Merge tag 'batman-adv-for-davem' of git://git.open-mesh.org/linux-merge

Included changes:
- introduction of the new Network Coding component. This new mechanism aims to
  increase throughput by fusing multiple packets in one transmission.
- minor cleanups
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/ABI/testing/sysfs-class-net-mesh

@@ -67,6 +67,14 @@ Description:
                 Defines the penalty which will be applied to an
                 originator message's tq-field on every hop.
 
+What:           /sys/class/net/<mesh_iface>/mesh/network_coding
+Date:           Nov 2012
+Contact:        Martin Hundeboll <martin@hundeboll.net>
+Description:
+                Controls whether Network Coding (using some magic
+                to send fewer wifi packets but still the same
+                content) is enabled or not.
+
 What:           /sys/class/net/<mesh_iface>/mesh/orig_interval
 Date:           May 2010
 Contact:        Marek Lindner <lindner_marek@yahoo.de>

net/batman-adv/Kconfig

@@ -36,6 +36,20 @@ config BATMAN_ADV_DAT
 	  mesh networks. If you think that your network does not need
 	  this option you can safely remove it and save some space.
 
+config BATMAN_ADV_NC
+	bool "Network Coding"
+	depends on BATMAN_ADV
+	default n
+	help
+	  This option enables network coding, a mechanism that aims to
+	  increase the overall network throughput by fusing multiple
+	  packets in one transmission.
+	  Note that interfaces controlled by batman-adv must be manually
+	  configured to have promiscuous mode enabled in order to make
+	  network coding work.
+	  If you think that your network does not need this feature you
+	  can safely disable it and save some space.
+
 config BATMAN_ADV_DEBUG
 	bool "B.A.T.M.A.N. debugging"
 	depends on BATMAN_ADV

net/batman-adv/Makefile

@@ -30,6 +30,7 @@ batman-adv-y += hard-interface.o
 batman-adv-y += hash.o
 batman-adv-y += icmp_socket.o
 batman-adv-y += main.o
+batman-adv-$(CONFIG_BATMAN_ADV_NC) += network-coding.o
 batman-adv-y += originator.o
 batman-adv-y += ring_buffer.o
 batman-adv-y += routing.o

net/batman-adv/bat_iv_ogm.c

@@ -27,6 +27,7 @@
 #include "hard-interface.h"
 #include "send.h"
 #include "bat_algo.h"
+#include "network-coding.h"
 
 static struct batadv_neigh_node *
 batadv_iv_ogm_neigh_new(struct batadv_hard_iface *hard_iface,
@@ -1185,6 +1186,10 @@ static void batadv_iv_ogm_process(const struct ethhdr *ethhdr,
 	if (!orig_neigh_node)
 		goto out;
 
+	/* Update nc_nodes of the originator */
+	batadv_nc_update_nc_node(bat_priv, orig_node, orig_neigh_node,
+				 batadv_ogm_packet, is_single_hop_neigh);
+
 	orig_neigh_router = batadv_orig_node_get_router(orig_neigh_node);
 
 	/* drop packet if sender is not a direct neighbor and if we

net/batman-adv/debugfs.c

@@ -32,6 +32,7 @@
 #include "icmp_socket.h"
 #include "bridge_loop_avoidance.h"
 #include "distributed-arp-table.h"
+#include "network-coding.h"
 
 static struct dentry *batadv_debugfs;
 
@@ -310,6 +311,14 @@ struct batadv_debuginfo {
 	const struct file_operations fops;
 };
 
+#ifdef CONFIG_BATMAN_ADV_NC
+static int batadv_nc_nodes_open(struct inode *inode, struct file *file)
+{
+	struct net_device *net_dev = (struct net_device *)inode->i_private;
+	return single_open(file, batadv_nc_nodes_seq_print_text, net_dev);
+}
+#endif
+
 #define BATADV_DEBUGINFO(_name, _mode, _open)		\
 struct batadv_debuginfo batadv_debuginfo_##_name = {	\
 	.attr = { .name = __stringify(_name),		\
@@ -348,6 +357,9 @@ static BATADV_DEBUGINFO(dat_cache, S_IRUGO, batadv_dat_cache_open);
 static BATADV_DEBUGINFO(transtable_local, S_IRUGO,
 			batadv_transtable_local_open);
 static BATADV_DEBUGINFO(vis_data, S_IRUGO, batadv_vis_data_open);
+#ifdef CONFIG_BATMAN_ADV_NC
+static BATADV_DEBUGINFO(nc_nodes, S_IRUGO, batadv_nc_nodes_open);
+#endif
 
 static struct batadv_debuginfo *batadv_mesh_debuginfos[] = {
 	&batadv_debuginfo_originators,
@@ -362,6 +374,9 @@ static struct batadv_debuginfo *batadv_mesh_debuginfos[] = {
 #endif
 	&batadv_debuginfo_transtable_local,
 	&batadv_debuginfo_vis_data,
+#ifdef CONFIG_BATMAN_ADV_NC
+	&batadv_debuginfo_nc_nodes,
+#endif
 	NULL,
 };
 
@@ -431,6 +446,9 @@ int batadv_debugfs_add_meshif(struct net_device *dev)
 		}
 	}
 
+	if (batadv_nc_init_debugfs(bat_priv) < 0)
+		goto rem_attr;
+
 	return 0;
 rem_attr:
 	debugfs_remove_recursive(bat_priv->debug_dir);

net/batman-adv/distributed-arp-table.c

@@ -816,7 +816,6 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 	bool ret = false;
 	struct batadv_dat_entry *dat_entry = NULL;
 	struct sk_buff *skb_new;
-	struct batadv_hard_iface *primary_if = NULL;
 
 	if (!atomic_read(&bat_priv->distributed_arp_table))
 		goto out;
@@ -838,22 +837,18 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 
 	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
 	if (dat_entry) {
-		primary_if = batadv_primary_if_get_selected(bat_priv);
-		if (!primary_if)
-			goto out;
-
 		skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
-				     primary_if->soft_iface, ip_dst, hw_src,
+				     bat_priv->soft_iface, ip_dst, hw_src,
 				     dat_entry->mac_addr, hw_src);
 		if (!skb_new)
 			goto out;
 
 		skb_reset_mac_header(skb_new);
 		skb_new->protocol = eth_type_trans(skb_new,
-						   primary_if->soft_iface);
+						   bat_priv->soft_iface);
 		bat_priv->stats.rx_packets++;
 		bat_priv->stats.rx_bytes += skb->len + ETH_HLEN;
-		primary_if->soft_iface->last_rx = jiffies;
+		bat_priv->soft_iface->last_rx = jiffies;
 
 		netif_rx(skb_new);
 		batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
@@ -866,8 +861,6 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 out:
 	if (dat_entry)
 		batadv_dat_entry_free_ref(dat_entry);
-	if (primary_if)
-		batadv_hardif_free_ref(primary_if);
 	return ret;
 }
 
