Merge branch 'master' into for-next

Conflicts:
	drivers/devfreq/exynos4_bus.c

Sync with Linus' tree to be able to apply patches that are
against newer code (mvneta).

1 files changed, 1083 insertions, 0 deletions

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
new file mode 100644
index 000000000000..183f97a86bb2
--- /dev/null
+++ b/net/batman-adv/distributed-arp-table.c
@@ -0,0 +1,1083 @@
+/* Copyright (C) 2011-2012 B.A.T.M.A.N. contributors:
+ *
+ * Antonio Quartulli
+ *
+ * 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/if_ether.h>
+#include <linux/if_arp.h>
+#include <net/arp.h>
+
+#include "main.h"
+#include "hash.h"
+#include "distributed-arp-table.h"
+#include "hard-interface.h"
+#include "originator.h"
+#include "send.h"
+#include "types.h"
+#include "translation-table.h"
+#include "unicast.h"
+
+static void batadv_dat_purge(struct work_struct *work);
+
+/**
+ * batadv_dat_start_timer - initialise the DAT periodic worker
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
+{
+	INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
+	queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
+			   msecs_to_jiffies(10000));
+}
+
+/**
+ * batadv_dat_entry_free_ref - decrements the dat_entry refcounter and possibly
+ * free it
+ * @dat_entry: the oentry to free
+ */
+static void batadv_dat_entry_free_ref(struct batadv_dat_entry *dat_entry)
+{
+	if (atomic_dec_and_test(&dat_entry->refcount))
+		kfree_rcu(dat_entry, rcu);
+}
+
+/**
+ * batadv_dat_to_purge - checks whether a dat_entry has to be purged or not
+ * @dat_entry: the entry to check
+ *
+ * Returns true if the entry has to be purged now, false otherwise
+ */
+static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
+{
+	return batadv_has_timed_out(dat_entry->last_update,
+				    BATADV_DAT_ENTRY_TIMEOUT);
+}
+
+/**
+ * __batadv_dat_purge - delete entries from the DAT local storage
+ * @bat_priv: the bat priv with all the soft interface information
+ * @to_purge: function in charge to decide whether an entry has to be purged or
+ *	      not. This function takes the dat_entry as argument and has to
+ *	      returns a boolean value: true is the entry has to be deleted,
+ *	      false otherwise
+ *
+ * Loops over each entry in the DAT local storage and delete it if and only if
+ * the to_purge function passed as argument returns true
+ */
+static void __batadv_dat_purge(struct batadv_priv *bat_priv,
+			       bool (*to_purge)(struct batadv_dat_entry *))
+{
+	spinlock_t *list_lock; /* protects write access to the hash lists */
+	struct batadv_dat_entry *dat_entry;
+	struct hlist_node *node, *node_tmp;
+	struct hlist_head *head;
+	uint32_t i;
+
+	if (!bat_priv->dat.hash)
+		return;
+
+	for (i = 0; i < bat_priv->dat.hash->size; i++) {
+		head = &bat_priv->dat.hash->table[i];
+		list_lock = &bat_priv->dat.hash->list_locks[i];
+
+		spin_lock_bh(list_lock);
+		hlist_for_each_entry_safe(dat_entry, node, 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(dat_entry))
+				continue;
+
+			hlist_del_rcu(node);
+			batadv_dat_entry_free_ref(dat_entry);
+		}
+		spin_unlock_bh(list_lock);
+	}
+}
+
+/**
+ * batadv_dat_purge - periodic task that deletes old entries from the local DAT
+ * hash table
+ * @work: kernel work struct
+ */
+static void batadv_dat_purge(struct work_struct *work)
+{
+	struct delayed_work *delayed_work;
+	struct batadv_priv_dat *priv_dat;
+	struct batadv_priv *bat_priv;
+
+	delayed_work = container_of(work, struct delayed_work, work);
+	priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
+	bat_priv = container_of(priv_dat, struct batadv_priv, dat);
+
+	__batadv_dat_purge(bat_priv, batadv_dat_to_purge);
+	batadv_dat_start_timer(bat_priv);
+}
+
+/**
+ * batadv_compare_dat - comparing function used in the local DAT hash table
+ * @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_compare_dat(const struct hlist_node *node, const void *data2)
+{
+	const void *data1 = container_of(node, struct batadv_dat_entry,
+					 hash_entry);
+
+	return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0);
+}
+
+/**
+ * batadv_arp_hw_src - extract the hw_src field from an ARP packet
