packaging: install license for rpm package instead of license package
[profile/mobile/platform/kernel/linux-3.10-sc7730.git] / net / batman-adv / hard-interface.c
1 /* Copyright (C) 2007-2013 B.A.T.M.A.N. contributors:
2  *
3  * Marek Lindner, Simon Wunderlich
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of version 2 of the GNU General Public
7  * License as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA
18  */
19
20 #include "main.h"
21 #include "distributed-arp-table.h"
22 #include "hard-interface.h"
23 #include "soft-interface.h"
24 #include "send.h"
25 #include "translation-table.h"
26 #include "routing.h"
27 #include "sysfs.h"
28 #include "originator.h"
29 #include "hash.h"
30 #include "bridge_loop_avoidance.h"
31
32 #include <linux/if_arp.h>
33 #include <linux/if_ether.h>
34
35 void batadv_hardif_free_rcu(struct rcu_head *rcu)
36 {
37         struct batadv_hard_iface *hard_iface;
38
39         hard_iface = container_of(rcu, struct batadv_hard_iface, rcu);
40         dev_put(hard_iface->net_dev);
41         kfree(hard_iface);
42 }
43
44 struct batadv_hard_iface *
45 batadv_hardif_get_by_netdev(const struct net_device *net_dev)
46 {
47         struct batadv_hard_iface *hard_iface;
48
49         rcu_read_lock();
50         list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
51                 if (hard_iface->net_dev == net_dev &&
52                     atomic_inc_not_zero(&hard_iface->refcount))
53                         goto out;
54         }
55
56         hard_iface = NULL;
57
58 out:
59         rcu_read_unlock();
60         return hard_iface;
61 }
62
63 /**
64  * batadv_is_on_batman_iface - check if a device is a batman iface descendant
65  * @net_dev: the device to check
66  *
67  * If the user creates any virtual device on top of a batman-adv interface, it
68  * is important to prevent this new interface to be used to create a new mesh
69  * network (this behaviour would lead to a batman-over-batman configuration).
70  * This function recursively checks all the fathers of the device passed as
71  * argument looking for a batman-adv soft interface.
72  *
73  * Returns true if the device is descendant of a batman-adv mesh interface (or
74  * if it is a batman-adv interface itself), false otherwise
75  */
76 static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
77 {
78         struct net_device *parent_dev;
79         bool ret;
80
81         /* check if this is a batman-adv mesh interface */
82         if (batadv_softif_is_valid(net_dev))
83                 return true;
84
85         /* no more parents..stop recursion */
86         if (net_dev->iflink == net_dev->ifindex)
87                 return false;
88
89         /* recurse over the parent device */
90         parent_dev = dev_get_by_index(&init_net, net_dev->iflink);
91         /* if we got a NULL parent_dev there is something broken.. */
92         if (WARN(!parent_dev, "Cannot find parent device"))
93                 return false;
94
95         ret = batadv_is_on_batman_iface(parent_dev);
96
97         if (parent_dev)
98                 dev_put(parent_dev);
99         return ret;
100 }
101
102 static int batadv_is_valid_iface(const struct net_device *net_dev)
103 {
104         if (net_dev->flags & IFF_LOOPBACK)
105                 return 0;
106
107         if (net_dev->type != ARPHRD_ETHER)
108                 return 0;
109
110         if (net_dev->addr_len != ETH_ALEN)
111                 return 0;
112
113         /* no batman over batman */
114         if (batadv_is_on_batman_iface(net_dev))
115                 return 0;
116
117         return 1;
118 }
119
120 static struct batadv_hard_iface *
121 batadv_hardif_get_active(const struct net_device *soft_iface)
122 {
123         struct batadv_hard_iface *hard_iface;
124
125         rcu_read_lock();
126         list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
127                 if (hard_iface->soft_iface != soft_iface)
128                         continue;
129
