net/rxrpc/call_accept.c

   1 /* incoming call handling
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/errqueue.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/in6.h>
  21 #include <linux/icmp.h>
  22 #include <linux/gfp.h>
  23 #include <linux/circ_buf.h>
  24 #include <net/sock.h>
  25 #include <net/af_rxrpc.h>
  26 #include <net/ip.h>
  27 #include "ar-internal.h"
  28
  29 /*
  30  * Preallocate a single service call, connection and peer and, if possible,
  31  * give them a user ID and attach the user's side of the ID to them.
  32  */
  33 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
  34                                       struct rxrpc_backlog *b,
  35                                       rxrpc_notify_rx_t notify_rx,
  36                                       rxrpc_user_attach_call_t user_attach_call,
  37                                       unsigned long user_call_ID, gfp_t gfp)
  38 {
  39         const void *here = __builtin_return_address(0);
  40         struct rxrpc_call *call;
  41         int max, tmp;
  42         unsigned int size = RXRPC_BACKLOG_MAX;
  43         unsigned int head, tail, call_head, call_tail;
  44
  45         max = rx->sk.sk_max_ack_backlog;
  46         tmp = rx->sk.sk_ack_backlog;
  47         if (tmp >= max) {
  48                 _leave(" = -ENOBUFS [full %u]", max);
  49                 return -ENOBUFS;
  50         }
  51         max -= tmp;
  52
  53         /* We don't need more conns and peers than we have calls, but on the
  54          * other hand, we shouldn't ever use more peers than conns or conns
  55          * than calls.
  56          */
  57         call_head = b->call_backlog_head;
  58         call_tail = READ_ONCE(b->call_backlog_tail);
  59         tmp = CIRC_CNT(call_head, call_tail, size);
  60         if (tmp >= max) {
  61                 _leave(" = -ENOBUFS [enough %u]", tmp);
  62                 return -ENOBUFS;
  63         }
  64         max = tmp + 1;
  65
  66         head = b->peer_backlog_head;
  67         tail = READ_ONCE(b->peer_backlog_tail);
  68         if (CIRC_CNT(head, tail, size) < max) {
  69                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
  70                 if (!peer)
  71                         return -ENOMEM;
  72                 b->peer_backlog[head] = peer;
  73                 smp_store_release(&b->peer_backlog_head,
  74                                   (head + 1) & (size - 1));
  75         }
  76
  77         head = b->conn_backlog_head;
  78         tail = READ_ONCE(b->conn_backlog_tail);
  79         if (CIRC_CNT(head, tail, size) < max) {
  80                 struct rxrpc_connection *conn;
  81
  82                 conn = rxrpc_prealloc_service_connection(gfp);
  83                 if (!conn)
  84                         return -ENOMEM;
  85                 b->conn_backlog[head] = conn;
  86                 smp_store_release(&b->conn_backlog_head,
  87                                   (head + 1) & (size - 1));
  88
  89                 trace_rxrpc_conn(conn, rxrpc_conn_new_service,
  90                                  atomic_read(&conn->usage), here);
  91         }
  92
  93         /* Now it gets complicated, because calls get registered with the
  94          * socket here, particularly if a user ID is preassigned by the user.
