net/tipc/node.c

   1 /*
   2  * net/tipc/node.c: TIPC node management routines
   3  *
   4  * Copyright (c) 2000-2006, 2012-2014, Ericsson AB
   5  * Copyright (c) 2005-2006, 2010-2014, Wind River Systems
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the names of the copyright holders nor the names of its
  17  *    contributors may be used to endorse or promote products derived from
  18  *    this software without specific prior written permission.
  19  *
  20  * Alternatively, this software may be distributed under the terms of the
  21  * GNU General Public License ("GPL") version 2 as published by the Free
  22  * Software Foundation.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "core.h"
  38 #include "link.h"
  39 #include "node.h"
  40 #include "name_distr.h"
  41 #include "socket.h"
  42
  43 static void node_lost_contact(struct tipc_node *n_ptr);
  44 static void node_established_contact(struct tipc_node *n_ptr);
  45 static void tipc_node_delete(struct tipc_node *node);
  46
  47 struct tipc_sock_conn {
  48         u32 port;
  49         u32 peer_port;
  50         u32 peer_node;
  51         struct list_head list;
  52 };
  53
  54 static const struct nla_policy tipc_nl_node_policy[TIPC_NLA_NODE_MAX + 1] = {
  55         [TIPC_NLA_NODE_UNSPEC]          = { .type = NLA_UNSPEC },
  56         [TIPC_NLA_NODE_ADDR]            = { .type = NLA_U32 },
  57         [TIPC_NLA_NODE_UP]              = { .type = NLA_FLAG }
  58 };
  59
  60 /*
  61  * A trivial power-of-two bitmask technique is used for speed, since this
  62  * operation is done for every incoming TIPC packet. The number of hash table
  63  * entries has been chosen so that no hash chain exceeds 8 nodes and will
  64  * usually be much smaller (typically only a single node).
  65  */
  66 static unsigned int tipc_hashfn(u32 addr)
  67 {
  68         return addr & (NODE_HTABLE_SIZE - 1);
  69 }
  70
  71 static void tipc_node_kref_release(struct kref *kref)
  72 {
  73         struct tipc_node *node = container_of(kref, struct tipc_node, kref);
  74
  75         tipc_node_delete(node);
  76 }
  77
  78 void tipc_node_put(struct tipc_node *node)
  79 {
  80         kref_put(&node->kref, tipc_node_kref_release);
  81 }
  82
  83 static void tipc_node_get(struct tipc_node *node)
  84 {
  85         kref_get(&node->kref);
  86 }
  87
  88 /*
  89  * tipc_node_find - locate specified node object, if it exists
  90  */
  91 struct tipc_node *tipc_node_find(struct net *net, u32 addr)
  92 {
  93         struct tipc_net *tn = net_generic(net, tipc_net_id);
  94         struct tipc_node *node;
  95
  96         if (unlikely(!in_own_cluster_exact(net, addr)))
  97                 return NULL;
  98
  99         rcu_read_lock();
 100         hlist_for_each_entry_rcu(node, &tn->node_htable[tipc_hashfn(addr)],
 101                                  hash) {
 102                 if (node->addr == addr) {
 103                         tipc_node_get(node);
 104                         rcu_read_unlock();
 105                         return node;
 106                 }
 107         }
 108         rcu_read_unlock();
 109         return NULL;
 110 }
 111
 112 struct tipc_node *tipc_node_create(struct net *net, u32 addr)
 113 {
 114         struct tipc_net *tn = net_generic(net, tipc_net_id);
 115         struct tipc_node *n_ptr, *temp_node;
 116
 117         spin_lock_bh(&tn->node_list_lock);
 118         n_ptr = tipc_node_find(net, addr);
 119         if (n_ptr)
 120                 goto exit;
 121         n_ptr = kzalloc(sizeof(*n_ptr), GFP_ATOMIC);
