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                 rxrpc_put_local(peer->local);
 211                 kfree(peer);
 212                 tail = (tail + 1) & (size - 1);
 213         }
 214
 215         head = b->conn_backlog_head;
 216         tail = b->conn_backlog_tail;
 217         while (CIRC_CNT(head, tail, size) > 0) {
 218                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 219                 write_lock(&rxnet->conn_lock);
 220                 list_del(&conn->link);
 221                 list_del(&conn->proc_link);
 222                 write_unlock(&rxnet->conn_lock);
 223                 kfree(conn);
 224                 if (atomic_dec_and_test(&rxnet->nr_conns))
 225                         wake_up_var(&rxnet->nr_conns);
 226                 tail = (tail + 1) & (size - 1);
 227         }
 228
 229         head = b->call_backlog_head;
 230         tail = b->call_backlog_tail;
 231         while (CIRC_CNT(head, tail, size) > 0) {
 232                 struct rxrpc_call *call = b->call_backlog[tail];
 233                 rcu_assign_pointer(call->socket, rx);
 234                 if (rx->discard_new_call) {
 235                         _debug("discard %lx", call->user_call_ID);
 236                         rx->discard_new_call(call, call->user_call_ID);
 237                         if (call->notify_rx)
 238                                 call->notify_rx = rxrpc_dummy_notify;
 239                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 240                 }
 241                 rxrpc_call_completed(call);
 242                 rxrpc_release_call(rx, call);
 243                 rxrpc_put_call(call, rxrpc_call_put);
 244                 tail = (tail + 1) & (size - 1);
 245         }
 246
 247         kfree(b);
 248 }
 249
 250 /*
 251  * Ping the other end to fill our RTT cache and to retrieve the rwind
 252  * and MTU parameters.
 253  */
 254 static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
 255 {
 256         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 257         ktime_t now = skb->tstamp;
 258
 259         if (call->peer->rtt_count < 3 ||
 260             ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
 261                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 262                                   true, true,
 263                                   rxrpc_propose_ack_ping_for_params);
 264 }
 265
 266 /*
 267  * Allocate a new incoming call from the prealloc pool, along with a connection
 268  * and a peer as necessary.
 269  */
 270 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 271                                                     struct rxrpc_local *local,
 272                                                     struct rxrpc_peer *peer,
 273                                                     struct rxrpc_connection *conn,
 274                                                     const struct rxrpc_security *sec,
 275                                                     struct key *key,
 276                                                     struct sk_buff *skb)
 277 {
 278         struct rxrpc_backlog *b = rx->backlog;
 279         struct rxrpc_call *call;
 280         unsigned short call_head, conn_head, peer_head;
 281         unsigned short call_tail, conn_tail, peer_tail;
 282         unsigned short call_count, conn_count;
 283
 284         /* #calls >= #conns >= #peers must hold true. */
 285         call_head = smp_load_acquire(&b->call_backlog_head);
 286         call_tail = b->call_backlog_tail;
 287         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 288         conn_head = smp_load_acquire(&b->conn_backlog_head);
 289         conn_tail = b->conn_backlog_tail;
 290         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 291         ASSERTCMP(conn_count, >=, call_count);
 292         peer_head = smp_load_acquire(&b->peer_backlog_head);
 293         peer_tail = b->peer_backlog_tail;
 294         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 295                   conn_count);
 296
 297         if (call_count == 0)
 298                 return NULL;
 299
 300         if (!conn) {
 301                 if (peer && !rxrpc_get_peer_maybe(peer))
 302                         peer = NULL;
 303                 if (!peer) {
 304                         peer = b->peer_backlog[peer_tail];
 305                         if (rxrpc_extract_addr_from_skb(&peer->srx, skb) < 0)
 306                                 return NULL;
 307                         b->peer_backlog[peer_tail] = NULL;
 308                         smp_store_release(&b->peer_backlog_tail,
 309                                           (peer_tail + 1) &
 310                                           (RXRPC_BACKLOG_MAX - 1));
 311
 312                         rxrpc_new_incoming_peer(rx, local, peer);
 313                 }
 314
 315                 /* Now allocate and set up the connection */
 316                 conn = b->conn_backlog[conn_tail];
 317                 b->conn_backlog[conn_tail] = NULL;
 318                 smp_store_release(&b->conn_backlog_tail,
 319                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 320                 conn->params.local = rxrpc_get_local(local);
 321                 conn->params.peer = peer;
 322                 rxrpc_see_connection(conn);
 323                 rxrpc_new_incoming_connection(rx, conn, sec, key, skb);
 324         } else {
 325                 rxrpc_get_connection(conn);
 326         }
 327
 328         /* And now we can allocate and set up a new call */
 329         call = b->call_backlog[call_tail];
 330         b->call_backlog[call_tail] = NULL;
 331         smp_store_release(&b->call_backlog_tail,
 332                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 333
 334         rxrpc_see_call(call);
 335         call->conn = conn;
 336         call->security = conn->security;
 337         call->peer = rxrpc_get_peer(conn->params.peer);
 338         call->cong_cwnd = call->peer->cong_cwnd;
 339         return call;
 340 }
 341
 342 /*
 343  * Set up a new incoming call.  Called in BH context with the RCU read lock
 344  * held.
