net/batman-adv/originator.c

   1 /*
   2  * Copyright (C) 2009-2011 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
  32 static void purge_orig(struct work_struct *work);
  33
  34 static void start_purge_timer(struct bat_priv *bat_priv)
  35 {
  36         INIT_DELAYED_WORK(&bat_priv->orig_work, purge_orig);
  37         queue_delayed_work(bat_event_workqueue, &bat_priv->orig_work, 1 * HZ);
  38 }
  39
  40 int originator_init(struct bat_priv *bat_priv)
  41 {
  42         if (bat_priv->orig_hash)
  43                 return 1;
  44
  45         bat_priv->orig_hash = hash_new(1024);
  46
  47         if (!bat_priv->orig_hash)
  48                 goto err;
  49
  50         start_purge_timer(bat_priv);
  51         return 1;
  52
  53 err:
  54         return 0;
  55 }
  56
  57 void neigh_node_free_ref(struct neigh_node *neigh_node)
  58 {
  59         if (atomic_dec_and_test(&neigh_node->refcount))
  60                 kfree_rcu(neigh_node, rcu);
  61 }
  62
  63 /* increases the refcounter of a found router */
  64 struct neigh_node *orig_node_get_router(struct orig_node *orig_node)
  65 {
  66         struct neigh_node *router;
  67
  68         rcu_read_lock();
  69         router = rcu_dereference(orig_node->router);
  70
  71         if (router && !atomic_inc_not_zero(&router->refcount))
  72                 router = NULL;
  73
  74         rcu_read_unlock();
  75         return router;
  76 }
  77
  78 struct neigh_node *create_neighbor(struct orig_node *orig_node,
  79                                    struct orig_node *orig_neigh_node,
  80                                    uint8_t *neigh,
  81                                    struct hard_iface *if_incoming)
  82 {
  83         struct bat_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
  84         struct neigh_node *neigh_node;
  85
  86         bat_dbg(DBG_BATMAN, bat_priv,
  87                 "Creating new last-hop neighbor of originator\n");
  88
  89         neigh_node = kzalloc(sizeof(struct neigh_node), GFP_ATOMIC);
  90         if (!neigh_node)
  91                 return NULL;
  92
  93         INIT_HLIST_NODE(&neigh_node->list);
  94         INIT_LIST_HEAD(&neigh_node->bonding_list);
  95         spin_lock_init(&neigh_node->tq_lock);
  96
  97         memcpy(neigh_node->addr, neigh, ETH_ALEN);
  98         neigh_node->orig_node = orig_neigh_node;
  99         neigh_node->if_incoming = if_incoming;
 100
 101         /* extra reference for return */
 102         atomic_set(&neigh_node->refcount, 2);
 103
 104         spin_lock_bh(&orig_node->neigh_list_lock);
 105         hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
 106         spin_unlock_bh(&orig_node->neigh_list_lock);
 107         return neigh_node;
 108 }
 109
 110 static void orig_node_free_rcu(struct rcu_head *rcu)
 111 {
 112         struct hlist_node *node, *node_tmp;
 113         struct neigh_node *neigh_node, *tmp_neigh_node;
 114         struct orig_node *orig_node;
 115
 116         orig_node = container_of(rcu, struct orig_node, rcu);
 117
 118         spin_lock_bh(&orig_node->neigh_list_lock);
 119
 120         /* for all bonding members ... */
 121         list_for_each_entry_safe(neigh_node, tmp_neigh_node,
 122                                  &orig_node->bond_list, bonding_list) {
 123                 list_del_rcu(&neigh_node->bonding_list);
 124                 neigh_node_free_ref(neigh_node);
 125         }
 126
 127         /* for all neighbors towards this originator ... */
 128         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 129                                   &orig_node->neigh_list, list) {
 130                 hlist_del_rcu(&neigh_node->list);
 131                 neigh_node_free_ref(neigh_node);
 132         }
 133
 134         spin_unlock_bh(&orig_node->neigh_list_lock);
 135
 136         frag_list_free(&orig_node->frag_list);
 137         tt_global_del_orig(orig_node->bat_priv, orig_node,
 138                             "originator timed out");
 139
 140         kfree(orig_node->bcast_own);
 141         kfree(orig_node->bcast_own_sum);
 142         kfree(orig_node);
 143 }
 144
 145 void orig_node_free_ref(struct orig_node *orig_node)
 146 {
 147         if (atomic_dec_and_test(&orig_node->refcount))
 148                 call_rcu(&orig_node->rcu, orig_node_free_rcu);
 149 }
 150
 151 void originator_free(struct bat_priv *bat_priv)
 152 {
 153         struct hashtable_t *hash = bat_priv->orig_hash;
 154         struct hlist_node *node, *node_tmp;
 155         struct hlist_head *head;
