Merge tag 'fixes-for-v3.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux/fpc-iii.git] / net / batman-adv / bat_iv_ogm.c

/* Copyright (C) 2007-2014 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "main.h"
#include "translation-table.h"
#include "originator.h"
#include "routing.h"
#include "gateway_common.h"
#include "gateway_client.h"
#include "hard-interface.h"
#include "send.h"
#include "bat_algo.h"
#include "network-coding.h"


/**
 * batadv_dup_status - duplicate status
 * @BATADV_NO_DUP: the packet is a duplicate
 * @BATADV_ORIG_DUP: OGM is a duplicate in the originator (but not for the
 *  neighbor)
 * @BATADV_NEIGH_DUP: OGM is a duplicate for the neighbor
 * @BATADV_PROTECTED: originator is currently protected (after reboot)
 */
enum batadv_dup_status {
        BATADV_NO_DUP = 0,
        BATADV_ORIG_DUP,
        BATADV_NEIGH_DUP,
        BATADV_PROTECTED,
};

/**
 * batadv_ring_buffer_set - update the ring buffer with the given value
 * @lq_recv: pointer to the ring buffer
 * @lq_index: index to store the value at
 * @value: value to store in the ring buffer
 */
static void batadv_ring_buffer_set(uint8_t lq_recv[], uint8_t *lq_index,
                                   uint8_t value)
{
        lq_recv[*lq_index] = value;
        *lq_index = (*lq_index + 1) % BATADV_TQ_GLOBAL_WINDOW_SIZE;
}

/**
 * batadv_ring_buffer_set - compute the average of all non-zero values stored
 * in the given ring buffer
 * @lq_recv: pointer to the ring buffer
 *
 * Returns computed average value.
 */
static uint8_t batadv_ring_buffer_avg(const uint8_t lq_recv[])
{
        const uint8_t *ptr;
        uint16_t count = 0, i = 0, sum = 0;

        ptr = lq_recv;

        while (i < BATADV_TQ_GLOBAL_WINDOW_SIZE) {
                if (*ptr != 0) {
                        count++;
                        sum += *ptr;
                }

                i++;
                ptr++;
        }

        if (count == 0)
                return 0;

        return (uint8_t)(sum / count);
}

/**
 * batadv_iv_ogm_orig_free - free the private resources allocated for this
 *  orig_node
 * @orig_node: the orig_node for which the resources have to be free'd
 */
static void batadv_iv_ogm_orig_free(struct batadv_orig_node *orig_node)
{
        kfree(orig_node->bat_iv.bcast_own);
        kfree(orig_node->bat_iv.bcast_own_sum);
}

/**
 * batadv_iv_ogm_orig_add_if - change the private structures of the orig_node to
 *  include the new hard-interface
 * @orig_node: the orig_node that has to be changed
 * @max_if_num: the current amount of interfaces
 *
 * Returns 0 on success, a negative error code otherwise.
 */
static int batadv_iv_ogm_orig_add_if(struct batadv_orig_node *orig_node,
                                     int max_if_num)
{
        void *data_ptr;
        size_t old_size;
        int ret = -ENOMEM;

        spin_lock_bh(&orig_node->bat_iv.ogm_cnt_lock);

        old_size = (max_if_num - 1) * sizeof(unsigned long) * BATADV_NUM_WORDS;
        data_ptr = kmalloc_array(max_if_num,
                                 BATADV_NUM_WORDS * sizeof(unsigned long),
                                 GFP_ATOMIC);
        if (!data_ptr)
                goto unlock;

        memcpy(data_ptr, orig_node->bat_iv.bcast_own, old_size);
        kfree(orig_node->bat_iv.bcast_own);
        orig_node->bat_iv.bcast_own = data_ptr;

        data_ptr = kmalloc_array(max_if_num, sizeof(uint8_t), GFP_ATOMIC);
        if (!data_ptr) {
                kfree(orig_node->bat_iv.bcast_own);
                goto unlock;
        }

        memcpy(data_ptr, orig_node->bat_iv.bcast_own_sum,
               (max_if_num - 1) * sizeof(uint8_t));
        kfree(orig_node->bat_iv.bcast_own_sum);
        orig_node->bat_iv.bcast_own_sum = data_ptr;

        ret = 0;

unlock:
        spin_unlock_bh(&orig_node->bat_iv.ogm_cnt_lock);

        return ret;
}

/**
 * batadv_iv_ogm_orig_del_if - change the private structures of the orig_node to
 *  exclude the removed interface
 * @orig_node: the orig_node that has to be changed
 * @max_if_num: the current amount of interfaces
 * @del_if_num: the index of the interface being removed
 *
 * Returns 0 on success, a negative error code otherwise.
 */
static int batadv_iv_ogm_orig_del_if(struct batadv_orig_node *orig_node,
                                     int max_if_num, int del_if_num)
{
        int chunk_size,  ret = -ENOMEM, if_offset;
        void *data_ptr = NULL;

        spin_lock_bh(&orig_node->bat_iv.ogm_cnt_lock);

        /* last interface was removed */
        if (max_if_num == 0)
                goto free_bcast_own;

        chunk_size = sizeof(unsigned long) * BATADV_NUM_WORDS;
        data_ptr = kmalloc_array(max_if_num, chunk_size, GFP_ATOMIC);
        if (!data_ptr)
                goto unlock;

