net/batman-adv/hard-interface.c

   1 /*
   2  * Copyright (C) 2007-2011 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 "hard-interface.h"
  24 #include "soft-interface.h"
  25 #include "send.h"
  26 #include "translation-table.h"
  27 #include "routing.h"
  28 #include "bat_sysfs.h"
  29 #include "originator.h"
  30 #include "hash.h"
  31 #include "bat_ogm.h"
  32
  33 #include <linux/if_arp.h>
  34
  35
  36 static int batman_skb_recv(struct sk_buff *skb,
  37                            struct net_device *dev,
  38                            struct packet_type *ptype,
  39                            struct net_device *orig_dev);
  40
  41 void hardif_free_rcu(struct rcu_head *rcu)
  42 {
  43         struct hard_iface *hard_iface;
  44
  45         hard_iface = container_of(rcu, struct hard_iface, rcu);
  46         dev_put(hard_iface->net_dev);
  47         kfree(hard_iface);
  48 }
  49
  50 struct hard_iface *hardif_get_by_netdev(const struct net_device *net_dev)
  51 {
  52         struct hard_iface *hard_iface;
  53
  54         rcu_read_lock();
  55         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
  56                 if (hard_iface->net_dev == net_dev &&
  57                     atomic_inc_not_zero(&hard_iface->refcount))
  58                         goto out;
  59         }
  60
  61         hard_iface = NULL;
  62
  63 out:
  64         rcu_read_unlock();
  65         return hard_iface;
  66 }
  67
  68 static int is_valid_iface(const struct net_device *net_dev)
  69 {
  70         if (net_dev->flags & IFF_LOOPBACK)
  71                 return 0;
  72
  73         if (net_dev->type != ARPHRD_ETHER)
  74                 return 0;
  75
  76         if (net_dev->addr_len != ETH_ALEN)
  77                 return 0;
  78
  79         /* no batman over batman */
  80         if (softif_is_valid(net_dev))
  81                 return 0;
  82
  83         /* Device is being bridged */
  84         /* if (net_dev->priv_flags & IFF_BRIDGE_PORT)
  85                 return 0; */
  86
  87         return 1;
  88 }
  89
  90 static struct hard_iface *hardif_get_active(const struct net_device *soft_iface)
  91 {
  92         struct hard_iface *hard_iface;
  93
  94         rcu_read_lock();
  95         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
  96                 if (hard_iface->soft_iface != soft_iface)
  97                         continue;
  98
  99                 if (hard_iface->if_status == IF_ACTIVE &&
 100                     atomic_inc_not_zero(&hard_iface->refcount))
 101                         goto out;
 102         }
 103
 104         hard_iface = NULL;
 105
 106 out:
 107         rcu_read_unlock();
 108         return hard_iface;
 109 }
 110
 111 static void primary_if_update_addr(struct bat_priv *bat_priv)
 112 {
 113         struct vis_packet *vis_packet;
 114         struct hard_iface *primary_if;
 115
 116         primary_if = primary_if_get_selected(bat_priv);
 117         if (!primary_if)
 118                 goto out;
 119
 120         vis_packet = (struct vis_packet *)
 121                                 bat_priv->my_vis_info->skb_packet->data;
 122         memcpy(vis_packet->vis_orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 123         memcpy(vis_packet->sender_orig,
 124                primary_if->net_dev->dev_addr, ETH_ALEN);
 125
 126 out:
 127         if (primary_if)
 128                 hardif_free_ref(primary_if);
 129 }
 130
 131 static void primary_if_select(struct bat_priv *bat_priv,
 132                               struct hard_iface *new_hard_iface)
 133 {
 134         struct hard_iface *curr_hard_iface;
 135
 136         ASSERT_RTNL();
 137
 138         if (new_hard_iface && !atomic_inc_not_zero(&new_hard_iface->refcount))
 139                 new_hard_iface = NULL;
 140
 141         curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1);
 142         rcu_assign_pointer(bat_priv->primary_if, new_hard_iface);
 143
 144         if (curr_hard_iface)