 345  *
 346  * If this is for a kernel service, when we allocate the call, it will have
 347  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 348  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 349  * services only have the ref from the backlog buffer.  We want to pass this
 350  * ref to non-BH context to dispose of.
 351  *
 352  * If we want to report an error, we mark the skb with the packet type and
 353  * abort code and return NULL.
 354  *
 355  * The call is returned with the user access mutex held.
 356  */
 357 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 358                                            struct rxrpc_sock *rx,
 359                                            struct sk_buff *skb)
 360 {
 361         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 362         const struct rxrpc_security *sec = NULL;
 363         struct rxrpc_connection *conn;
 364         struct rxrpc_peer *peer = NULL;
 365         struct rxrpc_call *call = NULL;
 366         struct key *key = NULL;
 367
 368         _enter("");
 369
 370         spin_lock(&rx->incoming_lock);
 371         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
 372             rx->sk.sk_state == RXRPC_CLOSE) {
 373                 trace_rxrpc_abort(0, "CLS", sp->hdr.cid, sp->hdr.callNumber,
 374                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 375                 skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
 376                 skb->priority = RX_INVALID_OPERATION;
 377                 goto no_call;
 378         }
 379
 380         /* The peer, connection and call may all have sprung into existence due
 381          * to a duplicate packet being handled on another CPU in parallel, so
 382          * we have to recheck the routing.  However, we're now holding
 383          * rx->incoming_lock, so the values should remain stable.
 384          */
 385         conn = rxrpc_find_connection_rcu(local, skb, &peer);
 386
 387         if (!conn && !rxrpc_look_up_server_security(local, rx, &sec, &key, skb))
 388                 goto no_call;
 389
 390         call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, key, skb);
 391         key_put(key);
 392         if (!call) {
 393                 skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
 394                 goto no_call;
 395         }
 396
 397         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 398                             sp->hdr.serial, sp->hdr.seq);
 399
 400         /* Make the call live. */
 401         rxrpc_incoming_call(rx, call, skb);
 402         conn = call->conn;
 403
 404         if (rx->notify_new_call)
 405                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 406         else
 407                 sk_acceptq_added(&rx->sk);
 408
 409         spin_lock(&conn->state_lock);
 410         switch (conn->state) {
 411         case RXRPC_CONN_SERVICE_UNSECURED:
 412                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 413                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 414                 rxrpc_queue_conn(call->conn);
 415                 break;
 416
 417         case RXRPC_CONN_SERVICE:
 418                 write_lock(&call->state_lock);
 419                 if (call->state < RXRPC_CALL_COMPLETE) {
 420                         if (rx->discard_new_call)
 421                                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 422                         else
 423                                 call->state = RXRPC_CALL_SERVER_ACCEPTING;
 424                 }
 425                 write_unlock(&call->state_lock);
 426                 break;
 427
 428         case RXRPC_CONN_REMOTELY_ABORTED:
 429                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 430                                           conn->abort_code, conn->error);
 431                 break;
 432         case RXRPC_CONN_LOCALLY_ABORTED:
 433                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 434                                  conn->abort_code, conn->error);
 435                 break;
 436         default:
 437                 BUG();
 438         }
 439         spin_unlock(&conn->state_lock);
 440         spin_unlock(&rx->incoming_lock);
 441
 442         rxrpc_send_ping(call, skb);
 443
 444         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 445                 rxrpc_notify_socket(call);
 446
 447         /* We have to discard the prealloc queue's ref here and rely on a
 448          * combination of the RCU read lock and refs held either by the socket
 449          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
 450          * service to prevent the call from being deallocated too early.
