net/batman-adv/originator.c

   1 /*
   2  * Copyright (C) 2009-2012 B.A.T.M.A.N. contributors:
   3  *
   4  * Marek Lindner, Simon Wunderlich
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA
  19  *
  20  */
  21
  22 #include "main.h"
  23 #include "originator.h"
  24 #include "hash.h"
  25 #include "translation-table.h"
  26 #include "routing.h"
  27 #include "gateway_client.h"
  28 #include "hard-interface.h"
  29 #include "unicast.h"
  30 #include "soft-interface.h"
  31 #include "bridge_loop_avoidance.h"
  32
  33 static void purge_orig(struct work_struct *work);
  34
  35 static void start_purge_timer(struct bat_priv *bat_priv)
  36 {
  37         INIT_DELAYED_WORK(&bat_priv->orig_work, purge_orig);
  38         queue_delayed_work(bat_event_workqueue,
  39                            &bat_priv->orig_work, msecs_to_jiffies(1000));
  40 }
  41
  42 /* returns 1 if they are the same originator */
  43 static int compare_orig(const struct hlist_node *node, const void *data2)
  44 {
  45         const void *data1 = container_of(node, struct orig_node, hash_entry);
  46
  47         return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
  48 }
  49
  50 int originator_init(struct bat_priv *bat_priv)
  51 {
  52         if (bat_priv->orig_hash)
  53                 return 1;
  54
  55         bat_priv->orig_hash = hash_new(1024);
  56
  57         if (!bat_priv->orig_hash)
  58                 goto err;
  59
  60         start_purge_timer(bat_priv);
  61         return 1;
  62
  63 err:
  64         return 0;
  65 }
  66
  67 void neigh_node_free_ref(struct neigh_node *neigh_node)
  68 {
  69         if (atomic_dec_and_test(&neigh_node->refcount))
  70                 kfree_rcu(neigh_node, rcu);
  71 }
  72
  73 /* increases the refcounter of a found router */
  74 struct neigh_node *orig_node_get_router(struct orig_node *orig_node)
  75 {
  76         struct neigh_node *router;
  77
  78         rcu_read_lock();
  79         router = rcu_dereference(orig_node->router);
  80
  81         if (router && !atomic_inc_not_zero(&router->refcount))
  82                 router = NULL;
  83
  84         rcu_read_unlock();
  85         return router;
  86 }
  87
  88 struct neigh_node *batadv_neigh_node_new(struct hard_iface *hard_iface,
  89                                          const uint8_t *neigh_addr,
  90                                          uint32_t seqno)
  91 {
  92         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
  93         struct neigh_node *neigh_node;
  94
  95         neigh_node = kzalloc(sizeof(*neigh_node), GFP_ATOMIC);
  96         if (!neigh_node)
  97                 goto out;
  98
  99         INIT_HLIST_NODE(&neigh_node->list);
 100
 101         memcpy(neigh_node->addr, neigh_addr, ETH_ALEN);
 102         spin_lock_init(&neigh_node->lq_update_lock);
 103
 104         /* extra reference for return */
 105         atomic_set(&neigh_node->refcount, 2);
 106
 107         bat_dbg(DBG_BATMAN, bat_priv,
 108                 "Creating new neighbor %pM, initial seqno %d\n",
 109                 neigh_addr, seqno);
 110
 111 out:
 112         return neigh_node;
 113 }
 114
 115 static void orig_node_free_rcu(struct rcu_head *rcu)
 116 {
 117         struct hlist_node *node, *node_tmp;
 118         struct neigh_node *neigh_node, *tmp_neigh_node;
 119         struct orig_node *orig_node;
 120
 121         orig_node = container_of(rcu, struct orig_node, rcu);
 122
 123         spin_lock_bh(&orig_node->neigh_list_lock);
 124
 125         /* for all bonding members ... */
 126         list_for_each_entry_safe(neigh_node, tmp_neigh_node,
 127                                  &orig_node->bond_list, bonding_list) {
 128                 list_del_rcu(&neigh_node->bonding_list);
 129                 neigh_node_free_ref(neigh_node);
 130         }
 131
 132         /* for all neighbors towards this originator ... */
 133         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 134                                   &orig_node->neigh_list, list) {
 135                 hlist_del_rcu(&neigh_node->list);