+ * @skb: ARP packet
+ * @hdr_size: size of the possible header before the ARP packet
+ *
+ * Returns the value of the hw_src field in the ARP packet
+ */
+static uint8_t *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
+{
+	uint8_t *addr;
+
+	addr = (uint8_t *)(skb->data + hdr_size);
+	addr += ETH_HLEN + sizeof(struct arphdr);
+
+	return addr;
+}
+
+/**
+ * batadv_arp_ip_src - extract the ip_src field from an ARP packet
+ * @skb: ARP packet
+ * @hdr_size: size of the possible header before the ARP packet
+ *
+ * Returns the value of the ip_src field in the ARP packet
+ */
+static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
+{
+	return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
+}
+
+/**
+ * batadv_arp_hw_dst - extract the hw_dst field from an ARP packet
+ * @skb: ARP packet
+ * @hdr_size: size of the possible header before the ARP packet
+ *
+ * Returns the value of the hw_dst field in the ARP packet
+ */
+static uint8_t *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
+{
+	return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
+}
+
+/**
+ * batadv_arp_ip_dst - extract the ip_dst field from an ARP packet
+ * @skb: ARP packet
+ * @hdr_size: size of the possible header before the ARP packet
+ *
+ * Returns the value of the ip_dst field in the ARP packet
+ */
+static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
+{
+	return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
+}
+
+/**
+ * batadv_hash_dat - compute the hash value for an IP address
+ * @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_hash_dat(const void *data, uint32_t size)
+{
+	const unsigned char *key = data;
+	uint32_t hash = 0;
+	size_t i;
+
+	for (i = 0; i < 4; i++) {
+		hash += key[i];
+		hash += (hash << 10);
+		hash ^= (hash >> 6);
+	}
+
+	hash += (hash << 3);
+	hash ^= (hash >> 11);
+	hash += (hash << 15);
+
+	return hash % size;
+}
+
+/**
+ * batadv_dat_entry_hash_find - looks for a given dat_entry in the local hash
+ * table
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ip: search key
+ *
+ * Returns the dat_entry if found, NULL otherwise
+ */
+static struct batadv_dat_entry *
+batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct batadv_dat_entry *dat_entry, *dat_entry_tmp = NULL;
+	struct batadv_hashtable *hash = bat_priv->dat.hash;
+	uint32_t index;
+
+	if (!hash)
+		return NULL;
+
+	index = batadv_hash_dat(&ip, hash->size);
+	head = &hash->table[index];
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(dat_entry, node, head, hash_entry) {
+		if (dat_entry->ip != ip)
+			continue;
+
+		if (!atomic_inc_not_zero(&dat_entry->refcount))
+			continue;
+
+		dat_entry_tmp = dat_entry;
+		break;
+	}
+	rcu_read_unlock();
+
+	return dat_entry_tmp;
+}
+
+/**
+ * batadv_dat_entry_add - add a new dat entry or update it if already exists
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ip: ipv4 to add/edit
+ * @mac_addr: mac address to assign to the given ipv4
+ */
+static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
+				 uint8_t *mac_addr)
+{
+	struct batadv_dat_entry *dat_entry;
+	int hash_added;
+
+	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip);
+	/* if this entry is already known, just update it */
+	if (dat_entry) {
+		if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
+			memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN);
+		dat_entry->last_update = jiffies;
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "Entry updated: %pI4 %pM\n", &dat_entry->ip,
+			   dat_entry->mac_addr);
+		goto out;
+	}
+
+	dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
+	if (!dat_entry)
+		goto out;
+
+	dat_entry->ip = ip;
+	memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN);
+	dat_entry->last_update = jiffies;
+	atomic_set(&dat_entry->refcount, 2);
+
+	hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
+				     batadv_hash_dat, &dat_entry->ip,
+				     &dat_entry->hash_entry);
+
+	if (unlikely(hash_added != 0)) {
+		/* remove the reference for the hash */
+		batadv_dat_entry_free_ref(dat_entry);
+		goto out;
+	}
+
+	batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM\n",