        /* copy first part */
        memcpy(data_ptr, orig_node->bat_iv.bcast_own, del_if_num * chunk_size);

        /* copy second part */
        memcpy((char *)data_ptr + del_if_num * chunk_size,
               orig_node->bat_iv.bcast_own + ((del_if_num + 1) * chunk_size),
               (max_if_num - del_if_num) * chunk_size);

free_bcast_own:
        kfree(orig_node->bat_iv.bcast_own);
        orig_node->bat_iv.bcast_own = data_ptr;

        if (max_if_num == 0)
                goto free_own_sum;

        data_ptr = kmalloc_array(max_if_num, sizeof(uint8_t), GFP_ATOMIC);
        if (!data_ptr) {
                kfree(orig_node->bat_iv.bcast_own);
                goto unlock;
        }

        memcpy(data_ptr, orig_node->bat_iv.bcast_own_sum,
               del_if_num * sizeof(uint8_t));

        if_offset = (del_if_num + 1) * sizeof(uint8_t);
        memcpy((char *)data_ptr + del_if_num * sizeof(uint8_t),
               orig_node->bat_iv.bcast_own_sum + if_offset,
               (max_if_num - del_if_num) * sizeof(uint8_t));

free_own_sum:
        kfree(orig_node->bat_iv.bcast_own_sum);
        orig_node->bat_iv.bcast_own_sum = data_ptr;

        ret = 0;
unlock:
        spin_unlock_bh(&orig_node->bat_iv.ogm_cnt_lock);

        return ret;
}

/**
 * batadv_iv_ogm_orig_get - retrieve or create (if does not exist) an originator
 * @bat_priv: the bat priv with all the soft interface information
 * @addr: mac address of the originator
 *
 * Returns the originator object corresponding to the passed mac address or NULL
 * on failure.
 * If the object does not exists it is created an initialised.
 */
static struct batadv_orig_node *
batadv_iv_ogm_orig_get(struct batadv_priv *bat_priv, const uint8_t *addr)
{
        struct batadv_orig_node *orig_node;
        int size, hash_added;

        orig_node = batadv_orig_hash_find(bat_priv, addr);
        if (orig_node)
                return orig_node;

        orig_node = batadv_orig_node_new(bat_priv, addr);
        if (!orig_node)
                return NULL;

        spin_lock_init(&orig_node->bat_iv.ogm_cnt_lock);

        size = bat_priv->num_ifaces * sizeof(unsigned long) * BATADV_NUM_WORDS;
        orig_node->bat_iv.bcast_own = kzalloc(size, GFP_ATOMIC);
        if (!orig_node->bat_iv.bcast_own)
                goto free_orig_node;

        size = bat_priv->num_ifaces * sizeof(uint8_t);
        orig_node->bat_iv.bcast_own_sum = kzalloc(size, GFP_ATOMIC);
        if (!orig_node->bat_iv.bcast_own_sum)
                goto free_orig_node;

        hash_added = batadv_hash_add(bat_priv->orig_hash, batadv_compare_orig,
                                     batadv_choose_orig, orig_node,
                                     &orig_node->hash_entry);
        if (hash_added != 0)
                goto free_orig_node;

        return orig_node;

free_orig_node:
        /* free twice, as batadv_orig_node_new sets refcount to 2 */
        batadv_orig_node_free_ref(orig_node);
        batadv_orig_node_free_ref(orig_node);

        return NULL;
}

static struct batadv_neigh_node *
batadv_iv_ogm_neigh_new(struct batadv_hard_iface *hard_iface,
                        const uint8_t *neigh_addr,
                        struct batadv_orig_node *orig_node,
                        struct batadv_orig_node *orig_neigh)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        struct batadv_neigh_node *neigh_node, *tmp_neigh_node;

        neigh_node = batadv_neigh_node_new(hard_iface, neigh_addr, orig_node);
        if (!neigh_node)
                goto out;

        if (!atomic_inc_not_zero(&hard_iface->refcount)) {
                kfree(neigh_node);
                neigh_node = NULL;
                goto out;
        }

        neigh_node->orig_node = orig_neigh;
        neigh_node->if_incoming = hard_iface;

        spin_lock_bh(&orig_node->neigh_list_lock);
        tmp_neigh_node = batadv_neigh_node_get(orig_node, hard_iface,
                                               neigh_addr);
        if (!tmp_neigh_node) {
                hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
        } else {
                kfree(neigh_node);
                batadv_hardif_free_ref(hard_iface);
                neigh_node = tmp_neigh_node;
        }
        spin_unlock_bh(&orig_node->neigh_list_lock);

        if (!tmp_neigh_node)
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Creating new neighbor %pM for orig_node %pM on interface %s\n",
                           neigh_addr, orig_node->orig,
                           hard_iface->net_dev->name);

out:
        return neigh_node;
}

static int batadv_iv_ogm_iface_enable(struct batadv_hard_iface *hard_iface)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char *ogm_buff;
        uint32_t random_seqno;
        int res = -ENOMEM;

