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 /* returns 1 if they are the same originator */
  41 static int compare_orig(const struct hlist_node *node, const void *data2)
  42 {
  43         const void *data1 = container_of(node, struct orig_node, hash_entry);
  44
  45         return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
  46 }
  47
  48 int originator_init(struct bat_priv *bat_priv)
  49 {
  50         if (bat_priv->orig_hash)
  51                 return 1;
  52
  53         bat_priv->orig_hash = hash_new(1024);
  54
  55         if (!bat_priv->orig_hash)
  56                 goto err;
  57
  58         start_purge_timer(bat_priv);
  59         return 1;
  60
  61 err:
  62         return 0;
  63 }
  64
  65 void neigh_node_free_ref(struct neigh_node *neigh_node)
  66 {
  67         if (atomic_dec_and_test(&neigh_node->refcount))
  68                 kfree_rcu(neigh_node, rcu);
  69 }
  70
  71 /* increases the refcounter of a found router */
  72 struct neigh_node *orig_node_get_router(struct orig_node *orig_node)
  73 {
  74         struct neigh_node *router;
  75
  76         rcu_read_lock();
  77         router = rcu_dereference(orig_node->router);
  78
  79         if (router && !atomic_inc_not_zero(&router->refcount))
  80                 router = NULL;
  81
  82         rcu_read_unlock();
  83         return router;
  84 }
  85
  86 struct neigh_node *create_neighbor(struct orig_node *orig_node,
  87                                    struct orig_node *orig_neigh_node,
  88                                    const uint8_t *neigh,
  89                                    struct hard_iface *if_incoming)
  90 {
  91         struct bat_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
  92         struct neigh_node *neigh_node;
  93
  94         bat_dbg(DBG_BATMAN, bat_priv,
  95                 "Creating new last-hop neighbor of originator\n");
  96
  97         neigh_node = kzalloc(sizeof(*neigh_node), GFP_ATOMIC);
  98         if (!neigh_node)
  99                 return NULL;
 100
 101         INIT_HLIST_NODE(&neigh_node->list);
 102         INIT_LIST_HEAD(&neigh_node->bonding_list);
 103         spin_lock_init(&neigh_node->tq_lock);
 104
 105         memcpy(neigh_node->addr, neigh, ETH_ALEN);
 106         neigh_node->orig_node = orig_neigh_node;
 107         neigh_node->if_incoming = if_incoming;
 108
 109         /* extra reference for return */
 110         atomic_set(&neigh_node->refcount, 2);
 111
 112         spin_lock_bh(&orig_node->neigh_list_lock);
 113         hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
 114         spin_unlock_bh(&orig_node->neigh_list_lock);
 115         return neigh_node;
 116 }
 117
 118 static void orig_node_free_rcu(struct rcu_head *rcu)
 119 {
 120         struct hlist_node *node, *node_tmp;
 121         struct neigh_node *neigh_node, *tmp_neigh_node;
 122         struct orig_node *orig_node;
 123
 124         orig_node = container_of(rcu, struct orig_node, rcu);
 125
 126         spin_lock_bh(&orig_node->neigh_list_lock);
 127
 128         /* for all bonding members ... */
 129         list_for_each_entry_safe(neigh_node, tmp_neigh_node,
 130                                  &orig_node->bond_list, bonding_list) {
 131                 list_del_rcu(&neigh_node->bonding_list);
 132                 neigh_node_free_ref(neigh_node);
 133         }
 134
 135         /* for all neighbors towards this originator ... */
 136         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 137                                   &orig_node->neigh_list, list) {
 138                 hlist_del_rcu(&neigh_node->list);
 139                 neigh_node_free_ref(neigh_node);
 140         }
 141
 142         spin_unlock_bh(&orig_node->neigh_list_lock);
 143
 144         frag_list_free(&orig_node->frag_list);
 145         tt_global_del_orig(orig_node->bat_priv, orig_node,
 146                             "originator timed out");
 147
 148         kfree(orig_node->bcast_own);
 149         kfree(orig_node->bcast_own_sum);
 150         kfree(orig_node);
 151 }
 152
 153 void orig_node_free_ref(struct orig_node *orig_node)
 154 {
 155         if (atomic_dec_and_test(&orig_node->refcount))
 156                 call_rcu(&orig_node->rcu, orig_node_free_rcu);
 157 }
 158
 159 void originator_free(struct bat_priv *bat_priv)
 160 {
 161         struct hashtable_t *hash = bat_priv->orig_hash;
 162         struct hlist_node *node, *node_tmp;
 163         struct hlist_head *head;
 164         spinlock_t *list_lock; /* spinlock to protect write access */