  95          */
  96         call = rxrpc_alloc_call(gfp);
  97         if (!call)
  98                 return -ENOMEM;
  99         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
 100         call->state = RXRPC_CALL_SERVER_PREALLOC;
 101
 102         trace_rxrpc_call(call, rxrpc_call_new_service,
 103                          atomic_read(&call->usage),
 104                          here, (const void *)user_call_ID);
 105
 106         write_lock(&rx->call_lock);
 107         if (user_attach_call) {
 108                 struct rxrpc_call *xcall;
 109                 struct rb_node *parent, **pp;
 110
 111                 /* Check the user ID isn't already in use */
 112                 pp = &rx->calls.rb_node;
 113                 parent = NULL;
 114                 while (*pp) {
 115                         parent = *pp;
 116                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
 117                         if (user_call_ID < call->user_call_ID)
 118                                 pp = &(*pp)->rb_left;
 119                         else if (user_call_ID > call->user_call_ID)
 120                                 pp = &(*pp)->rb_right;
 121                         else
 122                                 goto id_in_use;
 123                 }
 124
 125                 call->user_call_ID = user_call_ID;
 126                 call->notify_rx = notify_rx;
 127                 rxrpc_get_call(call, rxrpc_call_got_kernel);
 128                 user_attach_call(call, user_call_ID);
 129                 rxrpc_get_call(call, rxrpc_call_got_userid);
 130                 rb_link_node(&call->sock_node, parent, pp);
 131                 rb_insert_color(&call->sock_node, &rx->calls);
 132                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
 133         }
 134
 135         list_add(&call->sock_link, &rx->sock_calls);
 136
 137         write_unlock(&rx->call_lock);
 138
 139         write_lock(&rxrpc_call_lock);
 140         list_add_tail(&call->link, &rxrpc_calls);
 141         write_unlock(&rxrpc_call_lock);
 142
 143         b->call_backlog[call_head] = call;
 144         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
 145         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
 146         return 0;
 147
 148 id_in_use:
 149         write_unlock(&rx->call_lock);
 150         rxrpc_cleanup_call(call);
 151         _leave(" = -EBADSLT");
 152         return -EBADSLT;
 153 }
 154
 155 /*
 156  * Preallocate sufficient service connections, calls and peers to cover the
 157  * entire backlog of a socket.  When a new call comes in, if we don't have
 158  * sufficient of each available, the call gets rejected as busy or ignored.
 159  *
 160  * The backlog is replenished when a connection is accepted or rejected.
 161  */
 162 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
 163 {
 164         struct rxrpc_backlog *b = rx->backlog;
 165
 166         if (!b) {
 167                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
 168                 if (!b)
 169                         return -ENOMEM;
 170                 rx->backlog = b;
 171         }
 172
 173         if (rx->discard_new_call)
 174                 return 0;
 175
 176         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp) == 0)
 177                 ;
 178
 179         return 0;
 180 }
 181
 182 /*
 183  * Discard the preallocation on a service.
 184  */
 185 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
 186 {
 187         struct rxrpc_backlog *b = rx->backlog;
 188         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
 189
 190         if (!b)
 191                 return;
 192         rx->backlog = NULL;
 193
 194         /* Make sure that there aren't any incoming calls in progress before we
 195          * clear the preallocation buffers.
 196          */
 197         spin_lock_bh(&rx->incoming_lock);
 198         spin_unlock_bh(&rx->incoming_lock);
 199
 200         head = b->peer_backlog_head;
 201         tail = b->peer_backlog_tail;
 202         while (CIRC_CNT(head, tail, size) > 0) {
 203                 struct rxrpc_peer *peer = b->peer_backlog[tail];
 204                 kfree(peer);
 205                 tail = (tail + 1) & (size - 1);
 206         }
 207
 208         head = b->conn_backlog_head;
 209         tail = b->conn_backlog_tail;
 210         while (CIRC_CNT(head, tail, size) > 0) {
 211                 struct rxrpc_connection *conn = b->conn_backlog[tail];
 212                 write_lock(&rxrpc_connection_lock);
 213                 list_del(&conn->link);
 214                 list_del(&conn->proc_link);
 215                 write_unlock(&rxrpc_connection_lock);
 216                 kfree(conn);
 217                 tail = (tail + 1) & (size - 1);
 218         }
 219
 220         head = b->call_backlog_head;
 221         tail = b->call_backlog_tail;
 222         while (CIRC_CNT(head, tail, size) > 0) {
 223                 struct rxrpc_call *call = b->call_backlog[tail];
 224                 if (rx->discard_new_call) {
 225                         _debug("discard %lx", call->user_call_ID);
 226                         rx->discard_new_call(call, call->user_call_ID);
 227                         rxrpc_put_call(call, rxrpc_call_put_kernel);
 228                 }
 229                 rxrpc_call_completed(call);
 230                 rxrpc_release_call(rx, call);
 231                 rxrpc_put_call(call, rxrpc_call_put);
 232                 tail = (tail + 1) & (size - 1);
 233         }
 234
 235         kfree(b);
 236 }
 237
 238 /*
 239  * Allocate a new incoming call from the prealloc pool, along with a connection
 240  * and a peer as necessary.
