Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1873 insertions, 0 deletions

diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c
new file mode 100644
index 0000000000..71ebd0284f
--- /dev/null
+++ b/net/batman-adv/network-coding.c
@@ -0,0 +1,1873 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) B.A.T.M.A.N. contributors:
+ *
+ * Martin Hundebøll, Jeppe Ledet-Pedersen
+ */
+
+#include "network-coding.h"
+#include "main.h"
+
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/byteorder/generic.h>
+#include <linux/compiler.h>
+#include <linux/container_of.h>
+#include <linux/errno.h>
+#include <linux/etherdevice.h>
+#include <linux/gfp.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/init.h>
+#include <linux/jhash.h>
+#include <linux/jiffies.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/printk.h>
+#include <linux/random.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/stddef.h>
+#include <linux/string.h>
+#include <linux/workqueue.h>
+#include <uapi/linux/batadv_packet.h>
+
+#include "hash.h"
+#include "log.h"
+#include "originator.h"
+#include "routing.h"
+#include "send.h"
+#include "tvlv.h"
+
+static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
+static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
+
+static void batadv_nc_worker(struct work_struct *work);
+static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
+				       struct batadv_hard_iface *recv_if);
+
+/**
+ * batadv_nc_init() - one-time initialization for network coding
+ *
+ * Return: 0 on success or negative error number in case of failure
+ */
+int __init batadv_nc_init(void)
+{
+	/* Register our packet type */
+	return batadv_recv_handler_register(BATADV_CODED,
+					    batadv_nc_recv_coded_packet);
+}
+
+/**
+ * batadv_nc_start_timer() - initialise the nc periodic worker
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
+{
+	queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
+			   msecs_to_jiffies(10));
+}
+
+/**
+ * batadv_nc_tvlv_container_update() - update the network coding tvlv container
+ *  after network coding setting change
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
+{
+	char nc_mode;
+
+	nc_mode = atomic_read(&bat_priv->network_coding);
+
+	switch (nc_mode) {
+	case 0:
+		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
+		break;
+	case 1:
+		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
+					       NULL, 0);
+		break;
+	}
+}
+
+/**
+ * batadv_nc_status_update() - update the network coding tvlv container after
+ *  network coding setting change
+ * @net_dev: the soft interface net device
+ */
+void batadv_nc_status_update(struct net_device *net_dev)
+{
+	struct batadv_priv *bat_priv = netdev_priv(net_dev);
+
+	batadv_nc_tvlv_container_update(bat_priv);
+}
+
+/**
+ * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig: the orig_node of the ogm
+ * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
+ * @tvlv_value: tvlv buffer containing the gateway data
+ * @tvlv_value_len: tvlv buffer length
+ */
+static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
+					  struct batadv_orig_node *orig,
+					  u8 flags,
+					  void *tvlv_value, u16 tvlv_value_len)
+{
+	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
+		clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
+	else
+		set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
+}
+
+/**
+ * batadv_nc_mesh_init() - initialise coding hash table and start housekeeping
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Return: 0 on success or negative error number in case of failure
+ */
+int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
+{
+	bat_priv->nc.timestamp_fwd_flush = jiffies;
+	bat_priv->nc.timestamp_sniffed_purge = jiffies;
+
+	if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
+		return 0;
+
+	bat_priv->nc.coding_hash = batadv_hash_new(128);
+	if (!bat_priv->nc.coding_hash)
+		goto err;
+
+	batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
+				   &batadv_nc_coding_hash_lock_class_key);
+
+	bat_priv->nc.decoding_hash = batadv_hash_new(128);
+	if (!bat_priv->nc.decoding_hash) {
+		batadv_hash_destroy(bat_priv->nc.coding_hash);
+		goto err;
+	}
+
+	batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
+				   &batadv_nc_decoding_hash_lock_class_key);
+
+	INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
+	batadv_nc_start_timer(bat_priv);
+
+	batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
+				     NULL, NULL, BATADV_TVLV_NC, 1,
+				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
+	batadv_nc_tvlv_container_update(bat_priv);
+	return 0;
+
+err:
+	return -ENOMEM;
+}
+
+/**
+ * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
+{
+	atomic_set(&bat_priv->network_coding, 0);
+	bat_priv->nc.min_tq = 200;
+	bat_priv->nc.max_fwd_delay = 10;
+	bat_priv->nc.max_buffer_time = 200;
+}
+
+/**
+ * batadv_nc_init_orig() - initialise the nc fields of an orig_node
+ * @orig_node: the orig_node which is going to be initialised
+ */
+void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
+{
+	INIT_LIST_HEAD(&orig_node->in_coding_list);
+	INIT_LIST_HEAD(&orig_node->out_coding_list);
+	spin_lock_init(&orig_node->in_coding_list_lock);
+	spin_lock_init(&orig_node->out_coding_list_lock);
+}
+
+/**
+ * batadv_nc_node_release() - release nc_node from lists and queue for free
+ *  after rcu grace period
+ * @ref: kref pointer of the nc_node
+ */
+static void batadv_nc_node_release(struct kref *ref)
+{
+	struct batadv_nc_node *nc_node;
+
+	nc_node = container_of(ref, struct batadv_nc_node, refcount);
+
+	batadv_orig_node_put(nc_node->orig_node);
+	kfree_rcu(nc_node, rcu);
+}
+
+/**
+ * batadv_nc_node_put() - decrement the nc_node refcounter and possibly
+ *  release it
+ * @nc_node: nc_node to be free'd
+ */
+static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
+{
+	if (!nc_node)
+		return;
+
+	kref_put(&nc_node->refcount, batadv_nc_node_release);
+}
+
+/**
+ * batadv_nc_path_release() - release nc_path from lists and queue for free
+ *  after rcu grace period
+ * @ref: kref pointer of the nc_path
+ */
+static void batadv_nc_path_release(struct kref *ref)
+{
+	struct batadv_nc_path *nc_path;
+
+	nc_path = container_of(ref, struct batadv_nc_path, refcount);
+
+	kfree_rcu(nc_path, rcu);
+}
+
+/**
+ * batadv_nc_path_put() - decrement the nc_path refcounter and possibly
+ *  release it
+ * @nc_path: nc_path to be free'd
+ */
+static void batadv_nc_path_put(struct batadv_nc_path *nc_path)
+{
+	if (!nc_path)
+		return;
+
+	kref_put(&nc_path->refcount, batadv_nc_path_release);
+}
+
+/**
+ * batadv_nc_packet_free() - frees nc packet
+ * @nc_packet: the nc packet to free
+ * @dropped: whether the packet is freed because is dropped
+ */
+static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
+				  bool dropped)
+{
+	if (dropped)
+		kfree_skb(nc_packet->skb);
+	else
+		consume_skb(nc_packet->skb);
+
+	batadv_nc_path_put(nc_packet->nc_path);
+	kfree(nc_packet);
+}
+
+/**
+ * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged
+ * @bat_priv: the bat priv with all the soft interface information
+ * @nc_node: the nc node to check
+ *
+ * Return: true if the entry has to be purged now, false otherwise
+ */
+static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
+				       struct batadv_nc_node *nc_node)
+{
+	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
+		return true;
+
+	return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
+}
+
+/**
+ * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out
+ * @bat_priv: the bat priv with all the soft interface information
+ * @nc_path: the nc path to check
+ *
+ * Return: true if the entry has to be purged now, false otherwise
+ */
+static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
+					      struct batadv_nc_path *nc_path)
+{
+	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
+		return true;
+
+	/* purge the path when no packets has been added for 10 times the
+	 * max_fwd_delay time
+	 */
+	return batadv_has_timed_out(nc_path->last_valid,
+				    bat_priv->nc.max_fwd_delay * 10);
+}
+
+/**
+ * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed
+ *  out
+ * @bat_priv: the bat priv with all the soft interface information
+ * @nc_path: the nc path to check
+ *
+ * Return: true if the entry has to be purged now, false otherwise
+ */
+static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
+						struct batadv_nc_path *nc_path)
+{
+	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
+		return true;
+
+	/* purge the path when no packets has been added for 10 times the
+	 * max_buffer time
+	 */
+	return batadv_has_timed_out(nc_path->last_valid,
+				    bat_priv->nc.max_buffer_time * 10);
+}
+
+/**
+ * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale
+ *  entries
+ * @bat_priv: the bat priv with all the soft interface information
+ * @list: list of nc nodes
+ * @lock: nc node list lock
+ * @to_purge: function in charge to decide whether an entry has to be purged or
+ *	      not. This function takes the nc node as argument and has to return
+ *	      a boolean value: true if the entry has to be deleted, false
+ *	      otherwise
+ */
+static void
+batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
+			      struct list_head *list,
+			      spinlock_t *lock,
+			      bool (*to_purge)(struct batadv_priv *,
+					       struct batadv_nc_node *))
+{
+	struct batadv_nc_node *nc_node, *nc_node_tmp;
+
+	/* For each nc_node in list */
+	spin_lock_bh(lock);
+	list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
+		/* if an helper function has been passed as parameter,
+		 * ask it if the entry has to be purged or not
+		 */
+		if (to_purge && !to_purge(bat_priv, nc_node))
+			continue;
+
+		batadv_dbg(BATADV_DBG_NC, bat_priv,
+			   "Removing nc_node %pM -> %pM\n",
+			   nc_node->addr, nc_node->orig_node->orig);
+		list_del_rcu(&nc_node->list);
+		batadv_nc_node_put(nc_node);
+	}
+	spin_unlock_bh(lock);
+}
+
+/**
+ * batadv_nc_purge_orig() - purges all nc node data attached of the given
+ *  originator
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: orig_node with the nc node entries to be purged
+ * @to_purge: function in charge to decide whether an entry has to be purged or
+ *	      not. This function takes the nc node as argument and has to return
+ *	      a boolean value: true is the entry has to be deleted, false
+ *	      otherwise
+ */
+void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
+			  struct batadv_orig_node *orig_node,
+			  bool (*to_purge)(struct batadv_priv *,
+					   struct batadv_nc_node *))
+{
+	/* Check ingoing nc_node's of this orig_node */
+	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
+				      &orig_node->in_coding_list_lock,
+				      to_purge);
+
+	/* Check outgoing nc_node's of this orig_node */
+	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
+				      &orig_node->out_coding_list_lock,
+				      to_purge);
+}
+
+/**
+ * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if
+ *  they have timed out nc nodes
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
+{
+	struct batadv_hashtable *hash = bat_priv->orig_hash;
+	struct hlist_head *head;
+	struct batadv_orig_node *orig_node;
+	u32 i;
+
+	if (!hash)
+		return;
+
+	/* For each orig_node */
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(orig_node, head, hash_entry)
+			batadv_nc_purge_orig(bat_priv, orig_node,
+					     batadv_nc_to_purge_nc_node);
+		rcu_read_unlock();
+	}
+}
+
+/**
+ * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove
+ *  unused ones
+ * @bat_priv: the bat priv with all the soft interface information
+ * @hash: hash table containing the nc paths to check
+ * @to_purge: function in charge to decide whether an entry has to be purged or
+ *	      not. This function takes the nc node as argument and has to return
+ *	      a boolean value: true is the entry has to be deleted, false
+ *	      otherwise
+ */
+static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
+				  struct batadv_hashtable *hash,
+				  bool (*to_purge)(struct batadv_priv *,
+						   struct batadv_nc_path *))
+{
+	struct hlist_head *head;
+	struct hlist_node *node_tmp;
+	struct batadv_nc_path *nc_path;
+	spinlock_t *lock; /* Protects lists in hash */
+	u32 i;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+		lock = &hash->list_locks[i];
+
+		/* For each nc_path in this bin */
+		spin_lock_bh(lock);
+		hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
+			/* if an helper function has been passed as parameter,
+			 * ask it if the entry has to be purged or not
+			 */
+			if (to_purge && !to_purge(bat_priv, nc_path))
+				continue;
+
+			/* purging an non-empty nc_path should never happen, but
+			 * is observed under high CPU load. Delay the purging
+			 * until next iteration to allow the packet_list to be
+			 * emptied first.
+			 */
+			if (!unlikely(list_empty(&nc_path->packet_list))) {
+				net_ratelimited_function(printk,
+							 KERN_WARNING
+							 "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
+							 nc_path->prev_hop,
+							 nc_path->next_hop);
+				continue;
+			}
+
+			/* nc_path is unused, so remove it */
+			batadv_dbg(BATADV_DBG_NC, bat_priv,
+				   "Remove nc_path %pM -> %pM\n",
+				   nc_path->prev_hop, nc_path->next_hop);
+			hlist_del_rcu(&nc_path->hash_entry);
+			batadv_nc_path_put(nc_path);
+		}
+		spin_unlock_bh(lock);
+	}
+}
+
+/**
+ * batadv_nc_hash_key_gen() - computes the nc_path hash key
+ * @key: buffer to hold the final hash key
+ * @src: source ethernet mac address going into the hash key
+ * @dst: destination ethernet mac address going into the hash key
+ */
+static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
+				   const char *dst)
+{
+	memcpy(key->prev_hop, src, sizeof(key->prev_hop));
+	memcpy(key->next_hop, dst, sizeof(key->next_hop));
+}
+
+/**
+ * batadv_nc_hash_choose() - compute the hash value for an nc path
+ * @data: data to hash
+ * @size: size of the hash table
+ *
+ * Return: the selected index in the hash table for the given data.