 122         if (!n_ptr) {
 123                 pr_warn("Node creation failed, no memory\n");
 124                 goto exit;
 125         }
 126         n_ptr->addr = addr;
 127         n_ptr->net = net;
 128         kref_init(&n_ptr->kref);
 129         spin_lock_init(&n_ptr->lock);
 130         INIT_HLIST_NODE(&n_ptr->hash);
 131         INIT_LIST_HEAD(&n_ptr->list);
 132         INIT_LIST_HEAD(&n_ptr->publ_list);
 133         INIT_LIST_HEAD(&n_ptr->conn_sks);
 134         __skb_queue_head_init(&n_ptr->bclink.deferdq);
 135         hlist_add_head_rcu(&n_ptr->hash, &tn->node_htable[tipc_hashfn(addr)]);
 136         list_for_each_entry_rcu(temp_node, &tn->node_list, list) {
 137                 if (n_ptr->addr < temp_node->addr)
 138                         break;
 139         }
 140         list_add_tail_rcu(&n_ptr->list, &temp_node->list);
 141         n_ptr->action_flags = TIPC_WAIT_PEER_LINKS_DOWN;
 142         n_ptr->signature = INVALID_NODE_SIG;
 143         tipc_node_get(n_ptr);
 144 exit:
 145         spin_unlock_bh(&tn->node_list_lock);
 146         return n_ptr;
 147 }
 148
 149 static void tipc_node_delete(struct tipc_node *node)
 150 {
 151         list_del_rcu(&node->list);
 152         hlist_del_rcu(&node->hash);
 153         kfree_rcu(node, rcu);
 154 }
 155
 156 void tipc_node_stop(struct net *net)
 157 {
 158         struct tipc_net *tn = net_generic(net, tipc_net_id);
 159         struct tipc_node *node, *t_node;
 160
 161         spin_lock_bh(&tn->node_list_lock);
 162         list_for_each_entry_safe(node, t_node, &tn->node_list, list)
 163                 tipc_node_put(node);
 164         spin_unlock_bh(&tn->node_list_lock);
 165 }
 166
 167 int tipc_node_add_conn(struct net *net, u32 dnode, u32 port, u32 peer_port)
 168 {
 169         struct tipc_node *node;
 170         struct tipc_sock_conn *conn;
 171         int err = 0;
 172
 173         if (in_own_node(net, dnode))
 174                 return 0;
 175
 176         node = tipc_node_find(net, dnode);
 177         if (!node) {
 178                 pr_warn("Connecting sock to node 0x%x failed\n", dnode);
 179                 return -EHOSTUNREACH;
 180         }
 181         conn = kmalloc(sizeof(*conn), GFP_ATOMIC);
 182         if (!conn) {
 183                 err = -EHOSTUNREACH;
 184                 goto exit;
 185         }
 186         conn->peer_node = dnode;
 187         conn->port = port;
 188         conn->peer_port = peer_port;
 189
 190         tipc_node_lock(node);
 191         list_add_tail(&conn->list, &node->conn_sks);
 192         tipc_node_unlock(node);
 193 exit:
 194         tipc_node_put(node);
 195         return err;
 196 }
 197
 198 void tipc_node_remove_conn(struct net *net, u32 dnode, u32 port)
 199 {
 200         struct tipc_node *node;
 201         struct tipc_sock_conn *conn, *safe;
 202
 203         if (in_own_node(net, dnode))
 204                 return;
 205
 206         node = tipc_node_find(net, dnode);
 207         if (!node)
 208                 return;
 209
 210         tipc_node_lock(node);
 211         list_for_each_entry_safe(conn, safe, &node->conn_sks, list) {
 212                 if (port != conn->port)
 213                         continue;
 214                 list_del(&conn->list);
 215                 kfree(conn);
 216         }
 217         tipc_node_unlock(node);
 218         tipc_node_put(node);
 219 }
 220
 221 /**
 222  * tipc_node_link_up - handle addition of link
 223  *
 224  * Link becomes active (alone or shared) or standby, depending on its priority.