130                 if (hard_iface->if_status == BATADV_IF_ACTIVE &&
131                     atomic_inc_not_zero(&hard_iface->refcount))
132                         goto out;
133         }
134
135         hard_iface = NULL;
136
137 out:
138         rcu_read_unlock();
139         return hard_iface;
140 }
141
142 static void batadv_primary_if_update_addr(struct batadv_priv *bat_priv,
143                                           struct batadv_hard_iface *oldif)
144 {
145         struct batadv_vis_packet *vis_packet;
146         struct batadv_hard_iface *primary_if;
147         struct sk_buff *skb;
148
149         primary_if = batadv_primary_if_get_selected(bat_priv);
150         if (!primary_if)
151                 goto out;
152
153         batadv_dat_init_own_addr(bat_priv, primary_if);
154
155         skb = bat_priv->vis.my_info->skb_packet;
156         vis_packet = (struct batadv_vis_packet *)skb->data;
157         memcpy(vis_packet->vis_orig, primary_if->net_dev->dev_addr, ETH_ALEN);
158         memcpy(vis_packet->sender_orig,
159                primary_if->net_dev->dev_addr, ETH_ALEN);
160
161         batadv_bla_update_orig_address(bat_priv, primary_if, oldif);
162 out:
163         if (primary_if)
164                 batadv_hardif_free_ref(primary_if);
165 }
166
167 static void batadv_primary_if_select(struct batadv_priv *bat_priv,
168                                      struct batadv_hard_iface *new_hard_iface)
169 {
170         struct batadv_hard_iface *curr_hard_iface;
171
172         ASSERT_RTNL();
173
174         if (new_hard_iface && !atomic_inc_not_zero(&new_hard_iface->refcount))
175                 new_hard_iface = NULL;
176
177         curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1);
178         rcu_assign_pointer(bat_priv->primary_if, new_hard_iface);
179
180         if (!new_hard_iface)
181                 goto out;
182
183         bat_priv->bat_algo_ops->bat_primary_iface_set(new_hard_iface);
184         batadv_primary_if_update_addr(bat_priv, curr_hard_iface);
185
186 out:
187         if (curr_hard_iface)
188                 batadv_hardif_free_ref(curr_hard_iface);
189 }
190
191 static bool
192 batadv_hardif_is_iface_up(const struct batadv_hard_iface *hard_iface)
193 {
194         if (hard_iface->net_dev->flags & IFF_UP)
195                 return true;
196
197         return false;
198 }
199
200 static void batadv_check_known_mac_addr(const struct net_device *net_dev)
201 {
202         const struct batadv_hard_iface *hard_iface;
203
204         rcu_read_lock();
205         list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
206                 if ((hard_iface->if_status != BATADV_IF_ACTIVE) &&
207                     (hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED))
208                         continue;
209
210                 if (hard_iface->net_dev == net_dev)
211                         continue;
212
213                 if (!batadv_compare_eth(hard_iface->net_dev->dev_addr,
214                                         net_dev->dev_addr))
215                         continue;
216
217                 pr_warn("The newly added mac address (%pM) already exists on: %s\n",
218                         net_dev->dev_addr, hard_iface->net_dev->name);
219                 pr_warn("It is strongly recommended to keep mac addresses unique to avoid problems!\n");
220         }
221         rcu_read_unlock();
222 }
223
224 int batadv_hardif_min_mtu(struct net_device *soft_iface)
225 {
226         const struct batadv_priv *bat_priv = netdev_priv(soft_iface);
227         const struct batadv_hard_iface *hard_iface;
228         /* allow big frames if all devices are capable to do so
229          * (have MTU > 1500 + BAT_HEADER_LEN)
230          */
231         int min_mtu = ETH_DATA_LEN;
232
233         if (atomic_read(&bat_priv->fragmentation))
234                 goto out;
235
236         rcu_read_lock();
237         list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
238                 if ((hard_iface->if_status != BATADV_IF_ACTIVE) &&