+ */
+static u32 batadv_nc_hash_choose(const void *data, u32 size)
+{
+	const struct batadv_nc_path *nc_path = data;
+	u32 hash = 0;
+
+	hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
+	hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
+
+	return hash % size;
+}
+
+/**
+ * batadv_nc_hash_compare() - comparing function used in the network coding hash
+ *  tables
+ * @node: node in the local table
+ * @data2: second object to compare the node to
+ *
+ * Return: true if the two entry are the same, false otherwise
+ */
+static bool batadv_nc_hash_compare(const struct hlist_node *node,
+				   const void *data2)
+{
+	const struct batadv_nc_path *nc_path1, *nc_path2;
+
+	nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
+	nc_path2 = data2;
+
+	/* Return 1 if the two keys are identical */
+	if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
+		return false;
+
+	if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_nc_hash_find() - search for an existing nc path and return it
+ * @hash: hash table containing the nc path
+ * @data: search key
+ *
+ * Return: the nc_path if found, NULL otherwise.
+ */
+static struct batadv_nc_path *
+batadv_nc_hash_find(struct batadv_hashtable *hash,
+		    void *data)
+{
+	struct hlist_head *head;
+	struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
+	int index;
+
+	if (!hash)
+		return NULL;
+
+	index = batadv_nc_hash_choose(data, hash->size);
+	head = &hash->table[index];
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
+		if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
+			continue;
+
+		if (!kref_get_unless_zero(&nc_path->refcount))
+			continue;
+
+		nc_path_tmp = nc_path;
+		break;
+	}
+	rcu_read_unlock();
+
+	return nc_path_tmp;
+}
+
+/**
+ * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct
+ * @nc_packet: the nc packet to send
+ */
+static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
+{
+	batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
+	nc_packet->skb = NULL;
+	batadv_nc_packet_free(nc_packet, false);
+}
+
+/**
+ * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet.
+ * @bat_priv: the bat priv with all the soft interface information
+ * @nc_path: the nc path the packet belongs to
+ * @nc_packet: the nc packet to be checked
+ *
+ * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
+ * timeout. If so, the packet is no longer kept and the entry deleted from the
+ * queue. Has to be called with the appropriate locks.
+ *
+ * Return: false as soon as the entry in the fifo queue has not been timed out
+ * yet and true otherwise.
+ */
+static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
+				    struct batadv_nc_path *nc_path,
+				    struct batadv_nc_packet *nc_packet)
+{
+	unsigned long timeout = bat_priv->nc.max_buffer_time;
+	bool res = false;
+
+	lockdep_assert_held(&nc_path->packet_list_lock);
+
+	/* Packets are added to tail, so the remaining packets did not time
+	 * out and we can stop processing the current queue
+	 */
+	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
+	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
+		goto out;
+
+	/* purge nc packet */
+	list_del(&nc_packet->list);
+	batadv_nc_packet_free(nc_packet, true);
+
+	res = true;
+
+out:
+	return res;
+}
+
+/**
+ * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet.
+ * @bat_priv: the bat priv with all the soft interface information
+ * @nc_path: the nc path the packet belongs to
+ * @nc_packet: the nc packet to be checked
+ *
+ * Checks whether the given nc packet has hit its forward timeout. If so, the
+ * packet is no longer delayed, immediately sent and the entry deleted from the
+ * queue. Has to be called with the appropriate locks.
+ *
+ * Return: false as soon as the entry in the fifo queue has not been timed out
+ * yet and true otherwise.
+ */
+static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
+				struct batadv_nc_path *nc_path,
+				struct batadv_nc_packet *nc_packet)
+{
+	unsigned long timeout = bat_priv->nc.max_fwd_delay;
+
+	lockdep_assert_held(&nc_path->packet_list_lock);
+
+	/* Packets are added to tail, so the remaining packets did not time
+	 * out and we can stop processing the current queue
+	 */
+	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
+	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
+		return false;
+
+	/* Send packet */
+	batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
+	batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
+			   nc_packet->skb->len + ETH_HLEN);
+	list_del(&nc_packet->list);
+	batadv_nc_send_packet(nc_packet);
+
+	return true;
+}
+
+/**
+ * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed
+ *  out nc packets
+ * @bat_priv: the bat priv with all the soft interface information
+ * @hash: to be processed hash table
+ * @process_fn: Function called to process given nc packet. Should return true
+ *	        to encourage this function to proceed with the next packet.
+ *	        Otherwise the rest of the current queue is skipped.
+ */
+static void
+batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
+			   struct batadv_hashtable *hash,
+			   bool (*process_fn)(struct batadv_priv *,
+					      struct batadv_nc_path *,
+					      struct batadv_nc_packet *))
+{
+	struct hlist_head *head;
+	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
+	struct batadv_nc_path *nc_path;
+	bool ret;
+	int i;
+
+	if (!hash)
+		return;
+
+	/* Loop hash table bins */
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		/* Loop coding paths */
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
+			/* Loop packets */
+			spin_lock_bh(&nc_path->packet_list_lock);
+			list_for_each_entry_safe(nc_packet, nc_packet_tmp,
+						 &nc_path->packet_list, list) {
+				ret = process_fn(bat_priv, nc_path, nc_packet);
+				if (!ret)
+					break;
+			}
+			spin_unlock_bh(&nc_path->packet_list_lock);
+		}
+		rcu_read_unlock();
+	}
+}
+
+/**
+ * batadv_nc_worker() - periodic task for housekeeping related to network
+ *  coding
+ * @work: kernel work struct
+ */
+static void batadv_nc_worker(struct work_struct *work)
+{
+	struct delayed_work *delayed_work;
+	struct batadv_priv_nc *priv_nc;
+	struct batadv_priv *bat_priv;
+	unsigned long timeout;
+
+	delayed_work = to_delayed_work(work);
+	priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
+	bat_priv = container_of(priv_nc, struct batadv_priv, nc);
+
+	batadv_nc_purge_orig_hash(bat_priv);
+	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
+			      batadv_nc_to_purge_nc_path_coding);
+	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
+			      batadv_nc_to_purge_nc_path_decoding);
+
+	timeout = bat_priv->nc.max_fwd_delay;
+
+	if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
+		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
+					   batadv_nc_fwd_flush);
+		bat_priv->nc.timestamp_fwd_flush = jiffies;
+	}
+
+	if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
+				 bat_priv->nc.max_buffer_time)) {
+		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
+					   batadv_nc_sniffed_purge);
+		bat_priv->nc.timestamp_sniffed_purge = jiffies;
+	}
+
+	/* Schedule a new check */
+	batadv_nc_start_timer(bat_priv);
+}
+
+/**
+ * batadv_can_nc_with_orig() - checks whether the given orig node is suitable
+ *  for coding or not
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: neighboring orig node which may be used as nc candidate
+ * @ogm_packet: incoming ogm packet also used for the checks
+ *
+ * Return: true if:
+ *  1) The OGM must have the most recent sequence number.
+ *  2) The TTL must be decremented by one and only one.