 451          */
 452         rxrpc_put_call(call, rxrpc_call_put);
 453
 454         _leave(" = %p{%d}", call, call->debug_id);
 455         return call;
 456
 457 no_call:
 458         spin_unlock(&rx->incoming_lock);
 459         _leave(" = NULL [%u]", skb->mark);
 460         return NULL;
 461 }
 462
 463 /*
 464  * handle acceptance of a call by userspace
 465  * - assign the user call ID to the call at the front of the queue
 466  * - called with the socket locked.
 467  */
 468 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 469                                      unsigned long user_call_ID,
 470                                      rxrpc_notify_rx_t notify_rx)
 471         __releases(&rx->sk.sk_lock.slock)
 472         __acquires(call->user_mutex)
 473 {
 474         struct rxrpc_call *call;
 475         struct rb_node *parent, **pp;
 476         int ret;
 477
 478         _enter(",%lx", user_call_ID);
 479
 480         ASSERT(!irqs_disabled());
 481
 482         write_lock(&rx->call_lock);
 483
 484         if (list_empty(&rx->to_be_accepted)) {
 485                 write_unlock(&rx->call_lock);
 486                 release_sock(&rx->sk);
 487                 kleave(" = -ENODATA [empty]");
 488                 return ERR_PTR(-ENODATA);
 489         }
 490
 491         /* check the user ID isn't already in use */
 492         pp = &rx->calls.rb_node;
 493         parent = NULL;
 494         while (*pp) {
 495                 parent = *pp;
 496                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 497
 498                 if (user_call_ID < call->user_call_ID)
 499                         pp = &(*pp)->rb_left;
 500                 else if (user_call_ID > call->user_call_ID)
 501                         pp = &(*pp)->rb_right;
 502                 else
 503                         goto id_in_use;
 504         }
 505
 506         /* Dequeue the first call and check it's still valid.  We gain
 507          * responsibility for the queue's reference.
 508          */
 509         call = list_entry(rx->to_be_accepted.next,
 510                           struct rxrpc_call, accept_link);
 511         write_unlock(&rx->call_lock);
 512
 513         /* We need to gain the mutex from the interrupt handler without
 514          * upsetting lockdep, so we have to release it there and take it here.
 515          * We are, however, still holding the socket lock, so other accepts
 516          * must wait for us and no one can add the user ID behind our backs.
 517          */
 518         if (mutex_lock_interruptible(&call->user_mutex) < 0) {
 519                 release_sock(&rx->sk);
 520                 kleave(" = -ERESTARTSYS");
 521                 return ERR_PTR(-ERESTARTSYS);
 522         }
 523
 524         write_lock(&rx->call_lock);
 525         list_del_init(&call->accept_link);
 526         sk_acceptq_removed(&rx->sk);
 527         rxrpc_see_call(call);
 528
 529         /* Find the user ID insertion point. */
 530         pp = &rx->calls.rb_node;
 531         parent = NULL;
 532         while (*pp) {
 533                 parent = *pp;
 534                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 535
 536                 if (user_call_ID < call->user_call_ID)
 537                         pp = &(*pp)->rb_left;
 538                 else if (user_call_ID > call->user_call_ID)
 539                         pp = &(*pp)->rb_right;
 540                 else
 541                         BUG();
 542         }
 543
 544         write_lock_bh(&call->state_lock);
 545         switch (call->state) {
 546         case RXRPC_CALL_SERVER_ACCEPTING:
 547                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 548                 break;
 549         case RXRPC_CALL_COMPLETE:
 550                 ret = call->error;
 551                 goto out_release;
 552         default:
 553                 BUG();
 554         }
 555
 556         /* formalise the acceptance */
 557         call->notify_rx = notify_rx;
 558         call->user_call_ID = user_call_ID;
 559         rxrpc_get_call(call, rxrpc_call_got_userid);
 560         rb_link_node(&call->sock_node, parent, pp);
 561         rb_insert_color(&call->sock_node, &rx->calls);
 562         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 563                 BUG();