@@ -887,7 +880,6 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 	__be32 ip_src, ip_dst;
 	uint8_t *hw_src;
 	struct sk_buff *skb_new;
-	struct batadv_hard_iface *primary_if = NULL;
 	struct batadv_dat_entry *dat_entry = NULL;
 	bool ret = false;
 	int err;
@@ -912,12 +904,8 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 	if (!dat_entry)
 		goto out;
 
-	primary_if = batadv_primary_if_get_selected(bat_priv);
-	if (!primary_if)
-		goto out;
-
 	skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
-			     primary_if->soft_iface, ip_dst, hw_src,
+			     bat_priv->soft_iface, ip_dst, hw_src,
 			     dat_entry->mac_addr, hw_src);
 
 	if (!skb_new)
@@ -941,8 +929,6 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 out:
 	if (dat_entry)
 		batadv_dat_entry_free_ref(dat_entry);
-	if (primary_if)
-		batadv_hardif_free_ref(primary_if);
 	if (ret)
 		kfree_skb(skb);
 	return ret;

net/batman-adv/main.c

@@ -35,6 +35,7 @@
 #include "vis.h"
 #include "hash.h"
 #include "bat_algo.h"
+#include "network-coding.h"
 
 
 /* List manipulations on hardif_list have to be rtnl_lock()'ed,
@@ -135,6 +136,10 @@ int batadv_mesh_init(struct net_device *soft_iface)
 	if (ret < 0)
 		goto err;
 
+	ret = batadv_nc_init(bat_priv);
+	if (ret < 0)
+		goto err;
+
 	atomic_set(&bat_priv->gw.reselect, 0);
 	atomic_set(&bat_priv->mesh_state, BATADV_MESH_ACTIVE);
 
@@ -157,6 +162,7 @@ void batadv_mesh_free(struct net_device *soft_iface)
 
 	batadv_gw_node_purge(bat_priv);
 	batadv_originator_free(bat_priv);
+	batadv_nc_free(bat_priv);
 
 	batadv_tt_free(bat_priv);
 

net/batman-adv/main.h

@@ -105,6 +105,8 @@
 #define BATADV_RESET_PROTECTION_MS 30000
 #define BATADV_EXPECTED_SEQNO_RANGE	65536
 
+#define BATADV_NC_NODE_TIMEOUT 10000 /* Milliseconds */
+
 enum batadv_mesh_state {
 	BATADV_MESH_INACTIVE,
 	BATADV_MESH_ACTIVE,
@@ -185,6 +187,7 @@ __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr);
  * @BATADV_DBG_TT: translation table messages
  * @BATADV_DBG_BLA: bridge loop avoidance messages
  * @BATADV_DBG_DAT: ARP snooping and DAT related messages
+ * @BATADV_DBG_NC: network coding related messages
  * @BATADV_DBG_ALL: the union of all the above log levels
  */
 enum batadv_dbg_level {
@@ -193,7 +196,8 @@ enum batadv_dbg_level {
 	BATADV_DBG_TT	  = BIT(2),
 	BATADV_DBG_BLA    = BIT(3),
 	BATADV_DBG_DAT    = BIT(4),
-	BATADV_DBG_ALL    = 31,
+	BATADV_DBG_NC	  = BIT(5),
+	BATADV_DBG_ALL    = 63,
 };
 
 #ifdef CONFIG_BATMAN_ADV_DEBUG
@@ -298,4 +302,10 @@ static inline uint64_t batadv_sum_counter(struct batadv_priv *bat_priv,
 	return sum;
 }
 
+/* Define a macro to reach the control buffer of the skb. The members of the
+ * control buffer are defined in struct batadv_skb_cb in types.h.
+ * The macro is inspired by the similar macro TCP_SKB_CB() in tcp.h.
+ */
+#define BATADV_SKB_CB(__skb)       ((struct batadv_skb_cb *)&((__skb)->cb[0]))
+
 #endif /* _NET_BATMAN_ADV_MAIN_H_ */