239                     (hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED))
240                         continue;
241
242                 if (hard_iface->soft_iface != soft_iface)
243                         continue;
244
245                 min_mtu = min_t(int,
246                                 hard_iface->net_dev->mtu - BATADV_HEADER_LEN,
247                                 min_mtu);
248         }
249         rcu_read_unlock();
250 out:
251         return min_mtu;
252 }
253
254 /* adjusts the MTU if a new interface with a smaller MTU appeared. */
255 void batadv_update_min_mtu(struct net_device *soft_iface)
256 {
257         int min_mtu;
258
259         min_mtu = batadv_hardif_min_mtu(soft_iface);
260         if (soft_iface->mtu != min_mtu)
261                 soft_iface->mtu = min_mtu;
262 }
263
264 static void
265 batadv_hardif_activate_interface(struct batadv_hard_iface *hard_iface)
266 {
267         struct batadv_priv *bat_priv;
268         struct batadv_hard_iface *primary_if = NULL;
269
270         if (hard_iface->if_status != BATADV_IF_INACTIVE)
271                 goto out;
272
273         bat_priv = netdev_priv(hard_iface->soft_iface);
274
275         bat_priv->bat_algo_ops->bat_iface_update_mac(hard_iface);
276         hard_iface->if_status = BATADV_IF_TO_BE_ACTIVATED;
277
278         /* the first active interface becomes our primary interface or
279          * the next active interface after the old primary interface was removed
280          */
281         primary_if = batadv_primary_if_get_selected(bat_priv);
282         if (!primary_if)
283                 batadv_primary_if_select(bat_priv, hard_iface);
284
285         batadv_info(hard_iface->soft_iface, "Interface activated: %s\n",
286                     hard_iface->net_dev->name);
287
288         batadv_update_min_mtu(hard_iface->soft_iface);
289
290 out:
291         if (primary_if)
292                 batadv_hardif_free_ref(primary_if);
293 }
294
295 static void
296 batadv_hardif_deactivate_interface(struct batadv_hard_iface *hard_iface)
297 {
298         if ((hard_iface->if_status != BATADV_IF_ACTIVE) &&
299             (hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED))
300                 return;
301
302         hard_iface->if_status = BATADV_IF_INACTIVE;
303
304         batadv_info(hard_iface->soft_iface, "Interface deactivated: %s\n",
305                     hard_iface->net_dev->name);
306
307         batadv_update_min_mtu(hard_iface->soft_iface);
308 }
309
310 /**
311  * batadv_master_del_slave - remove hard_iface from the current master interface
312  * @slave: the interface enslaved in another master
313  * @master: the master from which slave has to be removed
314  *
315  * Invoke ndo_del_slave on master passing slave as argument. In this way slave
316  * is free'd and master can correctly change its internal state.
317  * Return 0 on success, a negative value representing the error otherwise
318  */
319 static int batadv_master_del_slave(struct batadv_hard_iface *slave,
320                                    struct net_device *master)
321 {
322         int ret;
323
324         if (!master)
325                 return 0;
326
327         ret = -EBUSY;
328         if (master->netdev_ops->ndo_del_slave)
329                 ret = master->netdev_ops->ndo_del_slave(master, slave->net_dev);
330
331         return ret;
332 }
333
334 int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
335                                    const char *iface_name)
336 {
337         struct batadv_priv *bat_priv;
338         struct net_device *soft_iface, *master;
339         __be16 ethertype = __constant_htons(ETH_P_BATMAN);
340         int ret;
341
342         if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
343                 goto out;
344
345         if (!atomic_inc_not_zero(&hard_iface->refcount))
346                 goto out;
347
348         soft_iface = dev_get_by_name(&init_net, iface_name);
349
350         if (!soft_iface) {