 156         spinlock_t *list_lock; /* spinlock to protect write access */
 157         struct orig_node *orig_node;
 158         int i;
 159
 160         if (!hash)
 161                 return;
 162
 163         cancel_delayed_work_sync(&bat_priv->orig_work);
 164
 165         bat_priv->orig_hash = NULL;
 166
 167         for (i = 0; i < hash->size; i++) {
 168                 head = &hash->table[i];
 169                 list_lock = &hash->list_locks[i];
 170
 171                 spin_lock_bh(list_lock);
 172                 hlist_for_each_entry_safe(orig_node, node, node_tmp,
 173                                           head, hash_entry) {
 174
 175                         hlist_del_rcu(node);
 176                         orig_node_free_ref(orig_node);
 177                 }
 178                 spin_unlock_bh(list_lock);
 179         }
 180
 181         hash_destroy(hash);
 182 }
 183
 184 /* this function finds or creates an originator entry for the given
 185  * address if it does not exits */
 186 struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
 187 {
 188         struct orig_node *orig_node;
 189         int size;
 190         int hash_added;
 191
 192         orig_node = orig_hash_find(bat_priv, addr);
 193         if (orig_node)
 194                 return orig_node;
 195
 196         bat_dbg(DBG_BATMAN, bat_priv,
 197                 "Creating new originator: %pM\n", addr);
 198
 199         orig_node = kzalloc(sizeof(struct orig_node), GFP_ATOMIC);
 200         if (!orig_node)
 201                 return NULL;
 202
 203         INIT_HLIST_HEAD(&orig_node->neigh_list);
 204         INIT_LIST_HEAD(&orig_node->bond_list);
 205         spin_lock_init(&orig_node->ogm_cnt_lock);
 206         spin_lock_init(&orig_node->bcast_seqno_lock);
 207         spin_lock_init(&orig_node->neigh_list_lock);
 208
 209         /* extra reference for return */
 210         atomic_set(&orig_node->refcount, 2);
 211
 212         orig_node->bat_priv = bat_priv;
 213         memcpy(orig_node->orig, addr, ETH_ALEN);
 214         orig_node->router = NULL;
 215         orig_node->tt_buff = NULL;
 216         orig_node->bcast_seqno_reset = jiffies - 1
 217                                         - msecs_to_jiffies(RESET_PROTECTION_MS);
 218         orig_node->batman_seqno_reset = jiffies - 1
 219                                         - msecs_to_jiffies(RESET_PROTECTION_MS);
 220
 221         atomic_set(&orig_node->bond_candidates, 0);
 222
 223         size = bat_priv->num_ifaces * sizeof(unsigned long) * NUM_WORDS;
 224
 225         orig_node->bcast_own = kzalloc(size, GFP_ATOMIC);
 226         if (!orig_node->bcast_own)
 227                 goto free_orig_node;
 228
 229         size = bat_priv->num_ifaces * sizeof(uint8_t);
 230         orig_node->bcast_own_sum = kzalloc(size, GFP_ATOMIC);
 231
 232         INIT_LIST_HEAD(&orig_node->frag_list);
 233         orig_node->last_frag_packet = 0;
 234
 235         if (!orig_node->bcast_own_sum)
 236                 goto free_bcast_own;
 237
 238         hash_added = hash_add(bat_priv->orig_hash, compare_orig,
 239                               choose_orig, orig_node, &orig_node->hash_entry);
 240         if (hash_added < 0)
 241                 goto free_bcast_own_sum;
 242
 243         return orig_node;
 244 free_bcast_own_sum:
 245         kfree(orig_node->bcast_own_sum);
 246 free_bcast_own:
 247         kfree(orig_node->bcast_own);
 248 free_orig_node:
 249         kfree(orig_node);
 250         return NULL;
 251 }
 252
 253 static bool purge_orig_neighbors(struct bat_priv *bat_priv,
 254                                  struct orig_node *orig_node,
 255                                  struct neigh_node **best_neigh_node)
 256 {
 257         struct hlist_node *node, *node_tmp;
 258         struct neigh_node *neigh_node;
 259         bool neigh_purged = false;
 260
 261         *best_neigh_node = NULL;
 262
 263         spin_lock_bh(&orig_node->neigh_list_lock);
 264
 265         /* for all neighbors towards this originator ... */
 266         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 267                                   &orig_node->neigh_list, list) {
 268
 269                 if ((time_after(jiffies,
 270                         neigh_node->last_valid + PURGE_TIMEOUT * HZ)) ||
 271                     (neigh_node->if_incoming->if_status == IF_INACTIVE) ||
 272                     (neigh_node->if_incoming->if_status == IF_NOT_IN_USE) ||
 273                     (neigh_node->if_incoming->if_status == IF_TO_BE_REMOVED)) {