net/batman-adv/network-coding.c

+/* Copyright (C) 2012-2013 B.A.T.M.A.N. contributors:
+ *
+ * Martin Hundebøll, Jeppe Ledet-Pedersen
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ */
+
+#include <linux/debugfs.h>
+
+#include "main.h"
+#include "hash.h"
+#include "network-coding.h"
+#include "send.h"
+#include "originator.h"
+#include "hard-interface.h"
+#include "routing.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_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_init - initialise coding hash table and start house keeping
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+int batadv_nc_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)
+		goto err;
+
+	batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
+				   &batadv_nc_decoding_hash_lock_class_key);
+
+	/* Register our packet type */
+	if (batadv_recv_handler_register(BATADV_CODED,
+					 batadv_nc_recv_coded_packet) < 0)
+		goto err;
+
+	INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
+	batadv_nc_start_timer(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, 1);
+	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_free_rcu - rcu callback to free an nc node and remove
+ *  its refcount on the orig_node
+ * @rcu: rcu pointer of the nc node
+ */
+static void batadv_nc_node_free_rcu(struct rcu_head *rcu)
+{
+	struct batadv_nc_node *nc_node;
+
+	nc_node = container_of(rcu, struct batadv_nc_node, rcu);
+	batadv_orig_node_free_ref(nc_node->orig_node);
+	kfree(nc_node);
+}
+
+/**
+ * batadv_nc_node_free_ref - decrements the nc node refcounter and possibly
+ * frees it
+ * @nc_node: the nc node to free
+ */
+static void batadv_nc_node_free_ref(struct batadv_nc_node *nc_node)
+{
+	if (atomic_dec_and_test(&nc_node->refcount))
+		call_rcu(&nc_node->rcu, batadv_nc_node_free_rcu);
+}
+
+/**
+ * batadv_nc_path_free_ref - decrements the nc path refcounter and possibly
+ * frees it
+ * @nc_path: the nc node to free
+ */
+static void batadv_nc_path_free_ref(struct batadv_nc_path *nc_path)
+{
+	if (atomic_dec_and_test(&nc_path->refcount))
+		kfree_rcu(nc_path, rcu);
+}
+
+/**
+ * batadv_nc_packet_free - frees nc packet
+ * @nc_packet: the nc packet to free
+ */
+static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet)
+{
+	if (nc_packet->skb)
+		kfree_skb(nc_packet->skb);
+
+	batadv_nc_path_free_ref(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
+ *
+ * Returns 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
+ *
+ * Returns 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
+ *
+ * Returns 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_free_ref(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;
+	uint32_t 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 */
+	uint32_t 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_free_ref(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
+ *
+ * Returns the selected index in the hash table for the given data.
+ */
+static uint32_t batadv_nc_hash_choose(const void *data, uint32_t size)
+{
+	const struct batadv_nc_path *nc_path = data;
+	uint32_t hash = 0;
+
+	hash = batadv_hash_bytes(hash, &nc_path->prev_hop,
+				 sizeof(nc_path->prev_hop));
+	hash = batadv_hash_bytes(hash, &nc_path->next_hop,
+				 sizeof(nc_path->next_hop));
+
+	hash += (hash << 3);
+	hash ^= (hash >> 11);
+	hash += (hash << 15);
+
+	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
+ *
+ * Returns 1 if the two entry are the same, 0 otherwise
+ */
+static int 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 (memcmp(nc_path1->prev_hop, nc_path2->prev_hop,
+		   sizeof(nc_path1->prev_hop)) != 0)
+		return 0;
+
+	if (memcmp(nc_path1->next_hop, nc_path2->next_hop,
+		   sizeof(nc_path1->next_hop)) != 0)
+		return 0;
+
+	return 1;
+}
+
+/**
+ * batadv_nc_hash_find - search for an existing nc path and return it
+ * @hash: hash table containing the nc path
+ * @data: search key
+ *
+ * Returns 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 (!atomic_inc_not_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_skb_packet(nc_packet->skb,
+			       nc_packet->neigh_node->if_incoming,
+			       nc_packet->nc_path->next_hop);
+	nc_packet->skb = NULL;
+	batadv_nc_packet_free(nc_packet);
+}
+
+/**
+ * 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.
+ *
+ * Returns 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;
+
+	/* 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);
+
+	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.
+ *
+ * Returns 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;
+
+	/* 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 house keeping 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 = container_of(work, struct 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
+ *
+ * Returns 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)
+{
+	if (orig_node->last_real_seqno != ogm_packet->seqno)
+		return false;
+	if (orig_node->last_ttl != ogm_packet->header.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
+ *
+ * Returns 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 (!atomic_inc_not_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
+ *
+ * Returns 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;
+
+	/* 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)
+		return nc_node;
+
+	nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
+	if (!nc_node)
+		return NULL;
+
+	if (!atomic_inc_not_zero(&orig_neigh_node->refcount))
+		goto free;
+
+	/* Initialize nc_node */
+	INIT_LIST_HEAD(&nc_node->list);
+	memcpy(nc_node->addr, orig_node->orig, ETH_ALEN);
+	nc_node->orig_node = orig_neigh_node;
+	atomic_set(&nc_node->refcount, 2);
+
+	/* 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;
+	}
+
+	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 */
+	spin_lock_bh(lock);
+	list_add_tail_rcu(&nc_node->list, list);
+	spin_unlock_bh(lock);
+
+	return nc_node;
+
+free:
+	kfree(nc_node);
+	return NULL;
+}
+
+/**
+ * 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, *out_nc_node = NULL;
+
+	/* Check if network coding is enabled */
+	if (!atomic_read(&bat_priv->network_coding))
+		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:
+	if (in_nc_node)
+		batadv_nc_node_free_ref(in_nc_node);
+	if (out_nc_node)
+		batadv_nc_node_free_ref(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
+ *
+ * Returns 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,
+						 uint8_t *src,
+						 uint8_t *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);
+	atomic_set(&nc_path->refcount, 2);
+	nc_path->last_valid = jiffies;
+	memcpy(nc_path->next_hop, dst, ETH_ALEN);
+	memcpy(nc_path->prev_hop, src, ETH_ALEN);
+
+	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 */
+	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
+ */
+static uint8_t batadv_nc_random_weight_tq(uint8_t tq)
+{
+	uint8_t rand_val, rand_tq;
+
+	get_random_bytes(&rand_val, sizeof(rand_val));
+
+	/* randomize the estimated packet loss (max TQ - estimated TQ) */
+	rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);
+
+	/* normalize the randomized packet loss */
+	rand_tq /= BATADV_TQ_MAX_VALUE;
+
+	/* 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
+ *
+ * Returns 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)
+{
+	uint8_t tq_weighted_neigh, tq_weighted_coding;
+	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;
+	struct batadv_neigh_node *router_coding = NULL;
+	uint8_t *first_source, *first_dest, *second_source, *second_dest;
+	__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;
+
+	router_neigh = batadv_orig_node_get_router(neigh_node->orig_node);
+	if (!router_neigh)
+		goto out;
+
+	neigh_tmp = nc_packet->neigh_node;
+	router_coding = batadv_orig_node_get_router(neigh_tmp->orig_node);
+	if (!router_coding)
+		goto out;
+
+	tq_weighted_neigh = batadv_nc_random_weight_tq(router_neigh->tq_avg);
+	tq_weighted_coding = batadv_nc_random_weight_tq(router_coding->tq_avg);
+
+	/* 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->nc_path->next_hop;
+		first_source = nc_packet->nc_path->prev_hop;
+		second_dest = neigh_node->addr;
+		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->addr;
+		first_source = ethhdr->h_source;
+		second_dest = nc_packet->nc_path->next_hop;
