
 273         unsigned short call_tail, conn_tail, peer_tail;
 274         unsigned short call_count, conn_count;
 275
 276         /* #calls >= #conns >= #peers must hold true. */
 277         call_head = smp_load_acquire(&b->call_backlog_head);
 278         call_tail = b->call_backlog_tail;
 279         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 280         conn_head = smp_load_acquire(&b->conn_backlog_head);
 281         conn_tail = b->conn_backlog_tail;
 282         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 283         ASSERTCMP(conn_count, >=, call_count);
 284         peer_head = smp_load_acquire(&b->peer_backlog_head);
 285         peer_tail = b->peer_backlog_tail;
 286         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 287                   conn_count);
 288
 289         if (call_count == 0)
 290                 return NULL;
 291
 292         if (!conn) {
 293                 if (peer && !rxrpc_get_peer_maybe(peer))
 294                         peer = NULL;
 295                 if (!peer) {
 296                         peer = b->peer_backlog[peer_tail];
 297                         if (rxrpc_extract_addr_from_skb(&peer->srx, skb) < 0)
 298                                 return NULL;
 299                         b->peer_backlog[peer_tail] = NULL;
 300                         smp_store_release(&b->peer_backlog_tail,
 301                                           (peer_tail + 1) &
 302                                           (RXRPC_BACKLOG_MAX - 1));
 303
 304                         rxrpc_new_incoming_peer(rx, local, peer);
 305                 }
 306
 307                 /* Now allocate and set up the connection */
 308                 conn = b->conn_backlog[conn_tail];
 309                 b->conn_backlog[conn_tail] = NULL;
 310                 smp_store_release(&b->conn_backlog_tail,
 311                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 312                 conn->params.local = rxrpc_get_local(local);
 313                 conn->params.peer = peer;
 314                 rxrpc_see_connection(conn);
 315                 rxrpc_new_incoming_connection(rx, conn, sec, key, skb);
 316         } else {
 317                 rxrpc_get_connection(conn);
 318         }
 319
 320         /* And now we can allocate and set up a new call */
 321         call = b->call_backlog[call_tail];
 322         b->call_backlog[call_tail] = NULL;
 323         smp_store_release(&b->call_backlog_tail,
 324                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 325
 326         rxrpc_see_call(call);
 327         call->conn = conn;
 328         call->security = conn->security;
 329         call->peer = rxrpc_get_peer(conn->params.peer);
 330         call->cong_cwnd = call->peer->cong_cwnd;
 331         return call;
 332 }
 333
 334 /*
 335  * Set up a new incoming call.  Called in BH context with the RCU read lock
 336  * held.
 337  *
 338  * If this is for a kernel service, when we allocate the call, it will have
 339  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 340  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 341  * services only have the ref from the backlog buffer.  We want to pass this
 342  * ref to non-BH context to dispose of.
 343  *
 344  * If we want to report an error, we mark the skb with the packet type and
 345  * abort code and return NULL.
 346  *
 347  * The call is returned with the user access mutex held.
 348  */
 349 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 350                                            struct rxrpc_sock *rx,
 351                                            struct sk_buff *skb)
 352 {
 353         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 354         const struct rxrpc_security *sec = NULL;
 355         struct rxrpc_connection *conn;
 356         struct rxrpc_peer *peer = NULL;
 357         struct rxrpc_call *call = NULL;
 358         struct key *key = NULL;
 359
 360         _enter("");
 361
 362         spin_lock(&rx->incoming_lock);
 363         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
 364             rx->sk.sk_state == RXRPC_CLOSE) {
 365                 trace_rxrpc_abort(0, "CLS", sp->hdr.cid, sp->hdr.callNumber,
 366                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 367                 skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
 368                 skb->priority = RX_INVALID_OPERATION;
 369                 goto no_call;
 370         }
 371
 372         /* The peer, connection and call may all have sprung into existence due
 373          * to a duplicate packet being handled on another CPU in parallel, so
 374          * we have to recheck the routing.  However, we're now holding
 375          * rx->incoming_lock, so the values should remain stable.