 165         struct orig_node *orig_node;
 166         int i;
 167
 168         if (!hash)
 169                 return;
 170
 171         cancel_delayed_work_sync(&bat_priv->orig_work);
 172
 173         bat_priv->orig_hash = NULL;
 174
 175         for (i = 0; i < hash->size; i++) {
 176                 head = &hash->table[i];
 177                 list_lock = &hash->list_locks[i];
 178
 179                 spin_lock_bh(list_lock);
 180                 hlist_for_each_entry_safe(orig_node, node, node_tmp,
 181                                           head, hash_entry) {
 182
 183                         hlist_del_rcu(node);
 184                         orig_node_free_ref(orig_node);
 185                 }
 186                 spin_unlock_bh(list_lock);
 187         }
 188
 189         hash_destroy(hash);
 190 }
 191
 192 /* this function finds or creates an originator entry for the given
 193  * address if it does not exits */
 194 struct orig_node *get_orig_node(struct bat_priv *bat_priv, const uint8_t *addr)
 195 {
 196         struct orig_node *orig_node;
 197         int size;
 198         int hash_added;
 199
 200         orig_node = orig_hash_find(bat_priv, addr);
 201         if (orig_node)
 202                 return orig_node;
 203
 204         bat_dbg(DBG_BATMAN, bat_priv,
 205                 "Creating new originator: %pM\n", addr);
 206
 207         orig_node = kzalloc(sizeof(*orig_node), GFP_ATOMIC);
 208         if (!orig_node)
 209                 return NULL;
 210
 211         INIT_HLIST_HEAD(&orig_node->neigh_list);
 212         INIT_LIST_HEAD(&orig_node->bond_list);
 213         spin_lock_init(&orig_node->ogm_cnt_lock);
 214         spin_lock_init(&orig_node->bcast_seqno_lock);
 215         spin_lock_init(&orig_node->neigh_list_lock);
 216
 217         /* extra reference for return */
 218         atomic_set(&orig_node->refcount, 2);
 219
 220         orig_node->bat_priv = bat_priv;
 221         memcpy(orig_node->orig, addr, ETH_ALEN);
 222         orig_node->router = NULL;
 223         orig_node->tt_buff = NULL;
 224         orig_node->bcast_seqno_reset = jiffies - 1
 225                                         - msecs_to_jiffies(RESET_PROTECTION_MS);
 226         orig_node->batman_seqno_reset = jiffies - 1
 227                                         - msecs_to_jiffies(RESET_PROTECTION_MS);
 228
 229         atomic_set(&orig_node->bond_candidates, 0);
 230
 231         size = bat_priv->num_ifaces * sizeof(unsigned long) * NUM_WORDS;
 232
 233         orig_node->bcast_own = kzalloc(size, GFP_ATOMIC);
 234         if (!orig_node->bcast_own)
 235                 goto free_orig_node;
 236
 237         size = bat_priv->num_ifaces * sizeof(uint8_t);
 238         orig_node->bcast_own_sum = kzalloc(size, GFP_ATOMIC);
 239
 240         INIT_LIST_HEAD(&orig_node->frag_list);
 241         orig_node->last_frag_packet = 0;
 242
 243         if (!orig_node->bcast_own_sum)
 244                 goto free_bcast_own;
 245
 246         hash_added = hash_add(bat_priv->orig_hash, compare_orig,
 247                               choose_orig, orig_node, &orig_node->hash_entry);
 248         if (hash_added < 0)
 249                 goto free_bcast_own_sum;
 250
 251         return orig_node;
 252 free_bcast_own_sum:
 253         kfree(orig_node->bcast_own_sum);
 254 free_bcast_own:
 255         kfree(orig_node->bcast_own);
 256 free_orig_node:
 257         kfree(orig_node);
 258         return NULL;
 259 }
 260
 261 static bool purge_orig_neighbors(struct bat_priv *bat_priv,
 262                                  struct orig_node *orig_node,
 263                                  struct neigh_node **best_neigh_node)
 264 {
 265         struct hlist_node *node, *node_tmp;
 266         struct neigh_node *neigh_node;
 267         bool neigh_purged = false;
 268
 269         *best_neigh_node = NULL;
 270
 271         spin_lock_bh(&orig_node->neigh_list_lock);
 272
 273         /* for all neighbors towards this originator ... */
 274         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 275                                   &orig_node->neigh_list, list) {
 276
 277                 if ((time_after(jiffies,
 278                         neigh_node->last_valid + PURGE_TIMEOUT * HZ)) ||
 279                     (neigh_node->if_incoming->if_status == IF_INACTIVE) ||
 280                     (neigh_node->if_incoming->if_status == IF_NOT_IN_USE) ||
 281                     (neigh_node->if_incoming->if_status == IF_TO_BE_REMOVED)) {
 282
 283                         if ((neigh_node->if_incoming->if_status ==