+		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->header.packet_type = BATADV_CODED;
+	coded_packet->header.version = BATADV_COMPAT_VERSION;
+	coded_packet->header.ttl = packet1->header.ttl;
+
+	/* Info about first unicast packet */
+	memcpy(coded_packet->first_source, first_source, ETH_ALEN);
+	memcpy(coded_packet->first_orig_dest, packet1->dest, ETH_ALEN);
+	coded_packet->first_crc = packet_id1;
+	coded_packet->first_ttvn = packet1->ttvn;
+
+	/* Info about second unicast packet */
+	memcpy(coded_packet->second_dest, second_dest, ETH_ALEN);
+	memcpy(coded_packet->second_source, second_source, ETH_ALEN);
+	memcpy(coded_packet->second_orig_dest, packet2->dest, ETH_ALEN);
+	coded_packet->second_crc = packet_id2;
+	coded_packet->second_ttl = packet2->header.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 */
+	kfree_skb(skb_src);
+
+	/* avoid duplicate free of skb from nc_packet */
+	nc_packet->skb = NULL;
+	batadv_nc_packet_free(nc_packet);
+
+	/* Send the coded packet and return true */
+	batadv_send_skb_packet(skb_dest, neigh_node->if_incoming, first_dest);
+	res = true;
+out:
+	if (router_neigh)
+		batadv_neigh_node_free_ref(router_neigh);
+	if (router_coding)
+		batadv_neigh_node_free_ref(router_coding);
+	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.
+ *
+ * Returns true if coding of a decoded packet is allowed.
+ */
+static bool batadv_nc_skb_coding_possible(struct sk_buff *skb,
+					  uint8_t *dst, uint8_t *src)
+{
+	if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
+		return false;
+	else
+		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
+ *
+ * Returns 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,
+		      uint8_t *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 neighoring 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
+ *
+ * Returns 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,
+			 uint8_t *eth_dst,
+			 uint8_t *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_free_ref(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,
+					      uint8_t *eth_dst_new)
+{
+	struct ethhdr *ethhdr;
+
+	/* Copy skb header to change the mac header */
+	skb = pskb_copy(skb, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	/* Set the mac header as if we actually sent the packet uncoded */
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+	memcpy(ethhdr->h_source, ethhdr->h_dest, ETH_ALEN);
+	memcpy(ethhdr->h_dest, eth_dst_new, ETH_ALEN);
+
+	/* 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
+	 */
+	kfree_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 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.
+ *
+ * Returns 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
+ *
+ * Returns 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
+ * @ethhdr: pointer to the ethernet header inside the skb
+ *
+ * Returns 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,
+			   struct ethhdr *ethhdr)
+{
+	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;
+	__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->header.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_free_ref(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 = (struct ethhdr *)skb_mac_header(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->header.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_free_ref(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 = (struct ethhdr *)skb_mac_header(skb);
+
+	if (batadv_is_my_mac(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
+ * @skb: unicast skb to decode
+ * @nc_packet: decode data needed to decode the skb
+ *
+ * Returns 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 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;
+	uint8_t *orig_dest, ttl, ttvn;
+	unsigned int coding_len;
+
+	/* 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 = (struct ethhdr *)skb_mac_header(skb);
+	memcpy(ethhdr, &ethhdr_tmp, sizeof(*ethhdr));
+
+	/* Select the correct unicast header information based on the location
+	 * of our mac address in the coded_packet header
+	 */
+	if (batadv_is_my_mac(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
+		 */
+		memcpy(ethhdr->h_dest, coded_packet_tmp.second_dest, ETH_ALEN);
+		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.header.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)
+		pskb_trim_rcsum(skb, coding_len + h_size);
+
+	/* Create decoded unicast packet */
+	unicast_packet = (struct batadv_unicast_packet *)skb->data;
+	unicast_packet->header.packet_type = BATADV_UNICAST;
+	unicast_packet->header.version = BATADV_COMPAT_VERSION;
+	unicast_packet->header.ttl = ttl;
+	memcpy(unicast_packet->dest, orig_dest, ETH_ALEN);
+	unicast_packet->ttvn = ttvn;
+
+	batadv_nc_packet_free(nc_packet);
+	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
+ *
+ * Returns 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;
+	uint8_t *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(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
+ */
+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))
+		return NET_RX_DROP;
+
+	/* Make sure we can access (and remove) header */
+	if (unlikely(!pskb_may_pull(skb, hdr_size)))
+		return NET_RX_DROP;
+
+	coded_packet = (struct batadv_coded_packet *)skb->data;
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
+	/* Verify frame is destined for us */
+	if (!batadv_is_my_mac(ethhdr->h_dest) &&
+	    !batadv_is_my_mac(coded_packet->second_dest))
+		return NET_RX_DROP;
+
+	/* Update stat counter */
+	if (batadv_is_my_mac(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);
+		return NET_RX_DROP;
+	}
+
+	/* 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(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);
+	return NET_RX_DROP;
+}
+
+/**
+ * batadv_nc_free - clean up network coding memory
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+void batadv_nc_free(struct batadv_priv *bat_priv)
+{
+	batadv_recv_handler_unregister(BATADV_CODED);
+	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);
+}
+
+/**
+ * batadv_nc_nodes_seq_print_text - print the nc node information
+ * @seq: seq file to print on
+ * @offset: not used
+ */
+int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset)
+{
+	struct net_device *net_dev = (struct net_device *)seq->private;
+	struct batadv_priv *bat_priv = netdev_priv(net_dev);
+	struct batadv_hashtable *hash = bat_priv->orig_hash;
+	struct batadv_hard_iface *primary_if;
+	struct hlist_head *head;
+	struct batadv_orig_node *orig_node;
+	struct batadv_nc_node *nc_node;
+	int i;
+
+	primary_if = batadv_seq_print_text_primary_if_get(seq);
+	if (!primary_if)
+		goto out;
+
+	/* Traverse list of originators */
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		/* For each orig_node in this bin */
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
+			seq_printf(seq, "Node:      %pM\n", orig_node->orig);
+
+			seq_printf(seq, " Ingoing:  ");
+			/* For each in_nc_node to this orig_node */
+			list_for_each_entry_rcu(nc_node,
+						&orig_node->in_coding_list,
+						list)
+				seq_printf(seq, "%pM ",
+					   nc_node->addr);
+			seq_printf(seq, "\n");
+
+			seq_printf(seq, " Outgoing: ");
+			/* For out_nc_node to this orig_node */
+			list_for_each_entry_rcu(nc_node,
+						&orig_node->out_coding_list,
+						list)
+				seq_printf(seq, "%pM ",
+					   nc_node->addr);
+			seq_printf(seq, "\n\n");
+		}
+		rcu_read_unlock();
+	}
+
+out:
+	if (primary_if)
+		batadv_hardif_free_ref(primary_if);
+	return 0;
+}
+
+/**
+ * batadv_nc_init_debugfs - create nc folder and related files in debugfs
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+int batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
+{
+	struct dentry *nc_dir, *file;
+
+	nc_dir = debugfs_create_dir("nc", bat_priv->debug_dir);
+	if (!nc_dir)
+		goto out;
+
+	file = debugfs_create_u8("min_tq", S_IRUGO | S_IWUSR, nc_dir,
+				 &bat_priv->nc.min_tq);
+	if (!file)
+		goto out;
+
+	file = debugfs_create_u32("max_fwd_delay", S_IRUGO | S_IWUSR, nc_dir,
+				  &bat_priv->nc.max_fwd_delay);
+	if (!file)
+		goto out;
+
+	file = debugfs_create_u32("max_buffer_time", S_IRUGO | S_IWUSR, nc_dir,
+				  &bat_priv->nc.max_buffer_time);
+	if (!file)
+		goto out;
+
+	return 0;
+
+out:
+	return -ENOMEM;
+}