 136                 neigh_node_free_ref(neigh_node);
 137         }
 138
 139         spin_unlock_bh(&orig_node->neigh_list_lock);
 140
 141         frag_list_free(&orig_node->frag_list);
 142         tt_global_del_orig(orig_node->bat_priv, orig_node,
 143                            "originator timed out");
 144
 145         kfree(orig_node->tt_buff);
 146         kfree(orig_node->bcast_own);
 147         kfree(orig_node->bcast_own_sum);
 148         kfree(orig_node);
 149 }
 150
 151 void orig_node_free_ref(struct orig_node *orig_node)
 152 {
 153         if (atomic_dec_and_test(&orig_node->refcount))
 154                 call_rcu(&orig_node->rcu, orig_node_free_rcu);
 155 }
 156
 157 void originator_free(struct bat_priv *bat_priv)
 158 {
 159         struct hashtable_t *hash = bat_priv->orig_hash;
 160         struct hlist_node *node, *node_tmp;
 161         struct hlist_head *head;
 162         spinlock_t *list_lock; /* spinlock to protect write access */
 163         struct orig_node *orig_node;
 164         uint32_t i;
 165
 166         if (!hash)
 167                 return;
 168
 169         cancel_delayed_work_sync(&bat_priv->orig_work);
 170
 171         bat_priv->orig_hash = NULL;
 172
 173         for (i = 0; i < hash->size; i++) {
 174                 head = &hash->table[i];
 175                 list_lock = &hash->list_locks[i];
 176
 177                 spin_lock_bh(list_lock);
 178                 hlist_for_each_entry_safe(orig_node, node, node_tmp,
 179                                           head, hash_entry) {
 180
 181                         hlist_del_rcu(node);
 182                         orig_node_free_ref(orig_node);
 183                 }
 184                 spin_unlock_bh(list_lock);
 185         }
 186
 187         hash_destroy(hash);
 188 }
 189
 190 /* this function finds or creates an originator entry for the given
 191  * address if it does not exits */
 192 struct orig_node *get_orig_node(struct bat_priv *bat_priv, const uint8_t *addr)
 193 {
 194         struct orig_node *orig_node;
 195         int size;
 196         int hash_added;
 197
 198         orig_node = orig_hash_find(bat_priv, addr);
 199         if (orig_node)
 200                 return orig_node;
 201
 202         bat_dbg(DBG_BATMAN, bat_priv,
 203                 "Creating new originator: %pM\n", addr);
 204
 205         orig_node = kzalloc(sizeof(*orig_node), GFP_ATOMIC);
 206         if (!orig_node)
 207                 return NULL;
 208
 209         INIT_HLIST_HEAD(&orig_node->neigh_list);
 210         INIT_LIST_HEAD(&orig_node->bond_list);
 211         spin_lock_init(&orig_node->ogm_cnt_lock);
 212         spin_lock_init(&orig_node->bcast_seqno_lock);
 213         spin_lock_init(&orig_node->neigh_list_lock);
 214         spin_lock_init(&orig_node->tt_buff_lock);
 215
 216         /* extra reference for return */
 217         atomic_set(&orig_node->refcount, 2);
 218
 219         orig_node->tt_initialised = false;
 220         orig_node->tt_poss_change = false;
 221         orig_node->bat_priv = bat_priv;
 222         memcpy(orig_node->orig, addr, ETH_ALEN);
 223         orig_node->router = NULL;
 224         orig_node->tt_crc = 0;
 225         atomic_set(&orig_node->last_ttvn, 0);
 226         orig_node->tt_buff = NULL;
 227         orig_node->tt_buff_len = 0;
 228         atomic_set(&orig_node->tt_size, 0);
 229         orig_node->bcast_seqno_reset = jiffies - 1
 230                                         - msecs_to_jiffies(RESET_PROTECTION_MS);
 231         orig_node->batman_seqno_reset = jiffies - 1
 232                                         - msecs_to_jiffies(RESET_PROTECTION_MS);
 233
 234         atomic_set(&orig_node->bond_candidates, 0);
 235
 236         size = bat_priv->num_ifaces * sizeof(unsigned long) * NUM_WORDS;
 237
 238         orig_node->bcast_own = kzalloc(size, GFP_ATOMIC);
 239         if (!orig_node->bcast_own)
 240                 goto free_orig_node;
 241
 242         size = bat_priv->num_ifaces * sizeof(uint8_t);