 241  */
 242 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
 243                                                     struct rxrpc_local *local,
 244                                                     struct rxrpc_connection *conn,
 245                                                     struct sk_buff *skb)
 246 {
 247         struct rxrpc_backlog *b = rx->backlog;
 248         struct rxrpc_peer *peer, *xpeer;
 249         struct rxrpc_call *call;
 250         unsigned short call_head, conn_head, peer_head;
 251         unsigned short call_tail, conn_tail, peer_tail;
 252         unsigned short call_count, conn_count;
 253
 254         /* #calls >= #conns >= #peers must hold true. */
 255         call_head = smp_load_acquire(&b->call_backlog_head);
 256         call_tail = b->call_backlog_tail;
 257         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
 258         conn_head = smp_load_acquire(&b->conn_backlog_head);
 259         conn_tail = b->conn_backlog_tail;
 260         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
 261         ASSERTCMP(conn_count, >=, call_count);
 262         peer_head = smp_load_acquire(&b->peer_backlog_head);
 263         peer_tail = b->peer_backlog_tail;
 264         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
 265                   conn_count);
 266
 267         if (call_count == 0)
 268                 return NULL;
 269
 270         if (!conn) {
 271                 /* No connection.  We're going to need a peer to start off
 272                  * with.  If one doesn't yet exist, use a spare from the
 273                  * preallocation set.  We dump the address into the spare in
 274                  * anticipation - and to save on stack space.
 275                  */
 276                 xpeer = b->peer_backlog[peer_tail];
 277                 if (rxrpc_extract_addr_from_skb(&xpeer->srx, skb) < 0)
 278                         return NULL;
 279
 280                 peer = rxrpc_lookup_incoming_peer(local, xpeer);
 281                 if (peer == xpeer) {
 282                         b->peer_backlog[peer_tail] = NULL;
 283                         smp_store_release(&b->peer_backlog_tail,
 284                                           (peer_tail + 1) &
 285                                           (RXRPC_BACKLOG_MAX - 1));
 286                 }
 287
 288                 /* Now allocate and set up the connection */
 289                 conn = b->conn_backlog[conn_tail];
 290                 b->conn_backlog[conn_tail] = NULL;
 291                 smp_store_release(&b->conn_backlog_tail,
 292                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 293                 rxrpc_get_local(local);
 294                 conn->params.local = local;
 295                 conn->params.peer = peer;
 296                 rxrpc_see_connection(conn);
 297                 rxrpc_new_incoming_connection(conn, skb);
 298         } else {
 299                 rxrpc_get_connection(conn);
 300         }
 301
 302         /* And now we can allocate and set up a new call */
 303         call = b->call_backlog[call_tail];
 304         b->call_backlog[call_tail] = NULL;
 305         smp_store_release(&b->call_backlog_tail,
 306                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
 307
 308         rxrpc_see_call(call);
 309         call->conn = conn;
 310         call->peer = rxrpc_get_peer(conn->params.peer);
 311         return call;
 312 }
 313
 314 /*
 315  * Set up a new incoming call.  Called in BH context with the RCU read lock
 316  * held.
 317  *
 318  * If this is for a kernel service, when we allocate the call, it will have
 319  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 320  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 321  * services only have the ref from the backlog buffer.  We want to pass this
 322  * ref to non-BH context to dispose of.
 323  *
 324  * If we want to report an error, we mark the skb with the packet type and
 325  * abort code and return NULL.