+ *  3) The OGM must be received from the first hop from orig_node.
+ *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
+ */
+static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
+				    struct batadv_orig_node *orig_node,
+				    struct batadv_ogm_packet *ogm_packet)
+{
+	struct batadv_orig_ifinfo *orig_ifinfo;
+	u32 last_real_seqno;
+	u8 last_ttl;
+
+	orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
+	if (!orig_ifinfo)
+		return false;
+
+	last_ttl = orig_ifinfo->last_ttl;
+	last_real_seqno = orig_ifinfo->last_real_seqno;
+	batadv_orig_ifinfo_put(orig_ifinfo);
+
+	if (last_real_seqno != ntohl(ogm_packet->seqno))
+		return false;
+	if (last_ttl != ogm_packet->ttl + 1)
+		return false;
+	if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
+		return false;
+	if (ogm_packet->tq < bat_priv->nc.min_tq)
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_nc_find_nc_node() - search for an existing nc node and return it
+ * @orig_node: orig node originating the ogm packet
+ * @orig_neigh_node: neighboring orig node from which we received the ogm packet
+ *  (can be equal to orig_node)
+ * @in_coding: traverse incoming or outgoing network coding list
+ *
+ * Return: the nc_node if found, NULL otherwise.
+ */
+static struct batadv_nc_node *
+batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
+		       struct batadv_orig_node *orig_neigh_node,
+		       bool in_coding)
+{
+	struct batadv_nc_node *nc_node, *nc_node_out = NULL;
+	struct list_head *list;
+
+	if (in_coding)
+		list = &orig_neigh_node->in_coding_list;
+	else
+		list = &orig_neigh_node->out_coding_list;
+
+	/* Traverse list of nc_nodes to orig_node */
+	rcu_read_lock();
+	list_for_each_entry_rcu(nc_node, list, list) {
+		if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
+			continue;
+
+		if (!kref_get_unless_zero(&nc_node->refcount))
+			continue;
+
+		/* Found a match */
+		nc_node_out = nc_node;
+		break;
+	}
+	rcu_read_unlock();
+
+	return nc_node_out;
+}
+
+/**
+ * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was
+ *  not found
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: orig node originating the ogm packet
+ * @orig_neigh_node: neighboring orig node from which we received the ogm packet
+ *  (can be equal to orig_node)
+ * @in_coding: traverse incoming or outgoing network coding list
+ *
+ * Return: the nc_node if found or created, NULL in case of an error.
+ */
+static struct batadv_nc_node *
+batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
+		      struct batadv_orig_node *orig_node,
+		      struct batadv_orig_node *orig_neigh_node,
+		      bool in_coding)
+{
+	struct batadv_nc_node *nc_node;
+	spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
+	struct list_head *list;
+
+	/* Select ingoing or outgoing coding node */
+	if (in_coding) {
+		lock = &orig_neigh_node->in_coding_list_lock;
+		list = &orig_neigh_node->in_coding_list;
+	} else {
+		lock = &orig_neigh_node->out_coding_list_lock;
+		list = &orig_neigh_node->out_coding_list;
+	}
+
+	spin_lock_bh(lock);
+
+	/* Check if nc_node is already added */
+	nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
+
+	/* Node found */
+	if (nc_node)
+		goto unlock;
+
+	nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
+	if (!nc_node)
+		goto unlock;
+
+	/* Initialize nc_node */
+	INIT_LIST_HEAD(&nc_node->list);
+	kref_init(&nc_node->refcount);
+	ether_addr_copy(nc_node->addr, orig_node->orig);
+	kref_get(&orig_neigh_node->refcount);
+	nc_node->orig_node = orig_neigh_node;
+
+	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
+		   nc_node->addr, nc_node->orig_node->orig);
+
+	/* Add nc_node to orig_node */
+	kref_get(&nc_node->refcount);
+	list_add_tail_rcu(&nc_node->list, list);
+
+unlock:
+	spin_unlock_bh(lock);
+
+	return nc_node;
+}
+
+/**
+ * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node
+ *  structs (best called on incoming OGMs)
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_node: orig node originating the ogm packet
+ * @orig_neigh_node: neighboring orig node from which we received the ogm packet
+ *  (can be equal to orig_node)
+ * @ogm_packet: incoming ogm packet
+ * @is_single_hop_neigh: orig_node is a single hop neighbor
+ */
+void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
+			      struct batadv_orig_node *orig_node,
+			      struct batadv_orig_node *orig_neigh_node,
+			      struct batadv_ogm_packet *ogm_packet,
+			      int is_single_hop_neigh)
+{
+	struct batadv_nc_node *in_nc_node = NULL;
+	struct batadv_nc_node *out_nc_node = NULL;
+
+	/* Check if network coding is enabled */
+	if (!atomic_read(&bat_priv->network_coding))
+		goto out;
+
+	/* check if orig node is network coding enabled */
+	if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
+		goto out;
+
+	/* accept ogms from 'good' neighbors and single hop neighbors */
+	if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
+	    !is_single_hop_neigh)
+		goto out;
+
+	/* Add orig_node as in_nc_node on hop */
+	in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
+					   orig_neigh_node, true);
+	if (!in_nc_node)
+		goto out;
+
+	in_nc_node->last_seen = jiffies;
+
+	/* Add hop as out_nc_node on orig_node */
+	out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
+					    orig_node, false);
+	if (!out_nc_node)
+		goto out;
+
+	out_nc_node->last_seen = jiffies;
+
+out:
+	batadv_nc_node_put(in_nc_node);
+	batadv_nc_node_put(out_nc_node);
+}
+
+/**
+ * batadv_nc_get_path() - get existing nc_path or allocate a new one
+ * @bat_priv: the bat priv with all the soft interface information
+ * @hash: hash table containing the nc path
+ * @src: ethernet source address - first half of the nc path search key
+ * @dst: ethernet destination address - second half of the nc path search key
+ *
+ * Return: pointer to nc_path if the path was found or created, returns NULL
+ * on error.