351                 soft_iface = batadv_softif_create(iface_name);
352
353                 if (!soft_iface) {
354                         ret = -ENOMEM;
355                         goto err;
356                 }
357
358                 /* dev_get_by_name() increases the reference counter for us */
359                 dev_hold(soft_iface);
360         }
361
362         if (!batadv_softif_is_valid(soft_iface)) {
363                 pr_err("Can't create batman mesh interface %s: already exists as regular interface\n",
364                        soft_iface->name);
365                 ret = -EINVAL;
366                 goto err_dev;
367         }
368
369         /* check if the interface is enslaved in another virtual one and
370          * in that case unlink it first
371          */
372         master = netdev_master_upper_dev_get(hard_iface->net_dev);
373         ret = batadv_master_del_slave(hard_iface, master);
374         if (ret)
375                 goto err_dev;
376
377         hard_iface->soft_iface = soft_iface;
378         bat_priv = netdev_priv(hard_iface->soft_iface);
379
380         ret = netdev_master_upper_dev_link(hard_iface->net_dev, soft_iface);
381         if (ret)
382                 goto err_dev;
383
384         ret = bat_priv->bat_algo_ops->bat_iface_enable(hard_iface);
385         if (ret < 0)
386                 goto err_upper;
387
388         hard_iface->if_num = bat_priv->num_ifaces;
389         bat_priv->num_ifaces++;
390         hard_iface->if_status = BATADV_IF_INACTIVE;
391         ret = batadv_orig_hash_add_if(hard_iface, bat_priv->num_ifaces);
392         if (ret < 0) {
393                 bat_priv->bat_algo_ops->bat_iface_disable(hard_iface);
394                 bat_priv->num_ifaces--;
395                 hard_iface->if_status = BATADV_IF_NOT_IN_USE;
396                 goto err_upper;
397         }
398
399         hard_iface->batman_adv_ptype.type = ethertype;
400         hard_iface->batman_adv_ptype.func = batadv_batman_skb_recv;
401         hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
402         dev_add_pack(&hard_iface->batman_adv_ptype);
403
404         atomic_set(&hard_iface->frag_seqno, 1);
405         batadv_info(hard_iface->soft_iface, "Adding interface: %s\n",
406                     hard_iface->net_dev->name);
407
408         if (atomic_read(&bat_priv->fragmentation) &&
409             hard_iface->net_dev->mtu < ETH_DATA_LEN + BATADV_HEADER_LEN)
410                 batadv_info(hard_iface->soft_iface,
411                             "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %zi would solve the problem.\n",
412                             hard_iface->net_dev->name, hard_iface->net_dev->mtu,
413                             ETH_DATA_LEN + BATADV_HEADER_LEN);
414
415         if (!atomic_read(&bat_priv->fragmentation) &&
416             hard_iface->net_dev->mtu < ETH_DATA_LEN + BATADV_HEADER_LEN)
417                 batadv_info(hard_iface->soft_iface,
418                             "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %zi.\n",
419                             hard_iface->net_dev->name, hard_iface->net_dev->mtu,
420                             ETH_DATA_LEN + BATADV_HEADER_LEN);
421
422         if (batadv_hardif_is_iface_up(hard_iface))
423                 batadv_hardif_activate_interface(hard_iface);
424         else
425                 batadv_err(hard_iface->soft_iface,
426                            "Not using interface %s (retrying later): interface not active\n",
427                            hard_iface->net_dev->name);
428
429         /* begin scheduling originator messages on that interface */
430         batadv_schedule_bat_ogm(hard_iface);
431
432 out:
433         return 0;
434
435 err_upper:
436         netdev_upper_dev_unlink(hard_iface->net_dev, soft_iface);
437 err_dev:
438         hard_iface->soft_iface = NULL;
439         dev_put(soft_iface);
440 err:
441         batadv_hardif_free_ref(hard_iface);
442         return ret;
443 }
444
