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 static void rxrpc_dummy_notify(struct sock *sk, struct rxrpc_call *call,
  26                                unsigned long user_call_ID)
  27 {
  28 }
  29
  30 /*
  31  * Preallocate a single service call, connection and peer and, if possible,
  32  * give them a user ID and attach the user's side of the ID to them.
  33  */
  34 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
  35                                       struct rxrpc_backlog *b,
  36                                       rxrpc_notify_rx_t notify_rx,
  37                                       rxrpc_user_attach_call_t user_attach_call,
  38                                       unsigned long user_call_ID, gfp_t gfp,
  39                                       unsigned int debug_id)
  40 {
  41         const void *here = __builtin_return_address(0);
  42         struct rxrpc_call *call;
  43         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
  44         int max, tmp;
  45         unsigned int size = RXRPC_BACKLOG_MAX;
  46         unsigned int head, tail, call_head, call_tail;
  47
  48         max = rx->sk.sk_max_ack_backlog;
  49         tmp = rx->sk.sk_ack_backlog;
  50         if (tmp >= max) {
  51                 _leave(" = -ENOBUFS [full %u]", max);
  52                 return -ENOBUFS;
  53         }
  54         max -= tmp;
  55
  56         /* We don't need more conns and peers than we have calls, but on the
  57          * other hand, we shouldn't ever use more peers than conns or conns
  58          * than calls.
  59          */
  60         call_head = b->call_backlog_head;
  61         call_tail = READ_ONCE(b->call_backlog_tail);
  62         tmp = CIRC_CNT(call_head, call_tail, size);
  63         if (tmp >= max) {
  64                 _leave(" = -ENOBUFS [enough %u]", tmp);
  65                 return -ENOBUFS;
  66         }
  67         max = tmp + 1;
  68
  69         head = b->peer_backlog_head;
  70         tail = READ_ONCE(b->peer_backlog_tail);
  71         if (CIRC_CNT(head, tail, size) < max) {
  72                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
  73                 if (!peer)
  74                         return -ENOMEM;
  75                 b->peer_backlog[head] = peer;
  76                 smp_store_release(&b->peer_backlog_head,
  77                                   (head + 1) & (size - 1));
  78         }
  79
  80         head = b->conn_backlog_head;
  81         tail = READ_ONCE(b->conn_backlog_tail);
  82         if (CIRC_CNT(head, tail, size) < max) {
  83                 struct rxrpc_connection *conn;
  84
  85                 conn = rxrpc_prealloc_service_connection(rxnet, gfp);
  86                 if (!conn)
  87                         return -ENOMEM;
  88                 b->conn_backlog[head] = conn;
  89                 smp_store_release(&b->conn_backlog_head,
  90                                   (head + 1) & (size - 1));
  91
  92                 trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_service,
  93                                  atomic_read(&conn->usage), here);
  94         }
  95
  96         /* Now it gets complicated, because calls get registered with the
  97          * socket here, particularly if a user ID is preassigned by the user.