+ */
+static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
+						 struct batadv_hashtable *hash,
+						 u8 *src,
+						 u8 *dst)
+{
+	int hash_added;
+	struct batadv_nc_path *nc_path, nc_path_key;
+
+	batadv_nc_hash_key_gen(&nc_path_key, src, dst);
+
+	/* Search for existing nc_path */
+	nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
+
+	if (nc_path) {
+		/* Set timestamp to delay removal of nc_path */
+		nc_path->last_valid = jiffies;
+		return nc_path;
+	}
+
+	/* No existing nc_path was found; create a new */
+	nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
+
+	if (!nc_path)
+		return NULL;
+
+	/* Initialize nc_path */
+	INIT_LIST_HEAD(&nc_path->packet_list);
+	spin_lock_init(&nc_path->packet_list_lock);
+	kref_init(&nc_path->refcount);
+	nc_path->last_valid = jiffies;
+	ether_addr_copy(nc_path->next_hop, dst);
+	ether_addr_copy(nc_path->prev_hop, src);
+
+	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
+		   nc_path->prev_hop,
+		   nc_path->next_hop);
+
+	/* Add nc_path to hash table */
+	kref_get(&nc_path->refcount);
+	hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
+				     batadv_nc_hash_choose, &nc_path_key,
+				     &nc_path->hash_entry);
+
+	if (hash_added < 0) {
+		kfree(nc_path);
+		return NULL;
+	}
+
+	return nc_path;
+}
+
+/**
+ * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair
+ *  selection of a receiver with slightly lower TQ than the other
+ * @tq: to be weighted tq value
+ *
+ * Return: scaled tq value
+ */
+static u8 batadv_nc_random_weight_tq(u8 tq)
+{
+	/* randomize the estimated packet loss (max TQ - estimated TQ) */
+	u8 rand_tq = get_random_u32_below(BATADV_TQ_MAX_VALUE + 1 - tq);
+
+	/* convert to (randomized) estimated tq again */
+	return BATADV_TQ_MAX_VALUE - rand_tq;
+}
+
+/**
+ * batadv_nc_memxor() - XOR destination with source
+ * @dst: byte array to XOR into
+ * @src: byte array to XOR from
+ * @len: length of destination array
+ */
+static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
+{
+	unsigned int i;
+
+	for (i = 0; i < len; ++i)
+		dst[i] ^= src[i];
+}
+
+/**
+ * batadv_nc_code_packets() - code a received unicast_packet with an nc packet
+ *  into a coded_packet and send it
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: data skb to forward
+ * @ethhdr: pointer to the ethernet header inside the skb
+ * @nc_packet: structure containing the packet to the skb can be coded with
+ * @neigh_node: next hop to forward packet to
+ *
+ * Return: true if both packets are consumed, false otherwise.
+ */
+static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
+				   struct sk_buff *skb,
+				   struct ethhdr *ethhdr,
+				   struct batadv_nc_packet *nc_packet,
+				   struct batadv_neigh_node *neigh_node)
+{
+	u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
+	struct sk_buff *skb_dest, *skb_src;
+	struct batadv_unicast_packet *packet1;
+	struct batadv_unicast_packet *packet2;
+	struct batadv_coded_packet *coded_packet;
+	struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
+	struct batadv_neigh_node *router_coding = NULL, *second_dest;
+	struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
+	struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
+	u8 *first_source, *second_source;
+	__be32 packet_id1, packet_id2;
+	size_t count;
+	bool res = false;
+	int coding_len;
+	int unicast_size = sizeof(*packet1);
+	int coded_size = sizeof(*coded_packet);
+	int header_add = coded_size - unicast_size;
+
+	/* TODO: do we need to consider the outgoing interface for
+	 * coded packets?
+	 */
+	router_neigh = batadv_orig_router_get(neigh_node->orig_node,
+					      BATADV_IF_DEFAULT);
+	if (!router_neigh)
+		goto out;
+
+	router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
+						      BATADV_IF_DEFAULT);
+	if (!router_neigh_ifinfo)
+		goto out;
+
+	neigh_tmp = nc_packet->neigh_node;
+	router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
+					       BATADV_IF_DEFAULT);
+	if (!router_coding)
+		goto out;
+
+	router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
+						       BATADV_IF_DEFAULT);
+	if (!router_coding_ifinfo)
+		goto out;
+
+	tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
+	tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
+	tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
+	tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
+
+	/* Select one destination for the MAC-header dst-field based on
+	 * weighted TQ-values.
+	 */
+	if (tq_weighted_neigh >= tq_weighted_coding) {
+		/* Destination from nc_packet is selected for MAC-header */
+		first_dest = nc_packet->neigh_node;
+		first_source = nc_packet->nc_path->prev_hop;
+		second_dest = neigh_node;
+		second_source = ethhdr->h_source;
+		packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
+		packet2 = (struct batadv_unicast_packet *)skb->data;
+		packet_id1 = nc_packet->packet_id;
+		packet_id2 = batadv_skb_crc32(skb,
+					      skb->data + sizeof(*packet2));
+	} else {
+		/* Destination for skb is selected for MAC-header */
+		first_dest = neigh_node;
+		first_source = ethhdr->h_source;
+		second_dest = nc_packet->neigh_node;
+		second_source = nc_packet->nc_path->prev_hop;
+		packet1 = (struct batadv_unicast_packet *)skb->data;
+		packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
+		packet_id1 = batadv_skb_crc32(skb,
+					      skb->data + sizeof(*packet1));
+		packet_id2 = nc_packet->packet_id;
+	}
+
+	/* Instead of zero padding the smallest data buffer, we
+	 * code into the largest.
+	 */
+	if (skb->len <= nc_packet->skb->len) {
+		skb_dest = nc_packet->skb;
+		skb_src = skb;
+	} else {
+		skb_dest = skb;
+		skb_src = nc_packet->skb;
+	}
+
+	/* coding_len is used when decoding the packet shorter packet */
+	coding_len = skb_src->len - unicast_size;
+
+	if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
+		goto out;
+
+	skb_push(skb_dest, header_add);
+
+	coded_packet = (struct batadv_coded_packet *)skb_dest->data;
+	skb_reset_mac_header(skb_dest);
+
+	coded_packet->packet_type = BATADV_CODED;
+	coded_packet->version = BATADV_COMPAT_VERSION;
+	coded_packet->ttl = packet1->ttl;
+
+	/* Info about first unicast packet */
+	ether_addr_copy(coded_packet->first_source, first_source);
+	ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
+	coded_packet->first_crc = packet_id1;
+	coded_packet->first_ttvn = packet1->ttvn;
+
+	/* Info about second unicast packet */
+	ether_addr_copy(coded_packet->second_dest, second_dest->addr);
+	ether_addr_copy(coded_packet->second_source, second_source);
+	ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
+	coded_packet->second_crc = packet_id2;
+	coded_packet->second_ttl = packet2->ttl;
+	coded_packet->second_ttvn = packet2->ttvn;
+	coded_packet->coded_len = htons(coding_len);
+
+	/* This is where the magic happens: Code skb_src into skb_dest */
+	batadv_nc_memxor(skb_dest->data + coded_size,
+			 skb_src->data + unicast_size, coding_len);
+
+	/* Update counters accordingly */
+	if (BATADV_SKB_CB(skb_src)->decoded &&
+	    BATADV_SKB_CB(skb_dest)->decoded) {
+		/* Both packets are recoded */
+		count = skb_src->len + ETH_HLEN;
+		count += skb_dest->len + ETH_HLEN;
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
+	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
+		   !BATADV_SKB_CB(skb_dest)->decoded) {
+		/* Both packets are newly coded */
+		count = skb_src->len + ETH_HLEN;
+		count += skb_dest->len + ETH_HLEN;
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
+	} else if (BATADV_SKB_CB(skb_src)->decoded &&
+		   !BATADV_SKB_CB(skb_dest)->decoded) {
+		/* skb_src recoded and skb_dest is newly coded */
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
+				   skb_src->len + ETH_HLEN);
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
+				   skb_dest->len + ETH_HLEN);
+	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
+		   BATADV_SKB_CB(skb_dest)->decoded) {
+		/* skb_src is newly coded and skb_dest is recoded */
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
+				   skb_src->len + ETH_HLEN);
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
+		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
+				   skb_dest->len + ETH_HLEN);
+	}
+
+	/* skb_src is now coded into skb_dest, so free it */
+	consume_skb(skb_src);
+
+	/* avoid duplicate free of skb from nc_packet */
+	nc_packet->skb = NULL;
+	batadv_nc_packet_free(nc_packet, false);
+
+	/* Send the coded packet and return true */
+	batadv_send_unicast_skb(skb_dest, first_dest);
+	res = true;
+out:
+	batadv_neigh_node_put(router_neigh);
+	batadv_neigh_node_put(router_coding);
+	batadv_neigh_ifinfo_put(router_neigh_ifinfo);
+	batadv_neigh_ifinfo_put(router_coding_ifinfo);
+	return res;
+}
+
+/**
+ * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst.