 145                 hardif_free_ref(curr_hard_iface);
 146
 147         if (!new_hard_iface)
 148                 return;
 149
 150         bat_ogm_init_primary(new_hard_iface);
 151         primary_if_update_addr(bat_priv);
 152 }
 153
 154 static bool hardif_is_iface_up(const struct hard_iface *hard_iface)
 155 {
 156         if (hard_iface->net_dev->flags & IFF_UP)
 157                 return true;
 158
 159         return false;
 160 }
 161
 162 static void check_known_mac_addr(const struct net_device *net_dev)
 163 {
 164         const struct hard_iface *hard_iface;
 165
 166         rcu_read_lock();
 167         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
 168                 if ((hard_iface->if_status != IF_ACTIVE) &&
 169                     (hard_iface->if_status != IF_TO_BE_ACTIVATED))
 170                         continue;
 171
 172                 if (hard_iface->net_dev == net_dev)
 173                         continue;
 174
 175                 if (!compare_eth(hard_iface->net_dev->dev_addr,
 176                                  net_dev->dev_addr))
 177                         continue;
 178
 179                 pr_warning("The newly added mac address (%pM) already exists "
 180                            "on: %s\n", net_dev->dev_addr,
 181                            hard_iface->net_dev->name);
 182                 pr_warning("It is strongly recommended to keep mac addresses "
 183                            "unique to avoid problems!\n");
 184         }
 185         rcu_read_unlock();
 186 }
 187
 188 int hardif_min_mtu(struct net_device *soft_iface)
 189 {
 190         const struct bat_priv *bat_priv = netdev_priv(soft_iface);
 191         const struct hard_iface *hard_iface;
 192         /* allow big frames if all devices are capable to do so
 193          * (have MTU > 1500 + BAT_HEADER_LEN) */
 194         int min_mtu = ETH_DATA_LEN;
 195
 196         if (atomic_read(&bat_priv->fragmentation))
 197                 goto out;
 198
 199         rcu_read_lock();
 200         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
 201                 if ((hard_iface->if_status != IF_ACTIVE) &&
 202                     (hard_iface->if_status != IF_TO_BE_ACTIVATED))
 203                         continue;
 204
 205                 if (hard_iface->soft_iface != soft_iface)
 206                         continue;
 207
 208                 min_mtu = min_t(int, hard_iface->net_dev->mtu - BAT_HEADER_LEN,
 209                                 min_mtu);
 210         }
 211         rcu_read_unlock();
 212 out:
 213         return min_mtu;
 214 }
 215
 216 /* adjusts the MTU if a new interface with a smaller MTU appeared. */
 217 void update_min_mtu(struct net_device *soft_iface)
 218 {
 219         int min_mtu;
 220
 221         min_mtu = hardif_min_mtu(soft_iface);
 222         if (soft_iface->mtu != min_mtu)
 223                 soft_iface->mtu = min_mtu;
 224 }
 225
 226 static void hardif_activate_interface(struct hard_iface *hard_iface)
 227 {
 228         struct bat_priv *bat_priv;
 229         struct hard_iface *primary_if = NULL;
 230
 231         if (hard_iface->if_status != IF_INACTIVE)
 232                 goto out;
 233
 234         bat_priv = netdev_priv(hard_iface->soft_iface);
 235
 236         bat_ogm_update_mac(hard_iface);
 237         hard_iface->if_status = IF_TO_BE_ACTIVATED;
 238
 239         /**
 240          * the first active interface becomes our primary interface or
 241          * the next active interface after the old primary interface was removed
 242          */
 243         primary_if = primary_if_get_selected(bat_priv);
 244         if (!primary_if)
 245                 primary_if_select(bat_priv, hard_iface);
 246
 247         bat_info(hard_iface->soft_iface, "Interface activated: %s\n",
 248                  hard_iface->net_dev->name);
 249
 250         update_min_mtu(hard_iface->soft_iface);
 251
 252 out:
 253         if (primary_if)
 254                 hardif_free_ref(primary_if);
 255 }
 256
