1// SPDX-License-Identifier: GPL-2.0
   2/* Copyright (C) B.A.T.M.A.N. contributors:
   3 *
   4 * Martin Hundebøll, Jeppe Ledet-Pedersen
   5 */
   6
   7#include "network-coding.h"
   8#include "main.h"
   9
  10#include <linux/atomic.h>
  11#include <linux/bitops.h>
  12#include <linux/byteorder/generic.h>
  13#include <linux/compiler.h>
 
  14#include <linux/errno.h>
  15#include <linux/etherdevice.h>
  16#include <linux/gfp.h>
  17#include <linux/if_ether.h>
  18#include <linux/if_packet.h>
  19#include <linux/init.h>
  20#include <linux/jhash.h>
  21#include <linux/jiffies.h>
  22#include <linux/kernel.h>
  23#include <linux/kref.h>
  24#include <linux/list.h>
  25#include <linux/lockdep.h>
  26#include <linux/net.h>
  27#include <linux/netdevice.h>
  28#include <linux/prandom.h>
  29#include <linux/printk.h>
 
  30#include <linux/rculist.h>
  31#include <linux/rcupdate.h>
  32#include <linux/skbuff.h>
  33#include <linux/slab.h>
  34#include <linux/spinlock.h>
  35#include <linux/stddef.h>
  36#include <linux/string.h>
  37#include <linux/workqueue.h>
  38#include <uapi/linux/batadv_packet.h>
  39
  40#include "hash.h"
  41#include "log.h"
  42#include "originator.h"
  43#include "routing.h"
  44#include "send.h"
  45#include "tvlv.h"
  46
  47static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
  48static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
  49
  50static void batadv_nc_worker(struct work_struct *work);
  51static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
  52				       struct batadv_hard_iface *recv_if);
  53
  54/**
  55 * batadv_nc_init() - one-time initialization for network coding
  56 *
  57 * Return: 0 on success or negative error number in case of failure
  58 */
  59int __init batadv_nc_init(void)
  60{
  61	int ret;
  62
  63	/* Register our packet type */
  64	ret = batadv_recv_handler_register(BATADV_CODED,
  65					   batadv_nc_recv_coded_packet);
  66
  67	return ret;
  68}
  69
  70/**
  71 * batadv_nc_start_timer() - initialise the nc periodic worker
  72 * @bat_priv: the bat priv with all the soft interface information
  73 */
  74static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
  75{
  76	queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
  77			   msecs_to_jiffies(10));
  78}
  79
  80/**
  81 * batadv_nc_tvlv_container_update() - update the network coding tvlv container
  82 *  after network coding setting change
  83 * @bat_priv: the bat priv with all the soft interface information
  84 */
  85static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
  86{
  87	char nc_mode;
  88
  89	nc_mode = atomic_read(&bat_priv->network_coding);
  90
  91	switch (nc_mode) {
  92	case 0:
  93		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
  94		break;
  95	case 1:
  96		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
  97					       NULL, 0);
  98		break;
  99	}
 100}
 101
 102/**
 103 * batadv_nc_status_update() - update the network coding tvlv container after
 104 *  network coding setting change
 105 * @net_dev: the soft interface net device
 106 */
 107void batadv_nc_status_update(struct net_device *net_dev)
 108{
 109	struct batadv_priv *bat_priv = netdev_priv(net_dev);
 110
 111	batadv_nc_tvlv_container_update(bat_priv);
 112}
 113
 114/**
 115 * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container
 116 * @bat_priv: the bat priv with all the soft interface information
 117 * @orig: the orig_node of the ogm
 118 * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
 119 * @tvlv_value: tvlv buffer containing the gateway data
 120 * @tvlv_value_len: tvlv buffer length
 121 */
 122static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
 123					  struct batadv_orig_node *orig,
 124					  u8 flags,
 125					  void *tvlv_value, u16 tvlv_value_len)
 126{
 127	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
 128		clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 129	else
 130		set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 131}
 132
 133/**
 134 * batadv_nc_mesh_init() - initialise coding hash table and start housekeeping
 135 * @bat_priv: the bat priv with all the soft interface information
 136 *
 137 * Return: 0 on success or negative error number in case of failure
 138 */
 139int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
 140{
 141	bat_priv->nc.timestamp_fwd_flush = jiffies;
 142	bat_priv->nc.timestamp_sniffed_purge = jiffies;
 143
 144	if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
 145		return 0;
 146
 147	bat_priv->nc.coding_hash = batadv_hash_new(128);
 148	if (!bat_priv->nc.coding_hash)
 149		goto err;
 150
 151	batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
 152				   &batadv_nc_coding_hash_lock_class_key);
 153
 154	bat_priv->nc.decoding_hash = batadv_hash_new(128);
 155	if (!bat_priv->nc.decoding_hash)
 
 156		goto err;
 
 157
 158	batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
 159				   &batadv_nc_decoding_hash_lock_class_key);
 160
 161	INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
 162	batadv_nc_start_timer(bat_priv);
 163
 164	batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
 165				     NULL, BATADV_TVLV_NC, 1,
 166				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 167	batadv_nc_tvlv_container_update(bat_priv);
 168	return 0;
 169
 170err:
 171	return -ENOMEM;
 172}
 173
 174/**
 175 * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables
 176 * @bat_priv: the bat priv with all the soft interface information
 177 */
 178void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
 179{
 180	atomic_set(&bat_priv->network_coding, 0);
 181	bat_priv->nc.min_tq = 200;
 182	bat_priv->nc.max_fwd_delay = 10;
 183	bat_priv->nc.max_buffer_time = 200;
 184}
 185
 186/**
 187 * batadv_nc_init_orig() - initialise the nc fields of an orig_node
 188 * @orig_node: the orig_node which is going to be initialised
 189 */
 190void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
 191{
 192	INIT_LIST_HEAD(&orig_node->in_coding_list);
 193	INIT_LIST_HEAD(&orig_node->out_coding_list);
 194	spin_lock_init(&orig_node->in_coding_list_lock);
 195	spin_lock_init(&orig_node->out_coding_list_lock);
 196}
 197
 198/**
 199 * batadv_nc_node_release() - release nc_node from lists and queue for free
 200 *  after rcu grace period
 201 * @ref: kref pointer of the nc_node
 202 */
 203static void batadv_nc_node_release(struct kref *ref)
 204{
 205	struct batadv_nc_node *nc_node;
 206
 207	nc_node = container_of(ref, struct batadv_nc_node, refcount);
 208
 209	batadv_orig_node_put(nc_node->orig_node);
 210	kfree_rcu(nc_node, rcu);
 211}
 212
 213/**
 214 * batadv_nc_node_put() - decrement the nc_node refcounter and possibly
 215 *  release it
 216 * @nc_node: nc_node to be free'd
 217 */
 218static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
 219{
 
 
 
 220	kref_put(&nc_node->refcount, batadv_nc_node_release);
 221}
 222
 223/**
 224 * batadv_nc_path_release() - release nc_path from lists and queue for free
 225 *  after rcu grace period
 226 * @ref: kref pointer of the nc_path
 227 */
 228static void batadv_nc_path_release(struct kref *ref)
 229{
 230	struct batadv_nc_path *nc_path;
 231
 232	nc_path = container_of(ref, struct batadv_nc_path, refcount);
 233
 234	kfree_rcu(nc_path, rcu);
 235}
 236
 237/**
 238 * batadv_nc_path_put() - decrement the nc_path refcounter and possibly
 239 *  release it
 240 * @nc_path: nc_path to be free'd
 241 */
 242static void batadv_nc_path_put(struct batadv_nc_path *nc_path)
 243{
 
 
 
 244	kref_put(&nc_path->refcount, batadv_nc_path_release);
 245}
 246
 247/**
 248 * batadv_nc_packet_free() - frees nc packet
 249 * @nc_packet: the nc packet to free
 250 * @dropped: whether the packet is freed because is dropped
 251 */
 252static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
 253				  bool dropped)
 254{
 255	if (dropped)
 256		kfree_skb(nc_packet->skb);
 257	else
 258		consume_skb(nc_packet->skb);
 259
 260	batadv_nc_path_put(nc_packet->nc_path);