net/batman-adv/network-coding.h

+/* Copyright (C) 2012-2013 B.A.T.M.A.N. contributors:
+ *
+ * Martin Hundebøll, Jeppe Ledet-Pedersen
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ */
+
+#ifndef _NET_BATMAN_ADV_NETWORK_CODING_H_
+#define _NET_BATMAN_ADV_NETWORK_CODING_H_
+
+#ifdef CONFIG_BATMAN_ADV_NC
+
+int batadv_nc_init(struct batadv_priv *bat_priv);
+void batadv_nc_free(struct batadv_priv *bat_priv);
+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);
+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 *));
+void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv);
+void batadv_nc_init_orig(struct batadv_orig_node *orig_node);
+bool batadv_nc_skb_forward(struct sk_buff *skb,
+			   struct batadv_neigh_node *neigh_node,
+			   struct ethhdr *ethhdr);
+void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
+				      struct sk_buff *skb);
+void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb);
+int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset);
+int batadv_nc_init_debugfs(struct batadv_priv *bat_priv);
+
+#else /* ifdef CONFIG_BATMAN_ADV_NC */
+
+static inline int batadv_nc_init(struct batadv_priv *bat_priv)
+{
+	return 0;
+}
+
+static inline void batadv_nc_free(struct batadv_priv *bat_priv)
+{
+	return;
+}
+
+static inline 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)
+{
+	return;
+}
+
+static inline 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 *))
+{
+	return;
+}
+
+static inline void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
+{
+	return;
+}
+
+static inline void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
+{
+	return;
+}
+
+static inline bool batadv_nc_skb_forward(struct sk_buff *skb,
+					 struct batadv_neigh_node *neigh_node,
+					 struct ethhdr *ethhdr)
+{
+	return false;
+}
+
+static inline void
+batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
+				 struct sk_buff *skb)
+{
+	return;
+}
+
+static inline void
+batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
+				    struct sk_buff *skb)
+{
+	return;
+}
+
+static inline int batadv_nc_nodes_seq_print_text(struct seq_file *seq,
+						 void *offset)
+{
+	return 0;
+}
+
+static inline int batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
+{
+	return 0;
+}
+
+#endif /* ifdef CONFIG_BATMAN_ADV_NC */
+
+#endif /* _NET_BATMAN_ADV_NETWORK_CODING_H_ */

net/batman-adv/originator.c

@@ -28,6 +28,7 @@
 #include "unicast.h"
 #include "soft-interface.h"
 #include "bridge_loop_avoidance.h"
+#include "network-coding.h"
 
 /* hash class keys */
 static struct lock_class_key batadv_orig_hash_lock_class_key;
@@ -142,6 +143,9 @@ static void batadv_orig_node_free_rcu(struct rcu_head *rcu)
 
 	spin_unlock_bh(&orig_node->neigh_list_lock);
 
+	/* Free nc_nodes */
+	batadv_nc_purge_orig(orig_node->bat_priv, orig_node, NULL);
+
 	batadv_frag_list_free(&orig_node->frag_list);
 	batadv_tt_global_del_orig(orig_node->bat_priv, orig_node,
 				  "originator timed out");
@@ -219,6 +223,8 @@ struct batadv_orig_node *batadv_get_orig_node(struct batadv_priv *bat_priv,
 	spin_lock_init(&orig_node->neigh_list_lock);
 	spin_lock_init(&orig_node->tt_buff_lock);
 
+	batadv_nc_init_orig(orig_node);
+
 	/* extra reference for return */
 	atomic_set(&orig_node->refcount, 2);
 

net/batman-adv/packet.h

@@ -30,6 +30,7 @@ enum batadv_packettype {
 	BATADV_TT_QUERY		= 0x07,
 	BATADV_ROAM_ADV		= 0x08,
 	BATADV_UNICAST_4ADDR	= 0x09,
+	BATADV_CODED		= 0x0a,
 };
 
 /**
@@ -278,4 +279,36 @@ struct batadv_tt_change {
 	uint8_t addr[ETH_ALEN];
 } __packed;
 
+/**
+ * struct batadv_coded_packet - network coded packet
+ * @header: common batman packet header and ttl of first included packet
+ * @reserved: Align following fields to 2-byte boundaries
+ * @first_source: original source of first included packet
+ * @first_orig_dest: original destinal of first included packet
+ * @first_crc: checksum of first included packet
+ * @first_ttvn: tt-version number of first included packet
+ * @second_ttl: ttl of second packet
+ * @second_dest: second receiver of this coded packet
+ * @second_source: original source of second included packet
+ * @second_orig_dest: original destination of second included packet
+ * @second_crc: checksum of second included packet
+ * @second_ttvn: tt version number of second included packet
+ * @coded_len: length of network coded part of the payload
+ */
+struct batadv_coded_packet {
+	struct batadv_header header;
+	uint8_t  first_ttvn;
+	/* uint8_t  first_dest[ETH_ALEN]; - saved in mac header destination */
+	uint8_t  first_source[ETH_ALEN];
+	uint8_t  first_orig_dest[ETH_ALEN];
+	__be32   first_crc;
+	uint8_t  second_ttl;
+	uint8_t  second_ttvn;
+	uint8_t  second_dest[ETH_ALEN];
+	uint8_t  second_source[ETH_ALEN];
+	uint8_t  second_orig_dest[ETH_ALEN];
+	__be32   second_crc;
+	uint16_t coded_len;
+};
+
 #endif /* _NET_BATMAN_ADV_PACKET_H_ */

net/batman-adv/routing.c

@@ -29,6 +29,7 @@
 #include "unicast.h"
 #include "bridge_loop_avoidance.h"
 #include "distributed-arp-table.h"
+#include "network-coding.h"
 
 static int batadv_route_unicast_packet(struct sk_buff *skb,
 				       struct batadv_hard_iface *recv_if);
@@ -548,27 +549,37 @@ batadv_find_ifalter_router(struct batadv_orig_node *primary_orig,
 	return router;
 }
 
+/**
+ * batadv_check_unicast_packet - Check for malformed unicast packets
+ * @skb: packet to check
+ * @hdr_size: size of header to pull
+ *
+ * Check for short header and bad addresses in given packet. Returns negative
+ * value when check fails and 0 otherwise. The negative value depends on the
+ * reason: -ENODATA for bad header, -EBADR for broadcast destination or source,
+ * and -EREMOTE for non-local (other host) destination.
+ */
 static int batadv_check_unicast_packet(struct sk_buff *skb, int hdr_size)
 {
 	struct ethhdr *ethhdr;
 
 	/* drop packet if it has not necessary minimum size */
 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
-		return -1;
+		return -ENODATA;
 
 	ethhdr = (struct ethhdr *)skb_mac_header(skb);
 
 	/* packet with unicast indication but broadcast recipient */
 	if (is_broadcast_ether_addr(ethhdr->h_dest))
-		return -1;
+		return -EBADR;
 
 	/* packet with broadcast sender address */
 	if (is_broadcast_ether_addr(ethhdr->h_source))
-		return -1;
+		return -EBADR;
 
 	/* not for me */
 	if (!batadv_is_my_mac(ethhdr->h_dest))
-		return -1;
+		return -EREMOTE;
 
 	return 0;
 }
@@ -850,14 +861,17 @@ static int batadv_route_unicast_packet(struct sk_buff *skb,
 	/* decrement ttl */
 	unicast_packet->header.ttl--;
 
+	/* network code packet if possible */
+	if (batadv_nc_skb_forward(skb, neigh_node, ethhdr)) {
+		ret = NET_RX_SUCCESS;
+	} else if (batadv_send_skb_to_orig(skb, orig_node, recv_if)) {
+		ret = NET_RX_SUCCESS;
+
 		/* Update stats counter */
 		batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
 		batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
 				   skb->len + ETH_HLEN);
-
-	/* route it */
-	if (batadv_send_skb_to_orig(skb, orig_node, recv_if))
-		ret = NET_RX_SUCCESS;
+	}
 
 out:
 	if (neigh_node)
@@ -1033,7 +1047,7 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 	struct batadv_unicast_4addr_packet *unicast_4addr_packet;
 	uint8_t *orig_addr;
 	struct batadv_orig_node *orig_node = NULL;
-	int hdr_size = sizeof(*unicast_packet);
+	int check, hdr_size = sizeof(*unicast_packet);
 	bool is4addr;
 