+		   &dat_entry->ip, dat_entry->mac_addr);
+
+out:
+	if (dat_entry)
+		batadv_dat_entry_free_ref(dat_entry);
+}
+
+#ifdef CONFIG_BATMAN_ADV_DEBUG
+
+/**
+ * batadv_dbg_arp - print a debug message containing all the ARP packet details
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: ARP packet
+ * @type: ARP type
+ * @hdr_size: size of the possible header before the ARP packet
+ * @msg: message to print together with the debugging information
+ */
+static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			   uint16_t type, int hdr_size, char *msg)
+{
+	struct batadv_unicast_4addr_packet *unicast_4addr_packet;
+	struct batadv_bcast_packet *bcast_pkt;
+	uint8_t *orig_addr;
+	__be32 ip_src, ip_dst;
+
+	if (msg)
+		batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
+
+	ip_src = batadv_arp_ip_src(skb, hdr_size);
+	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
+	batadv_dbg(BATADV_DBG_DAT, bat_priv,
+		   "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
+		   batadv_arp_hw_src(skb, hdr_size), &ip_src,
+		   batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
+
+	if (hdr_size == 0)
+		return;
+
+	/* if the ARP packet is encapsulated in a batman packet, let's print
+	 * some debug messages
+	 */
+	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
+
+	switch (unicast_4addr_packet->u.header.packet_type) {
+	case BATADV_UNICAST:
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "* encapsulated within a UNICAST packet\n");
+		break;
+	case BATADV_UNICAST_4ADDR:
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
+			   unicast_4addr_packet->src);
+		switch (unicast_4addr_packet->subtype) {
+		case BATADV_P_DAT_DHT_PUT:
+			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
+			break;
+		case BATADV_P_DAT_DHT_GET:
+			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
+			break;
+		case BATADV_P_DAT_CACHE_REPLY:
+			batadv_dbg(BATADV_DBG_DAT, bat_priv,
+				   "* type: DAT_CACHE_REPLY\n");
+			break;
+		case BATADV_P_DATA:
+			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
+			break;
+		default:
+			batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
+				   unicast_4addr_packet->u.header.packet_type);
+		}
+		break;
+	case BATADV_BCAST:
+		bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
+		orig_addr = bcast_pkt->orig;
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "* encapsulated within a BCAST packet (src: %pM)\n",
+			   orig_addr);
+		break;
+	default:
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "* encapsulated within an unknown packet type (0x%x)\n",
+			   unicast_4addr_packet->u.header.packet_type);
+	}
+}
+
+#else
+
+static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			   uint16_t type, int hdr_size, char *msg)
+{
+}
+
+#endif /* CONFIG_BATMAN_ADV_DEBUG */
+
+/**
+ * batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
+ * @res: the array with the already selected candidates
+ * @select: number of already selected candidates
+ * @tmp_max: address of the currently evaluated node
+ * @max: current round max address
+ * @last_max: address of the last selected candidate
+ * @candidate: orig_node under evaluation
+ * @max_orig_node: last selected candidate
+ *
+ * Returns true if the node has been elected as next candidate or false othrwise
+ */
+static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
+					 int select, batadv_dat_addr_t tmp_max,
+					 batadv_dat_addr_t max,
+					 batadv_dat_addr_t last_max,
+					 struct batadv_orig_node *candidate,
+					 struct batadv_orig_node *max_orig_node)
+{
+	bool ret = false;
+	int j;
+
+	/* Check if this node has already been selected... */
+	for (j = 0; j < select; j++)
+		if (res[j].orig_node == candidate)
+			break;
+	/* ..and possibly skip it */
+	if (j < select)
+		goto out;
+	/* sanity check: has it already been selected? This should not happen */
+	if (tmp_max > last_max)
+		goto out;
+	/* check if during this iteration an originator with a closer dht
+	 * address has already been found
+	 */
+	if (tmp_max < max)
+		goto out;
+	/* this is an hash collision with the temporary selected node. Choose
+	 * the one with the lowest address
+	 */