445 void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface,
446                                      enum batadv_hard_if_cleanup autodel)
447 {
448         struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
449         struct batadv_hard_iface *primary_if = NULL;
450
451         if (hard_iface->if_status == BATADV_IF_ACTIVE)
452                 batadv_hardif_deactivate_interface(hard_iface);
453
454         if (hard_iface->if_status != BATADV_IF_INACTIVE)
455                 goto out;
456
457         batadv_info(hard_iface->soft_iface, "Removing interface: %s\n",
458                     hard_iface->net_dev->name);
459         dev_remove_pack(&hard_iface->batman_adv_ptype);
460
461         bat_priv->num_ifaces--;
462         batadv_orig_hash_del_if(hard_iface, bat_priv->num_ifaces);
463
464         primary_if = batadv_primary_if_get_selected(bat_priv);
465         if (hard_iface == primary_if) {
466                 struct batadv_hard_iface *new_if;
467
468                 new_if = batadv_hardif_get_active(hard_iface->soft_iface);
469                 batadv_primary_if_select(bat_priv, new_if);
470
471                 if (new_if)
472                         batadv_hardif_free_ref(new_if);
473         }
474
475         bat_priv->bat_algo_ops->bat_iface_disable(hard_iface);
476         hard_iface->if_status = BATADV_IF_NOT_IN_USE;
477
478         /* delete all references to this hard_iface */
479         batadv_purge_orig_ref(bat_priv);
480         batadv_purge_outstanding_packets(bat_priv, hard_iface);
481         dev_put(hard_iface->soft_iface);
482
483         /* nobody uses this interface anymore */
484         if (!bat_priv->num_ifaces && autodel == BATADV_IF_CLEANUP_AUTO)
485                 batadv_softif_destroy_sysfs(hard_iface->soft_iface);
486
487         netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->soft_iface);
488         hard_iface->soft_iface = NULL;
489         batadv_hardif_free_ref(hard_iface);
490
491 out:
492         if (primary_if)
493                 batadv_hardif_free_ref(primary_if);
494 }
495
496 /**
497  * batadv_hardif_remove_interface_finish - cleans up the remains of a hardif
498  * @work: work queue item
499  *
500  * Free the parts of the hard interface which can not be removed under
501  * rtnl lock (to prevent deadlock situations).
502  */
503 static void batadv_hardif_remove_interface_finish(struct work_struct *work)
504 {
505         struct batadv_hard_iface *hard_iface;
506
507         hard_iface = container_of(work, struct batadv_hard_iface,
508                                   cleanup_work);
509
510         batadv_sysfs_del_hardif(&hard_iface->hardif_obj);
511         batadv_hardif_free_ref(hard_iface);
512 }
513
514 static struct batadv_hard_iface *
515 batadv_hardif_add_interface(struct net_device *net_dev)
516 {
517         struct batadv_hard_iface *hard_iface;
518         int ret;
519
520         ASSERT_RTNL();
521
522         ret = batadv_is_valid_iface(net_dev);
523         if (ret != 1)
524                 goto out;
525
526         dev_hold(net_dev);
527
528         hard_iface = kmalloc(sizeof(*hard_iface), GFP_ATOMIC);
529         if (!hard_iface)
530                 goto release_dev;
531
532         ret = batadv_sysfs_add_hardif(&hard_iface->hardif_obj, net_dev);
533         if (ret)
534                 goto free_if;
535
536         hard_iface->if_num = -1;
537         hard_iface->net_dev = net_dev;
538         hard_iface->soft_iface = NULL;
539         hard_iface->if_status = BATADV_IF_NOT_IN_USE;
540         INIT_LIST_HEAD(&hard_iface->list);
541         INIT_WORK(&hard_iface->cleanup_work,
542                   batadv_hardif_remove_interface_finish);
543
544         /* extra reference for return */
545         atomic_set(&hard_iface->refcount, 2);
546
547         batadv_check_known_mac_addr(hard_iface->net_dev);
548         list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
549
550         /* This can't be called via a bat_priv callback because
551          * we have no bat_priv yet.