 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
@@ -1044,7 +1058,16 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 	if (is4addr)
 		hdr_size = sizeof(*unicast_4addr_packet);
 
-	if (batadv_check_unicast_packet(skb, hdr_size) < 0)
+	/* function returns -EREMOTE for promiscuous packets */
+	check = batadv_check_unicast_packet(skb, hdr_size);
+
+	/* Even though the packet is not for us, we might save it to use for
+	 * decoding a later received coded packet
+	 */
+	if (check == -EREMOTE)
+		batadv_nc_skb_store_sniffed_unicast(bat_priv, skb);
+
+	if (check < 0)
 		return NET_RX_DROP;
 
 	if (!batadv_check_unicast_ttvn(bat_priv, skb))

net/batman-adv/send.c

@@ -27,6 +27,7 @@
 #include "vis.h"
 #include "gateway_common.h"
 #include "originator.h"
+#include "network-coding.h"
 
 #include <linux/if_ether.h>
 
@@ -39,6 +40,7 @@ int batadv_send_skb_packet(struct sk_buff *skb,
 			   struct batadv_hard_iface *hard_iface,
 			   const uint8_t *dst_addr)
 {
+	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 	struct ethhdr *ethhdr;
 
 	if (hard_iface->if_status != BATADV_IF_ACTIVE)
@@ -70,6 +72,9 @@ int batadv_send_skb_packet(struct sk_buff *skb,
 
 	skb->dev = hard_iface->net_dev;
 
+	/* Save a clone of the skb to use when decoding coded packets */
+	batadv_nc_skb_store_for_decoding(bat_priv, skb);
+
 	/* dev_queue_xmit() returns a negative result on error.	 However on
 	 * congestion and traffic shaping, it drops and returns NET_XMIT_DROP
 	 * (which is > 0). This will not be treated as an error.

net/batman-adv/soft-interface.c

@@ -37,6 +37,7 @@
 #include <linux/if_ether.h>
 #include "unicast.h"
 #include "bridge_loop_avoidance.h"
+#include "network-coding.h"
 
 
 static int batadv_get_settings(struct net_device *dev, struct ethtool_cmd *cmd);
@@ -544,6 +545,8 @@ struct net_device *batadv_softif_create(const char *name)
 	if (ret < 0)
 		goto unreg_soft_iface;
 
+	batadv_nc_init_bat_priv(bat_priv);
+
 	ret = batadv_sysfs_add_meshif(soft_iface);
 	if (ret < 0)
 		goto unreg_soft_iface;
@@ -662,6 +665,17 @@ static const struct {
 	{ "dat_put_rx" },
 	{ "dat_cached_reply_tx" },
 #endif
+#ifdef CONFIG_BATMAN_ADV_NC
+	{ "nc_code" },
+	{ "nc_code_bytes" },
+	{ "nc_recode" },
+	{ "nc_recode_bytes" },
+	{ "nc_buffer" },
+	{ "nc_decode" },
+	{ "nc_decode_bytes" },
+	{ "nc_decode_failed" },
+	{ "nc_sniffed" },
+#endif
 };
 
 static void batadv_get_strings(struct net_device *dev, uint32_t stringset,

net/batman-adv/sysfs.c

@@ -442,6 +442,9 @@ static BATADV_ATTR(gw_bandwidth, S_IRUGO | S_IWUSR, batadv_show_gw_bwidth,
 #ifdef CONFIG_BATMAN_ADV_DEBUG
 BATADV_ATTR_SIF_UINT(log_level, S_IRUGO | S_IWUSR, 0, BATADV_DBG_ALL, NULL);
 #endif
+#ifdef CONFIG_BATMAN_ADV_NC
+BATADV_ATTR_SIF_BOOL(network_coding, S_IRUGO | S_IWUSR, NULL);
+#endif
 
 static struct batadv_attribute *batadv_mesh_attrs[] = {
 	&batadv_attr_aggregated_ogms,
@@ -463,6 +466,9 @@ static struct batadv_attribute *batadv_mesh_attrs[] = {
 	&batadv_attr_gw_bandwidth,
 #ifdef CONFIG_BATMAN_ADV_DEBUG
 	&batadv_attr_log_level,
+#endif
+#ifdef CONFIG_BATMAN_ADV_NC
+	&batadv_attr_network_coding,
 #endif
 	NULL,
 };
@@ -688,15 +694,10 @@ int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
 			enum batadv_uev_action action, const char *data)
 {
 	int ret = -ENOMEM;
-	struct batadv_hard_iface *primary_if;
 	struct kobject *bat_kobj;
 	char *uevent_env[4] = { NULL, NULL, NULL, NULL };
 
-	primary_if = batadv_primary_if_get_selected(bat_priv);
-	if (!primary_if)
-		goto out;
-
-	bat_kobj = &primary_if->soft_iface->dev.kobj;
+	bat_kobj = &bat_priv->soft_iface->dev.kobj;
 
 	uevent_env[0] = kmalloc(strlen(BATADV_UEV_TYPE_VAR) +
 				strlen(batadv_uev_type_str[type]) + 1,
@@ -732,9 +733,6 @@ int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
 	kfree(uevent_env[1]);
 	kfree(uevent_env[2]);
 
-	if (primary_if)
-		batadv_hardif_free_ref(primary_if);
-
 	if (ret)
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Impossible to send uevent for (%s,%s,%s) event (err: %d)\n",

net/batman-adv/translation-table.c

@@ -385,25 +385,19 @@ static void batadv_tt_prepare_packet_buff(struct batadv_priv *bat_priv,
 					  int *packet_buff_len,
 					  int min_packet_len)
 {
-	struct batadv_hard_iface *primary_if;
 	int req_len;
 
-	primary_if = batadv_primary_if_get_selected(bat_priv);
-
 	req_len = min_packet_len;
 	req_len += batadv_tt_len(atomic_read(&bat_priv->tt.local_changes));
 