+	if ((tmp_max == max) &&
+	    (batadv_compare_eth(candidate->orig, max_orig_node->orig) > 0))
+		goto out;
+
+	ret = true;
+out:
+	return ret;
+}
+
+/**
+ * batadv_choose_next_candidate - select the next DHT candidate
+ * @bat_priv: the bat priv with all the soft interface information
+ * @cands: candidates array
+ * @select: number of candidates already present in the array
+ * @ip_key: key to look up in the DHT
+ * @last_max: pointer where the address of the selected candidate will be saved
+ */
+static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
+					 struct batadv_dat_candidate *cands,
+					 int select, batadv_dat_addr_t ip_key,
+					 batadv_dat_addr_t *last_max)
+{
+	batadv_dat_addr_t max = 0, tmp_max = 0;
+	struct batadv_orig_node *orig_node, *max_orig_node = NULL;
+	struct batadv_hashtable *hash = bat_priv->orig_hash;
+	struct hlist_node *node;
+	struct hlist_head *head;
+	int i;
+
+	/* if no node is eligible as candidate, leave the candidate type as
+	 * NOT_FOUND
+	 */
+	cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
+
+	/* iterate over the originator list and find the node with closest
+	 * dat_address which has not been selected yet
+	 */
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
+			/* the dht space is a ring and addresses are unsigned */
+			tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
+				  ip_key;
+
+			if (!batadv_is_orig_node_eligible(cands, select,
+							  tmp_max, max,
+							  *last_max, orig_node,
+							  max_orig_node))
+				continue;
+
+			if (!atomic_inc_not_zero(&orig_node->refcount))
+				continue;
+
+			max = tmp_max;
+			if (max_orig_node)
+				batadv_orig_node_free_ref(max_orig_node);
+			max_orig_node = orig_node;
+		}
+		rcu_read_unlock();
+	}
+	if (max_orig_node) {
+		cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
+		cands[select].orig_node = max_orig_node;
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
+			   select, max_orig_node->orig, max_orig_node->dat_addr,
+			   max);
+	}
+	*last_max = max;
+}
+
+/**
+ * batadv_dat_select_candidates - selects the nodes which the DHT message has to
+ * be sent to
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ip_dst: ipv4 to look up in the DHT
+ *
+ * An originator O is selected if and only if its DHT_ID value is one of three
+ * closest values (from the LEFT, with wrap around if needed) then the hash
+ * value of the key. ip_dst is the key.
+ *
+ * Returns the candidate array of size BATADV_DAT_CANDIDATE_NUM
+ */
+static struct batadv_dat_candidate *
+batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst)
+{
+	int select;
+	batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
+	struct batadv_dat_candidate *res;
+
+	if (!bat_priv->orig_hash)
+		return NULL;
+
+	res = kmalloc(BATADV_DAT_CANDIDATES_NUM * sizeof(*res), GFP_ATOMIC);
+	if (!res)
+		return NULL;
+
+	ip_key = (batadv_dat_addr_t)batadv_hash_dat(&ip_dst,
+						    BATADV_DAT_ADDR_MAX);
+
+	batadv_dbg(BATADV_DBG_DAT, bat_priv,
+		   "dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
+		   ip_key);
+
+	for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
+		batadv_choose_next_candidate(bat_priv, res, select, ip_key,
+					     &last_max);
+
+	return res;
+}
+
+/**
+ * batadv_dat_send_data - send a payload to the selected candidates
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: payload to send
+ * @ip: the DHT key
+ * @packet_subtype: unicast4addr packet subtype to use
+ *
+ * In this function the skb is copied by means of pskb_copy() and is sent as
+ * unicast packet to each of the selected candidates
+ *
+ * Returns true if the packet is sent to at least one candidate, false otherwise
+ */
+static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
+				 struct sk_buff *skb, __be32 ip,
+				 int packet_subtype)
+{
+	int i;
+	bool ret = false;
+	int send_status;
+	struct batadv_neigh_node *neigh_node = NULL;
+	struct sk_buff *tmp_skb;
+	struct batadv_dat_candidate *cand;
+
+	cand = batadv_dat_select_candidates(bat_priv, ip);
+	if (!cand)
+		goto out;
+
+	batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
+
+	for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