+ * @skb: data skb to forward
+ * @dst: destination mac address of the other skb to code with
+ * @src: source mac address of skb
+ *
+ * Whenever we network code a packet we have to check whether we received it in
+ * a network coded form. If so, we may not be able to use it for coding because
+ * some neighbors may also have received (overheard) the packet in the network
+ * coded form without being able to decode it. It is hard to know which of the
+ * neighboring nodes was able to decode the packet, therefore we can only
+ * re-code the packet if the source of the previous encoded packet is involved.
+ * Since the source encoded the packet we can be certain it has all necessary
+ * decode information.
+ *
+ * Return: true if coding of a decoded packet is allowed.
+ */
+static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
+{
+	if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
+		return false;
+	return true;
+}
+
+/**
+ * batadv_nc_path_search() - Find the coding path matching in_nc_node and
+ *  out_nc_node to retrieve a buffered packet that can be used for coding.
+ * @bat_priv: the bat priv with all the soft interface information
+ * @in_nc_node: pointer to skb next hop's neighbor nc node
+ * @out_nc_node: pointer to skb source's neighbor nc node
+ * @skb: data skb to forward
+ * @eth_dst: next hop mac address of skb
+ *
+ * Return: true if coding of a decoded skb is allowed.
+ */
+static struct batadv_nc_packet *
+batadv_nc_path_search(struct batadv_priv *bat_priv,
+		      struct batadv_nc_node *in_nc_node,
+		      struct batadv_nc_node *out_nc_node,
+		      struct sk_buff *skb,
+		      u8 *eth_dst)
+{
+	struct batadv_nc_path *nc_path, nc_path_key;
+	struct batadv_nc_packet *nc_packet_out = NULL;
+	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
+	struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
+	int idx;
+
+	if (!hash)
+		return NULL;
+
+	/* Create almost path key */
+	batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
+			       out_nc_node->addr);
+	idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
+
+	/* Check for coding opportunities in this nc_path */
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
+		if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
+			continue;
+
+		if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
+			continue;
+
+		spin_lock_bh(&nc_path->packet_list_lock);
+		if (list_empty(&nc_path->packet_list)) {
+			spin_unlock_bh(&nc_path->packet_list_lock);
+			continue;
+		}
+
+		list_for_each_entry_safe(nc_packet, nc_packet_tmp,
+					 &nc_path->packet_list, list) {
+			if (!batadv_nc_skb_coding_possible(nc_packet->skb,
+							   eth_dst,
+							   in_nc_node->addr))
+				continue;
+
+			/* Coding opportunity is found! */
+			list_del(&nc_packet->list);
+			nc_packet_out = nc_packet;
+			break;
+		}
+
+		spin_unlock_bh(&nc_path->packet_list_lock);
+		break;
+	}
+	rcu_read_unlock();
+
+	return nc_packet_out;
+}
+
+/**
+ * batadv_nc_skb_src_search() - Loops through the list of neighboring nodes of
+ *  the skb's sender (may be equal to the originator).
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: data skb to forward
+ * @eth_dst: next hop mac address of skb
+ * @eth_src: source mac address of skb
+ * @in_nc_node: pointer to skb next hop's neighbor nc node
+ *
+ * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
+ */
+static struct batadv_nc_packet *
+batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
+			 struct sk_buff *skb,
+			 u8 *eth_dst,
+			 u8 *eth_src,
+			 struct batadv_nc_node *in_nc_node)
+{
+	struct batadv_orig_node *orig_node;
+	struct batadv_nc_node *out_nc_node;
+	struct batadv_nc_packet *nc_packet = NULL;
+
+	orig_node = batadv_orig_hash_find(bat_priv, eth_src);
+	if (!orig_node)
+		return NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(out_nc_node,
+				&orig_node->out_coding_list, list) {
+		/* Check if the skb is decoded and if recoding is possible */
+		if (!batadv_nc_skb_coding_possible(skb,
+						   out_nc_node->addr, eth_src))
+			continue;
+
+		/* Search for an opportunity in this nc_path */
+		nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
+						  out_nc_node, skb, eth_dst);
+		if (nc_packet)
+			break;
+	}
+	rcu_read_unlock();
+
+	batadv_orig_node_put(orig_node);
+	return nc_packet;
+}
+
+/**
+ * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the
+ *  unicast skb before it is stored for use in later decoding
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: data skb to store
+ * @eth_dst_new: new destination mac address of skb
+ */
+static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
+					      struct sk_buff *skb,
+					      u8 *eth_dst_new)
+{
+	struct ethhdr *ethhdr;
+
+	/* Copy skb header to change the mac header */
+	skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	/* Set the mac header as if we actually sent the packet uncoded */
+	ethhdr = eth_hdr(skb);
+	ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
+	ether_addr_copy(ethhdr->h_dest, eth_dst_new);
+
+	/* Set data pointer to MAC header to mimic packets from our tx path */
+	skb_push(skb, ETH_HLEN);
+
+	/* Add the packet to the decoding packet pool */
+	batadv_nc_skb_store_for_decoding(bat_priv, skb);
+
+	/* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
+	 * our ref
+	 */
+	consume_skb(skb);
+}
+
+/**
+ * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst.
+ * @skb: data skb to forward
+ * @neigh_node: next hop to forward packet to
+ * @ethhdr: pointer to the ethernet header inside the skb
+ *
+ * Loops through the list of neighboring nodes the next hop has a good
+ * connection to (receives OGMs with a sufficient quality). We need to find a
+ * neighbor of our next hop that potentially sent a packet which our next hop
+ * also received (overheard) and has stored for later decoding.