 243         orig_node->bcast_own_sum = kzalloc(size, GFP_ATOMIC);
 244
 245         INIT_LIST_HEAD(&orig_node->frag_list);
 246         orig_node->last_frag_packet = 0;
 247
 248         if (!orig_node->bcast_own_sum)
 249                 goto free_bcast_own;
 250
 251         hash_added = hash_add(bat_priv->orig_hash, compare_orig,
 252                               choose_orig, orig_node, &orig_node->hash_entry);
 253         if (hash_added != 0)
 254                 goto free_bcast_own_sum;
 255
 256         return orig_node;
 257 free_bcast_own_sum:
 258         kfree(orig_node->bcast_own_sum);
 259 free_bcast_own:
 260         kfree(orig_node->bcast_own);
 261 free_orig_node:
 262         kfree(orig_node);
 263         return NULL;
 264 }
 265
 266 static bool purge_orig_neighbors(struct bat_priv *bat_priv,
 267                                  struct orig_node *orig_node,
 268                                  struct neigh_node **best_neigh_node)
 269 {
 270         struct hlist_node *node, *node_tmp;
 271         struct neigh_node *neigh_node;
 272         bool neigh_purged = false;
 273         unsigned long last_seen;
 274
 275         *best_neigh_node = NULL;
 276
 277         spin_lock_bh(&orig_node->neigh_list_lock);
 278
 279         /* for all neighbors towards this originator ... */
 280         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 281                                   &orig_node->neigh_list, list) {
 282
 283                 if ((has_timed_out(neigh_node->last_seen, PURGE_TIMEOUT)) ||
 284                     (neigh_node->if_incoming->if_status == IF_INACTIVE) ||
 285                     (neigh_node->if_incoming->if_status == IF_NOT_IN_USE) ||
 286                     (neigh_node->if_incoming->if_status == IF_TO_BE_REMOVED)) {
 287
 288                         last_seen = neigh_node->last_seen;
 289
 290                         if ((neigh_node->if_incoming->if_status ==
 291                                                                 IF_INACTIVE) ||
 292                             (neigh_node->if_incoming->if_status ==
 293                                                         IF_NOT_IN_USE) ||
 294                             (neigh_node->if_incoming->if_status ==
 295                                                         IF_TO_BE_REMOVED))
 296                                 bat_dbg(DBG_BATMAN, bat_priv,
 297                                         "neighbor purge: originator %pM, neighbor: %pM, iface: %s\n",
 298                                         orig_node->orig, neigh_node->addr,
 299                                         neigh_node->if_incoming->net_dev->name);
 300                         else
 301                                 bat_dbg(DBG_BATMAN, bat_priv,
 302                                         "neighbor timeout: originator %pM, neighbor: %pM, last_seen: %u\n",
 303                                         orig_node->orig, neigh_node->addr,
 304                                         jiffies_to_msecs(last_seen));
 305
 306                         neigh_purged = true;
 307
 308                         hlist_del_rcu(&neigh_node->list);
 309                         bonding_candidate_del(orig_node, neigh_node);
 310                         neigh_node_free_ref(neigh_node);
 311                 } else {
 312                         if ((!*best_neigh_node) ||
 313                             (neigh_node->tq_avg > (*best_neigh_node)->tq_avg))
 314                                 *best_neigh_node = neigh_node;
 315                 }
 316         }
 317
 318         spin_unlock_bh(&orig_node->neigh_list_lock);
 319         return neigh_purged;
 320 }
 321
 322 static bool purge_orig_node(struct bat_priv *bat_priv,
 323                             struct orig_node *orig_node)
 324 {
 325         struct neigh_node *best_neigh_node;
 326
 327         if (has_timed_out(orig_node->last_seen, 2 * PURGE_TIMEOUT)) {
 328                 bat_dbg(DBG_BATMAN, bat_priv,
 329                         "Originator timeout: originator %pM, last_seen %u\n",
 330                         orig_node->orig,