        /* randomize initial seqno to avoid collision */
        get_random_bytes(&random_seqno, sizeof(random_seqno));
        atomic_set(&hard_iface->bat_iv.ogm_seqno, random_seqno);

        hard_iface->bat_iv.ogm_buff_len = BATADV_OGM_HLEN;
        ogm_buff = kmalloc(hard_iface->bat_iv.ogm_buff_len, GFP_ATOMIC);
        if (!ogm_buff)
                goto out;

        hard_iface->bat_iv.ogm_buff = ogm_buff;

        batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
        batadv_ogm_packet->packet_type = BATADV_IV_OGM;
        batadv_ogm_packet->version = BATADV_COMPAT_VERSION;
        batadv_ogm_packet->ttl = 2;
        batadv_ogm_packet->flags = BATADV_NO_FLAGS;
        batadv_ogm_packet->reserved = 0;
        batadv_ogm_packet->tq = BATADV_TQ_MAX_VALUE;

        res = 0;

out:
        return res;
}

static void batadv_iv_ogm_iface_disable(struct batadv_hard_iface *hard_iface)
{
        kfree(hard_iface->bat_iv.ogm_buff);
        hard_iface->bat_iv.ogm_buff = NULL;
}

static void batadv_iv_ogm_iface_update_mac(struct batadv_hard_iface *hard_iface)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff;

        batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
        ether_addr_copy(batadv_ogm_packet->orig,
                        hard_iface->net_dev->dev_addr);
        ether_addr_copy(batadv_ogm_packet->prev_sender,
                        hard_iface->net_dev->dev_addr);
}

static void
batadv_iv_ogm_primary_iface_set(struct batadv_hard_iface *hard_iface)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff;

        batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
        batadv_ogm_packet->flags = BATADV_PRIMARIES_FIRST_HOP;
        batadv_ogm_packet->ttl = BATADV_TTL;
}

/* when do we schedule our own ogm to be sent */
static unsigned long
batadv_iv_ogm_emit_send_time(const struct batadv_priv *bat_priv)
{
        unsigned int msecs;

        msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER;
        msecs += prandom_u32() % (2 * BATADV_JITTER);

        return jiffies + msecs_to_jiffies(msecs);
}

/* when do we schedule a ogm packet to be sent */
static unsigned long batadv_iv_ogm_fwd_send_time(void)
{
        return jiffies + msecs_to_jiffies(prandom_u32() % (BATADV_JITTER / 2));
}

/* apply hop penalty for a normal link */
static uint8_t batadv_hop_penalty(uint8_t tq,
                                  const struct batadv_priv *bat_priv)
{
        int hop_penalty = atomic_read(&bat_priv->hop_penalty);
        int new_tq;

        new_tq = tq * (BATADV_TQ_MAX_VALUE - hop_penalty);
        new_tq /= BATADV_TQ_MAX_VALUE;

        return new_tq;
}

/* is there another aggregated packet here? */
static int batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len,
                                     __be16 tvlv_len)
{
        int next_buff_pos = 0;

        next_buff_pos += buff_pos + BATADV_OGM_HLEN;
        next_buff_pos += ntohs(tvlv_len);

        return (next_buff_pos <= packet_len) &&
               (next_buff_pos <= BATADV_MAX_AGGREGATION_BYTES);
}

/* send a batman ogm to a given interface */
static void batadv_iv_ogm_send_to_if(struct batadv_forw_packet *forw_packet,
                                     struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        char *fwd_str;
        uint8_t packet_num;
        int16_t buff_pos;
        struct batadv_ogm_packet *batadv_ogm_packet;
        struct sk_buff *skb;
        uint8_t *packet_pos;

        if (hard_iface->if_status != BATADV_IF_ACTIVE)
                return;

        packet_num = 0;
        buff_pos = 0;
        packet_pos = forw_packet->skb->data;
        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;

        /* adjust all flags and log packets */
        while (batadv_iv_ogm_aggr_packet(buff_pos, forw_packet->packet_len,
                                         batadv_ogm_packet->tvlv_len)) {
                /* we might have aggregated direct link packets with an
                 * ordinary base packet
                 */
                if (forw_packet->direct_link_flags & BIT(packet_num) &&
                    forw_packet->if_incoming == hard_iface)
                        batadv_ogm_packet->flags |= BATADV_DIRECTLINK;
                else
                        batadv_ogm_packet->flags &= ~BATADV_DIRECTLINK;

                if (packet_num > 0 || !forw_packet->own)
                        fwd_str = "Forwarding";
                else
                        fwd_str = "Sending own";

                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "%s %spacket (originator %pM, seqno %u, TQ %d, TTL %d, IDF %s) on interface %s [%pM]\n",
                           fwd_str, (packet_num > 0 ? "aggregated " : ""),
                           batadv_ogm_packet->orig,
                           ntohl(batadv_ogm_packet->seqno),
                           batadv_ogm_packet->tq, batadv_ogm_packet->ttl,
                           (batadv_ogm_packet->flags & BATADV_DIRECTLINK ?
                            "on" : "off"),
                           hard_iface->net_dev->name,
                           hard_iface->net_dev->dev_addr);

                buff_pos += BATADV_OGM_HLEN;
                buff_pos += ntohs(batadv_ogm_packet->tvlv_len);
                packet_num++;
                packet_pos = forw_packet->skb->data + buff_pos;
                batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;
        }

        /* create clone because function is called more than once */
        skb = skb_clone(forw_packet->skb, GFP_ATOMIC);
        if (skb) {
                batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_TX);
                batadv_add_counter(bat_priv, BATADV_CNT_MGMT_TX_BYTES,
                                   skb->len + ETH_HLEN);
                batadv_send_skb_packet(skb, hard_iface, batadv_broadcast_addr);
        }
}