 225  */
 226 void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
 227 {
 228         struct tipc_link **active = &n_ptr->active_links[0];
 229
 230         n_ptr->working_links++;
 231         n_ptr->action_flags |= TIPC_NOTIFY_LINK_UP;
 232         n_ptr->link_id = l_ptr->peer_bearer_id << 16 | l_ptr->bearer_id;
 233
 234         pr_debug("Established link <%s> on network plane %c\n",
 235                  l_ptr->name, l_ptr->net_plane);
 236
 237         if (!active[0]) {
 238                 active[0] = active[1] = l_ptr;
 239                 node_established_contact(n_ptr);
 240                 goto exit;
 241         }
 242         if (l_ptr->priority < active[0]->priority) {
 243                 pr_debug("New link <%s> becomes standby\n", l_ptr->name);
 244                 goto exit;
 245         }
 246         tipc_link_dup_queue_xmit(active[0], l_ptr);
 247         if (l_ptr->priority == active[0]->priority) {
 248                 active[0] = l_ptr;
 249                 goto exit;
 250         }
 251         pr_debug("Old link <%s> becomes standby\n", active[0]->name);
 252         if (active[1] != active[0])
 253                 pr_debug("Old link <%s> becomes standby\n", active[1]->name);
 254         active[0] = active[1] = l_ptr;
 255 exit:
 256         /* Leave room for changeover header when returning 'mtu' to users: */
 257         n_ptr->act_mtus[0] = active[0]->mtu - INT_H_SIZE;
 258         n_ptr->act_mtus[1] = active[1]->mtu - INT_H_SIZE;
 259 }
 260
 261 /**
 262  * node_select_active_links - select active link
 263  */
 264 static void node_select_active_links(struct tipc_node *n_ptr)
 265 {
 266         struct tipc_link **active = &n_ptr->active_links[0];
 267         u32 i;
 268         u32 highest_prio = 0;
 269
 270         active[0] = active[1] = NULL;
 271
 272         for (i = 0; i < MAX_BEARERS; i++) {
 273                 struct tipc_link *l_ptr = n_ptr->links[i];
 274
 275                 if (!l_ptr || !tipc_link_is_up(l_ptr) ||
 276                     (l_ptr->priority < highest_prio))
 277                         continue;
 278
 279                 if (l_ptr->priority > highest_prio) {
 280                         highest_prio = l_ptr->priority;
 281                         active[0] = active[1] = l_ptr;
 282                 } else {
 283                         active[1] = l_ptr;
 284                 }
 285         }
 286 }
 287
 288 /**
 289  * tipc_node_link_down - handle loss of link
 290  */
 291 void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
 292 {
 293         struct tipc_net *tn = net_generic(n_ptr->net, tipc_net_id);
 294         struct tipc_link **active;
 295
 296         n_ptr->working_links--;
 297         n_ptr->action_flags |= TIPC_NOTIFY_LINK_DOWN;
 298         n_ptr->link_id = l_ptr->peer_bearer_id << 16 | l_ptr->bearer_id;
 299
 300         if (!tipc_link_is_active(l_ptr)) {
 301                 pr_debug("Lost standby link <%s> on network plane %c\n",
 302                          l_ptr->name, l_ptr->net_plane);
 303                 return;
 304         }
 305         pr_debug("Lost link <%s> on network plane %c\n",
 306                  l_ptr->name, l_ptr->net_plane);
 307
 308         active = &n_ptr->active_links[0];
 309         if (active[0] == l_ptr)
 310                 active[0] = active[1];
 311         if (active[1] == l_ptr)
 312                 active[1] = active[0];
 313         if (active[0] == l_ptr)
 314                 node_select_active_links(n_ptr);
 315         if (tipc_node_is_up(n_ptr))
 316                 tipc_link_failover_send_queue(l_ptr);
 317         else
 318                 node_lost_contact(n_ptr);
 319