552          */
553         atomic_set(&hard_iface->bat_iv.ogm_seqno, 1);
554         hard_iface->bat_iv.ogm_buff = NULL;
555
556         return hard_iface;
557
558 free_if:
559         kfree(hard_iface);
560 release_dev:
561         dev_put(net_dev);
562 out:
563         return NULL;
564 }
565
566 static void batadv_hardif_remove_interface(struct batadv_hard_iface *hard_iface)
567 {
568         ASSERT_RTNL();
569
570         /* first deactivate interface */
571         if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
572                 batadv_hardif_disable_interface(hard_iface,
573                                                 BATADV_IF_CLEANUP_AUTO);
574
575         if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
576                 return;
577
578         hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
579         queue_work(batadv_event_workqueue, &hard_iface->cleanup_work);
580 }
581
582 void batadv_hardif_remove_interfaces(void)
583 {
584         struct batadv_hard_iface *hard_iface, *hard_iface_tmp;
585
586         rtnl_lock();
587         list_for_each_entry_safe(hard_iface, hard_iface_tmp,
588                                  &batadv_hardif_list, list) {
589                 list_del_rcu(&hard_iface->list);
590                 batadv_hardif_remove_interface(hard_iface);
591         }
592         rtnl_unlock();
593 }
594
595 static int batadv_hard_if_event(struct notifier_block *this,
596                                 unsigned long event, void *ptr)
597 {
598         struct net_device *net_dev = ptr;
599         struct batadv_hard_iface *hard_iface;
600         struct batadv_hard_iface *primary_if = NULL;
601         struct batadv_priv *bat_priv;
602
603         if (batadv_softif_is_valid(net_dev) && event == NETDEV_REGISTER) {
604                 batadv_sysfs_add_meshif(net_dev);
605                 return NOTIFY_DONE;
606         }
607
608         hard_iface = batadv_hardif_get_by_netdev(net_dev);
609         if (!hard_iface && event == NETDEV_REGISTER)
610                 hard_iface = batadv_hardif_add_interface(net_dev);
611
612         if (!hard_iface)
613                 goto out;
614
615         switch (event) {
616         case NETDEV_UP:
617                 batadv_hardif_activate_interface(hard_iface);
618                 break;
619         case NETDEV_GOING_DOWN:
620         case NETDEV_DOWN:
621                 batadv_hardif_deactivate_interface(hard_iface);
622                 break;
623         case NETDEV_UNREGISTER:
624                 list_del_rcu(&hard_iface->list);
625
626                 batadv_hardif_remove_interface(hard_iface);
627                 break;
628         case NETDEV_CHANGEMTU:
629                 if (hard_iface->soft_iface)
630                         batadv_update_min_mtu(hard_iface->soft_iface);
631                 break;
632         case NETDEV_CHANGEADDR:
633                 if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
634                         goto hardif_put;
635
636                 batadv_check_known_mac_addr(hard_iface->net_dev);
637
638                 bat_priv = netdev_priv(hard_iface->soft_iface);
639                 bat_priv->bat_algo_ops->bat_iface_update_mac(hard_iface);
640
641                 primary_if = batadv_primary_if_get_selected(bat_priv);
642                 if (!primary_if)
643                         goto hardif_put;
644
645                 if (hard_iface == primary_if)
646                         batadv_primary_if_update_addr(bat_priv, NULL);
647                 break;
648         default:
649                 break;
650         }
651
652 hardif_put:
653         batadv_hardif_free_ref(hard_iface);
654 out:
655         if (primary_if)
656                 batadv_hardif_free_ref(primary_if);
657         return NOTIFY_DONE;
658 }
659
660 /* This function returns true if the interface represented by ifindex is a
661  * 802.11 wireless device
662  */
663 bool batadv_is_wifi_iface(int ifindex)
664 {
665         struct net_device *net_device = NULL;
666         bool ret = false;
667
668         if (ifindex == BATADV_NULL_IFINDEX)
669                 goto out;
670
671         net_device = dev_get_by_index(&init_net, ifindex);
672         if (!net_device)
673                 goto out;
674
675 #ifdef CONFIG_WIRELESS_EXT
676         /* pre-cfg80211 drivers have to implement WEXT, so it is possible to
677          * check for wireless_handlers != NULL
678          */
679         if (net_device->wireless_handlers)
680                 ret = true;
681         else
682 #endif
683                 /* cfg80211 drivers have to set ieee80211_ptr */
684                 if (net_device->ieee80211_ptr)
685                         ret = true;
686 out:
687         if (net_device)
688                 dev_put(net_device);
689         return ret;
690 }
691
692 struct notifier_block batadv_hard_if_notifier = {
693         .notifier_call = batadv_hard_if_event,
694 };