/* send a batman ogm packet */
static void batadv_iv_ogm_emit(struct batadv_forw_packet *forw_packet)
{
        struct net_device *soft_iface;
        struct batadv_priv *bat_priv;
        struct batadv_hard_iface *primary_if = NULL;

        if (!forw_packet->if_incoming) {
                pr_err("Error - can't forward packet: incoming iface not specified\n");
                goto out;
        }

        soft_iface = forw_packet->if_incoming->soft_iface;
        bat_priv = netdev_priv(soft_iface);

        if (WARN_ON(!forw_packet->if_outgoing))
                goto out;

        if (WARN_ON(forw_packet->if_outgoing->soft_iface != soft_iface))
                goto out;

        if (forw_packet->if_incoming->if_status != BATADV_IF_ACTIVE)
                goto out;

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto out;

        /* only for one specific outgoing interface */
        batadv_iv_ogm_send_to_if(forw_packet, forw_packet->if_outgoing);

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

/**
 * batadv_iv_ogm_can_aggregate - find out if an OGM can be aggregated on an
 *  existing forward packet
 * @new_bat_ogm_packet: OGM packet to be aggregated
 * @bat_priv: the bat priv with all the soft interface information
 * @packet_len: (total) length of the OGM
 * @send_time: timestamp (jiffies) when the packet is to be sent
 * @direktlink: true if this is a direct link packet
 * @if_incoming: interface where the packet was received
 * @if_outgoing: interface for which the retransmission should be considered
 * @forw_packet: the forwarded packet which should be checked
 *
 * Returns true if new_packet can be aggregated with forw_packet
 */
static bool
batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
                            struct batadv_priv *bat_priv,
                            int packet_len, unsigned long send_time,
                            bool directlink,
                            const struct batadv_hard_iface *if_incoming,
                            const struct batadv_hard_iface *if_outgoing,
                            const struct batadv_forw_packet *forw_packet)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        int aggregated_bytes = forw_packet->packet_len + packet_len;
        struct batadv_hard_iface *primary_if = NULL;
        bool res = false;
        unsigned long aggregation_end_time;

        batadv_ogm_packet = (struct batadv_ogm_packet *)forw_packet->skb->data;
        aggregation_end_time = send_time;
        aggregation_end_time += msecs_to_jiffies(BATADV_MAX_AGGREGATION_MS);

        /* we can aggregate the current packet to this aggregated packet
         * if:
         *
         * - the send time is within our MAX_AGGREGATION_MS time
         * - the resulting packet wont be bigger than
         *   MAX_AGGREGATION_BYTES
         */
        if (time_before(send_time, forw_packet->send_time) &&
            time_after_eq(aggregation_end_time, forw_packet->send_time) &&
            (aggregated_bytes <= BATADV_MAX_AGGREGATION_BYTES)) {
                /* check aggregation compatibility
                 * -> direct link packets are broadcasted on
                 *    their interface only
                 * -> aggregate packet if the current packet is
                 *    a "global" packet as well as the base
                 *    packet
                 */
                primary_if = batadv_primary_if_get_selected(bat_priv);
                if (!primary_if)
                        goto out;

                /* packet is not leaving on the same interface. */
                if (forw_packet->if_outgoing != if_outgoing)
                        goto out;

                /* packets without direct link flag and high TTL
                 * are flooded through the net
                 */
                if ((!directlink) &&
                    (!(batadv_ogm_packet->flags & BATADV_DIRECTLINK)) &&
                    (batadv_ogm_packet->ttl != 1) &&

                    /* own packets originating non-primary
                     * interfaces leave only that interface
                     */
                    ((!forw_packet->own) ||
                     (forw_packet->if_incoming == primary_if))) {
                        res = true;
                        goto out;
                }

                /* if the incoming packet is sent via this one
                 * interface only - we still can aggregate
                 */
                if ((directlink) &&
                    (new_bat_ogm_packet->ttl == 1) &&
                    (forw_packet->if_incoming == if_incoming) &&

                    /* packets from direct neighbors or
                     * own secondary interface packets
                     * (= secondary interface packets in general)
                     */
                    (batadv_ogm_packet->flags & BATADV_DIRECTLINK ||
                     (forw_packet->own &&
                      forw_packet->if_incoming != primary_if))) {
                        res = true;
                        goto out;
                }
        }

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return res;
}

/**
 * batadv_iv_ogm_aggregate_new - create a new aggregated packet and add this
 *  packet to it.
 * @packet_buff: pointer to the OGM
 * @packet_len: (total) length of the OGM
 * @send_time: timestamp (jiffies) when the packet is to be sent
 * @direct_link: whether this OGM has direct link status
 * @if_incoming: interface where the packet was received
 * @if_outgoing: interface for which the retransmission should be considered
 * @own_packet: true if it is a self-generated ogm
 */
static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
                                        int packet_len, unsigned long send_time,
                                        bool direct_link,
                                        struct batadv_hard_iface *if_incoming,
                                        struct batadv_hard_iface *if_outgoing,
                                        int own_packet)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_forw_packet *forw_packet_aggr;
        unsigned char *skb_buff;
        unsigned int skb_size;

        if (!atomic_inc_not_zero(&if_incoming->refcount))
                return;

        if (!atomic_inc_not_zero(&if_outgoing->refcount))
                goto out_free_incoming;