 257 static void hardif_deactivate_interface(struct hard_iface *hard_iface)
 258 {
 259         if ((hard_iface->if_status != IF_ACTIVE) &&
 260             (hard_iface->if_status != IF_TO_BE_ACTIVATED))
 261                 return;
 262
 263         hard_iface->if_status = IF_INACTIVE;
 264
 265         bat_info(hard_iface->soft_iface, "Interface deactivated: %s\n",
 266                  hard_iface->net_dev->name);
 267
 268         update_min_mtu(hard_iface->soft_iface);
 269 }
 270
 271 int hardif_enable_interface(struct hard_iface *hard_iface,
 272                             const char *iface_name)
 273 {
 274         struct bat_priv *bat_priv;
 275         struct net_device *soft_iface;
 276         int ret;
 277
 278         if (hard_iface->if_status != IF_NOT_IN_USE)
 279                 goto out;
 280
 281         if (!atomic_inc_not_zero(&hard_iface->refcount))
 282                 goto out;
 283
 284         soft_iface = dev_get_by_name(&init_net, iface_name);
 285
 286         if (!soft_iface) {
 287                 soft_iface = softif_create(iface_name);
 288
 289                 if (!soft_iface) {
 290                         ret = -ENOMEM;
 291                         goto err;
 292                 }
 293
 294                 /* dev_get_by_name() increases the reference counter for us */
 295                 dev_hold(soft_iface);
 296         }
 297
 298         if (!softif_is_valid(soft_iface)) {
 299                 pr_err("Can't create batman mesh interface %s: "
 300                        "already exists as regular interface\n",
 301                        soft_iface->name);
 302                 dev_put(soft_iface);
 303                 ret = -EINVAL;
 304                 goto err;
 305         }
 306
 307         hard_iface->soft_iface = soft_iface;
 308         bat_priv = netdev_priv(hard_iface->soft_iface);
 309
 310         bat_ogm_init(hard_iface);
 311
 312         if (!hard_iface->packet_buff) {
 313                 bat_err(hard_iface->soft_iface, "Can't add interface packet "
 314                         "(%s): out of memory\n", hard_iface->net_dev->name);
 315                 ret = -ENOMEM;
 316                 goto err;
 317         }
 318
 319         hard_iface->if_num = bat_priv->num_ifaces;
 320         bat_priv->num_ifaces++;
 321         hard_iface->if_status = IF_INACTIVE;
 322         orig_hash_add_if(hard_iface, bat_priv->num_ifaces);
 323
 324         hard_iface->batman_adv_ptype.type = __constant_htons(ETH_P_BATMAN);
 325         hard_iface->batman_adv_ptype.func = batman_skb_recv;
 326         hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
 327         dev_add_pack(&hard_iface->batman_adv_ptype);
 328
 329         atomic_set(&hard_iface->seqno, 1);
 330         atomic_set(&hard_iface->frag_seqno, 1);
 331         bat_info(hard_iface->soft_iface, "Adding interface: %s\n",
 332                  hard_iface->net_dev->name);
 333
 334         if (atomic_read(&bat_priv->fragmentation) && hard_iface->net_dev->mtu <
 335                 ETH_DATA_LEN + BAT_HEADER_LEN)
 336                 bat_info(hard_iface->soft_iface,
 337                         "The MTU of interface %s is too small (%i) to handle "
 338                         "the transport of batman-adv packets. Packets going "
 339                         "over this interface will be fragmented on layer2 "
 340                         "which could impact the performance. Setting the MTU "
 341                         "to %zi would solve the problem.\n",
 342                         hard_iface->net_dev->name, hard_iface->net_dev->mtu,
 343                         ETH_DATA_LEN + BAT_HEADER_LEN);
 344
 345         if (!atomic_read(&bat_priv->fragmentation) && hard_iface->net_dev->mtu <
 346                 ETH_DATA_LEN + BAT_HEADER_LEN)
 347                 bat_info(hard_iface->soft_iface,
 348                         "The MTU of interface %s is too small (%i) to handle "
 349                         "the transport of batman-adv packets. If you experience"