+		if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
+			continue;
+
+		neigh_node = batadv_orig_node_get_router(cand[i].orig_node);
+		if (!neigh_node)
+			goto free_orig;
+
+		tmp_skb = pskb_copy(skb, GFP_ATOMIC);
+		if (!batadv_unicast_4addr_prepare_skb(bat_priv, tmp_skb,
+						      cand[i].orig_node,
+						      packet_subtype)) {
+			kfree_skb(tmp_skb);
+			goto free_neigh;
+		}
+
+		send_status = batadv_send_skb_packet(tmp_skb,
+						     neigh_node->if_incoming,
+						     neigh_node->addr);
+		if (send_status == NET_XMIT_SUCCESS) {
+			/* count the sent packet */
+			switch (packet_subtype) {
+			case BATADV_P_DAT_DHT_GET:
+				batadv_inc_counter(bat_priv,
+						   BATADV_CNT_DAT_GET_TX);
+				break;
+			case BATADV_P_DAT_DHT_PUT:
+				batadv_inc_counter(bat_priv,
+						   BATADV_CNT_DAT_PUT_TX);
+				break;
+			}
+
+			/* packet sent to a candidate: return true */
+			ret = true;
+		}
+free_neigh:
+		batadv_neigh_node_free_ref(neigh_node);
+free_orig:
+		batadv_orig_node_free_ref(cand[i].orig_node);
+	}
+
+out:
+	kfree(cand);
+	return ret;
+}
+
+/**
+ * batadv_dat_hash_free - free the local DAT hash table
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
+{
+	if (!bat_priv->dat.hash)
+		return;
+
+	__batadv_dat_purge(bat_priv, NULL);
+
+	batadv_hash_destroy(bat_priv->dat.hash);
+
+	bat_priv->dat.hash = NULL;
+}
+
+/**
+ * batadv_dat_init - initialise the DAT internals
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+int batadv_dat_init(struct batadv_priv *bat_priv)
+{
+	if (bat_priv->dat.hash)
+		return 0;
+
+	bat_priv->dat.hash = batadv_hash_new(1024);
+
+	if (!bat_priv->dat.hash)
+		return -ENOMEM;
+
+	batadv_dat_start_timer(bat_priv);
+
+	return 0;
+}
+
+/**
+ * batadv_dat_free - free the DAT internals
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+void batadv_dat_free(struct batadv_priv *bat_priv)
+{
+	cancel_delayed_work_sync(&bat_priv->dat.work);
+
+	batadv_dat_hash_free(bat_priv);
+}
+
+/**
+ * batadv_dat_cache_seq_print_text - print the local DAT hash table
+ * @seq: seq file to print on
+ * @offset: not used
+ */
+int batadv_dat_cache_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->dat.hash;
+	struct batadv_dat_entry *dat_entry;
+	struct batadv_hard_iface *primary_if;
+	struct hlist_node *node;
+	struct hlist_head *head;
+	unsigned long last_seen_jiffies;
+	int last_seen_msecs, last_seen_secs, last_seen_mins;
+	uint32_t i;
+
+	primary_if = batadv_seq_print_text_primary_if_get(seq);
+	if (!primary_if)
+		goto out;
+
+	seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
+	seq_printf(seq, "          %-7s          %-13s %5s\n", "IPv4", "MAC",
+		   "last-seen");
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(dat_entry, node, head, hash_entry) {
+			last_seen_jiffies = jiffies - dat_entry->last_update;
+			last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
+			last_seen_mins = last_seen_msecs / 60000;
+			last_seen_msecs = last_seen_msecs % 60000;
+			last_seen_secs = last_seen_msecs / 1000;
+
+			seq_printf(seq, " * %15pI4 %14pM %6i:%02i\n",
+				   &dat_entry->ip, dat_entry->mac_addr,
+				   last_seen_mins, last_seen_secs);
+		}
+		rcu_read_unlock();
+	}
+
+out:
+	if (primary_if)
+		batadv_hardif_free_ref(primary_if);
+	return 0;
+}
+
+/**
+ * batadv_arp_get_type - parse an ARP packet and gets the type
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: packet to analyse
+ * @hdr_size: size of the possible header before the ARP packet in the skb
+ *
+ * Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise
+ */
+static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv,
+				    struct sk_buff *skb, int hdr_size)
+{
+	struct arphdr *arphdr;
+	struct ethhdr *ethhdr;
+	__be32 ip_src, ip_dst;
+	uint8_t *hw_src, *hw_dst;
+	uint16_t type = 0;
+
+	/* pull the ethernet header */
+	if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
+		goto out;
+
+	ethhdr = (struct ethhdr *)(skb->data + hdr_size);
+
+	if (ethhdr->h_proto != htons(ETH_P_ARP))
+		goto out;
+
+	/* pull the ARP payload */
+	if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
+				    arp_hdr_len(skb->dev))))