        /* own packet should always be scheduled */
        if (!own_packet) {
                if (!batadv_atomic_dec_not_zero(&bat_priv->batman_queue_left)) {
                        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                                   "batman packet queue full\n");
                        goto out;
                }
        }

        forw_packet_aggr = kmalloc(sizeof(*forw_packet_aggr), GFP_ATOMIC);
        if (!forw_packet_aggr) {
                if (!own_packet)
                        atomic_inc(&bat_priv->batman_queue_left);
                goto out;
        }

        if ((atomic_read(&bat_priv->aggregated_ogms)) &&
            (packet_len < BATADV_MAX_AGGREGATION_BYTES))
                skb_size = BATADV_MAX_AGGREGATION_BYTES;
        else
                skb_size = packet_len;

        skb_size += ETH_HLEN;

        forw_packet_aggr->skb = netdev_alloc_skb_ip_align(NULL, skb_size);
        if (!forw_packet_aggr->skb) {
                if (!own_packet)
                        atomic_inc(&bat_priv->batman_queue_left);
                kfree(forw_packet_aggr);
                goto out;
        }
        forw_packet_aggr->skb->priority = TC_PRIO_CONTROL;
        skb_reserve(forw_packet_aggr->skb, ETH_HLEN);

        skb_buff = skb_put(forw_packet_aggr->skb, packet_len);
        forw_packet_aggr->packet_len = packet_len;
        memcpy(skb_buff, packet_buff, packet_len);

        forw_packet_aggr->own = own_packet;
        forw_packet_aggr->if_incoming = if_incoming;
        forw_packet_aggr->if_outgoing = if_outgoing;
        forw_packet_aggr->num_packets = 0;
        forw_packet_aggr->direct_link_flags = BATADV_NO_FLAGS;
        forw_packet_aggr->send_time = send_time;

        /* save packet direct link flag status */
        if (direct_link)
                forw_packet_aggr->direct_link_flags |= 1;

        /* add new packet to packet list */
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        hlist_add_head(&forw_packet_aggr->list, &bat_priv->forw_bat_list);
        spin_unlock_bh(&bat_priv->forw_bat_list_lock);

        /* start timer for this packet */
        INIT_DELAYED_WORK(&forw_packet_aggr->delayed_work,
                          batadv_send_outstanding_bat_ogm_packet);
        queue_delayed_work(batadv_event_workqueue,
                           &forw_packet_aggr->delayed_work,
                           send_time - jiffies);

        return;
out:
        batadv_hardif_free_ref(if_outgoing);
out_free_incoming:
        batadv_hardif_free_ref(if_incoming);
}

/* aggregate a new packet into the existing ogm packet */
static void batadv_iv_ogm_aggregate(struct batadv_forw_packet *forw_packet_aggr,
                                    const unsigned char *packet_buff,
                                    int packet_len, bool direct_link)
{
        unsigned char *skb_buff;
        unsigned long new_direct_link_flag;

        skb_buff = skb_put(forw_packet_aggr->skb, packet_len);
        memcpy(skb_buff, packet_buff, packet_len);
        forw_packet_aggr->packet_len += packet_len;
        forw_packet_aggr->num_packets++;

        /* save packet direct link flag status */
        if (direct_link) {
                new_direct_link_flag = BIT(forw_packet_aggr->num_packets);
                forw_packet_aggr->direct_link_flags |= new_direct_link_flag;
        }
}

/**
 * batadv_iv_ogm_queue_add - queue up an OGM for transmission
 * @bat_priv: the bat priv with all the soft interface information
 * @packet_buff: pointer to the OGM
 * @packet_len: (total) length of the OGM
 * @if_incoming: interface where the packet was received
 * @if_outgoing: interface for which the retransmission should be considered
 * @own_packet: true if it is a self-generated ogm
 * @send_time: timestamp (jiffies) when the packet is to be sent
 */
static void batadv_iv_ogm_queue_add(struct batadv_priv *bat_priv,
                                    unsigned char *packet_buff,
                                    int packet_len,
                                    struct batadv_hard_iface *if_incoming,
                                    struct batadv_hard_iface *if_outgoing,
                                    int own_packet, unsigned long send_time)
{
        /* _aggr -> pointer to the packet we want to aggregate with
         * _pos -> pointer to the position in the queue
         */
        struct batadv_forw_packet *forw_packet_aggr = NULL;
        struct batadv_forw_packet *forw_packet_pos = NULL;
        struct batadv_ogm_packet *batadv_ogm_packet;
        bool direct_link;
        unsigned long max_aggregation_jiffies;

        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_buff;
        direct_link = batadv_ogm_packet->flags & BATADV_DIRECTLINK ? 1 : 0;
        max_aggregation_jiffies = msecs_to_jiffies(BATADV_MAX_AGGREGATION_MS);

        /* find position for the packet in the forward queue */
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        /* own packets are not to be aggregated */
        if ((atomic_read(&bat_priv->aggregated_ogms)) && (!own_packet)) {
                hlist_for_each_entry(forw_packet_pos,
                                     &bat_priv->forw_bat_list, list) {
                        if (batadv_iv_ogm_can_aggregate(batadv_ogm_packet,
                                                        bat_priv, packet_len,
                                                        send_time, direct_link,
                                                        if_incoming,
                                                        if_outgoing,
                                                        forw_packet_pos)) {
                                forw_packet_aggr = forw_packet_pos;
                                break;
                        }
                }
        }