 350                         " problems getting traffic through try increasing the "
 351                         "MTU to %zi.\n",
 352                         hard_iface->net_dev->name, hard_iface->net_dev->mtu,
 353                         ETH_DATA_LEN + BAT_HEADER_LEN);
 354
 355         if (hardif_is_iface_up(hard_iface))
 356                 hardif_activate_interface(hard_iface);
 357         else
 358                 bat_err(hard_iface->soft_iface, "Not using interface %s "
 359                         "(retrying later): interface not active\n",
 360                         hard_iface->net_dev->name);
 361
 362         /* begin scheduling originator messages on that interface */
 363         schedule_bat_ogm(hard_iface);
 364
 365 out:
 366         return 0;
 367
 368 err:
 369         hardif_free_ref(hard_iface);
 370         return ret;
 371 }
 372
 373 void hardif_disable_interface(struct hard_iface *hard_iface)
 374 {
 375         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 376         struct hard_iface *primary_if = NULL;
 377
 378         if (hard_iface->if_status == IF_ACTIVE)
 379                 hardif_deactivate_interface(hard_iface);
 380
 381         if (hard_iface->if_status != IF_INACTIVE)
 382                 goto out;
 383
 384         bat_info(hard_iface->soft_iface, "Removing interface: %s\n",
 385                  hard_iface->net_dev->name);
 386         dev_remove_pack(&hard_iface->batman_adv_ptype);
 387
 388         bat_priv->num_ifaces--;
 389         orig_hash_del_if(hard_iface, bat_priv->num_ifaces);
 390
 391         primary_if = primary_if_get_selected(bat_priv);
 392         if (hard_iface == primary_if) {
 393                 struct hard_iface *new_if;
 394
 395                 new_if = hardif_get_active(hard_iface->soft_iface);
 396                 primary_if_select(bat_priv, new_if);
 397
 398                 if (new_if)
 399                         hardif_free_ref(new_if);
 400         }
 401
 402         kfree(hard_iface->packet_buff);
 403         hard_iface->packet_buff = NULL;
 404         hard_iface->if_status = IF_NOT_IN_USE;
 405
 406         /* delete all references to this hard_iface */
 407         purge_orig_ref(bat_priv);
 408         purge_outstanding_packets(bat_priv, hard_iface);
 409         dev_put(hard_iface->soft_iface);
 410
 411         /* nobody uses this interface anymore */
 412         if (!bat_priv->num_ifaces)
 413                 softif_destroy(hard_iface->soft_iface);
 414
 415         hard_iface->soft_iface = NULL;
 416         hardif_free_ref(hard_iface);
 417
 418 out:
 419         if (primary_if)
 420                 hardif_free_ref(primary_if);
 421 }
 422
 423 static struct hard_iface *hardif_add_interface(struct net_device *net_dev)
 424 {
 425         struct hard_iface *hard_iface;
 426         int ret;
 427
 428         ASSERT_RTNL();
 429
 430         ret = is_valid_iface(net_dev);
 431         if (ret != 1)
 432                 goto out;
 433
 434         dev_hold(net_dev);
 435
 436         hard_iface = kmalloc(sizeof(*hard_iface), GFP_ATOMIC);
 437         if (!hard_iface)
 438                 goto release_dev;
 439
 440         ret = sysfs_add_hardif(&hard_iface->hardif_obj, net_dev);
 441         if (ret)
 442                 goto free_if;
 443
 444         hard_iface->if_num = -1;
 445         hard_iface->net_dev = net_dev;
 446         hard_iface->soft_iface = NULL;
 447         hard_iface->if_status = IF_NOT_IN_USE;
 448         INIT_LIST_HEAD(&hard_iface->list);
 449         /* extra reference for return */
 450         atomic_set(&hard_iface->refcount, 2);
 451
 452         check_known_mac_addr(hard_iface->net_dev);
 453         list_add_tail_rcu(&hard_iface->list, &hardif_list);
 454
 455         return hard_iface;
 456
 457 free_if:
 458         kfree(hard_iface);
 459 release_dev:
 460         dev_put(net_dev);
 461 out:
 462         return NULL;
 463 }
 464
 465 static void hardif_remove_interface(struct hard_iface *hard_iface)
 466 {
 467         ASSERT_RTNL();
 468