 274
 275                         if ((neigh_node->if_incoming->if_status ==
 276                                                                 IF_INACTIVE) ||
 277                             (neigh_node->if_incoming->if_status ==
 278                                                         IF_NOT_IN_USE) ||
 279                             (neigh_node->if_incoming->if_status ==
 280                                                         IF_TO_BE_REMOVED))
 281                                 bat_dbg(DBG_BATMAN, bat_priv,
 282                                         "neighbor purge: originator %pM, "
 283                                         "neighbor: %pM, iface: %s\n",
 284                                         orig_node->orig, neigh_node->addr,
 285                                         neigh_node->if_incoming->net_dev->name);
 286                         else
 287                                 bat_dbg(DBG_BATMAN, bat_priv,
 288                                         "neighbor timeout: originator %pM, "
 289                                         "neighbor: %pM, last_valid: %lu\n",
 290                                         orig_node->orig, neigh_node->addr,
 291                                         (neigh_node->last_valid / HZ));
 292
 293                         neigh_purged = true;
 294
 295                         hlist_del_rcu(&neigh_node->list);
 296                         bonding_candidate_del(orig_node, neigh_node);
 297                         neigh_node_free_ref(neigh_node);
 298                 } else {
 299                         if ((!*best_neigh_node) ||
 300                             (neigh_node->tq_avg > (*best_neigh_node)->tq_avg))
 301                                 *best_neigh_node = neigh_node;
 302                 }
 303         }
 304
 305         spin_unlock_bh(&orig_node->neigh_list_lock);
 306         return neigh_purged;
 307 }
 308
 309 static bool purge_orig_node(struct bat_priv *bat_priv,
 310                             struct orig_node *orig_node)
 311 {
 312         struct neigh_node *best_neigh_node;
 313
 314         if (time_after(jiffies,
 315                 orig_node->last_valid + 2 * PURGE_TIMEOUT * HZ)) {
 316
 317                 bat_dbg(DBG_BATMAN, bat_priv,
 318                         "Originator timeout: originator %pM, last_valid %lu\n",
 319                         orig_node->orig, (orig_node->last_valid / HZ));
 320                 return true;
 321         } else {
 322                 if (purge_orig_neighbors(bat_priv, orig_node,
 323                                                         &best_neigh_node)) {
 324                         update_routes(bat_priv, orig_node,
 325                                       best_neigh_node,
 326                                       orig_node->tt_buff,
 327                                       orig_node->tt_buff_len);
 328                 }
 329         }
 330
 331         return false;
 332 }
 333
 334 static void _purge_orig(struct bat_priv *bat_priv)
 335 {
 336         struct hashtable_t *hash = bat_priv->orig_hash;
 337         struct hlist_node *node, *node_tmp;
 338         struct hlist_head *head;
 339         spinlock_t *list_lock; /* spinlock to protect write access */
 340         struct orig_node *orig_node;
 341         int i;
 342
 343         if (!hash)
 344                 return;
 345
 346         /* for all origins... */
 347         for (i = 0; i < hash->size; i++) {
 348                 head = &hash->table[i];
 349                 list_lock = &hash->list_locks[i];
 350
 351                 spin_lock_bh(list_lock);
 352                 hlist_for_each_entry_safe(orig_node, node, node_tmp,
 353                                           head, hash_entry) {
 354                         if (purge_orig_node(bat_priv, orig_node)) {
 355                                 if (orig_node->gw_flags)
 356                                         gw_node_delete(bat_priv, orig_node);
 357                                 hlist_del_rcu(node);
 358                                 orig_node_free_ref(orig_node);
 359                                 continue;
 360                         }
 361
 362                         if (time_after(jiffies, orig_node->last_frag_packet +
 363                                                 msecs_to_jiffies(FRAG_TIMEOUT)))
 364                                 frag_list_free(&orig_node->frag_list);
 365                 }
 366                 spin_unlock_bh(list_lock);
 367         }