 	/* if we have too many changes for one packet don't send any
 	 * and wait for the tt table request which will be fragmented
 	 */
-	if ((!primary_if) || (req_len > primary_if->soft_iface->mtu))
+	if (req_len > bat_priv->soft_iface->mtu)
 		req_len = min_packet_len;
 
 	batadv_tt_realloc_packet_buff(packet_buff, packet_buff_len,
 				      min_packet_len, req_len);
-
-	if (primary_if)
-		batadv_hardif_free_ref(primary_if);
 }
 
 static int batadv_tt_changes_fill_buff(struct batadv_priv *bat_priv,
@@ -908,7 +902,7 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
 	/* remove address from local hash if present */
 	local_flags = batadv_tt_local_remove(bat_priv, tt_addr,
 					     "global tt received",
-					     !!(flags & BATADV_TT_CLIENT_ROAM));
+					     flags & BATADV_TT_CLIENT_ROAM);
 	tt_global_entry->common.flags |= local_flags & BATADV_TT_CLIENT_WIFI;
 
 	if (!(flags & BATADV_TT_CLIENT_ROAM))
@@ -1580,7 +1574,7 @@ static int batadv_tt_global_valid(const void *entry_ptr,
 static struct sk_buff *
 batadv_tt_response_fill_table(uint16_t tt_len, uint8_t ttvn,
 			      struct batadv_hashtable *hash,
-			      struct batadv_hard_iface *primary_if,
+			      struct batadv_priv *bat_priv,
 			      int (*valid_cb)(const void *, const void *),
 			      void *cb_data)
 {
@@ -1594,8 +1588,8 @@ batadv_tt_response_fill_table(uint16_t tt_len, uint8_t ttvn,
 	uint32_t i;
 	size_t len;
 
-	if (tt_query_size + tt_len > primary_if->soft_iface->mtu) {
-		tt_len = primary_if->soft_iface->mtu - tt_query_size;
+	if (tt_query_size + tt_len > bat_priv->soft_iface->mtu) {
+		tt_len = bat_priv->soft_iface->mtu - tt_query_size;
 		tt_len -= tt_len % sizeof(struct batadv_tt_change);
 	}
 	tt_tot = tt_len / sizeof(struct batadv_tt_change);
@@ -1715,7 +1709,6 @@ batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 {
 	struct batadv_orig_node *req_dst_orig_node;
 	struct batadv_orig_node *res_dst_orig_node = NULL;
-	struct batadv_hard_iface *primary_if = NULL;
 	uint8_t orig_ttvn, req_ttvn, ttvn;
 	int ret = false;
 	unsigned char *tt_buff;
@@ -1740,10 +1733,6 @@ batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 	if (!res_dst_orig_node)
 		goto out;
 
-	primary_if = batadv_primary_if_get_selected(bat_priv);
-	if (!primary_if)
-		goto out;
-
 	orig_ttvn = (uint8_t)atomic_read(&req_dst_orig_node->last_ttvn);
 	req_ttvn = tt_request->ttvn;
 
@@ -1791,7 +1780,7 @@ batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 
 		skb = batadv_tt_response_fill_table(tt_len, ttvn,
 						    bat_priv->tt.global_hash,
-						    primary_if,
+						    bat_priv,
 						    batadv_tt_global_valid,
 						    req_dst_orig_node);
 		if (!skb)
@@ -1828,8 +1817,6 @@ batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 		batadv_orig_node_free_ref(res_dst_orig_node);
 	if (req_dst_orig_node)
 		batadv_orig_node_free_ref(req_dst_orig_node);
-	if (primary_if)
-		batadv_hardif_free_ref(primary_if);
 	if (!ret)
 		kfree_skb(skb);
 	return ret;
@@ -1907,7 +1894,7 @@ batadv_send_my_tt_response(struct batadv_priv *bat_priv,
 
 		skb = batadv_tt_response_fill_table(tt_len, ttvn,
 						    bat_priv->tt.local_hash,
-						    primary_if,
+						    bat_priv,
 						    batadv_tt_local_valid_entry,
 						    NULL);
 		if (!skb)
@@ -2528,7 +2515,7 @@ bool batadv_tt_global_client_is_roaming(struct batadv_priv *bat_priv,
 	if (!tt_global_entry)
 		goto out;
 
-	ret = !!(tt_global_entry->common.flags & BATADV_TT_CLIENT_ROAM);
+	ret = tt_global_entry->common.flags & BATADV_TT_CLIENT_ROAM;
 	batadv_tt_global_entry_free_ref(tt_global_entry);
 out:
 	return ret;

net/batman-adv/types.h

@@ -128,6 +128,10 @@ struct batadv_hard_iface {
  * @bond_list: list of bonding candidates
  * @refcount: number of contexts the object is used
  * @rcu: struct used for freeing in an RCU-safe manner
+ * @in_coding_list: list of nodes this orig can hear
+ * @out_coding_list: list of nodes that can hear this orig
+ * @in_coding_list_lock: protects in_coding_list
+ * @out_coding_list_lock: protects out_coding_list
  */
 struct batadv_orig_node {
 	uint8_t orig[ETH_ALEN];
@@ -171,6 +175,12 @@ struct batadv_orig_node {
 	struct list_head bond_list;
 	atomic_t refcount;
 	struct rcu_head rcu;
+#ifdef CONFIG_BATMAN_ADV_NC
+	struct list_head in_coding_list;
+	struct list_head out_coding_list;
+	spinlock_t in_coding_list_lock; /* Protects in_coding_list */
+	spinlock_t out_coding_list_lock; /* Protects out_coding_list */
+#endif
 };
 
 /**
@@ -265,6 +275,17 @@ struct batadv_bcast_duplist_entry {
  * @BATADV_CNT_DAT_PUT_RX: received dht PUT traffic packet counter
  * @BATADV_CNT_DAT_CACHED_REPLY_TX: transmitted dat cache reply traffic packet
  *  counter
+ * @BATADV_CNT_NC_CODE: transmitted nc-combined traffic packet counter
+ * @BATADV_CNT_NC_CODE_BYTES: transmitted nc-combined traffic bytes counter
+ * @BATADV_CNT_NC_RECODE: transmitted nc-recombined traffic packet counter
+ * @BATADV_CNT_NC_RECODE_BYTES: transmitted nc-recombined traffic bytes counter
+ * @BATADV_CNT_NC_BUFFER: counter for packets buffered for later nc decoding
+ * @BATADV_CNT_NC_DECODE: received and nc-decoded traffic packet counter
+ * @BATADV_CNT_NC_DECODE_BYTES: received and nc-decoded traffic bytes counter
+ * @BATADV_CNT_NC_DECODE_FAILED: received and decode-failed traffic packet
+ *  counter
+ * @BATADV_CNT_NC_SNIFFED: counter for nc-decoded packets received in promisc
+ *  mode.
  * @BATADV_CNT_NUM: number of traffic counters
  */
 enum batadv_counters {
@@ -291,6 +312,17 @@ enum batadv_counters {
 	BATADV_CNT_DAT_PUT_TX,
 	BATADV_CNT_DAT_PUT_RX,
 	BATADV_CNT_DAT_CACHED_REPLY_TX,
+#endif
+#ifdef CONFIG_BATMAN_ADV_NC
+	BATADV_CNT_NC_CODE,
+	BATADV_CNT_NC_CODE_BYTES,
+	BATADV_CNT_NC_RECODE,
+	BATADV_CNT_NC_RECODE_BYTES,
+	BATADV_CNT_NC_BUFFER,
+	BATADV_CNT_NC_DECODE,
+	BATADV_CNT_NC_DECODE_BYTES,
+	BATADV_CNT_NC_DECODE_FAILED,
+	BATADV_CNT_NC_SNIFFED,
 #endif
 	BATADV_CNT_NUM,
 };
@@ -427,6 +459,35 @@ struct batadv_priv_dat {
 };
 #endif
 