  98          */
  99         call = rxrpc_alloc_call(rx, gfp, debug_id);
 100         if (!call)
 101                 return -ENOMEM;
 102         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
 103         call->state = RXRPC_CALL_SERVER_PREALLOC;
 104
 105         trace_rxrpc_call(call->debug_id, rxrpc_call_new_service,
 106                          atomic_read(&call->usage),
 107                          here, (const void *)user_call_ID);
 108
 109         write_lock(&rx->call_lock);
 110         if (user_attach_call) {
 111                 struct rxrpc_call *xcall;
 112                 struct rb_node *parent, **pp;
 113
 114                 /* Check the user ID isn't already in use */
 115                 pp = &rx->calls.rb_node;
 116                 parent = NULL;
 117                 while (*pp) {
 118                         parent = *pp;
 119                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 120                         if (user_call_ID < xcall->user_call_ID)
 121                                 pp = &(*pp)->rb_left;
 122                         else if (user_call_ID > xcall->user_call_ID)
 123                                 pp = &(*pp)->rb_right;
 124                         else
 125                                 goto id_in_use;
 126                 }
 127
 128                 call->user_call_ID = user_call_ID;
 129                 call->notify_rx = notify_rx;
 130                 rxrpc_get_call(call, rxrpc_call_got_kernel);
 131                 user_attach_call(call, user_call_ID);
 132                 rxrpc_get_call(call, rxrpc_call_got_userid);
 133                 rb_link_node(&call->sock_node, parent, pp);
 134                 rb_insert_color(&call->sock_node, &rx->calls);
 135                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 136         }
 137
 138         list_add(&call->sock_link, &rx->sock_calls);
 139
 140         write_unlock(&rx->call_lock);
 141
 142         rxnet = call->rxnet;
 143         write_lock(&rxnet->call_lock);
 144         list_add_tail(&call->link, &rxnet->calls);
 145         write_unlock(&rxnet->call_lock);
 146
 147         b->call_backlog[call_head] = call;
 148         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 149         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 150         return 0;
 151
 152 id_in_use:
 153         write_unlock(&rx->call_lock);
 154         rxrpc_cleanup_call(call);
 155         _leave(" = -EBADSLT");
 156         return -EBADSLT;
 157 }
 158
 159 /*
 160  * Preallocate sufficient service connections, calls and peers to cover the
 161  * entire backlog of a socket.  When a new call comes in, if we don't have
 162  * sufficient of each available, the call gets rejected as busy or ignored.
 163  *
 164  * The backlog is replenished when a connection is accepted or rejected.
 165  */
 166 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 167 {
 168         struct rxrpc_backlog *b = rx->backlog;
 169
 170         if (!b) {
 171                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 172                 if (!b)
 173                         return -ENOMEM;
 174                 rx->backlog = b;
 175         }
 176
 177         if (rx->discard_new_call)
 178                 return 0;
 179
 180         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp,
 181                                           atomic_inc_return(&rxrpc_debug_id)) == 0)
 182                 ;
 183
 184         return 0;
 185 }
 186
 187 /*
 188  * Discard the preallocation on a service.
 189  */
 190 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 191 {
 192         struct rxrpc_backlog *b = rx->backlog;
 193         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
 194         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 195
 196         if (!b)
 197                 return;
 198         rx->backlog = NULL;
 199
 200         /* Make sure that there aren't any incoming calls in progress before we
 201          * clear the preallocation buffers.
 202          */
 203         spin_lock_bh(&rx->incoming_lock);
 204         spin_unlock_bh(&rx->incoming_lock);
 205
 206         head = b->peer_backlog_head;
 207         tail = b->peer_backlog_tail;
 208         while (CIRC_CNT(head, tail, size) > 0) {
 209                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 210                 kfree(peer);
 211                 tail = (tail + 1) & (size - 1);
 212         }
 213
 214         head = b->conn_backlog_head;
 215         tail = b->conn_backlog_tail;
 216         while (CIRC_CNT(head, tail, size) > 0) {
 217                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 218                 write_lock(&rxnet->conn_lock);
 219                 list_del(&conn->link);
 220                 list_del(&conn->proc_link);
 221                 write_unlock(&rxnet->conn_lock);
 222                 kfree(conn);
 223                 if (atomic_dec_and_test(&rxnet->nr_conns))
 224                         wake_up_var(&rxnet->nr_conns);
 225                 tail = (tail + 1) & (size - 1);
 226         }
 227
 228         head = b->call_backlog_head;
 229         tail = b->call_backlog_tail;
 230         while (CIRC_CNT(head, tail, size) > 0) {
 231                 struct rxrpc_call *call = b->call_backlog[tail];
 232                 rcu_assign_pointer(call->socket, rx);
 233                 if (rx->discard_new_call) {
 234                         _debug("discard %lx", call->user_call_ID);
 235                         rx->discard_new_call(call, call->user_call_ID);
 236                         if (call->notify_rx)
 237                                 call->notify_rx = rxrpc_dummy_notify;
 238                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 239                 }
 240                 rxrpc_call_completed(call);
 241                 rxrpc_release_call(rx, call);
 242                 rxrpc_put_call(call, rxrpc_call_put);
 243                 tail = (tail + 1) & (size - 1);
 244         }
 245
 246         kfree(b);
 247 }
 248
 249 /*
 250  * Ping the other end to fill our RTT cache and to retrieve the rwind
 251  * and MTU parameters.