 331                         jiffies_to_msecs(orig_node->last_seen));
 332                 return true;
 333         } else {
 334                 if (purge_orig_neighbors(bat_priv, orig_node,
 335                                          &best_neigh_node))
 336                         update_route(bat_priv, orig_node, best_neigh_node);
 337         }
 338
 339         return false;
 340 }
 341
 342 static void _purge_orig(struct bat_priv *bat_priv)
 343 {
 344         struct hashtable_t *hash = bat_priv->orig_hash;
 345         struct hlist_node *node, *node_tmp;
 346         struct hlist_head *head;
 347         spinlock_t *list_lock; /* spinlock to protect write access */
 348         struct orig_node *orig_node;
 349         uint32_t i;
 350
 351         if (!hash)
 352                 return;
 353
 354         /* for all origins... */
 355         for (i = 0; i < hash->size; i++) {
 356                 head = &hash->table[i];
 357                 list_lock = &hash->list_locks[i];
 358
 359                 spin_lock_bh(list_lock);
 360                 hlist_for_each_entry_safe(orig_node, node, node_tmp,
 361                                           head, hash_entry) {
 362                         if (purge_orig_node(bat_priv, orig_node)) {
 363                                 if (orig_node->gw_flags)
 364                                         gw_node_delete(bat_priv, orig_node);
 365                                 hlist_del_rcu(node);
 366                                 orig_node_free_ref(orig_node);
 367                                 continue;
 368                         }
 369
 370                         if (has_timed_out(orig_node->last_frag_packet,
 371                                           FRAG_TIMEOUT))
 372                                 frag_list_free(&orig_node->frag_list);
 373                 }
 374                 spin_unlock_bh(list_lock);
 375         }
 376
 377         gw_node_purge(bat_priv);
 378         gw_election(bat_priv);
 379 }
 380
 381 static void purge_orig(struct work_struct *work)
 382 {
 383         struct delayed_work *delayed_work =
 384                 container_of(work, struct delayed_work, work);
 385         struct bat_priv *bat_priv =
 386                 container_of(delayed_work, struct bat_priv, orig_work);
 387
 388         _purge_orig(bat_priv);
 389         start_purge_timer(bat_priv);
 390 }
 391
 392 void purge_orig_ref(struct bat_priv *bat_priv)
 393 {
 394         _purge_orig(bat_priv);
 395 }
 396
 397 int orig_seq_print_text(struct seq_file *seq, void *offset)
 398 {
 399         struct net_device *net_dev = (struct net_device *)seq->private;
 400         struct bat_priv *bat_priv = netdev_priv(net_dev);
 401         struct hashtable_t *hash = bat_priv->orig_hash;
 402         struct hlist_node *node, *node_tmp;
 403         struct hlist_head *head;
 404         struct hard_iface *primary_if;
 405         struct orig_node *orig_node;
 406         struct neigh_node *neigh_node, *neigh_node_tmp;
 407         int batman_count = 0;
 408         int last_seen_secs;
 409         int last_seen_msecs;
 410         uint32_t i;
 411         int ret = 0;
 412
 413         primary_if = primary_if_get_selected(bat_priv);
 414
 415         if (!primary_if) {
 416                 ret = seq_printf(seq,
 417                                  "BATMAN mesh %s disabled - please specify interfaces to enable it\n",
 418                                  net_dev->name);
 419                 goto out;
 420         }
 421
 422         if (primary_if->if_status != IF_ACTIVE) {
 423                 ret = seq_printf(seq,
 424                                  "BATMAN mesh %s disabled - primary interface not active\n",
 425                                  net_dev->name);
 426                 goto out;
 427         }
 428
 429         seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
 430                    SOURCE_VERSION, primary_if->net_dev->name,
 431                    primary_if->net_dev->dev_addr, net_dev->name);