 261	kfree(nc_packet);
 262}
 263
 264/**
 265 * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged
 266 * @bat_priv: the bat priv with all the soft interface information
 267 * @nc_node: the nc node to check
 268 *
 269 * Return: true if the entry has to be purged now, false otherwise
 270 */
 271static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
 272				       struct batadv_nc_node *nc_node)
 273{
 274	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 275		return true;
 276
 277	return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
 278}
 279
 280/**
 281 * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out
 282 * @bat_priv: the bat priv with all the soft interface information
 283 * @nc_path: the nc path to check
 284 *
 285 * Return: true if the entry has to be purged now, false otherwise
 286 */
 287static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
 288					      struct batadv_nc_path *nc_path)
 289{
 290	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 291		return true;
 292
 293	/* purge the path when no packets has been added for 10 times the
 294	 * max_fwd_delay time
 295	 */
 296	return batadv_has_timed_out(nc_path->last_valid,
 297				    bat_priv->nc.max_fwd_delay * 10);
 298}
 299
 300/**
 301 * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed
 302 *  out
 303 * @bat_priv: the bat priv with all the soft interface information
 304 * @nc_path: the nc path to check
 305 *
 306 * Return: true if the entry has to be purged now, false otherwise
 307 */
 308static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
 309						struct batadv_nc_path *nc_path)
 310{
 311	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 312		return true;
 313
 314	/* purge the path when no packets has been added for 10 times the
 315	 * max_buffer time
 316	 */
 317	return batadv_has_timed_out(nc_path->last_valid,
 318				    bat_priv->nc.max_buffer_time * 10);
 319}
 320
 321/**
 322 * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale
 323 *  entries
 324 * @bat_priv: the bat priv with all the soft interface information
 325 * @list: list of nc nodes
 326 * @lock: nc node list lock
 327 * @to_purge: function in charge to decide whether an entry has to be purged or
 328 *	      not. This function takes the nc node as argument and has to return
 329 *	      a boolean value: true if the entry has to be deleted, false
 330 *	      otherwise
 331 */
 332static void
 333batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
 334			      struct list_head *list,
 335			      spinlock_t *lock,
 336			      bool (*to_purge)(struct batadv_priv *,
 337					       struct batadv_nc_node *))
 338{
 339	struct batadv_nc_node *nc_node, *nc_node_tmp;
 340
 341	/* For each nc_node in list */
 342	spin_lock_bh(lock);
 343	list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
 344		/* if an helper function has been passed as parameter,
 345		 * ask it if the entry has to be purged or not
 346		 */
 347		if (to_purge && !to_purge(bat_priv, nc_node))
 348			continue;
 349
 350		batadv_dbg(BATADV_DBG_NC, bat_priv,
 351			   "Removing nc_node %pM -> %pM\n",
 352			   nc_node->addr, nc_node->orig_node->orig);
 353		list_del_rcu(&nc_node->list);
 354		batadv_nc_node_put(nc_node);
 355	}
 356	spin_unlock_bh(lock);
 357}
 358
 359/**
 360 * batadv_nc_purge_orig() - purges all nc node data attached of the given
 361 *  originator
 362 * @bat_priv: the bat priv with all the soft interface information
 363 * @orig_node: orig_node with the nc node entries to be purged
 364 * @to_purge: function in charge to decide whether an entry has to be purged or
 365 *	      not. This function takes the nc node as argument and has to return
 366 *	      a boolean value: true is the entry has to be deleted, false
 367 *	      otherwise
 368 */
 369void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
 370			  struct batadv_orig_node *orig_node,
 371			  bool (*to_purge)(struct batadv_priv *,
 372					   struct batadv_nc_node *))
 373{
 374	/* Check ingoing nc_node's of this orig_node */
 375	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
 376				      &orig_node->in_coding_list_lock,
 377				      to_purge);
 378
 379	/* Check outgoing nc_node's of this orig_node */
 380	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
 381				      &orig_node->out_coding_list_lock,
 382				      to_purge);
 383}
 384
 385/**
 386 * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if
 387 *  they have timed out nc nodes
 388 * @bat_priv: the bat priv with all the soft interface information
 389 */
 390static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
 391{
 392	struct batadv_hashtable *hash = bat_priv->orig_hash;
 393	struct hlist_head *head;
 394	struct batadv_orig_node *orig_node;
 395	u32 i;
 396
 397	if (!hash)
 398		return;
 399
 400	/* For each orig_node */
 401	for (i = 0; i < hash->size; i++) {
 402		head = &hash->table[i];
 403
 404		rcu_read_lock();
 405		hlist_for_each_entry_rcu(orig_node, head, hash_entry)
 406			batadv_nc_purge_orig(bat_priv, orig_node,
 407					     batadv_nc_to_purge_nc_node);
 408		rcu_read_unlock();
 409	}
 410}
 411
 412/**
 413 * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove
 414 *  unused ones
 415 * @bat_priv: the bat priv with all the soft interface information
 416 * @hash: hash table containing the nc paths to check
 417 * @to_purge: function in charge to decide whether an entry has to be purged or
 418 *	      not. This function takes the nc node as argument and has to return
 419 *	      a boolean value: true is the entry has to be deleted, false
 420 *	      otherwise
 421 */
 422static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
 423				  struct batadv_hashtable *hash,
 424				  bool (*to_purge)(struct batadv_priv *,
 425						   struct batadv_nc_path *))
 426{
 427	struct hlist_head *head;
 428	struct hlist_node *node_tmp;
 429	struct batadv_nc_path *nc_path;
 430	spinlock_t *lock; /* Protects lists in hash */
 431	u32 i;
 432
 433	for (i = 0; i < hash->size; i++) {
 434		head = &hash->table[i];
 435		lock = &hash->list_locks[i];
 436
 437		/* For each nc_path in this bin */
 438		spin_lock_bh(lock);
 439		hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
 440			/* if an helper function has been passed as parameter,
 441			 * ask it if the entry has to be purged or not
 442			 */
 443			if (to_purge && !to_purge(bat_priv, nc_path))
 444				continue;
 445
 446			/* purging an non-empty nc_path should never happen, but
 447			 * is observed under high CPU load. Delay the purging
 448			 * until next iteration to allow the packet_list to be
 449			 * emptied first.
 450			 */
 451			if (!unlikely(list_empty(&nc_path->packet_list))) {
 452				net_ratelimited_function(printk,
 453							 KERN_WARNING
 454							 "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
 455							 nc_path->prev_hop,
 456							 nc_path->next_hop);
 457				continue;
 458			}
 459
 460			/* nc_path is unused, so remove it */
 461			batadv_dbg(BATADV_DBG_NC, bat_priv,
 462				   "Remove nc_path %pM -> %pM\n",
 463				   nc_path->prev_hop, nc_path->next_hop);
 464			hlist_del_rcu(&nc_path->hash_entry);
 465			batadv_nc_path_put(nc_path);
 466		}
 467		spin_unlock_bh(lock);
 468	}
 469}
 470
 471/**
 472 * batadv_nc_hash_key_gen() - computes the nc_path hash key
 473 * @key: buffer to hold the final hash key
 474 * @src: source ethernet mac address going into the hash key
 475 * @dst: destination ethernet mac address going into the hash key
 476 */
 477static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
 478				   const char *dst)
 479{
 480	memcpy(key->prev_hop, src, sizeof(key->prev_hop));
 481	memcpy(key->next_hop, dst, sizeof(key->next_hop));
 482}
 483
 484/**
 485 * batadv_nc_hash_choose() - compute the hash value for an nc path
 486 * @data: data to hash
 487 * @size: size of the hash table
 488 *
 489 * Return: the selected index in the hash table for the given data.