 320         /* Leave room for changeover header when returning 'mtu' to users: */
 321         if (active[0]) {
 322                 n_ptr->act_mtus[0] = active[0]->mtu - INT_H_SIZE;
 323                 n_ptr->act_mtus[1] = active[1]->mtu - INT_H_SIZE;
 324                 return;
 325         }
 326         /* Loopback link went down? No fragmentation needed from now on. */
 327         if (n_ptr->addr == tn->own_addr) {
 328                 n_ptr->act_mtus[0] = MAX_MSG_SIZE;
 329                 n_ptr->act_mtus[1] = MAX_MSG_SIZE;
 330         }
 331 }
 332
 333 int tipc_node_active_links(struct tipc_node *n_ptr)
 334 {
 335         return n_ptr->active_links[0] != NULL;
 336 }
 337
 338 int tipc_node_is_up(struct tipc_node *n_ptr)
 339 {
 340         return tipc_node_active_links(n_ptr);
 341 }
 342
 343 void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
 344 {
 345         n_ptr->links[l_ptr->bearer_id] = l_ptr;
 346         n_ptr->link_cnt++;
 347 }
 348
 349 void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
 350 {
 351         int i;
 352
 353         for (i = 0; i < MAX_BEARERS; i++) {
 354                 if (l_ptr != n_ptr->links[i])
 355                         continue;
 356                 n_ptr->links[i] = NULL;
 357                 n_ptr->link_cnt--;
 358         }
 359 }
 360
 361 static void node_established_contact(struct tipc_node *n_ptr)
 362 {
 363         n_ptr->action_flags |= TIPC_NOTIFY_NODE_UP;
 364         n_ptr->bclink.oos_state = 0;
 365         n_ptr->bclink.acked = tipc_bclink_get_last_sent(n_ptr->net);
 366         tipc_bclink_add_node(n_ptr->net, n_ptr->addr);
 367 }
 368
 369 static void node_lost_contact(struct tipc_node *n_ptr)
 370 {
 371         char addr_string[16];
 372         struct tipc_sock_conn *conn, *safe;
 373         struct list_head *conns = &n_ptr->conn_sks;
 374         struct sk_buff *skb;
 375         struct tipc_net *tn = net_generic(n_ptr->net, tipc_net_id);
 376         uint i;
 377
 378         pr_debug("Lost contact with %s\n",
 379                  tipc_addr_string_fill(addr_string, n_ptr->addr));
 380
 381         /* Flush broadcast link info associated with lost node */
 382         if (n_ptr->bclink.recv_permitted) {
 383                 __skb_queue_purge(&n_ptr->bclink.deferdq);
 384
 385                 if (n_ptr->bclink.reasm_buf) {
 386                         kfree_skb(n_ptr->bclink.reasm_buf);
 387                         n_ptr->bclink.reasm_buf = NULL;
 388                 }
 389
 390                 tipc_bclink_remove_node(n_ptr->net, n_ptr->addr);
 391                 tipc_bclink_acknowledge(n_ptr, INVALID_LINK_SEQ);
 392
 393                 n_ptr->bclink.recv_permitted = false;
 394         }
 395
 396         /* Abort any ongoing link failover */
 397         for (i = 0; i < MAX_BEARERS; i++) {
 398                 struct tipc_link *l_ptr = n_ptr->links[i];
 399                 if (!l_ptr)
 400                         continue;
 401                 l_ptr->flags &= ~LINK_FAILINGOVER;
 402                 l_ptr->failover_checkpt = 0;
 403                 l_ptr->failover_pkts = 0;
 404                 kfree_skb(l_ptr->failover_skb);
 405                 l_ptr->failover_skb = NULL;
 406                 tipc_link_reset_fragments(l_ptr);
 407         }
 408
 409         n_ptr->action_flags &= ~TIPC_WAIT_OWN_LINKS_DOWN;
 410
 411         /* Prevent re-contact with node until cleanup is done */
 412         n_ptr->action_flags |= TIPC_WAIT_PEER_LINKS_DOWN;
 413
 414         /* Notify publications from this node */
 415         n_ptr->action_flags |= TIPC_NOTIFY_NODE_DOWN;
 416
 417         /* Notify sockets connected to node */
 418         list_for_each_entry_safe(conn, safe, conns, list) {