 376          */
 377         conn = rxrpc_find_connection_rcu(local, skb, &peer);
 378
 379         if (!conn && !rxrpc_look_up_server_security(local, rx, &sec, &key, skb))
 380                 goto no_call;
 381
 382         call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, key, skb);
 383         key_put(key);
 384         if (!call) {
 385                 skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
 386                 goto no_call;
 387         }
 388
 389         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 390                             sp->hdr.serial, sp->hdr.seq);
 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 (call->state < RXRPC_CALL_COMPLETE) {
 412                         if (rx->discard_new_call)
 413                                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 414                         else
 415                                 call->state = RXRPC_CALL_SERVER_ACCEPTING;
 416                 }
 417                 write_unlock(&call->state_lock);
 418                 break;
 419
 420         case RXRPC_CONN_REMOTELY_ABORTED:
 421                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 422                                           conn->abort_code, conn->error);
 423                 break;
 424         case RXRPC_CONN_LOCALLY_ABORTED:
 425                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 426                                  conn->abort_code, conn->error);
 427                 break;
 428         default:
 429                 BUG();
 430         }
 431         spin_unlock(&conn->state_lock);
 432         spin_unlock(&rx->incoming_lock);
 433
 434         rxrpc_send_ping(call, skb);
 435
 436         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 437                 rxrpc_notify_socket(call);
 438
 439         /* We have to discard the prealloc queue's ref here and rely on a
 440          * combination of the RCU read lock and refs held either by the socket
 441          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
 442          * service to prevent the call from being deallocated too early.
 443          */
 444         rxrpc_put_call(call, rxrpc_call_put);
 445
 446         _leave(" = %p{%d}", call, call->debug_id);
 447         return call;
 448
 449 no_call:
 450         spin_unlock(&rx->incoming_lock);
 451         _leave(" = NULL [%u]", skb->mark);
 452         return NULL;
 453 }
 454
 455 /*
 456  * handle acceptance of a call by userspace
 457  * - assign the user call ID to the call at the front of the queue
 458  * - called with the socket locked.
 459  */
 460 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 461                                      unsigned long user_call_ID,
 462                                      rxrpc_notify_rx_t notify_rx)
 463         __releases(&rx->sk.sk_lock.slock)
 464         __acquires(call->user_mutex)
 465 {
 466         struct rxrpc_call *call;
 467         struct rb_node *parent, **pp;
 468         int ret;
 469
 470         _enter(",%lx", user_call_ID);
 471
 472         ASSERT(!irqs_disabled());
 473
 474         write_lock(&rx->call_lock);
 475
 476         if (list_empty(&rx->to_be_accepted)) {
 477                 write_unlock(&rx->call_lock);
 478                 release_sock(&rx->sk);
 479                 kleave(" = -ENODATA [empty]");
 480                 return ERR_PTR(-ENODATA);
 481         }
 482
 483         /* check the user ID isn't already in use */
 484         pp = &rx->calls.rb_node;
 485         parent = NULL;
 486         while (*pp) {
 487                 parent = *pp;
 488                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 489
 490                 if (user_call_ID < call->user_call_ID)
 491                         pp = &(*pp)->rb_left;
 492                 else if (user_call_ID > call->user_call_ID)
 493                         pp = &(*pp)->rb_right;
 494                 else
 495                         goto id_in_use;
 496         }
 497
 498         /* Dequeue the first call and check it's still valid.  We gain
 499          * responsibility for the queue's reference.
 500          */
 501         call = list_entry(rx->to_be_accepted.next,
 502                           struct rxrpc_call, accept_link);
 503         write_unlock(&rx->call_lock);
 504
 505         /* We need to gain the mutex from the interrupt handler without
 506          * upsetting lockdep, so we have to release it there and take it here.
 507          * We are, however, still holding the socket lock, so other accepts
 508          * must wait for us and no one can add the user ID behind our backs.