 469         /* first deactivate interface */
 470         if (hard_iface->if_status != IF_NOT_IN_USE)
 471                 hardif_disable_interface(hard_iface);
 472
 473         if (hard_iface->if_status != IF_NOT_IN_USE)
 474                 return;
 475
 476         hard_iface->if_status = IF_TO_BE_REMOVED;
 477         sysfs_del_hardif(&hard_iface->hardif_obj);
 478         hardif_free_ref(hard_iface);
 479 }
 480
 481 void hardif_remove_interfaces(void)
 482 {
 483         struct hard_iface *hard_iface, *hard_iface_tmp;
 484
 485         rtnl_lock();
 486         list_for_each_entry_safe(hard_iface, hard_iface_tmp,
 487                                  &hardif_list, list) {
 488                 list_del_rcu(&hard_iface->list);
 489                 hardif_remove_interface(hard_iface);
 490         }
 491         rtnl_unlock();
 492 }
 493
 494 static int hard_if_event(struct notifier_block *this,
 495                          unsigned long event, void *ptr)
 496 {
 497         struct net_device *net_dev = ptr;
 498         struct hard_iface *hard_iface = hardif_get_by_netdev(net_dev);
 499         struct hard_iface *primary_if = NULL;
 500         struct bat_priv *bat_priv;
 501
 502         if (!hard_iface && event == NETDEV_REGISTER)
 503                 hard_iface = hardif_add_interface(net_dev);
 504
 505         if (!hard_iface)
 506                 goto out;
 507
 508         switch (event) {
 509         case NETDEV_UP:
 510                 hardif_activate_interface(hard_iface);
 511                 break;
 512         case NETDEV_GOING_DOWN:
 513         case NETDEV_DOWN:
 514                 hardif_deactivate_interface(hard_iface);
 515                 break;
 516         case NETDEV_UNREGISTER:
 517                 list_del_rcu(&hard_iface->list);
 518
 519                 hardif_remove_interface(hard_iface);
 520                 break;
 521         case NETDEV_CHANGEMTU:
 522                 if (hard_iface->soft_iface)
 523                         update_min_mtu(hard_iface->soft_iface);
 524                 break;
 525         case NETDEV_CHANGEADDR:
 526                 if (hard_iface->if_status == IF_NOT_IN_USE)
 527                         goto hardif_put;
 528
 529                 check_known_mac_addr(hard_iface->net_dev);
 530                 bat_ogm_update_mac(hard_iface);
 531
 532                 bat_priv = netdev_priv(hard_iface->soft_iface);
 533                 primary_if = primary_if_get_selected(bat_priv);
 534                 if (!primary_if)
 535                         goto hardif_put;
 536
 537                 if (hard_iface == primary_if)
 538                         primary_if_update_addr(bat_priv);
 539                 break;
 540         default:
 541                 break;
 542         }
 543
 544 hardif_put:
 545         hardif_free_ref(hard_iface);
 546 out:
 547         if (primary_if)
 548                 hardif_free_ref(primary_if);
 549         return NOTIFY_DONE;
 550 }
 551
 552 /* incoming packets with the batman ethertype received on any active hard
 553  * interface */
 554 static int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 555                            struct packet_type *ptype,
 556                            struct net_device *orig_dev)
 557 {
 558         struct bat_priv *bat_priv;
 559         struct batman_ogm_packet *batman_ogm_packet;
 560         struct hard_iface *hard_iface;
 561         int ret;
 562
 563         hard_iface = container_of(ptype, struct hard_iface, batman_adv_ptype);
 564         skb = skb_share_check(skb, GFP_ATOMIC);
 565
 566         /* skb was released by skb_share_check() */
 567         if (!skb)
 568                 goto err_out;
 569
 570         /* packet should hold at least type and version */
 571         if (unlikely(!pskb_may_pull(skb, 2)))
 572                 goto err_free;
 573
 574         /* expect a valid ethernet header here. */
 575         if (unlikely(skb->mac_len != sizeof(struct ethhdr)
 576                                 || !skb_mac_header(skb)))