 284                                                                 IF_INACTIVE) ||
 285                             (neigh_node->if_incoming->if_status ==
 286                                                         IF_NOT_IN_USE) ||
 287                             (neigh_node->if_incoming->if_status ==
 288                                                         IF_TO_BE_REMOVED))
 289                                 bat_dbg(DBG_BATMAN, bat_priv,
 290                                         "neighbor purge: originator %pM, "
 291                                         "neighbor: %pM, iface: %s\n",
 292                                         orig_node->orig, neigh_node->addr,
 293                                         neigh_node->if_incoming->net_dev->name);
 294                         else
 295                                 bat_dbg(DBG_BATMAN, bat_priv,
 296                                         "neighbor timeout: originator %pM, "
 297                                         "neighbor: %pM, last_valid: %lu\n",
 298                                         orig_node->orig, neigh_node->addr,
 299                                         (neigh_node->last_valid / HZ));
 300
 301                         neigh_purged = true;
 302
 303                         hlist_del_rcu(&neigh_node->list);
 304                         bonding_candidate_del(orig_node, neigh_node);
 305                         neigh_node_free_ref(neigh_node);
 306                 } else {
 307                         if ((!*best_neigh_node) ||
 308                             (neigh_node->tq_avg > (*best_neigh_node)->tq_avg))
 309                                 *best_neigh_node = neigh_node;
 310                 }
 311         }
 312
 313         spin_unlock_bh(&orig_node->neigh_list_lock);
 314         return neigh_purged;
 315 }
 316
 317 static bool purge_orig_node(struct bat_priv *bat_priv,
 318                             struct orig_node *orig_node)
 319 {
 320         struct neigh_node *best_neigh_node;
 321
 322         if (time_after(jiffies,
 323                 orig_node->last_valid + 2 * PURGE_TIMEOUT * HZ)) {
 324
 325                 bat_dbg(DBG_BATMAN, bat_priv,
 326                         "Originator timeout: originator %pM, last_valid %lu\n",
 327                         orig_node->orig, (orig_node->last_valid / HZ));
 328                 return true;
 329         } else {
 330                 if (purge_orig_neighbors(bat_priv, orig_node,
 331                                                         &best_neigh_node)) {
 332                         update_routes(bat_priv, orig_node,
 333                                       best_neigh_node,
 334                                       orig_node->tt_buff,
 335                                       orig_node->tt_buff_len);
 336                 }
 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         int 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 (time_after(jiffies, orig_node->last_frag_packet +
 371                                                 msecs_to_jiffies(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         softif_neigh_purge(bat_priv);
 381 }
 382
 383 static void purge_orig(struct work_struct *work)
 384 {
 385         struct delayed_work *delayed_work =
 386                 container_of(work, struct delayed_work, work);
 387         struct bat_priv *bat_priv =
 388                 container_of(delayed_work, struct bat_priv, orig_work);
 389
 390         _purge_orig(bat_priv);
 391         start_purge_timer(bat_priv);
 392 }
 393
 394 void purge_orig_ref(struct bat_priv *bat_priv)
 395 {
 396         _purge_orig(bat_priv);
 397 }
 398
 399 int orig_seq_print_text(struct seq_file *seq, void *offset)
 400 {
 401         struct net_device *net_dev = (struct net_device *)seq->private;
 402         struct bat_priv *bat_priv = netdev_priv(net_dev);
 403         struct hashtable_t *hash = bat_priv->orig_hash;
 404         struct hlist_node *node, *node_tmp;
 405         struct hlist_head *head;
 406         struct hard_iface *primary_if;
 407         struct orig_node *orig_node;
 408         struct neigh_node *neigh_node, *neigh_node_tmp;
 409         int batman_count = 0;
 410         int last_seen_secs;
 411         int last_seen_msecs;
 412         int i, ret = 0;
 413
 414         primary_if = primary_if_get_selected(bat_priv);
 415
 416         if (!primary_if) {
 417                 ret = seq_printf(seq, "BATMAN mesh %s disabled - "
 418                                  "please specify interfaces to enable it\n",