 509          */
 510         if (mutex_lock_interruptible(&call->user_mutex) < 0) {
 511                 release_sock(&rx->sk);
 512                 kleave(" = -ERESTARTSYS");
 513                 return ERR_PTR(-ERESTARTSYS);
 514         }
 515
 516         write_lock(&rx->call_lock);
 517         list_del_init(&call->accept_link);
 518         sk_acceptq_removed(&rx->sk);
 519         rxrpc_see_call(call);
 520
 521         /* Find the user ID insertion point. */
 522         pp = &rx->calls.rb_node;
 523         parent = NULL;
 524         while (*pp) {
 525                 parent = *pp;
 526                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 527
 528                 if (user_call_ID < call->user_call_ID)
 529                         pp = &(*pp)->rb_left;
 530                 else if (user_call_ID > call->user_call_ID)
 531                         pp = &(*pp)->rb_right;
 532                 else
 533                         BUG();
 534         }
 535
 536         write_lock_bh(&call->state_lock);
 537         switch (call->state) {
 538         case RXRPC_CALL_SERVER_ACCEPTING:
 539                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 540                 break;
 541         case RXRPC_CALL_COMPLETE:
 542                 ret = call->error;
 543                 goto out_release;
 544         default:
 545                 BUG();
 546         }
 547
 548         /* formalise the acceptance */
 549         call->notify_rx = notify_rx;
 550         call->user_call_ID = user_call_ID;
 551         rxrpc_get_call(call, rxrpc_call_got_userid);
 552         rb_link_node(&call->sock_node, parent, pp);
 553         rb_insert_color(&call->sock_node, &rx->calls);
 554         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 555                 BUG();
 556
 557         write_unlock_bh(&call->state_lock);
 558         write_unlock(&rx->call_lock);
 559         rxrpc_notify_socket(call);
 560         rxrpc_service_prealloc(rx, GFP_KERNEL);
 561         release_sock(&rx->sk);
 562         _leave(" = %p{%d}", call, call->debug_id);
 563         return call;
 564
 565 out_release:
 566         _debug("release %p", call);
 567         write_unlock_bh(&call->state_lock);
 568         write_unlock(&rx->call_lock);
 569         rxrpc_release_call(rx, call);
 570         rxrpc_put_call(call, rxrpc_call_put);
 571         goto out;
 572
 573 id_in_use:
 574         ret = -EBADSLT;
 575         write_unlock(&rx->call_lock);
 576 out:
 577         rxrpc_service_prealloc(rx, GFP_KERNEL);
 578         release_sock(&rx->sk);
 579         _leave(" = %d", ret);
 580         return ERR_PTR(ret);
 581 }
 582
 583 /*
 584  * Handle rejection of a call by userspace
 585  * - reject the call at the front of the queue
 586  */
 587 int rxrpc_reject_call(struct rxrpc_sock *rx)
 588 {
 589         struct rxrpc_call *call;
 590         bool abort = false;
 591         int ret;
 592
 593         _enter("");
 594
 595         ASSERT(!irqs_disabled());
 596
 597         write_lock(&rx->call_lock);
 598
 599         if (list_empty(&rx->to_be_accepted)) {
 600                 write_unlock(&rx->call_lock);
 601                 return -ENODATA;
 602         }
 603
 604         /* Dequeue the first call and check it's still valid.  We gain
 605          * responsibility for the queue's reference.
 606          */
 607         call = list_entry(rx->to_be_accepted.next,
 608                           struct rxrpc_call, accept_link);
 609         list_del_init(&call->accept_link);
 610         sk_acceptq_removed(&rx->sk);
 611         rxrpc_see_call(call);
 612
 613         write_lock_bh(&call->state_lock);
 614         switch (call->state) {
 615         case RXRPC_CALL_SERVER_ACCEPTING:
 616                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, -ECONNABORTED);
 617                 abort = true;
 618                 /* fall through */
 619         case RXRPC_CALL_COMPLETE:
 620                 ret = call->error;
 621                 goto out_discard;
 622         default:
 623                 BUG();
 624         }
 625
 626 out_discard:
 627         write_unlock_bh(&call->state_lock);
 628         write_unlock(&rx->call_lock);
 629         if (abort) {
 630                 rxrpc_send_abort_packet(call);
 631                 rxrpc_release_call(rx, call);
 632                 rxrpc_put_call(call, rxrpc_call_put);
 633         }
 634         rxrpc_service_prealloc(rx, GFP_KERNEL);
 635         _leave(" = %d", ret);
 636         return ret;
 637 }
 638
 639 /*
 640  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 641  * @sock: The socket on which to preallocate
 642  * @notify_rx: Event notification function for the call
 643  * @user_attach_call: Func to attach call to user_call_ID
 644  * @user_call_ID: The tag to attach to the preallocated call
 645  * @gfp: The allocation conditions.
 646  * @debug_id: The tracing debug ID.
 647  *
 648  * Charge up the socket with preallocated calls, each with a user ID.  A
 649  * function should be provided to effect the attachment from the user's side.
 650  * The user is given a ref to hold on the call.
 651  *
 652  * Note that the call may be come connected before this function returns.
 653  */
 654 int rxrpc_kernel_charge_accept(struct socket *sock,
 655                                rxrpc_notify_rx_t notify_rx,
 656                                rxrpc_user_attach_call_t user_attach_call,
 657                                unsigned long user_call_ID, gfp_t gfp,
 658                                unsigned int debug_id)
 659 {
 660         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 661         struct rxrpc_backlog *b = rx->backlog;
 662
 663         if (sock->sk->sk_state == RXRPC_CLOSE)
 664                 return -ESHUTDOWN;
 665
 666         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 667                                           user_attach_call, user_call_ID,
 668                                           gfp, debug_id);
 669 }
 670 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);