 490 */
 491static u32 batadv_nc_hash_choose(const void *data, u32 size)
 492{
 493	const struct batadv_nc_path *nc_path = data;
 494	u32 hash = 0;
 495
 496	hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
 497	hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
 498
 499	return hash % size;
 500}
 501
 502/**
 503 * batadv_nc_hash_compare() - comparing function used in the network coding hash
 504 *  tables
 505 * @node: node in the local table
 506 * @data2: second object to compare the node to
 507 *
 508 * Return: true if the two entry are the same, false otherwise
 509 */
 510static bool batadv_nc_hash_compare(const struct hlist_node *node,
 511				   const void *data2)
 512{
 513	const struct batadv_nc_path *nc_path1, *nc_path2;
 514
 515	nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
 516	nc_path2 = data2;
 517
 518	/* Return 1 if the two keys are identical */
 519	if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
 520		return false;
 521
 522	if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
 523		return false;
 524
 525	return true;
 526}
 527
 528/**
 529 * batadv_nc_hash_find() - search for an existing nc path and return it
 530 * @hash: hash table containing the nc path
 531 * @data: search key
 532 *
 533 * Return: the nc_path if found, NULL otherwise.
 534 */
 535static struct batadv_nc_path *
 536batadv_nc_hash_find(struct batadv_hashtable *hash,
 537		    void *data)
 538{
 539	struct hlist_head *head;
 540	struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
 541	int index;
 542
 543	if (!hash)
 544		return NULL;
 545
 546	index = batadv_nc_hash_choose(data, hash->size);
 547	head = &hash->table[index];
 548
 549	rcu_read_lock();
 550	hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
 551		if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
 552			continue;
 553
 554		if (!kref_get_unless_zero(&nc_path->refcount))
 555			continue;
 556
 557		nc_path_tmp = nc_path;
 558		break;
 559	}
 560	rcu_read_unlock();
 561
 562	return nc_path_tmp;
 563}
 564
 565/**
 566 * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct
 567 * @nc_packet: the nc packet to send
 568 */
 569static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
 570{
 571	batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
 572	nc_packet->skb = NULL;
 573	batadv_nc_packet_free(nc_packet, false);
 574}
 575
 576/**
 577 * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet.
 578 * @bat_priv: the bat priv with all the soft interface information
 579 * @nc_path: the nc path the packet belongs to
 580 * @nc_packet: the nc packet to be checked
 581 *
 582 * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
 583 * timeout. If so, the packet is no longer kept and the entry deleted from the
 584 * queue. Has to be called with the appropriate locks.
 585 *
 586 * Return: false as soon as the entry in the fifo queue has not been timed out
 587 * yet and true otherwise.
 588 */
 589static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
 590				    struct batadv_nc_path *nc_path,
 591				    struct batadv_nc_packet *nc_packet)
 592{
 593	unsigned long timeout = bat_priv->nc.max_buffer_time;
 594	bool res = false;
 595
 596	lockdep_assert_held(&nc_path->packet_list_lock);
 597
 598	/* Packets are added to tail, so the remaining packets did not time
 599	 * out and we can stop processing the current queue
 600	 */
 601	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
 602	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
 603		goto out;
 604
 605	/* purge nc packet */
 606	list_del(&nc_packet->list);
 607	batadv_nc_packet_free(nc_packet, true);
 608
 609	res = true;
 610
 611out:
 612	return res;
 613}
 614
 615/**
 616 * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet.
 617 * @bat_priv: the bat priv with all the soft interface information
 618 * @nc_path: the nc path the packet belongs to
 619 * @nc_packet: the nc packet to be checked
 620 *
 621 * Checks whether the given nc packet has hit its forward timeout. If so, the
 622 * packet is no longer delayed, immediately sent and the entry deleted from the
 623 * queue. Has to be called with the appropriate locks.
 624 *
 625 * Return: false as soon as the entry in the fifo queue has not been timed out
 626 * yet and true otherwise.
 627 */
 628static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
 629				struct batadv_nc_path *nc_path,
 630				struct batadv_nc_packet *nc_packet)
 631{
 632	unsigned long timeout = bat_priv->nc.max_fwd_delay;
 633
 634	lockdep_assert_held(&nc_path->packet_list_lock);
 635
 636	/* Packets are added to tail, so the remaining packets did not time
 637	 * out and we can stop processing the current queue
 638	 */
 639	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
 640	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
 641		return false;
 642
 643	/* Send packet */
 644	batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
 645	batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
 646			   nc_packet->skb->len + ETH_HLEN);
 647	list_del(&nc_packet->list);
 648	batadv_nc_send_packet(nc_packet);
 649
 650	return true;
 651}
 652
 653/**
 654 * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed
 655 *  out nc packets
 656 * @bat_priv: the bat priv with all the soft interface information
 657 * @hash: to be processed hash table
 658 * @process_fn: Function called to process given nc packet. Should return true
 659 *	        to encourage this function to proceed with the next packet.
 660 *	        Otherwise the rest of the current queue is skipped.
 661 */
 662static void
 663batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
 664			   struct batadv_hashtable *hash,
 665			   bool (*process_fn)(struct batadv_priv *,
 666					      struct batadv_nc_path *,
 667					      struct batadv_nc_packet *))
 668{
 669	struct hlist_head *head;
 670	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
 671	struct batadv_nc_path *nc_path;
 672	bool ret;
 673	int i;
 674
 675	if (!hash)
 676		return;
 677
 678	/* Loop hash table bins */
 679	for (i = 0; i < hash->size; i++) {
 680		head = &hash->table[i];
 681
 682		/* Loop coding paths */
 683		rcu_read_lock();
 684		hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
 685			/* Loop packets */
 686			spin_lock_bh(&nc_path->packet_list_lock);
 687			list_for_each_entry_safe(nc_packet, nc_packet_tmp,
 688						 &nc_path->packet_list, list) {
 689				ret = process_fn(bat_priv, nc_path, nc_packet);
 690				if (!ret)
 691					break;
 692			}
 693			spin_unlock_bh(&nc_path->packet_list_lock);
 694		}
 695		rcu_read_unlock();
 696	}
 697}
 698
 699/**
 700 * batadv_nc_worker() - periodic task for housekeeping related to network
 701 *  coding
 702 * @work: kernel work struct
 703 */
 704static void batadv_nc_worker(struct work_struct *work)
 705{
 706	struct delayed_work *delayed_work;
 707	struct batadv_priv_nc *priv_nc;
 708	struct batadv_priv *bat_priv;
 709	unsigned long timeout;
 710
 711	delayed_work = to_delayed_work(work);
 712	priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
 713	bat_priv = container_of(priv_nc, struct batadv_priv, nc);
 714
 715	batadv_nc_purge_orig_hash(bat_priv);
 716	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
 717			      batadv_nc_to_purge_nc_path_coding);
 718	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
 719			      batadv_nc_to_purge_nc_path_decoding);
 720
 721	timeout = bat_priv->nc.max_fwd_delay;
 722
 723	if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
 724		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
 725					   batadv_nc_fwd_flush);
 726		bat_priv->nc.timestamp_fwd_flush = jiffies;
 727	}
 728
 729	if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
 730				 bat_priv->nc.max_buffer_time)) {
 731		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
 732					   batadv_nc_sniffed_purge);
 733		bat_priv->nc.timestamp_sniffed_purge = jiffies;
 734	}
 735
 736	/* Schedule a new check */
 737	batadv_nc_start_timer(bat_priv);
 738}
 739
 740/**
 741 * batadv_can_nc_with_orig() - checks whether the given orig node is suitable
 742 *  for coding or not
 743 * @bat_priv: the bat priv with all the soft interface information
 744 * @orig_node: neighboring orig node which may be used as nc candidate
 745 * @ogm_packet: incoming ogm packet also used for the checks
 746 *
 747 * Return: true if:
 748 *  1) The OGM must have the most recent sequence number.