        /* nothing to aggregate with - either aggregation disabled or no
         * suitable aggregation packet found
         */
        if (!forw_packet_aggr) {
                /* the following section can run without the lock */
                spin_unlock_bh(&bat_priv->forw_bat_list_lock);

                /* if we could not aggregate this packet with one of the others
                 * we hold it back for a while, so that it might be aggregated
                 * later on
                 */
                if (!own_packet && atomic_read(&bat_priv->aggregated_ogms))
                        send_time += max_aggregation_jiffies;

                batadv_iv_ogm_aggregate_new(packet_buff, packet_len,
                                            send_time, direct_link,
                                            if_incoming, if_outgoing,
                                            own_packet);
        } else {
                batadv_iv_ogm_aggregate(forw_packet_aggr, packet_buff,
                                        packet_len, direct_link);
                spin_unlock_bh(&bat_priv->forw_bat_list_lock);
        }
}

static void batadv_iv_ogm_forward(struct batadv_orig_node *orig_node,
                                  const struct ethhdr *ethhdr,
                                  struct batadv_ogm_packet *batadv_ogm_packet,
                                  bool is_single_hop_neigh,
                                  bool is_from_best_next_hop,
                                  struct batadv_hard_iface *if_incoming,
                                  struct batadv_hard_iface *if_outgoing)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        uint16_t tvlv_len;

        if (batadv_ogm_packet->ttl <= 1) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "ttl exceeded\n");
                return;
        }

        if (!is_from_best_next_hop) {
                /* Mark the forwarded packet when it is not coming from our
                 * best next hop. We still need to forward the packet for our
                 * neighbor link quality detection to work in case the packet
                 * originated from a single hop neighbor. Otherwise we can
                 * simply drop the ogm.
                 */
                if (is_single_hop_neigh)
                        batadv_ogm_packet->flags |= BATADV_NOT_BEST_NEXT_HOP;
                else
                        return;
        }

        tvlv_len = ntohs(batadv_ogm_packet->tvlv_len);

        batadv_ogm_packet->ttl--;
        ether_addr_copy(batadv_ogm_packet->prev_sender, ethhdr->h_source);

        /* apply hop penalty */
        batadv_ogm_packet->tq = batadv_hop_penalty(batadv_ogm_packet->tq,
                                                   bat_priv);

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Forwarding packet: tq: %i, ttl: %i\n",
                   batadv_ogm_packet->tq, batadv_ogm_packet->ttl);

        /* switch of primaries first hop flag when forwarding */
        batadv_ogm_packet->flags &= ~BATADV_PRIMARIES_FIRST_HOP;
        if (is_single_hop_neigh)
                batadv_ogm_packet->flags |= BATADV_DIRECTLINK;
        else
                batadv_ogm_packet->flags &= ~BATADV_DIRECTLINK;

        batadv_iv_ogm_queue_add(bat_priv, (unsigned char *)batadv_ogm_packet,
                                BATADV_OGM_HLEN + tvlv_len,
                                if_incoming, if_outgoing, 0,
                                batadv_iv_ogm_fwd_send_time());
}

/**
 * batadv_iv_ogm_slide_own_bcast_window - bitshift own OGM broadcast windows for
 * the given interface
 * @hard_iface: the interface for which the windows have to be shifted
 */
static void
batadv_iv_ogm_slide_own_bcast_window(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        struct hlist_head *head;
        struct batadv_orig_node *orig_node;
        unsigned long *word;
        uint32_t i;
        size_t word_index;
        uint8_t *w;
        int if_num;

        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        spin_lock_bh(&orig_node->bat_iv.ogm_cnt_lock);
                        word_index = hard_iface->if_num * BATADV_NUM_WORDS;
                        word = &(orig_node->bat_iv.bcast_own[word_index]);

                        batadv_bit_get_packet(bat_priv, word, 1, 0);
                        if_num = hard_iface->if_num;
                        w = &orig_node->bat_iv.bcast_own_sum[if_num];
                        *w = bitmap_weight(word, BATADV_TQ_LOCAL_WINDOW_SIZE);
                        spin_unlock_bh(&orig_node->bat_iv.ogm_cnt_lock);
                }
                rcu_read_unlock();
        }
}

static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        unsigned char **ogm_buff = &hard_iface->bat_iv.ogm_buff;
        struct batadv_ogm_packet *batadv_ogm_packet;
        struct batadv_hard_iface *primary_if, *tmp_hard_iface;
        int *ogm_buff_len = &hard_iface->bat_iv.ogm_buff_len;
        uint32_t seqno;
        uint16_t tvlv_len = 0;
        unsigned long send_time;

        primary_if = batadv_primary_if_get_selected(bat_priv);

        if (hard_iface == primary_if) {
                /* tt changes have to be committed before the tvlv data is
                 * appended as it may alter the tt tvlv container
                 */
                batadv_tt_local_commit_changes(bat_priv);
                tvlv_len = batadv_tvlv_container_ogm_append(bat_priv, ogm_buff,
                                                            ogm_buff_len,
                                                            BATADV_OGM_HLEN);
        }

        batadv_ogm_packet = (struct batadv_ogm_packet *)(*ogm_buff);
        batadv_ogm_packet->tvlv_len = htons(tvlv_len);