 326  */
 327 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
 328                                            struct rxrpc_connection *conn,
 329                                            struct sk_buff *skb)
 330 {
 331         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 332         struct rxrpc_sock *rx;
 333         struct rxrpc_call *call;
 334         u16 service_id = sp->hdr.serviceId;
 335
 336         _enter("");
 337
 338         /* Get the socket providing the service */
 339         rx = rcu_dereference(local->service);
 340         if (rx && service_id == rx->srx.srx_service)
 341                 goto found_service;
 342
 343         trace_rxrpc_abort("INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
 344                           RX_INVALID_OPERATION, EOPNOTSUPP);
 345         skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 346         skb->priority = RX_INVALID_OPERATION;
 347         _leave(" = NULL [service]");
 348         return NULL;
 349
 350 found_service:
 351         spin_lock(&rx->incoming_lock);
 352         if (rx->sk.sk_state == RXRPC_CLOSE) {
 353                 trace_rxrpc_abort("CLS", sp->hdr.cid, sp->hdr.callNumber,
 354                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
 355                 skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
 356                 skb->priority = RX_INVALID_OPERATION;
 357                 _leave(" = NULL [close]");
 358                 call = NULL;
 359                 goto out;
 360         }
 361
 362         call = rxrpc_alloc_incoming_call(rx, local, conn, skb);
 363         if (!call) {
 364                 skb->mark = RXRPC_SKB_MARK_BUSY;
 365                 _leave(" = NULL [busy]");
 366                 call = NULL;
 367                 goto out;
 368         }
 369
 370         trace_rxrpc_receive(call, rxrpc_receive_incoming,
 371                             sp->hdr.serial, sp->hdr.seq);
 372
 373         /* Make the call live. */
 374         rxrpc_incoming_call(rx, call, skb);
 375         conn = call->conn;
 376
 377         if (rx->notify_new_call)
 378                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
 379         else
 380                 sk_acceptq_added(&rx->sk);
 381
 382         spin_lock(&conn->state_lock);
 383         switch (conn->state) {
 384         case RXRPC_CONN_SERVICE_UNSECURED:
 385                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
 386                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
 387                 rxrpc_queue_conn(call->conn);
 388                 break;
 389
 390         case RXRPC_CONN_SERVICE:
 391                 write_lock(&call->state_lock);
 392                 if (rx->discard_new_call)
 393                         call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 394                 else
 395                         call->state = RXRPC_CALL_SERVER_ACCEPTING;
 396                 write_unlock(&call->state_lock);
 397                 break;
 398
 399         case RXRPC_CONN_REMOTELY_ABORTED:
 400                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 401                                           conn->remote_abort, ECONNABORTED);
 402                 break;
 403         case RXRPC_CONN_LOCALLY_ABORTED:
 404                 rxrpc_abort_call("CON", call, sp->hdr.seq,
 405                                  conn->local_abort, ECONNABORTED);
 406                 break;
 407         default:
 408                 BUG();
 409         }
 410         spin_unlock(&conn->state_lock);
 411
 412         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
 413                 rxrpc_notify_socket(call);
 414
 415         /* We have to discard the prealloc queue's ref here and rely on a
 416          * combination of the RCU read lock and refs held either by the socket
 417          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
 418          * service to prevent the call from being deallocated too early.
 419          */
 420         rxrpc_put_call(call, rxrpc_call_put);
 421
 422         _leave(" = %p{%d}", call, call->debug_id);
 423 out:
 424         spin_unlock(&rx->incoming_lock);
 425         return call;
 426 }
 427
 428 /*
 429  * handle acceptance of a call by userspace
 430  * - assign the user call ID to the call at the front of the queue
 431  */
 432 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
 433                                      unsigned long user_call_ID,
 434                                      rxrpc_notify_rx_t notify_rx)
 435 {
 436         struct rxrpc_call *call;
 437         struct rb_node *parent, **pp;
 438         int ret;
 439
 440         _enter(",%lx", user_call_ID);
 441
 442         ASSERT(!irqs_disabled());
 443
 444         write_lock(&rx->call_lock);
 445
 446         if (list_empty(&rx->to_be_accepted)) {
 447                 write_unlock(&rx->call_lock);
 448                 kleave(" = -ENODATA [empty]");
 449                 return ERR_PTR(-ENODATA);
 450         }
 451
 452         /* check the user ID isn't already in use */
 453         pp = &rx->calls.rb_node;
 454         parent = NULL;
 455         while (*pp) {
 456                 parent = *pp;
 457                 call = rb_entry(parent, struct rxrpc_call, sock_node);
 458
 459                 if (user_call_ID < call->user_call_ID)
 460                         pp = &(*pp)->rb_left;
 461                 else if (user_call_ID > call->user_call_ID)
 462                         pp = &(*pp)->rb_right;
 463                 else
 464                         goto id_in_use;
 465         }
 466
 467         /* Dequeue the first call and check it's still valid.  We gain
 468          * responsibility for the queue's reference.