 419                 skb = tipc_msg_create(TIPC_CRITICAL_IMPORTANCE, TIPC_CONN_MSG,
 420                                       SHORT_H_SIZE, 0, tn->own_addr,
 421                                       conn->peer_node, conn->port,
 422                                       conn->peer_port, TIPC_ERR_NO_NODE);
 423                 if (likely(skb)) {
 424                         skb_queue_tail(n_ptr->inputq, skb);
 425                         n_ptr->action_flags |= TIPC_MSG_EVT;
 426                 }
 427                 list_del(&conn->list);
 428                 kfree(conn);
 429         }
 430 }
 431
 432 /**
 433  * tipc_node_get_linkname - get the name of a link
 434  *
 435  * @bearer_id: id of the bearer
 436  * @node: peer node address
 437  * @linkname: link name output buffer
 438  *
 439  * Returns 0 on success
 440  */
 441 int tipc_node_get_linkname(struct net *net, u32 bearer_id, u32 addr,
 442                            char *linkname, size_t len)
 443 {
 444         struct tipc_link *link;
 445         int err = -EINVAL;
 446         struct tipc_node *node = tipc_node_find(net, addr);
 447
 448         if (!node)
 449                 return err;
 450
 451         if (bearer_id >= MAX_BEARERS)
 452                 goto exit;
 453
 454         tipc_node_lock(node);
 455         link = node->links[bearer_id];
 456         if (link) {
 457                 strncpy(linkname, link->name, len);
 458                 err = 0;
 459         }
 460 exit:
 461         tipc_node_unlock(node);
 462         tipc_node_put(node);
 463         return err;
 464 }
 465
 466 void tipc_node_unlock(struct tipc_node *node)
 467 {
 468         struct net *net = node->net;
 469         u32 addr = 0;
 470         u32 flags = node->action_flags;
 471         u32 link_id = 0;
 472         struct list_head *publ_list;
 473         struct sk_buff_head *inputq = node->inputq;
 474         struct sk_buff_head *namedq;
 475
 476         if (likely(!flags || (flags == TIPC_MSG_EVT))) {
 477                 node->action_flags = 0;
 478                 spin_unlock_bh(&node->lock);
 479                 if (flags == TIPC_MSG_EVT)
 480                         tipc_sk_rcv(net, inputq);
 481                 return;
 482         }
 483
 484         addr = node->addr;
 485         link_id = node->link_id;
 486         namedq = node->namedq;
 487         publ_list = &node->publ_list;
 488
 489         node->action_flags &= ~(TIPC_MSG_EVT |
 490                                 TIPC_NOTIFY_NODE_DOWN | TIPC_NOTIFY_NODE_UP |
 491                                 TIPC_NOTIFY_LINK_DOWN | TIPC_NOTIFY_LINK_UP |
 492                                 TIPC_WAKEUP_BCAST_USERS | TIPC_BCAST_MSG_EVT |
 493                                 TIPC_NAMED_MSG_EVT | TIPC_BCAST_RESET);
 494
 495         spin_unlock_bh(&node->lock);
 496
 497         if (flags & TIPC_NOTIFY_NODE_DOWN)
 498                 tipc_publ_notify(net, publ_list, addr);
 499
 500         if (flags & TIPC_WAKEUP_BCAST_USERS)
 501                 tipc_bclink_wakeup_users(net);
 502
 503         if (flags & TIPC_NOTIFY_NODE_UP)
 504                 tipc_named_node_up(net, addr);
 505
 506         if (flags & TIPC_NOTIFY_LINK_UP)
 507                 tipc_nametbl_publish(net, TIPC_LINK_STATE, addr, addr,
 508                                      TIPC_NODE_SCOPE, link_id, addr);
 509
 510         if (flags & TIPC_NOTIFY_LINK_DOWN)
 511                 tipc_nametbl_withdraw(net, TIPC_LINK_STATE, addr,
 512                                       link_id, addr);
 513
 514         if (flags & TIPC_MSG_EVT)
 515                 tipc_sk_rcv(net, inputq);
 516
 517         if (flags & TIPC_NAMED_MSG_EVT)