 368
 369         gw_node_purge(bat_priv);
 370         gw_election(bat_priv);
 371
 372         softif_neigh_purge(bat_priv);
 373 }
 374
 375 static void purge_orig(struct work_struct *work)
 376 {
 377         struct delayed_work *delayed_work =
 378                 container_of(work, struct delayed_work, work);
 379         struct bat_priv *bat_priv =
 380                 container_of(delayed_work, struct bat_priv, orig_work);
 381
 382         _purge_orig(bat_priv);
 383         start_purge_timer(bat_priv);
 384 }
 385
 386 void purge_orig_ref(struct bat_priv *bat_priv)
 387 {
 388         _purge_orig(bat_priv);
 389 }
 390
 391 int orig_seq_print_text(struct seq_file *seq, void *offset)
 392 {
 393         struct net_device *net_dev = (struct net_device *)seq->private;
 394         struct bat_priv *bat_priv = netdev_priv(net_dev);
 395         struct hashtable_t *hash = bat_priv->orig_hash;
 396         struct hlist_node *node, *node_tmp;
 397         struct hlist_head *head;
 398         struct hard_iface *primary_if;
 399         struct orig_node *orig_node;
 400         struct neigh_node *neigh_node, *neigh_node_tmp;
 401         int batman_count = 0;
 402         int last_seen_secs;
 403         int last_seen_msecs;
 404         int i, ret = 0;
 405
 406         primary_if = primary_if_get_selected(bat_priv);
 407
 408         if (!primary_if) {
 409                 ret = seq_printf(seq, "BATMAN mesh %s disabled - "
 410                                  "please specify interfaces to enable it\n",
 411                                  net_dev->name);
 412                 goto out;
 413         }
 414
 415         if (primary_if->if_status != IF_ACTIVE) {
 416                 ret = seq_printf(seq, "BATMAN mesh %s "
 417                                  "disabled - primary interface not active\n",
 418                                  net_dev->name);
 419                 goto out;
 420         }
 421
 422         seq_printf(seq, "[B.A.T.M.A.N. adv %s%s, MainIF/MAC: %s/%pM (%s)]\n",
 423                    SOURCE_VERSION, REVISION_VERSION_STR,
 424                    primary_if->net_dev->name,
 425                    primary_if->net_dev->dev_addr, net_dev->name);
 426         seq_printf(seq, "  %-15s %s (%s/%i) %17s [%10s]: %20s ...\n",
 427                    "Originator", "last-seen", "#", TQ_MAX_VALUE, "Nexthop",
 428                    "outgoingIF", "Potential nexthops");
 429
 430         for (i = 0; i < hash->size; i++) {
 431                 head = &hash->table[i];
 432
 433                 rcu_read_lock();
 434                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 435                         neigh_node = orig_node_get_router(orig_node);
 436                         if (!neigh_node)
 437                                 continue;
 438
 439                         if (neigh_node->tq_avg == 0)
 440                                 goto next;
 441
 442                         last_seen_secs = jiffies_to_msecs(jiffies -
 443                                                 orig_node->last_valid) / 1000;
 444                         last_seen_msecs = jiffies_to_msecs(jiffies -
 445                                                 orig_node->last_valid) % 1000;
 446
 447                         seq_printf(seq, "%pM %4i.%03is   (%3i) %pM [%10s]:",
 448                                    orig_node->orig, last_seen_secs,
 449                                    last_seen_msecs, neigh_node->tq_avg,
 450                                    neigh_node->addr,
 451                                    neigh_node->if_incoming->net_dev->name);
 452
 453                         hlist_for_each_entry_rcu(neigh_node_tmp, node_tmp,
 454                                                  &orig_node->neigh_list, list) {
 455                                 seq_printf(seq, " %pM (%3i)",
 456                                            neigh_node_tmp->addr,
 457                                            neigh_node_tmp->tq_avg);
 458                         }
 459
 460                         seq_printf(seq, "\n");
 461                         batman_count++;
 462
 463 next:
 464                         neigh_node_free_ref(neigh_node);
 465                 }
 466                 rcu_read_unlock();
 467         }
 468
 469         if (batman_count == 0)
 470                 seq_printf(seq, "No batman nodes in range ...\n");
 471
 472 out:
 473         if (primary_if)
 474                 hardif_free_ref(primary_if);
 475         return ret;
 476 }
 477