 419                                  net_dev->name);
 420                 goto out;
 421         }
 422
 423         if (primary_if->if_status != IF_ACTIVE) {
 424                 ret = seq_printf(seq, "BATMAN mesh %s "
 425                                  "disabled - primary interface not active\n",
 426                                  net_dev->name);
 427                 goto out;
 428         }
 429
 430         seq_printf(seq, "[B.A.T.M.A.N. adv %s%s, MainIF/MAC: %s/%pM (%s)]\n",
 431                    SOURCE_VERSION, REVISION_VERSION_STR,
 432                    primary_if->net_dev->name,
 433                    primary_if->net_dev->dev_addr, net_dev->name);
 434         seq_printf(seq, "  %-15s %s (%s/%i) %17s [%10s]: %20s ...\n",
 435                    "Originator", "last-seen", "#", TQ_MAX_VALUE, "Nexthop",
 436                    "outgoingIF", "Potential nexthops");
 437
 438         for (i = 0; i < hash->size; i++) {
 439                 head = &hash->table[i];
 440
 441                 rcu_read_lock();
 442                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 443                         neigh_node = orig_node_get_router(orig_node);
 444                         if (!neigh_node)
 445                                 continue;
 446
 447                         if (neigh_node->tq_avg == 0)
 448                                 goto next;
 449
 450                         last_seen_secs = jiffies_to_msecs(jiffies -
 451                                                 orig_node->last_valid) / 1000;
 452                         last_seen_msecs = jiffies_to_msecs(jiffies -
 453                                                 orig_node->last_valid) % 1000;
 454
 455                         seq_printf(seq, "%pM %4i.%03is   (%3i) %pM [%10s]:",
 456                                    orig_node->orig, last_seen_secs,
 457                                    last_seen_msecs, neigh_node->tq_avg,
 458                                    neigh_node->addr,
 459                                    neigh_node->if_incoming->net_dev->name);
 460
 461                         hlist_for_each_entry_rcu(neigh_node_tmp, node_tmp,
 462                                                  &orig_node->neigh_list, list) {
 463                                 seq_printf(seq, " %pM (%3i)",
 464                                            neigh_node_tmp->addr,
 465                                            neigh_node_tmp->tq_avg);
 466                         }
 467
 468                         seq_printf(seq, "\n");
 469                         batman_count++;
 470
 471 next:
 472                         neigh_node_free_ref(neigh_node);
 473                 }
 474                 rcu_read_unlock();
 475         }
 476
 477         if (batman_count == 0)
 478                 seq_printf(seq, "No batman nodes in range ...\n");
 479
 480 out:
 481         if (primary_if)
 482                 hardif_free_ref(primary_if);
 483         return ret;
 484 }
 485
 486 static int orig_node_add_if(struct orig_node *orig_node, int max_if_num)
 487 {
 488         void *data_ptr;
 489
 490         data_ptr = kmalloc(max_if_num * sizeof(unsigned long) * NUM_WORDS,
 491                            GFP_ATOMIC);
 492         if (!data_ptr) {
 493                 pr_err("Can't resize orig: out of memory\n");
 494                 return -1;
 495         }
 496
 497         memcpy(data_ptr, orig_node->bcast_own,
 498                (max_if_num - 1) * sizeof(unsigned long) * NUM_WORDS);
 499         kfree(orig_node->bcast_own);
 500         orig_node->bcast_own = data_ptr;
 501
 502         data_ptr = kmalloc(max_if_num * sizeof(uint8_t), GFP_ATOMIC);
 503         if (!data_ptr) {
 504                 pr_err("Can't resize orig: out of memory\n");
 505                 return -1;
 506         }
 507
 508         memcpy(data_ptr, orig_node->bcast_own_sum,
 509                (max_if_num - 1) * sizeof(uint8_t));
 510         kfree(orig_node->bcast_own_sum);
 511         orig_node->bcast_own_sum = data_ptr;
 512
 513         return 0;
 514 }
 515
 516 int orig_hash_add_if(struct hard_iface *hard_iface, int max_if_num)
 517 {
 518         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 519         struct hashtable_t *hash = bat_priv->orig_hash;
 520         struct hlist_node *node;
 521         struct hlist_head *head;
 522         struct orig_node *orig_node;
 523         int i, ret;
 524
 525         /* resize all orig nodes because orig_node->bcast_own(_sum) depend on
 526          * if_num */
 527         for (i = 0; i < hash->size; i++) {