 564
 565         write_unlock_bh(&call->state_lock);
 566         write_unlock(&rx->call_lock);
 567         rxrpc_notify_socket(call);
 568         rxrpc_service_prealloc(rx, GFP_KERNEL);
 569         release_sock(&rx->sk);
 570         _leave(" = %p{%d}", call, call->debug_id);
 571         return call;
 572
 573 out_release:
 574         _debug("release %p", call);
 575         write_unlock_bh(&call->state_lock);
 576         write_unlock(&rx->call_lock);
 577         rxrpc_release_call(rx, call);
 578         rxrpc_put_call(call, rxrpc_call_put);
 579         goto out;
 580
 581 id_in_use:
 582         ret = -EBADSLT;
 583         write_unlock(&rx->call_lock);
 584 out:
 585         rxrpc_service_prealloc(rx, GFP_KERNEL);
 586         release_sock(&rx->sk);
 587         _leave(" = %d", ret);
 588         return ERR_PTR(ret);
 589 }
 590
 591 /*
 592  * Handle rejection of a call by userspace
 593  * - reject the call at the front of the queue
 594  */
 595 int rxrpc_reject_call(struct rxrpc_sock *rx)
 596 {
 597         struct rxrpc_call *call;
 598         bool abort = false;
 599         int ret;
 600
 601         _enter("");
 602
 603         ASSERT(!irqs_disabled());
 604
 605         write_lock(&rx->call_lock);
 606
 607         if (list_empty(&rx->to_be_accepted)) {
 608                 write_unlock(&rx->call_lock);
 609                 return -ENODATA;
 610         }
 611
 612         /* Dequeue the first call and check it's still valid.  We gain
 613          * responsibility for the queue's reference.
 614          */
 615         call = list_entry(rx->to_be_accepted.next,
 616                           struct rxrpc_call, accept_link);
 617         list_del_init(&call->accept_link);
 618         sk_acceptq_removed(&rx->sk);
 619         rxrpc_see_call(call);
 620
 621         write_lock_bh(&call->state_lock);
 622         switch (call->state) {
 623         case RXRPC_CALL_SERVER_ACCEPTING:
 624                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, -ECONNABORTED);
 625                 abort = true;
 626                 /* fall through */
 627         case RXRPC_CALL_COMPLETE:
 628                 ret = call->error;
 629                 goto out_discard;
 630         default:
 631                 BUG();
 632         }
 633
 634 out_discard:
 635         write_unlock_bh(&call->state_lock);
 636         write_unlock(&rx->call_lock);
 637         if (abort) {
 638                 rxrpc_send_abort_packet(call);
 639                 rxrpc_release_call(rx, call);
 640                 rxrpc_put_call(call, rxrpc_call_put);
 641         }
 642         rxrpc_service_prealloc(rx, GFP_KERNEL);
 643         _leave(" = %d", ret);
 644         return ret;
 645 }
 646
 647 /*
 648  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 649  * @sock: The socket on which to preallocate
 650  * @notify_rx: Event notification function for the call
 651  * @user_attach_call: Func to attach call to user_call_ID
 652  * @user_call_ID: The tag to attach to the preallocated call
 653  * @gfp: The allocation conditions.
 654  * @debug_id: The tracing debug ID.
 655  *
 656  * Charge up the socket with preallocated calls, each with a user ID.  A
 657  * function should be provided to effect the attachment from the user's side.
 658  * The user is given a ref to hold on the call.
 659  *
 660  * Note that the call may be come connected before this function returns.
 661  */
 662 int rxrpc_kernel_charge_accept(struct socket *sock,
 663                                rxrpc_notify_rx_t notify_rx,
 664                                rxrpc_user_attach_call_t user_attach_call,
 665                                unsigned long user_call_ID, gfp_t gfp,
 666                                unsigned int debug_id)
 667 {
 668         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 669         struct rxrpc_backlog *b = rx->backlog;
 670
 671         if (sock->sk->sk_state == RXRPC_CLOSE)
 672                 return -ESHUTDOWN;
 673
 674         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 675                                           user_attach_call, user_call_ID,
 676                                           gfp, debug_id);
 677 }
 678 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);