 252  */
 253 static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
 254 {
 255         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 256         ktime_t now = skb->tstamp;
 257
 258         if (call->peer->rtt_count < 3 ||
 259             ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
 260                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 261                                   true, true,
 262                                   rxrpc_propose_ack_ping_for_params);
 263 }
 264
 265 /*
 266  * Allocate a new incoming call from the prealloc pool, along with a connection
 267  * and a peer as necessary.
 268  */
 269 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 270                                                     struct rxrpc_local *local,
 271                                                     struct rxrpc_peer *peer,
 272                                                     struct rxrpc_connection *conn,
 273                                                     const struct rxrpc_security *sec,
 274                                                     struct key *key,
 275                                                     struct sk_buff *skb)
 276 {
 277         struct rxrpc_backlog *b = rx->backlog;
 278         struct rxrpc_call *call;
 279         unsigned short call_head, conn_head, peer_head;
 280         unsigned short call_tail, conn_tail, peer_tail;
 281         unsigned short call_count, conn_count;
 282
 283         /* #calls >= #conns >= #peers must hold true. */
 284         call_head = smp_load_acquire(&b->call_backlog_head);
 285         call_tail = b->call_backlog_tail;
 286         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 287         conn_head = smp_load_acquire(&b->conn_backlog_head);
 288         conn_tail = b->conn_backlog_tail;
 289         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 290         ASSERTCMP(conn_count, >=, call_count);
 291         peer_head = smp_load_acquire(&b->peer_backlog_head);
 292         peer_tail = b->peer_backlog_tail;
 293         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 294                   conn_count);
 295
 296         if (call_count == 0)
 297                 return NULL;
 298
 299         if (!conn) {
 300                 if (peer && !rxrpc_get_peer_maybe(peer))
 301                         peer = NULL;
 302                 if (!peer) {
 303                         peer = b->peer_backlog[peer_tail];
 304                         if (rxrpc_extract_addr_from_skb(&peer->srx, skb) < 0)
 305                                 return NULL;
 306                         b->peer_backlog[peer_tail] = NULL;
 307                         smp_store_release(&b->peer_backlog_tail,
 308                                           (peer_tail + 1) &
 309                                           (RXRPC_BACKLOG_MAX - 1));
 310
 311                         rxrpc_new_incoming_peer(rx, local, peer);
 312                 }
 313
 314                 /* Now allocate and set up the connection */
 315                 conn = b->conn_backlog[conn_tail];
 316                 b->conn_backlog[conn_tail] = NULL;
 317                 smp_store_release(&b->conn_backlog_tail,
 318                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 319                 conn->params.local = rxrpc_get_local(local);
 320                 conn->params.peer = peer;
 321                 rxrpc_see_connection(conn);
 322                 rxrpc_new_incoming_connection(rx, conn, sec, key, skb);
 323         } else {
 324                 rxrpc_get_connection(conn);
 325         }
 326
 327         /* And now we can allocate and set up a new call */
 328         call = b->call_backlog[call_tail];
 329         b->call_backlog[call_tail] = NULL;
 330         smp_store_release(&b->call_backlog_tail,
 331                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 332
 333         rxrpc_see_call(call);
 334         call->conn = conn;
 335         call->security = conn->security;
 336         call->peer = rxrpc_get_peer(conn->params.peer);
 337         call->cong_cwnd = call->peer->cong_cwnd;
 338         return call;
 339 }
 340
 341 /*
 342  * Set up a new incoming call.  Called in BH context with the RCU read lock
 343  * held.