+		goto out;
+
+	arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
+
+	/* Check whether the ARP packet carries a valid
+	 * IP information
+	 */
+	if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
+		goto out;
+
+	if (arphdr->ar_pro != htons(ETH_P_IP))
+		goto out;
+
+	if (arphdr->ar_hln != ETH_ALEN)
+		goto out;
+
+	if (arphdr->ar_pln != 4)
+		goto out;
+
+	/* Check for bad reply/request. If the ARP message is not sane, DAT
+	 * will simply ignore it
+	 */
+	ip_src = batadv_arp_ip_src(skb, hdr_size);
+	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
+	if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
+	    ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
+	    ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
+	    ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
+		goto out;
+
+	hw_src = batadv_arp_hw_src(skb, hdr_size);
+	if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
+		goto out;
+
+	/* we don't care about the destination MAC address in ARP requests */
+	if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
+		hw_dst = batadv_arp_hw_dst(skb, hdr_size);
+		if (is_zero_ether_addr(hw_dst) ||
+		    is_multicast_ether_addr(hw_dst))
+			goto out;
+	}
+
+	type = ntohs(arphdr->ar_op);
+out:
+	return type;
+}
+
+/**
+ * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to
+ * answer using DAT
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: packet to check
+ *
+ * Returns true if the message has been sent to the dht candidates, false
+ * otherwise. In case of true the message has to be enqueued to permit the
+ * fallback
+ */
+bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
+					   struct sk_buff *skb)
+{
+	uint16_t type = 0;
+	__be32 ip_dst, ip_src;
+	uint8_t *hw_src;
+	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;
+
+	type = batadv_arp_get_type(bat_priv, skb, 0);
+	/* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
+	 * message to the selected DHT candidates
+	 */
+	if (type != ARPOP_REQUEST)
+		goto out;
+
+	batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REQUEST");
+
+	ip_src = batadv_arp_ip_src(skb, 0);
+	hw_src = batadv_arp_hw_src(skb, 0);
+	ip_dst = batadv_arp_ip_dst(skb, 0);
+
+	batadv_dat_entry_add(bat_priv, ip_src, hw_src);
+
+	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,
+				     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->stats.rx_packets++;
+		bat_priv->stats.rx_bytes += skb->len + ETH_HLEN;
+		primary_if->soft_iface->last_rx = jiffies;
+
+		netif_rx(skb_new);
+		batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
+		ret = true;
+	} else {
+		/* Send the request on the DHT */
+		ret = batadv_dat_send_data(bat_priv, skb, ip_dst,
+					   BATADV_P_DAT_DHT_GET);
+	}
+out:
+	if (dat_entry)
+		batadv_dat_entry_free_ref(dat_entry);
+	if (primary_if)
+		batadv_hardif_free_ref(primary_if);
+	return ret;
+}
+
+/**
+ * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to
+ * answer using the local DAT storage
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns true if the request has been answered, false otherwise
+ */
+bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
+					   struct sk_buff *skb, int hdr_size)
+{
+	uint16_t type;
+	__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;
+
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
+	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
+	if (type != ARPOP_REQUEST)
+		goto out;
+
+	hw_src = batadv_arp_hw_src(skb, hdr_size);
+	ip_src = batadv_arp_ip_src(skb, hdr_size);
+	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
+
+	batadv_dbg_arp(bat_priv, skb, type, hdr_size,
+		       "Parsing incoming ARP REQUEST");
+
+	batadv_dat_entry_add(bat_priv, ip_src, hw_src);
+
+	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
+	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,
+			     dat_entry->mac_addr, hw_src);
+
+	if (!skb_new)
+		goto out;
+
+	/* to preserve backwards compatibility, here the node has to answer
+	 * using the same packet type it received for the request. This is due
+	 * to that if a node is not using the 4addr packet format it may not
+	 * support it.