 749 *  2) The TTL must be decremented by one and only one.
 750 *  3) The OGM must be received from the first hop from orig_node.
 751 *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
 752 */
 753static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
 754				    struct batadv_orig_node *orig_node,
 755				    struct batadv_ogm_packet *ogm_packet)
 756{
 757	struct batadv_orig_ifinfo *orig_ifinfo;
 758	u32 last_real_seqno;
 759	u8 last_ttl;
 760
 761	orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
 762	if (!orig_ifinfo)
 763		return false;
 764
 765	last_ttl = orig_ifinfo->last_ttl;
 766	last_real_seqno = orig_ifinfo->last_real_seqno;
 767	batadv_orig_ifinfo_put(orig_ifinfo);
 768
 769	if (last_real_seqno != ntohl(ogm_packet->seqno))
 770		return false;
 771	if (last_ttl != ogm_packet->ttl + 1)
 772		return false;
 773	if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
 774		return false;
 775	if (ogm_packet->tq < bat_priv->nc.min_tq)
 776		return false;
 777
 778	return true;
 779}
 780
 781/**
 782 * batadv_nc_find_nc_node() - search for an existing nc node and return it
 783 * @orig_node: orig node originating the ogm packet
 784 * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 785 *  (can be equal to orig_node)
 786 * @in_coding: traverse incoming or outgoing network coding list
 787 *
 788 * Return: the nc_node if found, NULL otherwise.
 789 */
 790static struct batadv_nc_node *
 791batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
 792		       struct batadv_orig_node *orig_neigh_node,
 793		       bool in_coding)
 794{
 795	struct batadv_nc_node *nc_node, *nc_node_out = NULL;
 796	struct list_head *list;
 797
 798	if (in_coding)
 799		list = &orig_neigh_node->in_coding_list;
 800	else
 801		list = &orig_neigh_node->out_coding_list;
 802
 803	/* Traverse list of nc_nodes to orig_node */
 804	rcu_read_lock();
 805	list_for_each_entry_rcu(nc_node, list, list) {
 806		if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
 807			continue;
 808
 809		if (!kref_get_unless_zero(&nc_node->refcount))
 810			continue;
 811
 812		/* Found a match */
 813		nc_node_out = nc_node;
 814		break;
 815	}
 816	rcu_read_unlock();
 817
 818	return nc_node_out;
 819}
 820
 821/**
 822 * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was
 823 *  not found
 824 * @bat_priv: the bat priv with all the soft interface information
 825 * @orig_node: orig node originating the ogm packet
 826 * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 827 *  (can be equal to orig_node)
 828 * @in_coding: traverse incoming or outgoing network coding list
 829 *
 830 * Return: the nc_node if found or created, NULL in case of an error.
 831 */
 832static struct batadv_nc_node *
 833batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
 834		      struct batadv_orig_node *orig_node,
 835		      struct batadv_orig_node *orig_neigh_node,
 836		      bool in_coding)
 837{
 838	struct batadv_nc_node *nc_node;
 839	spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
 840	struct list_head *list;
 841
 842	/* Select ingoing or outgoing coding node */
 843	if (in_coding) {
 844		lock = &orig_neigh_node->in_coding_list_lock;
 845		list = &orig_neigh_node->in_coding_list;
 846	} else {
 847		lock = &orig_neigh_node->out_coding_list_lock;
 848		list = &orig_neigh_node->out_coding_list;
 849	}
 850
 851	spin_lock_bh(lock);
 852
 853	/* Check if nc_node is already added */
 854	nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
 855
 856	/* Node found */
 857	if (nc_node)
 858		goto unlock;
 859
 860	nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
 861	if (!nc_node)
 862		goto unlock;
 863
 864	/* Initialize nc_node */
 865	INIT_LIST_HEAD(&nc_node->list);
 866	kref_init(&nc_node->refcount);
 867	ether_addr_copy(nc_node->addr, orig_node->orig);
 868	kref_get(&orig_neigh_node->refcount);
 869	nc_node->orig_node = orig_neigh_node;
 870
 871	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
 872		   nc_node->addr, nc_node->orig_node->orig);
 873
 874	/* Add nc_node to orig_node */
 875	kref_get(&nc_node->refcount);
 876	list_add_tail_rcu(&nc_node->list, list);
 877
 878unlock:
 879	spin_unlock_bh(lock);
 880
 881	return nc_node;
 882}
 883
 884/**
 885 * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node
 886 *  structs (best called on incoming OGMs)
 887 * @bat_priv: the bat priv with all the soft interface information
 888 * @orig_node: orig node originating the ogm packet
 889 * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 890 *  (can be equal to orig_node)
 891 * @ogm_packet: incoming ogm packet
 892 * @is_single_hop_neigh: orig_node is a single hop neighbor
 893 */
 894void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
 895			      struct batadv_orig_node *orig_node,
 896			      struct batadv_orig_node *orig_neigh_node,
 897			      struct batadv_ogm_packet *ogm_packet,
 898			      int is_single_hop_neigh)
 899{
 900	struct batadv_nc_node *in_nc_node = NULL;
 901	struct batadv_nc_node *out_nc_node = NULL;
 902
 903	/* Check if network coding is enabled */
 904	if (!atomic_read(&bat_priv->network_coding))
 905		goto out;
 906
 907	/* check if orig node is network coding enabled */
 908	if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
 909		goto out;
 910
 911	/* accept ogms from 'good' neighbors and single hop neighbors */
 912	if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
 913	    !is_single_hop_neigh)
 914		goto out;
 915
 916	/* Add orig_node as in_nc_node on hop */
 917	in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
 918					   orig_neigh_node, true);
 919	if (!in_nc_node)
 920		goto out;
 921
 922	in_nc_node->last_seen = jiffies;
 923
 924	/* Add hop as out_nc_node on orig_node */
 925	out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
 926					    orig_node, false);
 927	if (!out_nc_node)
 928		goto out;
 929
 930	out_nc_node->last_seen = jiffies;
 931
 932out:
 933	if (in_nc_node)
 934		batadv_nc_node_put(in_nc_node);
 935	if (out_nc_node)
 936		batadv_nc_node_put(out_nc_node);
 937}
 938
 939/**
 940 * batadv_nc_get_path() - get existing nc_path or allocate a new one
 941 * @bat_priv: the bat priv with all the soft interface information
 942 * @hash: hash table containing the nc path
 943 * @src: ethernet source address - first half of the nc path search key
 944 * @dst: ethernet destination address - second half of the nc path search key
 945 *
 946 * Return: pointer to nc_path if the path was found or created, returns NULL
 947 * on error.