        /* change sequence number to network order */
        seqno = (uint32_t)atomic_read(&hard_iface->bat_iv.ogm_seqno);
        batadv_ogm_packet->seqno = htonl(seqno);
        atomic_inc(&hard_iface->bat_iv.ogm_seqno);

        batadv_iv_ogm_slide_own_bcast_window(hard_iface);

        send_time = batadv_iv_ogm_emit_send_time(bat_priv);

        if (hard_iface != primary_if) {
                /* OGMs from secondary interfaces are only scheduled on their
                 * respective interfaces.
                 */
                batadv_iv_ogm_queue_add(bat_priv, *ogm_buff, *ogm_buff_len,
                                        hard_iface, hard_iface, 1, send_time);
                goto out;
        }

        /* OGMs from primary interfaces are scheduled on all
         * interfaces.
         */
        rcu_read_lock();
        list_for_each_entry_rcu(tmp_hard_iface, &batadv_hardif_list, list) {
                if (tmp_hard_iface->soft_iface != hard_iface->soft_iface)
                                continue;
                batadv_iv_ogm_queue_add(bat_priv, *ogm_buff,
                                        *ogm_buff_len, hard_iface,
                                        tmp_hard_iface, 1, send_time);
        }
        rcu_read_unlock();

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

/**
 * batadv_iv_ogm_orig_update - use OGM to update corresponding data in an
 *  originator
 * @bat_priv: the bat priv with all the soft interface information
 * @orig_node: the orig node who originally emitted the ogm packet
 * @orig_ifinfo: ifinfo for the outgoing interface of the orig_node
 * @ethhdr: Ethernet header of the OGM
 * @batadv_ogm_packet: the ogm packet
 * @if_incoming: interface where the packet was received
 * @if_outgoing: interface for which the retransmission should be considered
 * @dup_status: the duplicate status of this ogm packet.
 */
static void
batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv,
                          struct batadv_orig_node *orig_node,
                          struct batadv_orig_ifinfo *orig_ifinfo,
                          const struct ethhdr *ethhdr,
                          const struct batadv_ogm_packet *batadv_ogm_packet,
                          struct batadv_hard_iface *if_incoming,
                          struct batadv_hard_iface *if_outgoing,
                          enum batadv_dup_status dup_status)
{
        struct batadv_neigh_ifinfo *neigh_ifinfo = NULL;
        struct batadv_neigh_ifinfo *router_ifinfo = NULL;
        struct batadv_neigh_node *neigh_node = NULL, *tmp_neigh_node = NULL;
        struct batadv_neigh_node *router = NULL;
        struct batadv_orig_node *orig_node_tmp;
        int if_num;
        uint8_t sum_orig, sum_neigh;
        uint8_t *neigh_addr;
        uint8_t tq_avg;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "update_originator(): Searching and updating originator entry of received packet\n");

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_neigh_node,
                                 &orig_node->neigh_list, list) {
                neigh_addr = tmp_neigh_node->addr;
                if (batadv_compare_eth(neigh_addr, ethhdr->h_source) &&
                    tmp_neigh_node->if_incoming == if_incoming &&
                    atomic_inc_not_zero(&tmp_neigh_node->refcount)) {
                        if (WARN(neigh_node, "too many matching neigh_nodes"))
                                batadv_neigh_node_free_ref(neigh_node);
                        neigh_node = tmp_neigh_node;
                        continue;
                }

                if (dup_status != BATADV_NO_DUP)
                        continue;

                /* only update the entry for this outgoing interface */
                neigh_ifinfo = batadv_neigh_ifinfo_get(tmp_neigh_node,
                                                       if_outgoing);
                if (!neigh_ifinfo)
                        continue;

                spin_lock_bh(&tmp_neigh_node->ifinfo_lock);
                batadv_ring_buffer_set(neigh_ifinfo->bat_iv.tq_recv,
                                       &neigh_ifinfo->bat_iv.tq_index, 0);
                tq_avg = batadv_ring_buffer_avg(neigh_ifinfo->bat_iv.tq_recv);
                neigh_ifinfo->bat_iv.tq_avg = tq_avg;
                spin_unlock_bh(&tmp_neigh_node->ifinfo_lock);

                batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
                neigh_ifinfo = NULL;
        }

        if (!neigh_node) {
                struct batadv_orig_node *orig_tmp;

                orig_tmp = batadv_iv_ogm_orig_get(bat_priv, ethhdr->h_source);
                if (!orig_tmp)
                        goto unlock;

                neigh_node = batadv_iv_ogm_neigh_new(if_incoming,
                                                     ethhdr->h_source,
                                                     orig_node, orig_tmp);

                batadv_orig_node_free_ref(orig_tmp);
                if (!neigh_node)
                        goto unlock;
        } else
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Updating existing last-hop neighbor of originator\n");

        rcu_read_unlock();
        neigh_ifinfo = batadv_neigh_ifinfo_new(neigh_node, if_outgoing);
        if (!neigh_ifinfo)
                goto out;

        neigh_node->last_seen = jiffies;

        spin_lock_bh(&neigh_node->ifinfo_lock);
        batadv_ring_buffer_set(neigh_ifinfo->bat_iv.tq_recv,
                               &neigh_ifinfo->bat_iv.tq_index,
                               batadv_ogm_packet->tq);
        tq_avg = batadv_ring_buffer_avg(neigh_ifinfo->bat_iv.tq_recv);
        neigh_ifinfo->bat_iv.tq_avg = tq_avg;
        spin_unlock_bh(&neigh_node->ifinfo_lock);

        if (dup_status == BATADV_NO_DUP) {
                orig_ifinfo->last_ttl = batadv_ogm_packet->ttl;
                neigh_ifinfo->last_ttl = batadv_ogm_packet->ttl;
        }

