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