+/**
+ * struct batadv_priv_nc - per mesh interface network coding private data
+ * @work: work queue callback item for cleanup
+ * @debug_dir: dentry for nc subdir in batman-adv directory in debugfs
+ * @min_tq: only consider neighbors for encoding if neigh_tq > min_tq
+ * @max_fwd_delay: maximum packet forward delay to allow coding of packets
+ * @max_buffer_time: buffer time for sniffed packets used to decoding
+ * @timestamp_fwd_flush: timestamp of last forward packet queue flush
+ * @timestamp_sniffed_purge: timestamp of last sniffed packet queue purge
+ * @coding_hash: Hash table used to buffer skbs while waiting for another
+ *  incoming skb to code it with. Skbs are added to the buffer just before being
+ *  forwarded in routing.c
+ * @decoding_hash: Hash table used to buffer skbs that might be needed to decode
+ *  a received coded skb. The buffer is used for 1) skbs arriving on the
+ *  soft-interface; 2) skbs overheard on the hard-interface; and 3) skbs
+ *  forwarded by batman-adv.
+ */
+struct batadv_priv_nc {
+	struct delayed_work work;
+	struct dentry *debug_dir;
+	u8 min_tq;
+	u32 max_fwd_delay;
+	u32 max_buffer_time;
+	unsigned long timestamp_fwd_flush;
+	unsigned long timestamp_sniffed_purge;
+	struct batadv_hashtable *coding_hash;
+	struct batadv_hashtable *decoding_hash;
+};
+
 /**
  * struct batadv_priv - per mesh interface data
  * @mesh_state: current status of the mesh (inactive/active/deactivating)
@@ -470,6 +531,8 @@ struct batadv_priv_dat {
  * @tt: translation table data
  * @vis: vis data
  * @dat: distributed arp table data
+ * @network_coding: bool indicating whether network coding is enabled
+ * @batadv_priv_nc: network coding data
  */
 struct batadv_priv {
 	atomic_t mesh_state;
@@ -522,6 +585,10 @@ struct batadv_priv {
 #ifdef CONFIG_BATMAN_ADV_DAT
 	struct batadv_priv_dat dat;
 #endif
+#ifdef CONFIG_BATMAN_ADV_NC
+	atomic_t network_coding;
+	struct batadv_priv_nc nc;
+#endif /* CONFIG_BATMAN_ADV_NC */
 };
 
 /**
@@ -701,6 +768,75 @@ struct batadv_tt_roam_node {
 	struct list_head list;
 };
 
+/**
+ * struct batadv_nc_node - network coding node
+ * @list: next and prev pointer for the list handling
+ * @addr: the node's mac address
+ * @refcount: number of contexts the object is used by
+ * @rcu: struct used for freeing in an RCU-safe manner
+ * @orig_node: pointer to corresponding orig node struct
+ * @last_seen: timestamp of last ogm received from this node
+ */
+struct batadv_nc_node {
+	struct list_head list;
+	uint8_t addr[ETH_ALEN];
+	atomic_t refcount;
+	struct rcu_head rcu;
+	struct batadv_orig_node *orig_node;
+	unsigned long last_seen;
+};
+
+/**
+ * struct batadv_nc_path - network coding path
+ * @hash_entry: next and prev pointer for the list handling
+ * @rcu: struct used for freeing in an RCU-safe manner
+ * @refcount: number of contexts the object is used by
+ * @packet_list: list of buffered packets for this path
+ * @packet_list_lock: access lock for packet list
+ * @next_hop: next hop (destination) of path
+ * @prev_hop: previous hop (source) of path
+ * @last_valid: timestamp for last validation of path
+ */
+struct batadv_nc_path {
+	struct hlist_node hash_entry;
+	struct rcu_head rcu;
+	atomic_t refcount;
+	struct list_head packet_list;
+	spinlock_t packet_list_lock; /* Protects packet_list */
+	uint8_t next_hop[ETH_ALEN];
+	uint8_t prev_hop[ETH_ALEN];
+	unsigned long last_valid;
+};
+
+/**
+ * struct batadv_nc_packet - network coding packet used when coding and
+ *  decoding packets
+ * @list: next and prev pointer for the list handling
+ * @packet_id: crc32 checksum of skb data
+ * @timestamp: field containing the info when the packet was added to path
+ * @neigh_node: pointer to original next hop neighbor of skb
+ * @skb: skb which can be encoded or used for decoding
+ * @nc_path: pointer to path this nc packet is attached to
+ */
+struct batadv_nc_packet {
+	struct list_head list;
+	__be32 packet_id;
+	unsigned long timestamp;
+	struct batadv_neigh_node *neigh_node;
+	struct sk_buff *skb;
+	struct batadv_nc_path *nc_path;
+};
+
+/**
+ * batadv_skb_cb - control buffer structure used to store private data relevant
+ *  to batman-adv in the skb->cb buffer in skbs.
+ * @decoded: Marks a skb as decoded, which is checked when searching for coding
+ *  opportunities in network-coding.c
+ */
+struct batadv_skb_cb {
+	bool decoded;
+};
+
 /**
  * struct batadv_forw_packet - structure for bcast packets to be sent/forwarded
  * @list: list node for batadv_socket_client::queue_list

net/batman-adv/unicast.c

@@ -122,7 +122,7 @@ batadv_frag_search_packet(struct list_head *head,
 {
 	struct batadv_frag_packet_list_entry *tfp;
 	struct batadv_unicast_frag_packet *tmp_up = NULL;
-	int is_head_tmp, is_head;
+	bool is_head_tmp, is_head;
 	uint16_t search_seqno;
 
 	if (up->flags & BATADV_UNI_FRAG_HEAD)
@@ -130,7 +130,7 @@ batadv_frag_search_packet(struct list_head *head,
 	else
 		search_seqno = ntohs(up->seqno)-1;
 
-	is_head = !!(up->flags & BATADV_UNI_FRAG_HEAD);
+	is_head = up->flags & BATADV_UNI_FRAG_HEAD;
 
 	list_for_each_entry(tfp, head, list) {
 		if (!tfp->skb)
@@ -142,7 +142,7 @@ batadv_frag_search_packet(struct list_head *head,
 		tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;
 
 		if (tfp->seqno == search_seqno) {
-			is_head_tmp = !!(tmp_up->flags & BATADV_UNI_FRAG_HEAD);
+			is_head_tmp = tmp_up->flags & BATADV_UNI_FRAG_HEAD;
 			if (is_head_tmp != is_head)
 				return tfp;
 			else