 344  *
 345  * If this is for a kernel service, when we allocate the call, it will have
 346  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 347  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 348  * services only have the ref from the backlog buffer.  We want to pass this
 349  * ref to non-BH context to dispose of.
 350  *
 351  * If we want to report an error, we mark the skb with the packet type and
 352  * abort code and return NULL.
 353  *
 354  * The call is returned with the user access mutex held.
 355  */
 356 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 357                                            struct rxrpc_sock *rx,
 358                                            struct sk_buff *skb)
 359 {
 360         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 361         const struct rxrpc_security *sec = NULL;
 362         struct rxrpc_connection *conn;
 363         struct rxrpc_peer *peer = NULL;
 364         struct rxrpc_call *call = NULL;
 365         struct key *key = NULL;
 366
 367         _enter("");
 368
 369         spin_lock(&rx->incoming_lock);
 370         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
 371             rx->sk.sk_state == RXRPC_CLOSE) {
 372                 trace_rxrpc_abort(0, "CLS", sp->hdr.cid, sp->hdr.callNumber,
 373                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 374                 skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
 375                 skb->priority = RX_INVALID_OPERATION;
 376                 goto no_call;
 377         }
 378
 379         /* The peer, connection and call may all have sprung into existence due
 380          * to a duplicate packet being handled on another CPU in parallel, so
 381          * we have to recheck the routing.  However, we're now holding
 382          * rx->incoming_lock, so the values should remain stable.
 383          */
 384         conn = rxrpc_find_connection_rcu(local, skb, &peer);
 385
 386         if (!conn && !rxrpc_look_up_server_security(local, rx, &sec, &key, skb))
 387                 goto no_call;
 388
 389         call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, key, skb);
 390         key_put(key);
 391         if (!call) {
 392                 skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
 393                 goto no_call;
 394         }
 395
 396         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 397                             sp->hdr.serial, sp->hdr.seq);
 398
 399         /* Make the call live. */
 400         rxrpc_incoming_call(rx, call, skb);
 401         conn = call->conn;
 402
 403         if (rx->notify_new_call)
 404                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 405         else
 406                 sk_acceptq_added(&rx->sk);
 407
 408         spin_lock(&conn->state_lock);
 409         switch (conn->state) {
 410         case RXRPC_CONN_SERVICE_UNSECURED:
 411                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 412                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 413                 rxrpc_queue_conn(call->conn);
 414                 break;
 415
 416         case RXRPC_CONN_SERVICE:
 417                 write_lock(&call->state_lock);
 418                 if (call->state < RXRPC_CALL_COMPLETE) {
 419                         if (rx->discard_new_call)
 420                                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 421                         else
 422                                 call->state = RXRPC_CALL_SERVER_ACCEPTING;
 423                 }
 424                 write_unlock(&call->state_lock);
 425                 break;
 426
 427         case RXRPC_CONN_REMOTELY_ABORTED:
 428                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 429                                           conn->abort_code, conn->error);
 430                 break;
 431         case RXRPC_CONN_LOCALLY_ABORTED:
 432                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 433                                  conn->abort_code, conn->error);
 434                 break;
 435         default:
 436                 BUG();
 437         }
 438         spin_unlock(&conn->state_lock);
 439         spin_unlock(&rx->incoming_lock);
 440
 441         rxrpc_send_ping(call, skb);
 442
 443         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 444                 rxrpc_notify_socket(call);
 445
 446         /* We have to discard the prealloc queue's ref here and rely on a
 447          * combination of the RCU read lock and refs held either by the socket
 448          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
 449          * service to prevent the call from being deallocated too early.
 450          */
 451         rxrpc_put_call(call, rxrpc_call_put);
 452
 453         _leave(" = %p{%d}", call, call->debug_id);
 454         return call;
 455
 456 no_call:
 457         spin_unlock(&rx->incoming_lock);
 458         _leave(" = NULL [%u]", skb->mark);
 459         return NULL;
 460 }
 461
 462 /*
 463  * handle acceptance of a call by userspace
 464  * - assign the user call ID to the call at the front of the queue
 465  * - called with the socket locked.