+ *
+ * Return: true if the skb was consumed (encoded packet sent) or false otherwise
+ */
+static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
+				     struct batadv_neigh_node *neigh_node,
+				     struct ethhdr *ethhdr)
+{
+	struct net_device *netdev = neigh_node->if_incoming->soft_iface;
+	struct batadv_priv *bat_priv = netdev_priv(netdev);
+	struct batadv_orig_node *orig_node = neigh_node->orig_node;
+	struct batadv_nc_node *nc_node;
+	struct batadv_nc_packet *nc_packet = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
+		/* Search for coding opportunity with this in_nc_node */
+		nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
+						     neigh_node->addr,
+						     ethhdr->h_source, nc_node);
+
+		/* Opportunity was found, so stop searching */
+		if (nc_packet)
+			break;
+	}
+	rcu_read_unlock();
+
+	if (!nc_packet)
+		return false;
+
+	/* Save packets for later decoding */
+	batadv_nc_skb_store_before_coding(bat_priv, skb,
+					  neigh_node->addr);
+	batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
+					  nc_packet->neigh_node->addr);
+
+	/* Code and send packets */
+	if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
+				   neigh_node))
+		return true;
+
+	/* out of mem ? Coding failed - we have to free the buffered packet
+	 * to avoid memleaks. The skb passed as argument will be dealt with
+	 * by the calling function.
+	 */
+	batadv_nc_send_packet(nc_packet);
+	return false;
+}
+
+/**
+ * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding
+ * @skb: skb to add to path
+ * @nc_path: path to add skb to
+ * @neigh_node: next hop to forward packet to
+ * @packet_id: checksum to identify packet
+ *
+ * Return: true if the packet was buffered or false in case of an error.
+ */
+static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
+				      struct batadv_nc_path *nc_path,
+				      struct batadv_neigh_node *neigh_node,
+				      __be32 packet_id)
+{
+	struct batadv_nc_packet *nc_packet;
+
+	nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
+	if (!nc_packet)
+		return false;
+
+	/* Initialize nc_packet */
+	nc_packet->timestamp = jiffies;
+	nc_packet->packet_id = packet_id;
+	nc_packet->skb = skb;
+	nc_packet->neigh_node = neigh_node;
+	nc_packet->nc_path = nc_path;
+
+	/* Add coding packet to list */
+	spin_lock_bh(&nc_path->packet_list_lock);
+	list_add_tail(&nc_packet->list, &nc_path->packet_list);
+	spin_unlock_bh(&nc_path->packet_list_lock);
+
+	return true;
+}
+
+/**
+ * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet
+ *  buffer
+ * @skb: data skb to forward
+ * @neigh_node: next hop to forward packet to
+ *
+ * Return: true if the skb was consumed (encoded packet sent) or false otherwise
+ */
+bool batadv_nc_skb_forward(struct sk_buff *skb,
+			   struct batadv_neigh_node *neigh_node)
+{
+	const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
+	struct batadv_priv *bat_priv = netdev_priv(netdev);
+	struct batadv_unicast_packet *packet;
+	struct batadv_nc_path *nc_path;
+	struct ethhdr *ethhdr = eth_hdr(skb);
+	__be32 packet_id;
+	u8 *payload;
+
+	/* Check if network coding is enabled */
+	if (!atomic_read(&bat_priv->network_coding))
+		goto out;
+
+	/* We only handle unicast packets */
+	payload = skb_network_header(skb);
+	packet = (struct batadv_unicast_packet *)payload;
+	if (packet->packet_type != BATADV_UNICAST)
+		goto out;
+
+	/* Try to find a coding opportunity and send the skb if one is found */
+	if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
+		return true;
+
+	/* Find or create a nc_path for this src-dst pair */
+	nc_path = batadv_nc_get_path(bat_priv,
+				     bat_priv->nc.coding_hash,
+				     ethhdr->h_source,
+				     neigh_node->addr);
+
+	if (!nc_path)
+		goto out;
+
+	/* Add skb to nc_path */
+	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
+	if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
+		goto free_nc_path;
+
+	/* Packet is consumed */
+	return true;
+
+free_nc_path:
+	batadv_nc_path_put(nc_path);
+out:
+	/* Packet is not consumed */
+	return false;
+}
+
+/**
+ * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be
+ *  used when decoding coded packets
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: data skb to store
+ */
+void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
+				      struct sk_buff *skb)
+{
+	struct batadv_unicast_packet *packet;
+	struct batadv_nc_path *nc_path;
+	struct ethhdr *ethhdr = eth_hdr(skb);
+	__be32 packet_id;
+	u8 *payload;
+
+	/* Check if network coding is enabled */
+	if (!atomic_read(&bat_priv->network_coding))
+		goto out;
+
+	/* Check for supported packet type */
+	payload = skb_network_header(skb);
+	packet = (struct batadv_unicast_packet *)payload;
+	if (packet->packet_type != BATADV_UNICAST)
+		goto out;
+
+	/* Find existing nc_path or create a new */
+	nc_path = batadv_nc_get_path(bat_priv,
+				     bat_priv->nc.decoding_hash,
+				     ethhdr->h_source,
+				     ethhdr->h_dest);
+
+	if (!nc_path)
+		goto out;
+
+	/* Clone skb and adjust skb->data to point at batman header */
+	skb = skb_clone(skb, GFP_ATOMIC);
+	if (unlikely(!skb))
+		goto free_nc_path;
+
+	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
+		goto free_skb;
+
+	if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
+		goto free_skb;
+
+	/* Add skb to nc_path */
+	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
+	if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
+		goto free_skb;
+
+	batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
+	return;
+
+free_skb:
+	kfree_skb(skb);
+free_nc_path:
+	batadv_nc_path_put(nc_path);
+out:
+	return;
+}
+
+/**
+ * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet
+ *  should be saved in the decoding buffer and, if so, store it there
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: unicast skb to store
+ */
+void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb)
+{
+	struct ethhdr *ethhdr = eth_hdr(skb);
+
+	if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
+		return;
+
+	/* Set data pointer to MAC header to mimic packets from our tx path */
+	skb_push(skb, ETH_HLEN);
+
+	batadv_nc_skb_store_for_decoding(bat_priv, skb);
+}
+
+/**
+ * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored
+ *  in nc_packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: unicast skb to decode
+ * @nc_packet: decode data needed to decode the skb
+ *
+ * Return: pointer to decoded unicast packet if the packet was decoded or NULL
+ * in case of an error.