 469          */
 470         call = list_entry(rx->to_be_accepted.next,
 471                           struct rxrpc_call, accept_link);
 472         list_del_init(&call->accept_link);
 473         sk_acceptq_removed(&rx->sk);
 474         rxrpc_see_call(call);
 475
 476         write_lock_bh(&call->state_lock);
 477         switch (call->state) {
 478         case RXRPC_CALL_SERVER_ACCEPTING:
 479                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
 480                 break;
 481         case RXRPC_CALL_COMPLETE:
 482                 ret = call->error;
 483                 goto out_release;
 484         default:
 485                 BUG();
 486         }
 487
 488         /* formalise the acceptance */
 489         call->notify_rx = notify_rx;
 490         call->user_call_ID = user_call_ID;
 491         rxrpc_get_call(call, rxrpc_call_got_userid);
 492         rb_link_node(&call->sock_node, parent, pp);
 493         rb_insert_color(&call->sock_node, &rx->calls);
 494         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
 495                 BUG();
 496
 497         write_unlock_bh(&call->state_lock);
 498         write_unlock(&rx->call_lock);
 499         rxrpc_notify_socket(call);
 500         rxrpc_service_prealloc(rx, GFP_KERNEL);
 501         _leave(" = %p{%d}", call, call->debug_id);
 502         return call;
 503
 504 out_release:
 505         _debug("release %p", call);
 506         write_unlock_bh(&call->state_lock);
 507         write_unlock(&rx->call_lock);
 508         rxrpc_release_call(rx, call);
 509         rxrpc_put_call(call, rxrpc_call_put);
 510         goto out;
 511
 512 id_in_use:
 513         ret = -EBADSLT;
 514         write_unlock(&rx->call_lock);
 515 out:
 516         rxrpc_service_prealloc(rx, GFP_KERNEL);
 517         _leave(" = %d", ret);
 518         return ERR_PTR(ret);
 519 }
 520
 521 /*
 522  * Handle rejection of a call by userspace
 523  * - reject the call at the front of the queue
 524  */
 525 int rxrpc_reject_call(struct rxrpc_sock *rx)
 526 {
 527         struct rxrpc_call *call;
 528         bool abort = false;
 529         int ret;
 530
 531         _enter("");
 532
 533         ASSERT(!irqs_disabled());
 534
 535         write_lock(&rx->call_lock);
 536
 537         if (list_empty(&rx->to_be_accepted)) {
 538                 write_unlock(&rx->call_lock);
 539                 return -ENODATA;
 540         }
 541
 542         /* Dequeue the first call and check it's still valid.  We gain
 543          * responsibility for the queue's reference.
 544          */
 545         call = list_entry(rx->to_be_accepted.next,
 546                           struct rxrpc_call, accept_link);
 547         list_del_init(&call->accept_link);
 548         sk_acceptq_removed(&rx->sk);
 549         rxrpc_see_call(call);
 550
 551         write_lock_bh(&call->state_lock);
 552         switch (call->state) {
 553         case RXRPC_CALL_SERVER_ACCEPTING:
 554                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, ECONNABORTED);
 555                 abort = true;
 556                 /* fall through */
 557         case RXRPC_CALL_COMPLETE:
 558                 ret = call->error;
 559                 goto out_discard;
 560         default:
 561                 BUG();
 562         }
 563
 564 out_discard:
 565         write_unlock_bh(&call->state_lock);
 566         write_unlock(&rx->call_lock);
 567         if (abort) {
 568                 rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
 569                 rxrpc_release_call(rx, call);
 570                 rxrpc_put_call(call, rxrpc_call_put);
 571         }
 572         rxrpc_service_prealloc(rx, GFP_KERNEL);
 573         _leave(" = %d", ret);
 574         return ret;
 575 }
 576
 577 /*
 578  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 579  * @sock: The socket on which to preallocate
 580  * @notify_rx: Event notification function for the call
 581  * @user_attach_call: Func to attach call to user_call_ID
 582  * @user_call_ID: The tag to attach to the preallocated call
 583  * @gfp: The allocation conditions.
 584  *
 585  * Charge up the socket with preallocated calls, each with a user ID.  A
 586  * function should be provided to effect the attachment from the user's side.
 587  * The user is given a ref to hold on the call.
 588  *
 589  * Note that the call may be come connected before this function returns.
 590  */
 591 int rxrpc_kernel_charge_accept(struct socket *sock,
 592                                rxrpc_notify_rx_t notify_rx,
 593                                rxrpc_user_attach_call_t user_attach_call,
 594                                unsigned long user_call_ID, gfp_t gfp)
 595 {
 596         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 597         struct rxrpc_backlog *b = rx->backlog;
 598
 599         if (sock->sk->sk_state == RXRPC_CLOSE)
 600                 return -ESHUTDOWN;
 601
 602         return rxrpc_service_prealloc_one(rx, b, notify_rx,
 603                                           user_attach_call, user_call_ID,
 604                                           gfp);
 605 }
 606 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);