 948 */
 949static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
 950						 struct batadv_hashtable *hash,
 951						 u8 *src,
 952						 u8 *dst)
 953{
 954	int hash_added;
 955	struct batadv_nc_path *nc_path, nc_path_key;
 956
 957	batadv_nc_hash_key_gen(&nc_path_key, src, dst);
 958
 959	/* Search for existing nc_path */
 960	nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
 961
 962	if (nc_path) {
 963		/* Set timestamp to delay removal of nc_path */
 964		nc_path->last_valid = jiffies;
 965		return nc_path;
 966	}
 967
 968	/* No existing nc_path was found; create a new */
 969	nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
 970
 971	if (!nc_path)
 972		return NULL;
 973
 974	/* Initialize nc_path */
 975	INIT_LIST_HEAD(&nc_path->packet_list);
 976	spin_lock_init(&nc_path->packet_list_lock);
 977	kref_init(&nc_path->refcount);
 978	nc_path->last_valid = jiffies;
 979	ether_addr_copy(nc_path->next_hop, dst);
 980	ether_addr_copy(nc_path->prev_hop, src);
 981
 982	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
 983		   nc_path->prev_hop,
 984		   nc_path->next_hop);
 985
 986	/* Add nc_path to hash table */
 987	kref_get(&nc_path->refcount);
 988	hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
 989				     batadv_nc_hash_choose, &nc_path_key,
 990				     &nc_path->hash_entry);
 991
 992	if (hash_added < 0) {
 993		kfree(nc_path);
 994		return NULL;
 995	}
 996
 997	return nc_path;
 998}
 999
1000/**
1001 * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair
1002 *  selection of a receiver with slightly lower TQ than the other
1003 * @tq: to be weighted tq value
1004 *
1005 * Return: scaled tq value
1006 */
1007static u8 batadv_nc_random_weight_tq(u8 tq)
1008{
1009	/* randomize the estimated packet loss (max TQ - estimated TQ) */
1010	u8 rand_tq = prandom_u32_max(BATADV_TQ_MAX_VALUE + 1 - tq);
1011
1012	/* convert to (randomized) estimated tq again */
1013	return BATADV_TQ_MAX_VALUE - rand_tq;
1014}
1015
1016/**
1017 * batadv_nc_memxor() - XOR destination with source
1018 * @dst: byte array to XOR into
1019 * @src: byte array to XOR from
1020 * @len: length of destination array
1021 */
1022static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
1023{
1024	unsigned int i;
1025
1026	for (i = 0; i < len; ++i)
1027		dst[i] ^= src[i];
1028}
1029
1030/**
1031 * batadv_nc_code_packets() - code a received unicast_packet with an nc packet
1032 *  into a coded_packet and send it
1033 * @bat_priv: the bat priv with all the soft interface information
1034 * @skb: data skb to forward
1035 * @ethhdr: pointer to the ethernet header inside the skb
1036 * @nc_packet: structure containing the packet to the skb can be coded with
1037 * @neigh_node: next hop to forward packet to
1038 *
1039 * Return: true if both packets are consumed, false otherwise.
1040 */
1041static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1042				   struct sk_buff *skb,
1043				   struct ethhdr *ethhdr,
1044				   struct batadv_nc_packet *nc_packet,
1045				   struct batadv_neigh_node *neigh_node)
1046{
1047	u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1048	struct sk_buff *skb_dest, *skb_src;
1049	struct batadv_unicast_packet *packet1;
1050	struct batadv_unicast_packet *packet2;
1051	struct batadv_coded_packet *coded_packet;
1052	struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
1053	struct batadv_neigh_node *router_coding = NULL, *second_dest;
1054	struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1055	struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1056	u8 *first_source, *second_source;
1057	__be32 packet_id1, packet_id2;
1058	size_t count;
1059	bool res = false;
1060	int coding_len;
1061	int unicast_size = sizeof(*packet1);
1062	int coded_size = sizeof(*coded_packet);
1063	int header_add = coded_size - unicast_size;
1064
1065	/* TODO: do we need to consider the outgoing interface for
1066	 * coded packets?
1067	 */
1068	router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1069					      BATADV_IF_DEFAULT);
1070	if (!router_neigh)
1071		goto out;
1072
1073	router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1074						      BATADV_IF_DEFAULT);
1075	if (!router_neigh_ifinfo)
1076		goto out;
1077
1078	neigh_tmp = nc_packet->neigh_node;
1079	router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1080					       BATADV_IF_DEFAULT);
1081	if (!router_coding)
1082		goto out;
1083
1084	router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1085						       BATADV_IF_DEFAULT);
1086	if (!router_coding_ifinfo)
1087		goto out;
1088
1089	tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1090	tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1091	tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1092	tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1093
1094	/* Select one destination for the MAC-header dst-field based on
1095	 * weighted TQ-values.
1096	 */
1097	if (tq_weighted_neigh >= tq_weighted_coding) {
1098		/* Destination from nc_packet is selected for MAC-header */
1099		first_dest = nc_packet->neigh_node;
1100		first_source = nc_packet->nc_path->prev_hop;
1101		second_dest = neigh_node;
1102		second_source = ethhdr->h_source;
1103		packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1104		packet2 = (struct batadv_unicast_packet *)skb->data;
1105		packet_id1 = nc_packet->packet_id;
1106		packet_id2 = batadv_skb_crc32(skb,
1107					      skb->data + sizeof(*packet2));
1108	} else {
1109		/* Destination for skb is selected for MAC-header */
1110		first_dest = neigh_node;
1111		first_source = ethhdr->h_source;
1112		second_dest = nc_packet->neigh_node;
1113		second_source = nc_packet->nc_path->prev_hop;
1114		packet1 = (struct batadv_unicast_packet *)skb->data;
1115		packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1116		packet_id1 = batadv_skb_crc32(skb,
1117					      skb->data + sizeof(*packet1));
1118		packet_id2 = nc_packet->packet_id;
1119	}
1120
1121	/* Instead of zero padding the smallest data buffer, we
1122	 * code into the largest.