 466  */
 467 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 468                                      unsigned long user_call_ID,
 469                                      rxrpc_notify_rx_t notify_rx)
 470         __releases(&rx->sk.sk_lock.slock)
 471         __acquires(call->user_mutex)
 472 {
 473         struct rxrpc_call *call;
 474         struct rb_node *parent, **pp;
 475         int ret;
 476
 477         _enter(",%lx", user_call_ID);
 478
 479         ASSERT(!irqs_disabled());
 480
 481         write_lock(&rx->call_lock);
 482
 483         if (list_empty(&rx->to_be_accepted)) {
 484                 write_unlock(&rx->call_lock);
 485                 release_sock(&rx->sk);
 486                 kleave(" = -ENODATA [empty]");
 487                 return ERR_PTR(-ENODATA);
 488         }
 489
 490         /* check the user ID isn't already in use */
 491         pp = &rx->calls.rb_node;
 492         parent = NULL;
 493         while (*pp) {
 494                 parent = *pp;
 495                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 496
 497                 if (user_call_ID < call->user_call_ID)
 498                         pp = &(*pp)->rb_left;
 499                 else if (user_call_ID > call->user_call_ID)
 500                         pp = &(*pp)->rb_right;
 501                 else
 502                         goto id_in_use;
 503         }
 504
 505         /* Dequeue the first call and check it's still valid.  We gain
 506          * responsibility for the queue's reference.
 507          */
 508         call = list_entry(rx->to_be_accepted.next,
 509                           struct rxrpc_call, accept_link);
 510         write_unlock(&rx->call_lock);
 511
 512         /* We need to gain the mutex from the interrupt handler without
 513          * upsetting lockdep, so we have to release it there and take it here.
 514          * We are, however, still holding the socket lock, so other accepts
 515          * must wait for us and no one can add the user ID behind our backs.
 516          */
 517         if (mutex_lock_interruptible(&call->user_mutex) < 0) {
 518                 release_sock(&rx->sk);
 519                 kleave(" = -ERESTARTSYS");
 520                 return ERR_PTR(-ERESTARTSYS);
 521         }
 522
 523         write_lock(&rx->call_lock);
 524         list_del_init(&call->accept_link);
 525         sk_acceptq_removed(&rx->sk);
 526         rxrpc_see_call(call);
 527
 528         /* Find the user ID insertion point. */
 529         pp = &rx->calls.rb_node;
 530         parent = NULL;
 531         while (*pp) {
 532                 parent = *pp;
 533                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 534
 535                 if (user_call_ID < call->user_call_ID)
 536                         pp = &(*pp)->rb_left;
 537                 else if (user_call_ID > call->user_call_ID)
 538                         pp = &(*pp)->rb_right;
 539                 else
 540                         BUG();
 541         }
 542
 543         write_lock_bh(&call->state_lock);
 544         switch (call->state) {
 545         case RXRPC_CALL_SERVER_ACCEPTING:
 546                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 547                 break;
 548         case RXRPC_CALL_COMPLETE:
 549                 ret = call->error;
 550                 goto out_release;
 551         default:
 552                 BUG();
 553         }
 554
 555         /* formalise the acceptance */
 556         call->notify_rx = notify_rx;
 557         call->user_call_ID = user_call_ID;
 558         rxrpc_get_call(call, rxrpc_call_got_userid);
 559         rb_link_node(&call->sock_node, parent, pp);
 560         rb_insert_color(&call->sock_node, &rx->calls);
 561         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 562                 BUG();
 563
 564         write_unlock_bh(&call->state_lock);
 565         write_unlock(&rx->call_lock);
 566         rxrpc_notify_socket(call);
 567         rxrpc_service_prealloc(rx, GFP_KERNEL);
 568         release_sock(&rx->sk);