 478 static int orig_node_add_if(struct orig_node *orig_node, int max_if_num)
 479 {
 480         void *data_ptr;
 481
 482         data_ptr = kmalloc(max_if_num * sizeof(unsigned long) * NUM_WORDS,
 483                            GFP_ATOMIC);
 484         if (!data_ptr) {
 485                 pr_err("Can't resize orig: out of memory\n");
 486                 return -1;
 487         }
 488
 489         memcpy(data_ptr, orig_node->bcast_own,
 490                (max_if_num - 1) * sizeof(unsigned long) * NUM_WORDS);
 491         kfree(orig_node->bcast_own);
 492         orig_node->bcast_own = data_ptr;
 493
 494         data_ptr = kmalloc(max_if_num * sizeof(uint8_t), GFP_ATOMIC);
 495         if (!data_ptr) {
 496                 pr_err("Can't resize orig: out of memory\n");
 497                 return -1;
 498         }
 499
 500         memcpy(data_ptr, orig_node->bcast_own_sum,
 501                (max_if_num - 1) * sizeof(uint8_t));
 502         kfree(orig_node->bcast_own_sum);
 503         orig_node->bcast_own_sum = data_ptr;
 504
 505         return 0;
 506 }
 507
 508 int orig_hash_add_if(struct hard_iface *hard_iface, int max_if_num)
 509 {
 510         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 511         struct hashtable_t *hash = bat_priv->orig_hash;
 512         struct hlist_node *node;
 513         struct hlist_head *head;
 514         struct orig_node *orig_node;
 515         int i, ret;
 516
 517         /* resize all orig nodes because orig_node->bcast_own(_sum) depend on
 518          * if_num */
 519         for (i = 0; i < hash->size; i++) {
 520                 head = &hash->table[i];
 521
 522                 rcu_read_lock();
 523                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 524                         spin_lock_bh(&orig_node->ogm_cnt_lock);
 525                         ret = orig_node_add_if(orig_node, max_if_num);
 526                         spin_unlock_bh(&orig_node->ogm_cnt_lock);
 527
 528                         if (ret == -1)
 529                                 goto err;
 530                 }
 531                 rcu_read_unlock();
 532         }
 533
 534         return 0;
 535
 536 err:
 537         rcu_read_unlock();
 538         return -ENOMEM;
 539 }
 540
 541 static int orig_node_del_if(struct orig_node *orig_node,
 542                      int max_if_num, int del_if_num)
 543 {
 544         void *data_ptr = NULL;
 545         int chunk_size;
 546
 547         /* last interface was removed */
 548         if (max_if_num == 0)
 549                 goto free_bcast_own;
 550
 551         chunk_size = sizeof(unsigned long) * NUM_WORDS;
 552         data_ptr = kmalloc(max_if_num * chunk_size, GFP_ATOMIC);
 553         if (!data_ptr) {
 554                 pr_err("Can't resize orig: out of memory\n");
 555                 return -1;
 556         }
 557
 558         /* copy first part */
 559         memcpy(data_ptr, orig_node->bcast_own, del_if_num * chunk_size);
 560
 561         /* copy second part */
 562         memcpy(data_ptr + del_if_num * chunk_size,
 563                orig_node->bcast_own + ((del_if_num + 1) * chunk_size),
 564                (max_if_num - del_if_num) * chunk_size);
 565
 566 free_bcast_own:
 567         kfree(orig_node->bcast_own);
 568         orig_node->bcast_own = data_ptr;
 569
 570         if (max_if_num == 0)
 571                 goto free_own_sum;
 572
 573         data_ptr = kmalloc(max_if_num * sizeof(uint8_t), GFP_ATOMIC);
 574         if (!data_ptr) {
 575                 pr_err("Can't resize orig: out of memory\n");
 576                 return -1;
 577         }
 578
 579         memcpy(data_ptr, orig_node->bcast_own_sum,
 580                del_if_num * sizeof(uint8_t));
 581
 582         memcpy(data_ptr + del_if_num * sizeof(uint8_t),
 583                orig_node->bcast_own_sum + ((del_if_num + 1) * sizeof(uint8_t)),
 584                (max_if_num - del_if_num) * sizeof(uint8_t));
 585
 586 free_own_sum:
 587         kfree(orig_node->bcast_own_sum);
 588         orig_node->bcast_own_sum = data_ptr;
 589
 590         return 0;
 591 }
 592
 593 int orig_hash_del_if(struct hard_iface *hard_iface, int max_if_num)
 594 {
 595         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 596         struct hashtable_t *hash = bat_priv->orig_hash;
 597         struct hlist_node *node;
 598         struct hlist_head *head;
 599         struct hard_iface *hard_iface_tmp;
 600         struct orig_node *orig_node;
 601         int i, 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 }