 432         seq_printf(seq, "  %-15s %s (%s/%i) %17s [%10s]: %20s ...\n",
 433                    "Originator", "last-seen", "#", TQ_MAX_VALUE, "Nexthop",
 434                    "outgoingIF", "Potential nexthops");
 435
 436         for (i = 0; i < hash->size; i++) {
 437                 head = &hash->table[i];
 438
 439                 rcu_read_lock();
 440                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 441                         neigh_node = orig_node_get_router(orig_node);
 442                         if (!neigh_node)
 443                                 continue;
 444
 445                         if (neigh_node->tq_avg == 0)
 446                                 goto next;
 447
 448                         last_seen_secs = jiffies_to_msecs(jiffies -
 449                                                 orig_node->last_seen) / 1000;
 450                         last_seen_msecs = jiffies_to_msecs(jiffies -
 451                                                 orig_node->last_seen) % 1000;
 452
 453                         seq_printf(seq, "%pM %4i.%03is   (%3i) %pM [%10s]:",
 454                                    orig_node->orig, last_seen_secs,
 455                                    last_seen_msecs, neigh_node->tq_avg,
 456                                    neigh_node->addr,
 457                                    neigh_node->if_incoming->net_dev->name);
 458
 459                         hlist_for_each_entry_rcu(neigh_node_tmp, node_tmp,
 460                                                  &orig_node->neigh_list, list) {
 461                                 seq_printf(seq, " %pM (%3i)",
 462                                            neigh_node_tmp->addr,
 463                                            neigh_node_tmp->tq_avg);
 464                         }
 465
 466                         seq_printf(seq, "\n");
 467                         batman_count++;
 468
 469 next:
 470                         neigh_node_free_ref(neigh_node);
 471                 }
 472                 rcu_read_unlock();
 473         }
 474
 475         if (batman_count == 0)
 476                 seq_printf(seq, "No batman nodes in range ...\n");
 477
 478 out:
 479         if (primary_if)
 480                 hardif_free_ref(primary_if);
 481         return ret;
 482 }
 483
 484 static int orig_node_add_if(struct orig_node *orig_node, int max_if_num)
 485 {
 486         void *data_ptr;
 487
 488         data_ptr = kmalloc(max_if_num * sizeof(unsigned long) * NUM_WORDS,
 489                            GFP_ATOMIC);
 490         if (!data_ptr)
 491                 return -1;
 492
 493         memcpy(data_ptr, orig_node->bcast_own,
 494                (max_if_num - 1) * sizeof(unsigned long) * NUM_WORDS);
 495         kfree(orig_node->bcast_own);
 496         orig_node->bcast_own = data_ptr;
 497
 498         data_ptr = kmalloc(max_if_num * sizeof(uint8_t), GFP_ATOMIC);
 499         if (!data_ptr)
 500                 return -1;
 501
 502         memcpy(data_ptr, orig_node->bcast_own_sum,
 503                (max_if_num - 1) * sizeof(uint8_t));
 504         kfree(orig_node->bcast_own_sum);
 505         orig_node->bcast_own_sum = data_ptr;
 506
 507         return 0;
 508 }
 509
 510 int orig_hash_add_if(struct hard_iface *hard_iface, int max_if_num)
 511 {
 512         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 513         struct hashtable_t *hash = bat_priv->orig_hash;
 514         struct hlist_node *node;
 515         struct hlist_head *head;
 516         struct orig_node *orig_node;
 517         uint32_t i;
 518         int ret;
 519
 520         /* resize all orig nodes because orig_node->bcast_own(_sum) depend on
 521          * if_num */
 522         for (i = 0; i < hash->size; i++) {
 523                 head = &hash->table[i];
 524
 525                 rcu_read_lock();
 526                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 527                         spin_lock_bh(&orig_node->ogm_cnt_lock);
 528                         ret = orig_node_add_if(orig_node, max_if_num);