 518                 tipc_named_rcv(net, namedq);
 519
 520         if (flags & TIPC_BCAST_MSG_EVT)
 521                 tipc_bclink_input(net);
 522
 523         if (flags & TIPC_BCAST_RESET)
 524                 tipc_link_reset_all(node);
 525 }
 526
 527 /* Caller should hold node lock for the passed node */
 528 static int __tipc_nl_add_node(struct tipc_nl_msg *msg, struct tipc_node *node)
 529 {
 530         void *hdr;
 531         struct nlattr *attrs;
 532
 533         hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
 534                           NLM_F_MULTI, TIPC_NL_NODE_GET);
 535         if (!hdr)
 536                 return -EMSGSIZE;
 537
 538         attrs = nla_nest_start(msg->skb, TIPC_NLA_NODE);
 539         if (!attrs)
 540                 goto msg_full;
 541
 542         if (nla_put_u32(msg->skb, TIPC_NLA_NODE_ADDR, node->addr))
 543                 goto attr_msg_full;
 544         if (tipc_node_is_up(node))
 545                 if (nla_put_flag(msg->skb, TIPC_NLA_NODE_UP))
 546                         goto attr_msg_full;
 547
 548         nla_nest_end(msg->skb, attrs);
 549         genlmsg_end(msg->skb, hdr);
 550
 551         return 0;
 552
 553 attr_msg_full:
 554         nla_nest_cancel(msg->skb, attrs);
 555 msg_full:
 556         genlmsg_cancel(msg->skb, hdr);
 557
 558         return -EMSGSIZE;
 559 }
 560
 561 int tipc_nl_node_dump(struct sk_buff *skb, struct netlink_callback *cb)
 562 {
 563         int err;
 564         struct net *net = sock_net(skb->sk);
 565         struct tipc_net *tn = net_generic(net, tipc_net_id);
 566         int done = cb->args[0];
 567         int last_addr = cb->args[1];
 568         struct tipc_node *node;
 569         struct tipc_nl_msg msg;
 570
 571         if (done)
 572                 return 0;
 573
 574         msg.skb = skb;
 575         msg.portid = NETLINK_CB(cb->skb).portid;
 576         msg.seq = cb->nlh->nlmsg_seq;
 577
 578         rcu_read_lock();
 579         if (last_addr) {
 580                 node = tipc_node_find(net, last_addr);
 581                 if (!node) {
 582                         rcu_read_unlock();
 583                         /* We never set seq or call nl_dump_check_consistent()
 584                          * this means that setting prev_seq here will cause the
 585                          * consistence check to fail in the netlink callback
 586                          * handler. Resulting in the NLMSG_DONE message having
 587                          * the NLM_F_DUMP_INTR flag set if the node state
 588                          * changed while we released the lock.
 589                          */
 590                         cb->prev_seq = 1;
 591                         return -EPIPE;
 592                 }
 593                 tipc_node_put(node);
 594         }
 595
 596         list_for_each_entry_rcu(node, &tn->node_list, list) {
 597                 if (last_addr) {
 598                         if (node->addr == last_addr)
 599                                 last_addr = 0;
 600                         else
 601                                 continue;
 602                 }
 603
 604                 tipc_node_lock(node);
 605                 err = __tipc_nl_add_node(&msg, node);
 606                 if (err) {
 607                         last_addr = node->addr;
 608                         tipc_node_unlock(node);
 609                         goto out;
 610                 }
 611
 612                 tipc_node_unlock(node);
 613         }
 614         done = 1;
 615 out:
 616         cb->args[0] = done;
 617         cb->args[1] = last_addr;
 618         rcu_read_unlock();
 619
 620         return skb->len;
 621 }