1123	 */
1124	if (skb->len <= nc_packet->skb->len) {
1125		skb_dest = nc_packet->skb;
1126		skb_src = skb;
1127	} else {
1128		skb_dest = skb;
1129		skb_src = nc_packet->skb;
1130	}
1131
1132	/* coding_len is used when decoding the packet shorter packet */
1133	coding_len = skb_src->len - unicast_size;
1134
1135	if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1136		goto out;
1137
1138	skb_push(skb_dest, header_add);
1139
1140	coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1141	skb_reset_mac_header(skb_dest);
1142
1143	coded_packet->packet_type = BATADV_CODED;
1144	coded_packet->version = BATADV_COMPAT_VERSION;
1145	coded_packet->ttl = packet1->ttl;
1146
1147	/* Info about first unicast packet */
1148	ether_addr_copy(coded_packet->first_source, first_source);
1149	ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1150	coded_packet->first_crc = packet_id1;
1151	coded_packet->first_ttvn = packet1->ttvn;
1152
1153	/* Info about second unicast packet */
1154	ether_addr_copy(coded_packet->second_dest, second_dest->addr);
1155	ether_addr_copy(coded_packet->second_source, second_source);
1156	ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1157	coded_packet->second_crc = packet_id2;
1158	coded_packet->second_ttl = packet2->ttl;
1159	coded_packet->second_ttvn = packet2->ttvn;
1160	coded_packet->coded_len = htons(coding_len);
1161
1162	/* This is where the magic happens: Code skb_src into skb_dest */
1163	batadv_nc_memxor(skb_dest->data + coded_size,
1164			 skb_src->data + unicast_size, coding_len);
1165
1166	/* Update counters accordingly */
1167	if (BATADV_SKB_CB(skb_src)->decoded &&
1168	    BATADV_SKB_CB(skb_dest)->decoded) {
1169		/* Both packets are recoded */
1170		count = skb_src->len + ETH_HLEN;
1171		count += skb_dest->len + ETH_HLEN;
1172		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1173		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1174	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1175		   !BATADV_SKB_CB(skb_dest)->decoded) {
1176		/* Both packets are newly coded */
1177		count = skb_src->len + ETH_HLEN;
1178		count += skb_dest->len + ETH_HLEN;
1179		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1180		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1181	} else if (BATADV_SKB_CB(skb_src)->decoded &&
1182		   !BATADV_SKB_CB(skb_dest)->decoded) {
1183		/* skb_src recoded and skb_dest is newly coded */
1184		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1185		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1186				   skb_src->len + ETH_HLEN);
1187		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1188		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1189				   skb_dest->len + ETH_HLEN);
1190	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1191		   BATADV_SKB_CB(skb_dest)->decoded) {
1192		/* skb_src is newly coded and skb_dest is recoded */
1193		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1194		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1195				   skb_src->len + ETH_HLEN);
1196		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1197		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1198				   skb_dest->len + ETH_HLEN);
1199	}
1200
1201	/* skb_src is now coded into skb_dest, so free it */
1202	consume_skb(skb_src);
1203
1204	/* avoid duplicate free of skb from nc_packet */
1205	nc_packet->skb = NULL;
1206	batadv_nc_packet_free(nc_packet, false);
1207
1208	/* Send the coded packet and return true */
1209	batadv_send_unicast_skb(skb_dest, first_dest);
1210	res = true;
1211out:
1212	if (router_neigh)
1213		batadv_neigh_node_put(router_neigh);
1214	if (router_coding)
1215		batadv_neigh_node_put(router_coding);
1216	if (router_neigh_ifinfo)
1217		batadv_neigh_ifinfo_put(router_neigh_ifinfo);
1218	if (router_coding_ifinfo)
1219		batadv_neigh_ifinfo_put(router_coding_ifinfo);
1220	return res;
1221}
1222
1223/**
1224 * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst.
1225 * @skb: data skb to forward
1226 * @dst: destination mac address of the other skb to code with
1227 * @src: source mac address of skb
1228 *
1229 * Whenever we network code a packet we have to check whether we received it in
1230 * a network coded form. If so, we may not be able to use it for coding because
1231 * some neighbors may also have received (overheard) the packet in the network
1232 * coded form without being able to decode it. It is hard to know which of the
1233 * neighboring nodes was able to decode the packet, therefore we can only
1234 * re-code the packet if the source of the previous encoded packet is involved.
1235 * Since the source encoded the packet we can be certain it has all necessary
1236 * decode information.
1237 *
1238 * Return: true if coding of a decoded packet is allowed.
1239 */
1240static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
1241{
1242	if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1243		return false;
1244	return true;
1245}
1246
1247/**
1248 * batadv_nc_path_search() - Find the coding path matching in_nc_node and
1249 *  out_nc_node to retrieve a buffered packet that can be used for coding.
1250 * @bat_priv: the bat priv with all the soft interface information
1251 * @in_nc_node: pointer to skb next hop's neighbor nc node
1252 * @out_nc_node: pointer to skb source's neighbor nc node
1253 * @skb: data skb to forward
1254 * @eth_dst: next hop mac address of skb
1255 *
1256 * Return: true if coding of a decoded skb is allowed.
1257 */
1258static struct batadv_nc_packet *
1259batadv_nc_path_search(struct batadv_priv *bat_priv,
1260		      struct batadv_nc_node *in_nc_node,
1261		      struct batadv_nc_node *out_nc_node,
1262		      struct sk_buff *skb,
1263		      u8 *eth_dst)
1264{
1265	struct batadv_nc_path *nc_path, nc_path_key;
1266	struct batadv_nc_packet *nc_packet_out = NULL;
1267	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1268	struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1269	int idx;
1270
1271	if (!hash)
1272		return NULL;
1273
1274	/* Create almost path key */
1275	batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1276			       out_nc_node->addr);
1277	idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1278
1279	/* Check for coding opportunities in this nc_path */
1280	rcu_read_lock();
1281	hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1282		if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1283			continue;
1284
1285		if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1286			continue;
1287
1288		spin_lock_bh(&nc_path->packet_list_lock);
1289		if (list_empty(&nc_path->packet_list)) {
1290			spin_unlock_bh(&nc_path->packet_list_lock);
1291			continue;
1292		}
1293
1294		list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1295					 &nc_path->packet_list, list) {
1296			if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1297							   eth_dst,
1298							   in_nc_node->addr))
1299				continue;
1300
1301			/* Coding opportunity is found! */
1302			list_del(&nc_packet->list);
1303			nc_packet_out = nc_packet;
1304			break;
1305		}
1306
1307		spin_unlock_bh(&nc_path->packet_list_lock);
1308		break;
1309	}
1310	rcu_read_unlock();
1311
1312	return nc_packet_out;
1313}
1314
1315/**
1316 * batadv_nc_skb_src_search() - Loops through the list of neighboring nodes of
1317 *  the skb's sender (may be equal to the originator).
1318 * @bat_priv: the bat priv with all the soft interface information
1319 * @skb: data skb to forward
1320 * @eth_dst: next hop mac address of skb
1321 * @eth_src: source mac address of skb
1322 * @in_nc_node: pointer to skb next hop's neighbor nc node
1323 *
1324 * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
1325 */
1326static struct batadv_nc_packet *
1327batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1328			 struct sk_buff *skb,
1329			 u8 *eth_dst,
1330			 u8 *eth_src,
1331			 struct batadv_nc_node *in_nc_node)
1332{
1333	struct batadv_orig_node *orig_node;
1334	struct batadv_nc_node *out_nc_node;
1335	struct batadv_nc_packet *nc_packet = NULL;
1336
1337	orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1338	if (!orig_node)
1339		return NULL;
1340
1341	rcu_read_lock();
1342	list_for_each_entry_rcu(out_nc_node,
1343				&orig_node->out_coding_list, list) {
1344		/* Check if the skb is decoded and if recoding is possible */
1345		if (!batadv_nc_skb_coding_possible(skb,
1346						   out_nc_node->addr, eth_src))
1347			continue;
1348
1349		/* Search for an opportunity in this nc_path */
1350		nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1351						  out_nc_node, skb, eth_dst);
1352		if (nc_packet)
1353			break;
1354	}
1355	rcu_read_unlock();
1356
1357	batadv_orig_node_put(orig_node);
1358	return nc_packet;
1359}
1360
1361/**
1362 * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the
1363 *  unicast skb before it is stored for use in later decoding
1364 * @bat_priv: the bat priv with all the soft interface information
1365 * @skb: data skb to store
1366 * @eth_dst_new: new destination mac address of skb
1367 */
1368static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1369					      struct sk_buff *skb,
1370					      u8 *eth_dst_new)
1371{
1372	struct ethhdr *ethhdr;
1373
1374	/* Copy skb header to change the mac header */
1375	skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1376	if (!skb)
1377		return;
1378
1379	/* Set the mac header as if we actually sent the packet uncoded */
1380	ethhdr = eth_hdr(skb);
1381	ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1382	ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1383
1384	/* Set data pointer to MAC header to mimic packets from our tx path */
1385	skb_push(skb, ETH_HLEN);
1386
1387	/* Add the packet to the decoding packet pool */
1388	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1389
1390	/* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1391	 * our ref
1392	 */
1393	consume_skb(skb);
1394}
1395
1396/**
1397 * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst.