 577                 goto err_free;
 578
 579         if (!hard_iface->soft_iface)
 580                 goto err_free;
 581
 582         bat_priv = netdev_priv(hard_iface->soft_iface);
 583
 584         if (atomic_read(&bat_priv->mesh_state) != MESH_ACTIVE)
 585                 goto err_free;
 586
 587         /* discard frames on not active interfaces */
 588         if (hard_iface->if_status != IF_ACTIVE)
 589                 goto err_free;
 590
 591         batman_ogm_packet = (struct batman_ogm_packet *)skb->data;
 592
 593         if (batman_ogm_packet->version != COMPAT_VERSION) {
 594                 bat_dbg(DBG_BATMAN, bat_priv,
 595                         "Drop packet: incompatible batman version (%i)\n",
 596                         batman_ogm_packet->version);
 597                 goto err_free;
 598         }
 599
 600         /* all receive handlers return whether they received or reused
 601          * the supplied skb. if not, we have to free the skb. */
 602
 603         switch (batman_ogm_packet->packet_type) {
 604                 /* batman originator packet */
 605         case BAT_OGM:
 606                 ret = recv_bat_ogm_packet(skb, hard_iface);
 607                 break;
 608
 609                 /* batman icmp packet */
 610         case BAT_ICMP:
 611                 ret = recv_icmp_packet(skb, hard_iface);
 612                 break;
 613
 614                 /* unicast packet */
 615         case BAT_UNICAST:
 616                 ret = recv_unicast_packet(skb, hard_iface);
 617                 break;
 618
 619                 /* fragmented unicast packet */
 620         case BAT_UNICAST_FRAG:
 621                 ret = recv_ucast_frag_packet(skb, hard_iface);
 622                 break;
 623
 624                 /* broadcast packet */
 625         case BAT_BCAST:
 626                 ret = recv_bcast_packet(skb, hard_iface);
 627                 break;
 628
 629                 /* vis packet */
 630         case BAT_VIS:
 631                 ret = recv_vis_packet(skb, hard_iface);
 632                 break;
 633                 /* Translation table query (request or response) */
 634         case BAT_TT_QUERY:
 635                 ret = recv_tt_query(skb, hard_iface);
 636                 break;
 637                 /* Roaming advertisement */
 638         case BAT_ROAM_ADV:
 639                 ret = recv_roam_adv(skb, hard_iface);
 640                 break;
 641         default:
 642                 ret = NET_RX_DROP;
 643         }
 644
 645         if (ret == NET_RX_DROP)
 646                 kfree_skb(skb);
 647
 648         /* return NET_RX_SUCCESS in any case as we
 649          * most probably dropped the packet for
 650          * routing-logical reasons. */
 651
 652         return NET_RX_SUCCESS;
 653
 654 err_free:
 655         kfree_skb(skb);
 656 err_out:
 657         return NET_RX_DROP;
 658 }
 659
 660 /* This function returns true if the interface represented by ifindex is a
 661  * 802.11 wireless device */
 662 bool is_wifi_iface(int ifindex)
 663 {
 664         struct net_device *net_device = NULL;
 665         bool ret = false;
 666
 667         if (ifindex == NULL_IFINDEX)
 668                 goto out;
 669
 670         net_device = dev_get_by_index(&init_net, ifindex);
 671         if (!net_device)
 672                 goto out;
 673
 674 #ifdef CONFIG_WIRELESS_EXT
 675         /* pre-cfg80211 drivers have to implement WEXT, so it is possible to
 676          * check for wireless_handlers != NULL */
 677         if (net_device->wireless_handlers)
 678                 ret = true;
 679         else
 680 #endif
 681                 /* cfg80211 drivers have to set ieee80211_ptr */
 682                 if (net_device->ieee80211_ptr)
 683                         ret = true;
 684 out:
 685         if (net_device)
 686                 dev_put(net_device);
 687         return ret;
 688 }
 689
 690 struct notifier_block hard_if_notifier = {
 691         .notifier_call = hard_if_event,
 692 };