+ */
+static struct batadv_unicast_packet *
+batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			    struct batadv_nc_packet *nc_packet)
+{
+	const int h_size = sizeof(struct batadv_unicast_packet);
+	const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
+	struct batadv_unicast_packet *unicast_packet;
+	struct batadv_coded_packet coded_packet_tmp;
+	struct ethhdr *ethhdr, ethhdr_tmp;
+	u8 *orig_dest, ttl, ttvn;
+	unsigned int coding_len;
+	int err;
+
+	/* Save headers temporarily */
+	memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
+	memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
+
+	if (skb_cow(skb, 0) < 0)
+		return NULL;
+
+	if (unlikely(!skb_pull_rcsum(skb, h_diff)))
+		return NULL;
+
+	/* Data points to batman header, so set mac header 14 bytes before
+	 * and network to data
+	 */
+	skb_set_mac_header(skb, -ETH_HLEN);
+	skb_reset_network_header(skb);
+
+	/* Reconstruct original mac header */
+	ethhdr = eth_hdr(skb);
+	*ethhdr = ethhdr_tmp;
+
+	/* Select the correct unicast header information based on the location
+	 * of our mac address in the coded_packet header
+	 */
+	if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
+		/* If we are the second destination the packet was overheard,
+		 * so the Ethernet address must be copied to h_dest and
+		 * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
+		 */
+		ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
+		skb->pkt_type = PACKET_HOST;
+
+		orig_dest = coded_packet_tmp.second_orig_dest;
+		ttl = coded_packet_tmp.second_ttl;
+		ttvn = coded_packet_tmp.second_ttvn;
+	} else {
+		orig_dest = coded_packet_tmp.first_orig_dest;
+		ttl = coded_packet_tmp.ttl;
+		ttvn = coded_packet_tmp.first_ttvn;
+	}
+
+	coding_len = ntohs(coded_packet_tmp.coded_len);
+
+	if (coding_len > skb->len)
+		return NULL;
+
+	/* Here the magic is reversed:
+	 *   extract the missing packet from the received coded packet
+	 */
+	batadv_nc_memxor(skb->data + h_size,
+			 nc_packet->skb->data + h_size,
+			 coding_len);
+
+	/* Resize decoded skb if decoded with larger packet */
+	if (nc_packet->skb->len > coding_len + h_size) {
+		err = pskb_trim_rcsum(skb, coding_len + h_size);
+		if (err)
+			return NULL;
+	}
+
+	/* Create decoded unicast packet */
+	unicast_packet = (struct batadv_unicast_packet *)skb->data;
+	unicast_packet->packet_type = BATADV_UNICAST;
+	unicast_packet->version = BATADV_COMPAT_VERSION;
+	unicast_packet->ttl = ttl;
+	ether_addr_copy(unicast_packet->dest, orig_dest);
+	unicast_packet->ttvn = ttvn;
+
+	batadv_nc_packet_free(nc_packet, false);
+	return unicast_packet;
+}
+
+/**
+ * batadv_nc_find_decoding_packet() - search through buffered decoding data to
+ *  find the data needed to decode the coded packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ethhdr: pointer to the ethernet header inside the coded packet
+ * @coded: coded packet we try to find decode data for
+ *
+ * Return: pointer to nc packet if the needed data was found or NULL otherwise.
+ */
+static struct batadv_nc_packet *
+batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
+			       struct ethhdr *ethhdr,
+			       struct batadv_coded_packet *coded)
+{
+	struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
+	struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
+	struct batadv_nc_path *nc_path, nc_path_key;
+	u8 *dest, *source;
+	__be32 packet_id;
+	int index;
+
+	if (!hash)
+		return NULL;
+
+	/* Select the correct packet id based on the location of our mac-addr */
+	dest = ethhdr->h_source;
+	if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
+		source = coded->second_source;
+		packet_id = coded->second_crc;
+	} else {
+		source = coded->first_source;
+		packet_id = coded->first_crc;
+	}
+
+	batadv_nc_hash_key_gen(&nc_path_key, source, dest);
+	index = batadv_nc_hash_choose(&nc_path_key, hash->size);
+
+	/* Search for matching coding path */
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
+		/* Find matching nc_packet */
+		spin_lock_bh(&nc_path->packet_list_lock);
+		list_for_each_entry(tmp_nc_packet,
+				    &nc_path->packet_list, list) {
+			if (packet_id == tmp_nc_packet->packet_id) {
+				list_del(&tmp_nc_packet->list);
+
+				nc_packet = tmp_nc_packet;
+				break;
+			}
+		}
+		spin_unlock_bh(&nc_path->packet_list_lock);
+
+		if (nc_packet)
+			break;
+	}
+	rcu_read_unlock();
+
+	if (!nc_packet)
+		batadv_dbg(BATADV_DBG_NC, bat_priv,
+			   "No decoding packet found for %u\n", packet_id);
+
+	return nc_packet;
+}
+
+/**
+ * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the
+ *  resulting unicast packet
+ * @skb: incoming coded packet
+ * @recv_if: pointer to interface this packet was received on
+ *
+ * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
+ * otherwise.
+ */
+static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
+				       struct batadv_hard_iface *recv_if)
+{
+	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
+	struct batadv_unicast_packet *unicast_packet;
+	struct batadv_coded_packet *coded_packet;
+	struct batadv_nc_packet *nc_packet;
+	struct ethhdr *ethhdr;
+	int hdr_size = sizeof(*coded_packet);
+
+	/* Check if network coding is enabled */
+	if (!atomic_read(&bat_priv->network_coding))
+		goto free_skb;
+
+	/* Make sure we can access (and remove) header */
+	if (unlikely(!pskb_may_pull(skb, hdr_size)))
+		goto free_skb;
+
+	coded_packet = (struct batadv_coded_packet *)skb->data;
+	ethhdr = eth_hdr(skb);
+
+	/* Verify frame is destined for us */
+	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
+	    !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
+		goto free_skb;
+
+	/* Update stat counter */
+	if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
+
+	nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
+						   coded_packet);
+	if (!nc_packet) {
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
+		goto free_skb;
+	}
+
+	/* Make skb's linear, because decoding accesses the entire buffer */
+	if (skb_linearize(skb) < 0)
+		goto free_nc_packet;
+
+	if (skb_linearize(nc_packet->skb) < 0)
+		goto free_nc_packet;
+
+	/* Decode the packet */
+	unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
+	if (!unicast_packet) {
+		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
+		goto free_nc_packet;
+	}
+
+	/* Mark packet as decoded to do correct recoding when forwarding */
+	BATADV_SKB_CB(skb)->decoded = true;
+	batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
+	batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
+			   skb->len + ETH_HLEN);
+	return batadv_recv_unicast_packet(skb, recv_if);
+
+free_nc_packet:
+	batadv_nc_packet_free(nc_packet, true);
+free_skb:
+	kfree_skb(skb);
+
+	return NET_RX_DROP;
+}
+
+/**
+ * batadv_nc_mesh_free() - clean up network coding memory
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
+{
+	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
+	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
+	cancel_delayed_work_sync(&bat_priv->nc.work);
+
+	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
+	batadv_hash_destroy(bat_priv->nc.coding_hash);
+	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
+	batadv_hash_destroy(bat_priv->nc.decoding_hash);
+}