+	 */
+	if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
+		err = batadv_unicast_4addr_send_skb(bat_priv, skb_new,
+						    BATADV_P_DAT_CACHE_REPLY);
+	else
+		err = batadv_unicast_send_skb(bat_priv, skb_new);
+
+	if (!err) {
+		batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
+		ret = true;
+	}
+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;
+}
+
+/**
+ * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: packet to check
+ */
+void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb)
+{
+	uint16_t type;
+	__be32 ip_src, ip_dst;
+	uint8_t *hw_src, *hw_dst;
+
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		return;
+
+	type = batadv_arp_get_type(bat_priv, skb, 0);
+	if (type != ARPOP_REPLY)
+		return;
+
+	batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REPLY");
+
+	hw_src = batadv_arp_hw_src(skb, 0);
+	ip_src = batadv_arp_ip_src(skb, 0);
+	hw_dst = batadv_arp_hw_dst(skb, 0);
+	ip_dst = batadv_arp_ip_dst(skb, 0);
+
+	batadv_dat_entry_add(bat_priv, ip_src, hw_src);
+	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);
+
+	/* Send the ARP reply to the candidates for both the IP addresses that
+	 * the node got within the ARP reply
+	 */
+	batadv_dat_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT);
+	batadv_dat_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT);
+}
+/**
+ * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local
+ * DAT storage only
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: packet to check
+ * @hdr_size: siaze of the encapsulation header
+ */
+bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb, int hdr_size)
+{
+	uint16_t type;
+	__be32 ip_src, ip_dst;
+	uint8_t *hw_src, *hw_dst;
+	bool ret = false;
+
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
+	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
+	if (type != ARPOP_REPLY)
+		goto out;
+
+	batadv_dbg_arp(bat_priv, skb, type, hdr_size,
+		       "Parsing incoming ARP REPLY");
+
+	hw_src = batadv_arp_hw_src(skb, hdr_size);
+	ip_src = batadv_arp_ip_src(skb, hdr_size);
+	hw_dst = batadv_arp_hw_dst(skb, hdr_size);
+	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
+
+	/* Update our internal cache with both the IP addresses the node got
+	 * within the ARP reply
+	 */
+	batadv_dat_entry_add(bat_priv, ip_src, hw_src);
+	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);
+
+	/* if this REPLY is directed to a client of mine, let's deliver the
+	 * packet to the interface
+	 */
+	ret = !batadv_is_my_client(bat_priv, hw_dst);
+out:
+	if (ret)
+		kfree_skb(skb);
+	/* if ret == false -> packet has to be delivered to the interface */
+	return ret;
+}
+
+/**
+ * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped
+ * (because the node has already got the reply via DAT) or not
+ * @bat_priv: the bat priv with all the soft interface information
+ * @forw_packet: the broadcast packet
+ *
+ * Returns true if the node can drop the packet, false otherwise
+ */
+bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
+				      struct batadv_forw_packet *forw_packet)
+{
+	uint16_t type;
+	__be32 ip_dst;
+	struct batadv_dat_entry *dat_entry = NULL;
+	bool ret = false;
+	const size_t bcast_len = sizeof(struct batadv_bcast_packet);
+
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
+	/* If this packet is an ARP_REQUEST and the node already has the
+	 * information that it is going to ask, then the packet can be dropped
+	 */
+	if (forw_packet->num_packets)
+		goto out;
+
+	type = batadv_arp_get_type(bat_priv, forw_packet->skb, bcast_len);
+	if (type != ARPOP_REQUEST)
+		goto out;
+
+	ip_dst = batadv_arp_ip_dst(forw_packet->skb, bcast_len);
+	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
+	/* check if the node already got this entry */
+	if (!dat_entry) {
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "ARP Request for %pI4: fallback\n", &ip_dst);
+		goto out;
+	}
+
+	batadv_dbg(BATADV_DBG_DAT, bat_priv,
+		   "ARP Request for %pI4: fallback prevented\n", &ip_dst);
+	ret = true;
+
+out:
+	if (dat_entry)
+		batadv_dat_entry_free_ref(dat_entry);
+	return ret;
+}