 528                 head = &hash->table[i];
 529
 530                 rcu_read_lock();
 531                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 532                         spin_lock_bh(&orig_node->ogm_cnt_lock);
 533                         ret = orig_node_add_if(orig_node, max_if_num);
 534                         spin_unlock_bh(&orig_node->ogm_cnt_lock);
 535
 536                         if (ret == -1)
 537                                 goto err;
 538                 }
 539                 rcu_read_unlock();
 540         }
 541
 542         return 0;
 543
 544 err:
 545         rcu_read_unlock();
 546         return -ENOMEM;
 547 }
 548
 549 static int orig_node_del_if(struct orig_node *orig_node,
 550                      int max_if_num, int del_if_num)
 551 {
 552         void *data_ptr = NULL;
 553         int chunk_size;
 554
 555         /* last interface was removed */
 556         if (max_if_num == 0)
 557                 goto free_bcast_own;
 558
 559         chunk_size = sizeof(unsigned long) * NUM_WORDS;
 560         data_ptr = kmalloc(max_if_num * chunk_size, GFP_ATOMIC);
 561         if (!data_ptr) {
 562                 pr_err("Can't resize orig: out of memory\n");
 563                 return -1;
 564         }
 565
 566         /* copy first part */
 567         memcpy(data_ptr, orig_node->bcast_own, del_if_num * chunk_size);
 568
 569         /* copy second part */
 570         memcpy((char *)data_ptr + del_if_num * chunk_size,
 571                orig_node->bcast_own + ((del_if_num + 1) * chunk_size),
 572                (max_if_num - del_if_num) * chunk_size);
 573
 574 free_bcast_own:
 575         kfree(orig_node->bcast_own);
 576         orig_node->bcast_own = data_ptr;
 577
 578         if (max_if_num == 0)
 579                 goto free_own_sum;
 580
 581         data_ptr = kmalloc(max_if_num * sizeof(uint8_t), GFP_ATOMIC);
 582         if (!data_ptr) {
 583                 pr_err("Can't resize orig: out of memory\n");
 584                 return -1;
 585         }
 586
 587         memcpy(data_ptr, orig_node->bcast_own_sum,
 588                del_if_num * sizeof(uint8_t));
 589
 590         memcpy((char *)data_ptr + del_if_num * sizeof(uint8_t),
 591                orig_node->bcast_own_sum + ((del_if_num + 1) * sizeof(uint8_t)),
 592                (max_if_num - del_if_num) * sizeof(uint8_t));
 593
 594 free_own_sum:
 595         kfree(orig_node->bcast_own_sum);
 596         orig_node->bcast_own_sum = data_ptr;
 597
 598         return 0;
 599 }
 600
 601 int orig_hash_del_if(struct hard_iface *hard_iface, int max_if_num)
 602 {
 603         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 604         struct hashtable_t *hash = bat_priv->orig_hash;
 605         struct hlist_node *node;
 606         struct hlist_head *head;
 607         struct hard_iface *hard_iface_tmp;
 608         struct orig_node *orig_node;
 609         int i, ret;
 610
 611         /* resize all orig nodes because orig_node->bcast_own(_sum) depend on
 612          * if_num */
 613         for (i = 0; i < hash->size; i++) {
 614                 head = &hash->table[i];
 615
 616                 rcu_read_lock();
 617                 hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
 618                         spin_lock_bh(&orig_node->ogm_cnt_lock);
 619                         ret = orig_node_del_if(orig_node, max_if_num,
 620                                         hard_iface->if_num);
 621                         spin_unlock_bh(&orig_node->ogm_cnt_lock);
 622
 623                         if (ret == -1)
 624                                 goto err;
 625                 }
 626                 rcu_read_unlock();
 627         }
 628
 629         /* renumber remaining batman interfaces _inside_ of orig_hash_lock */
 630         rcu_read_lock();
 631         list_for_each_entry_rcu(hard_iface_tmp, &hardif_list, list) {
 632                 if (hard_iface_tmp->if_status == IF_NOT_IN_USE)
 633                         continue;
 634
 635                 if (hard_iface == hard_iface_tmp)
 636                         continue;
 637
 638                 if (hard_iface->soft_iface != hard_iface_tmp->soft_iface)
 639                         continue;
 640
 641                 if (hard_iface_tmp->if_num > hard_iface->if_num)
 642                         hard_iface_tmp->if_num--;
 643         }
 644         rcu_read_unlock();
 645
 646         hard_iface->if_num = -1;
 647         return 0;
 648
 649 err:
 650         rcu_read_unlock();
 651         return -ENOMEM;
 652 }