 529                         spin_unlock_bh(&orig_node->ogm_cnt_lock);
 530
 531                         if (ret == -1)
 532                                 goto err;
 533                 }
 534                 rcu_read_unlock();
 535         }
 536
 537         return 0;
 538
 539 err:
 540         rcu_read_unlock();
 541         return -ENOMEM;
 542 }
 543
 544 static int orig_node_del_if(struct orig_node *orig_node,
 545                      int max_if_num, int del_if_num)
 546 {
 547         void *data_ptr = NULL;
 548         int chunk_size;
 549
 550         /* last interface was removed */
 551         if (max_if_num == 0)
 552                 goto free_bcast_own;
 553
 554         chunk_size = sizeof(unsigned long) * NUM_WORDS;
 555         data_ptr = kmalloc(max_if_num * chunk_size, GFP_ATOMIC);
 556         if (!data_ptr)
 557                 return -1;
 558
 559         /* copy first part */
 560         memcpy(data_ptr, orig_node->bcast_own, del_if_num * chunk_size);
 561
 562         /* copy second part */
 563         memcpy((char *)data_ptr + del_if_num * chunk_size,
 564                orig_node->bcast_own + ((del_if_num + 1) * chunk_size),
 565                (max_if_num - del_if_num) * chunk_size);
 566
 567 free_bcast_own:
 568         kfree(orig_node->bcast_own);
 569         orig_node->bcast_own = data_ptr;
 570
 571         if (max_if_num == 0)
 572                 goto free_own_sum;
 573
 574         data_ptr = kmalloc(max_if_num * sizeof(uint8_t), GFP_ATOMIC);
 575         if (!data_ptr)
 576                 return -1;
 577
 578         memcpy(data_ptr, orig_node->bcast_own_sum,
 579                del_if_num * sizeof(uint8_t));
 580
 581         memcpy((char *)data_ptr + del_if_num * sizeof(uint8_t),
 582                orig_node->bcast_own_sum + ((del_if_num + 1) * sizeof(uint8_t)),
 583                (max_if_num - del_if_num) * sizeof(uint8_t));
 584
 585 free_own_sum:
 586         kfree(orig_node->bcast_own_sum);
 587         orig_node->bcast_own_sum = data_ptr;
 588
 589         return 0;
 590 }
 591
 592 int orig_hash_del_if(struct hard_iface *hard_iface, int max_if_num)
 593 {
 594         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 595         struct hashtable_t *hash = bat_priv->orig_hash;
 596         struct hlist_node *node;
 597         struct hlist_head *head;
 598         struct hard_iface *hard_iface_tmp;
 599         struct orig_node *orig_node;
 600         uint32_t i;
 601         int ret;
 602
 603         /* resize all orig nodes because orig_node->bcast_own(_sum) depend on
 604          * if_num */
 605         for (i = 0; i < hash->size; i++) {
 606                 head = &hash->table[i];
 607
 608                 rcu_read_lock();
 609                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 610                         spin_lock_bh(&orig_node->ogm_cnt_lock);
 611                         ret = orig_node_del_if(orig_node, max_if_num,
 612                                         hard_iface->if_num);
 613                         spin_unlock_bh(&orig_node->ogm_cnt_lock);
 614
 615                         if (ret == -1)
 616                                 goto err;
 617                 }
 618                 rcu_read_unlock();
 619         }
 620
 621         /* renumber remaining batman interfaces _inside_ of orig_hash_lock */
 622         rcu_read_lock();
 623         list_for_each_entry_rcu(hard_iface_tmp, &hardif_list, list) {
 624                 if (hard_iface_tmp->if_status == IF_NOT_IN_USE)
 625                         continue;
 626
 627                 if (hard_iface == hard_iface_tmp)
 628                         continue;
 629
 630                 if (hard_iface->soft_iface != hard_iface_tmp->soft_iface)
 631                         continue;
 632
 633                 if (hard_iface_tmp->if_num > hard_iface->if_num)
 634                         hard_iface_tmp->if_num--;
 635         }
 636         rcu_read_unlock();
 637
 638         hard_iface->if_num = -1;
 639         return 0;
 640
 641 err:
 642         rcu_read_unlock();
 643         return -ENOMEM;
 644 }