1398 * @skb: data skb to forward
1399 * @neigh_node: next hop to forward packet to
1400 * @ethhdr: pointer to the ethernet header inside the skb
1401 *
1402 * Loops through the list of neighboring nodes the next hop has a good
1403 * connection to (receives OGMs with a sufficient quality). We need to find a
1404 * neighbor of our next hop that potentially sent a packet which our next hop
1405 * also received (overheard) and has stored for later decoding.
1406 *
1407 * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1408 */
1409static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1410				     struct batadv_neigh_node *neigh_node,
1411				     struct ethhdr *ethhdr)
1412{
1413	struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1414	struct batadv_priv *bat_priv = netdev_priv(netdev);
1415	struct batadv_orig_node *orig_node = neigh_node->orig_node;
1416	struct batadv_nc_node *nc_node;
1417	struct batadv_nc_packet *nc_packet = NULL;
1418
1419	rcu_read_lock();
1420	list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1421		/* Search for coding opportunity with this in_nc_node */
1422		nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1423						     neigh_node->addr,
1424						     ethhdr->h_source, nc_node);
1425
1426		/* Opportunity was found, so stop searching */
1427		if (nc_packet)
1428			break;
1429	}
1430	rcu_read_unlock();
1431
1432	if (!nc_packet)
1433		return false;
1434
1435	/* Save packets for later decoding */
1436	batadv_nc_skb_store_before_coding(bat_priv, skb,
1437					  neigh_node->addr);
1438	batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1439					  nc_packet->neigh_node->addr);
1440
1441	/* Code and send packets */
1442	if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1443				   neigh_node))
1444		return true;
1445
1446	/* out of mem ? Coding failed - we have to free the buffered packet
1447	 * to avoid memleaks. The skb passed as argument will be dealt with
1448	 * by the calling function.
1449	 */
1450	batadv_nc_send_packet(nc_packet);
1451	return false;
1452}
1453
1454/**
1455 * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding
1456 * @skb: skb to add to path
1457 * @nc_path: path to add skb to
1458 * @neigh_node: next hop to forward packet to
1459 * @packet_id: checksum to identify packet
1460 *
1461 * Return: true if the packet was buffered or false in case of an error.
1462 */
1463static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1464				      struct batadv_nc_path *nc_path,
1465				      struct batadv_neigh_node *neigh_node,
1466				      __be32 packet_id)
1467{
1468	struct batadv_nc_packet *nc_packet;
1469
1470	nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1471	if (!nc_packet)
1472		return false;
1473
1474	/* Initialize nc_packet */
1475	nc_packet->timestamp = jiffies;
1476	nc_packet->packet_id = packet_id;
1477	nc_packet->skb = skb;
1478	nc_packet->neigh_node = neigh_node;
1479	nc_packet->nc_path = nc_path;
1480
1481	/* Add coding packet to list */
1482	spin_lock_bh(&nc_path->packet_list_lock);
1483	list_add_tail(&nc_packet->list, &nc_path->packet_list);
1484	spin_unlock_bh(&nc_path->packet_list_lock);
1485
1486	return true;
1487}
1488
1489/**
1490 * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet
1491 *  buffer
1492 * @skb: data skb to forward
1493 * @neigh_node: next hop to forward packet to
1494 *
1495 * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1496 */
1497bool batadv_nc_skb_forward(struct sk_buff *skb,
1498			   struct batadv_neigh_node *neigh_node)
1499{
1500	const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1501	struct batadv_priv *bat_priv = netdev_priv(netdev);
1502	struct batadv_unicast_packet *packet;
1503	struct batadv_nc_path *nc_path;
1504	struct ethhdr *ethhdr = eth_hdr(skb);
1505	__be32 packet_id;
1506	u8 *payload;
1507
1508	/* Check if network coding is enabled */
1509	if (!atomic_read(&bat_priv->network_coding))
1510		goto out;
1511
1512	/* We only handle unicast packets */
1513	payload = skb_network_header(skb);
1514	packet = (struct batadv_unicast_packet *)payload;
1515	if (packet->packet_type != BATADV_UNICAST)
1516		goto out;
1517
1518	/* Try to find a coding opportunity and send the skb if one is found */
1519	if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1520		return true;
1521
1522	/* Find or create a nc_path for this src-dst pair */
1523	nc_path = batadv_nc_get_path(bat_priv,
1524				     bat_priv->nc.coding_hash,
1525				     ethhdr->h_source,
1526				     neigh_node->addr);
1527
1528	if (!nc_path)
1529		goto out;
1530
1531	/* Add skb to nc_path */
1532	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1533	if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1534		goto free_nc_path;
1535
1536	/* Packet is consumed */
1537	return true;
1538
1539free_nc_path:
1540	batadv_nc_path_put(nc_path);
1541out:
1542	/* Packet is not consumed */
1543	return false;
1544}
1545
1546/**
1547 * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be
1548 *  used when decoding coded packets
1549 * @bat_priv: the bat priv with all the soft interface information
1550 * @skb: data skb to store
1551 */
1552void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1553				      struct sk_buff *skb)
1554{
1555	struct batadv_unicast_packet *packet;
1556	struct batadv_nc_path *nc_path;
1557	struct ethhdr *ethhdr = eth_hdr(skb);
1558	__be32 packet_id;
1559	u8 *payload;
1560
1561	/* Check if network coding is enabled */
1562	if (!atomic_read(&bat_priv->network_coding))
1563		goto out;
1564
1565	/* Check for supported packet type */
1566	payload = skb_network_header(skb);
1567	packet = (struct batadv_unicast_packet *)payload;
1568	if (packet->packet_type != BATADV_UNICAST)
1569		goto out;
1570
1571	/* Find existing nc_path or create a new */
1572	nc_path = batadv_nc_get_path(bat_priv,
1573				     bat_priv->nc.decoding_hash,
1574				     ethhdr->h_source,
1575				     ethhdr->h_dest);
1576
1577	if (!nc_path)
1578		goto out;
1579
1580	/* Clone skb and adjust skb->data to point at batman header */
1581	skb = skb_clone(skb, GFP_ATOMIC);
1582	if (unlikely(!skb))
1583		goto free_nc_path;
1584
1585	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1586		goto free_skb;
1587
1588	if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1589		goto free_skb;
1590
1591	/* Add skb to nc_path */
1592	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1593	if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1594		goto free_skb;
1595
1596	batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1597	return;
1598
1599free_skb:
1600	kfree_skb(skb);
1601free_nc_path:
1602	batadv_nc_path_put(nc_path);
1603out:
1604	return;
1605}
1606
1607/**
1608 * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet
1609 *  should be saved in the decoding buffer and, if so, store it there
1610 * @bat_priv: the bat priv with all the soft interface information
1611 * @skb: unicast skb to store
1612 */
1613void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1614					 struct sk_buff *skb)
1615{
1616	struct ethhdr *ethhdr = eth_hdr(skb);
1617
1618	if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1619		return;
1620
1621	/* Set data pointer to MAC header to mimic packets from our tx path */
1622	skb_push(skb, ETH_HLEN);
1623
1624	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1625}
1626
1627/**
1628 * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored
1629 *  in nc_packet
1630 * @bat_priv: the bat priv with all the soft interface information
1631 * @skb: unicast skb to decode
1632 * @nc_packet: decode data needed to decode the skb
1633 *
1634 * Return: pointer to decoded unicast packet if the packet was decoded or NULL
1635 * in case of an error.