 569         _leave(" = %p{%d}", call, call->debug_id);
 570         return call;
 571
 572 out_release:
 573         _debug("release %p", call);
 574         write_unlock_bh(&call->state_lock);
 575         write_unlock(&rx->call_lock);
 576         rxrpc_release_call(rx, call);
 577         rxrpc_put_call(call, rxrpc_call_put);
 578         goto out;
 579
 580 id_in_use:
 581         ret = -EBADSLT;
 582         write_unlock(&rx->call_lock);
 583 out:
 584         rxrpc_service_prealloc(rx, GFP_KERNEL);
 585         release_sock(&rx->sk);
 586         _leave(" = %d", ret);
 587         return ERR_PTR(ret);
 588 }
 589
 590 /*
 591  * Handle rejection of a call by userspace
 592  * - reject the call at the front of the queue
 593  */
 594 int rxrpc_reject_call(struct rxrpc_sock *rx)
 595 {
 596         struct rxrpc_call *call;
 597         bool abort = false;
 598         int ret;
 599
 600         _enter("");
 601
 602         ASSERT(!irqs_disabled());
 603
 604         write_lock(&rx->call_lock);
 605
 606         if (list_empty(&rx->to_be_accepted)) {
 607                 write_unlock(&rx->call_lock);
 608                 return -ENODATA;
 609         }
 610
 611         /* Dequeue the first call and check it's still valid.  We gain
 612          * responsibility for the queue's reference.
 613          */
 614         call = list_entry(rx->to_be_accepted.next,
 615                           struct rxrpc_call, accept_link);
 616         list_del_init(&call->accept_link);
 617         sk_acceptq_removed(&rx->sk);
 618         rxrpc_see_call(call);
 619
 620         write_lock_bh(&call->state_lock);
 621         switch (call->state) {
 622         case RXRPC_CALL_SERVER_ACCEPTING:
 623                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, -ECONNABORTED);
 624                 abort = true;
 625                 /* fall through */
 626         case RXRPC_CALL_COMPLETE:
 627                 ret = call->error;
 628                 goto out_discard;
 629         default:
 630                 BUG();
 631         }
 632
 633 out_discard:
 634         write_unlock_bh(&call->state_lock);
 635         write_unlock(&rx->call_lock);
 636         if (abort) {
 637                 rxrpc_send_abort_packet(call);
 638                 rxrpc_release_call(rx, call);
 639                 rxrpc_put_call(call, rxrpc_call_put);
 640         }
 641         rxrpc_service_prealloc(rx, GFP_KERNEL);
 642         _leave(" = %d", ret);
 643         return ret;
 644 }
 645
 646 /*
 647  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 648  * @sock: The socket on which to preallocate
 649  * @notify_rx: Event notification function for the call
 650  * @user_attach_call: Func to attach call to user_call_ID
 651  * @user_call_ID: The tag to attach to the preallocated call
 652  * @gfp: The allocation conditions.
 653  * @debug_id: The tracing debug ID.
 654  *
 655  * Charge up the socket with preallocated calls, each with a user ID.  A
 656  * function should be provided to effect the attachment from the user's side.
 657  * The user is given a ref to hold on the call.
 658  *
 659  * Note that the call may be come connected before this function returns.
 660  */
 661 int rxrpc_kernel_charge_accept(struct socket *sock,
 662                                rxrpc_notify_rx_t notify_rx,
 663                                rxrpc_user_attach_call_t user_attach_call,
 664                                unsigned long user_call_ID, gfp_t gfp,
 665                                unsigned int debug_id)
 666 {
 667         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 668         struct rxrpc_backlog *b = rx->backlog;
 669
 670         if (sock->sk->sk_state == RXRPC_CLOSE)
 671                 return -ESHUTDOWN;
 672
 673         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 674                                           user_attach_call, user_call_ID,
 675                                           gfp, debug_id);
 676 }
 677 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);