1636 */
1637static struct batadv_unicast_packet *
1638batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1639			    struct batadv_nc_packet *nc_packet)
1640{
1641	const int h_size = sizeof(struct batadv_unicast_packet);
1642	const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1643	struct batadv_unicast_packet *unicast_packet;
1644	struct batadv_coded_packet coded_packet_tmp;
1645	struct ethhdr *ethhdr, ethhdr_tmp;
1646	u8 *orig_dest, ttl, ttvn;
1647	unsigned int coding_len;
1648	int err;
1649
1650	/* Save headers temporarily */
1651	memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1652	memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1653
1654	if (skb_cow(skb, 0) < 0)
1655		return NULL;
1656
1657	if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1658		return NULL;
1659
1660	/* Data points to batman header, so set mac header 14 bytes before
1661	 * and network to data
1662	 */
1663	skb_set_mac_header(skb, -ETH_HLEN);
1664	skb_reset_network_header(skb);
1665
1666	/* Reconstruct original mac header */
1667	ethhdr = eth_hdr(skb);
1668	*ethhdr = ethhdr_tmp;
1669
1670	/* Select the correct unicast header information based on the location
1671	 * of our mac address in the coded_packet header
1672	 */
1673	if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1674		/* If we are the second destination the packet was overheard,
1675		 * so the Ethernet address must be copied to h_dest and
1676		 * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1677		 */
1678		ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1679		skb->pkt_type = PACKET_HOST;
1680
1681		orig_dest = coded_packet_tmp.second_orig_dest;
1682		ttl = coded_packet_tmp.second_ttl;
1683		ttvn = coded_packet_tmp.second_ttvn;
1684	} else {
1685		orig_dest = coded_packet_tmp.first_orig_dest;
1686		ttl = coded_packet_tmp.ttl;
1687		ttvn = coded_packet_tmp.first_ttvn;
1688	}
1689
1690	coding_len = ntohs(coded_packet_tmp.coded_len);
1691
1692	if (coding_len > skb->len)
1693		return NULL;
1694
1695	/* Here the magic is reversed:
1696	 *   extract the missing packet from the received coded packet
1697	 */
1698	batadv_nc_memxor(skb->data + h_size,
1699			 nc_packet->skb->data + h_size,
1700			 coding_len);
1701
1702	/* Resize decoded skb if decoded with larger packet */
1703	if (nc_packet->skb->len > coding_len + h_size) {
1704		err = pskb_trim_rcsum(skb, coding_len + h_size);
1705		if (err)
1706			return NULL;
1707	}
1708
1709	/* Create decoded unicast packet */
1710	unicast_packet = (struct batadv_unicast_packet *)skb->data;
1711	unicast_packet->packet_type = BATADV_UNICAST;
1712	unicast_packet->version = BATADV_COMPAT_VERSION;
1713	unicast_packet->ttl = ttl;
1714	ether_addr_copy(unicast_packet->dest, orig_dest);
1715	unicast_packet->ttvn = ttvn;
1716
1717	batadv_nc_packet_free(nc_packet, false);
1718	return unicast_packet;
1719}
1720
1721/**
1722 * batadv_nc_find_decoding_packet() - search through buffered decoding data to
1723 *  find the data needed to decode the coded packet
1724 * @bat_priv: the bat priv with all the soft interface information
1725 * @ethhdr: pointer to the ethernet header inside the coded packet
1726 * @coded: coded packet we try to find decode data for
1727 *
1728 * Return: pointer to nc packet if the needed data was found or NULL otherwise.
1729 */
1730static struct batadv_nc_packet *
1731batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1732			       struct ethhdr *ethhdr,
1733			       struct batadv_coded_packet *coded)
1734{
1735	struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1736	struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1737	struct batadv_nc_path *nc_path, nc_path_key;
1738	u8 *dest, *source;
1739	__be32 packet_id;
1740	int index;
1741
1742	if (!hash)
1743		return NULL;
1744
1745	/* Select the correct packet id based on the location of our mac-addr */
1746	dest = ethhdr->h_source;
1747	if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1748		source = coded->second_source;
1749		packet_id = coded->second_crc;
1750	} else {
1751		source = coded->first_source;
1752		packet_id = coded->first_crc;
1753	}
1754
1755	batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1756	index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1757
1758	/* Search for matching coding path */
1759	rcu_read_lock();
1760	hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1761		/* Find matching nc_packet */
1762		spin_lock_bh(&nc_path->packet_list_lock);
1763		list_for_each_entry(tmp_nc_packet,
1764				    &nc_path->packet_list, list) {
1765			if (packet_id == tmp_nc_packet->packet_id) {
1766				list_del(&tmp_nc_packet->list);
1767
1768				nc_packet = tmp_nc_packet;
1769				break;
1770			}
1771		}
1772		spin_unlock_bh(&nc_path->packet_list_lock);
1773
1774		if (nc_packet)
1775			break;
1776	}
1777	rcu_read_unlock();
1778
1779	if (!nc_packet)
1780		batadv_dbg(BATADV_DBG_NC, bat_priv,
1781			   "No decoding packet found for %u\n", packet_id);
1782
1783	return nc_packet;
1784}
1785
1786/**
1787 * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the
1788 *  resulting unicast packet
1789 * @skb: incoming coded packet
1790 * @recv_if: pointer to interface this packet was received on
1791 *
1792 * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
1793 * otherwise.
1794 */
1795static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1796				       struct batadv_hard_iface *recv_if)
1797{
1798	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1799	struct batadv_unicast_packet *unicast_packet;
1800	struct batadv_coded_packet *coded_packet;
1801	struct batadv_nc_packet *nc_packet;
1802	struct ethhdr *ethhdr;
1803	int hdr_size = sizeof(*coded_packet);
1804
1805	/* Check if network coding is enabled */
1806	if (!atomic_read(&bat_priv->network_coding))
1807		goto free_skb;
1808
1809	/* Make sure we can access (and remove) header */
1810	if (unlikely(!pskb_may_pull(skb, hdr_size)))
1811		goto free_skb;
1812
1813	coded_packet = (struct batadv_coded_packet *)skb->data;
1814	ethhdr = eth_hdr(skb);
1815
1816	/* Verify frame is destined for us */
1817	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1818	    !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1819		goto free_skb;
1820
1821	/* Update stat counter */
1822	if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1823		batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1824
1825	nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1826						   coded_packet);
1827	if (!nc_packet) {
1828		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1829		goto free_skb;
1830	}
1831
1832	/* Make skb's linear, because decoding accesses the entire buffer */
1833	if (skb_linearize(skb) < 0)
1834		goto free_nc_packet;
1835
1836	if (skb_linearize(nc_packet->skb) < 0)
1837		goto free_nc_packet;
1838
1839	/* Decode the packet */
1840	unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1841	if (!unicast_packet) {
1842		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1843		goto free_nc_packet;
1844	}
1845
1846	/* Mark packet as decoded to do correct recoding when forwarding */
1847	BATADV_SKB_CB(skb)->decoded = true;
1848	batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1849	batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1850			   skb->len + ETH_HLEN);
1851	return batadv_recv_unicast_packet(skb, recv_if);
1852
1853free_nc_packet:
1854	batadv_nc_packet_free(nc_packet, true);
1855free_skb:
1856	kfree_skb(skb);
1857
1858	return NET_RX_DROP;
1859}
1860
1861/**
1862 * batadv_nc_mesh_free() - clean up network coding memory
1863 * @bat_priv: the bat priv with all the soft interface information
1864 */
1865void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1866{
1867	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1868	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1869	cancel_delayed_work_sync(&bat_priv->nc.work);
1870
1871	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1872	batadv_hash_destroy(bat_priv->nc.coding_hash);
1873	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1874	batadv_hash_destroy(bat_priv->nc.decoding_hash);
1875}