        /* if this neighbor already is our next hop there is nothing
         * to change
         */
        router = batadv_orig_router_get(orig_node, if_outgoing);
        if (router == neigh_node)
                goto out;

        if (router) {
                router_ifinfo = batadv_neigh_ifinfo_get(router, if_outgoing);
                if (!router_ifinfo)
                        goto out;

                /* if this neighbor does not offer a better TQ we won't
                 * consider it
                 */
                if (router_ifinfo->bat_iv.tq_avg > neigh_ifinfo->bat_iv.tq_avg)
                        goto out;
        }

        /* if the TQ is the same and the link not more symmetric we
         * won't consider it either
         */
        if (router_ifinfo &&
            (neigh_ifinfo->bat_iv.tq_avg == router_ifinfo->bat_iv.tq_avg)) {
                orig_node_tmp = router->orig_node;
                spin_lock_bh(&orig_node_tmp->bat_iv.ogm_cnt_lock);
                if_num = router->if_incoming->if_num;
                sum_orig = orig_node_tmp->bat_iv.bcast_own_sum[if_num];
                spin_unlock_bh(&orig_node_tmp->bat_iv.ogm_cnt_lock);

                orig_node_tmp = neigh_node->orig_node;
                spin_lock_bh(&orig_node_tmp->bat_iv.ogm_cnt_lock);
                if_num = neigh_node->if_incoming->if_num;
                sum_neigh = orig_node_tmp->bat_iv.bcast_own_sum[if_num];
                spin_unlock_bh(&orig_node_tmp->bat_iv.ogm_cnt_lock);

                if (sum_orig >= sum_neigh)
                        goto out;
        }

        batadv_update_route(bat_priv, orig_node, if_outgoing, neigh_node);
        goto out;

unlock:
        rcu_read_unlock();
out:
        if (neigh_node)
                batadv_neigh_node_free_ref(neigh_node);
        if (router)
                batadv_neigh_node_free_ref(router);
        if (neigh_ifinfo)
                batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
        if (router_ifinfo)
                batadv_neigh_ifinfo_free_ref(router_ifinfo);
}

/**
 * batadv_iv_ogm_calc_tq - calculate tq for current received ogm packet
 * @orig_node: the orig node who originally emitted the ogm packet
 * @orig_neigh_node: the orig node struct of the neighbor who sent the packet
 * @batadv_ogm_packet: the ogm packet
 * @if_incoming: interface where the packet was received
 * @if_outgoing: interface for which the retransmission should be considered
 *
 * Returns 1 if the link can be considered bidirectional, 0 otherwise
 */
static int batadv_iv_ogm_calc_tq(struct batadv_orig_node *orig_node,
                                 struct batadv_orig_node *orig_neigh_node,
                                 struct batadv_ogm_packet *batadv_ogm_packet,
                                 struct batadv_hard_iface *if_incoming,
                                 struct batadv_hard_iface *if_outgoing)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_neigh_node *neigh_node = NULL, *tmp_neigh_node;
        struct batadv_neigh_ifinfo *neigh_ifinfo;
        uint8_t total_count;
        uint8_t orig_eq_count, neigh_rq_count, neigh_rq_inv, tq_own;
        unsigned int neigh_rq_inv_cube, neigh_rq_max_cube;
        int tq_asym_penalty, inv_asym_penalty, if_num, ret = 0;
        unsigned int combined_tq;
        int tq_iface_penalty;

        /* find corresponding one hop neighbor */
        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_neigh_node,
                                 &orig_neigh_node->neigh_list, list) {
                if (!batadv_compare_eth(tmp_neigh_node->addr,
                                        orig_neigh_node->orig))
                        continue;

                if (tmp_neigh_node->if_incoming != if_incoming)
                        continue;

                if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
                        continue;

                neigh_node = tmp_neigh_node;
                break;
        }
        rcu_read_unlock();

        if (!neigh_node)
                neigh_node = batadv_iv_ogm_neigh_new(if_incoming,
                                                     orig_neigh_node->orig,
                                                     orig_neigh_node,
                                                     orig_neigh_node);

        if (!neigh_node)
                goto out;

        /* if orig_node is direct neighbor update neigh_node last_seen */
        if (orig_node == orig_neigh_node)
                neigh_node->last_seen = jiffies;

        orig_node->last_seen = jiffies;

        /* find packet count of corresponding one hop neighbor */
        spin_lock_bh(&orig_node->bat_iv.ogm_cnt_lock);
        if_num = if_incoming->if_num;
        orig_eq_count = orig_neigh_node->bat_iv.bcast_own_sum[if_num];
        neigh_ifinfo = batadv_neigh_ifinfo_new(neigh_node, if_outgoing);
        if (neigh_ifinfo) {
                neigh_rq_count = neigh_ifinfo->bat_iv.real_packet_count;
                batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
        } else {
                neigh_rq_count = 0;
        }
        spin_unlock_bh(&orig_node->bat_iv.ogm_cnt_lock);

        /* pay attention to not get a value bigger than 100 % */
        if (orig_eq_count > neigh_rq_count)
                total_count = neigh_rq_count;
        else
                total_count = orig_eq_count;

        /* if we have too few packets (too less data) we set tq_own to zero
         * if we receive too few packets it is not considered bidirectional
         */
        if (total_count < BATADV_TQ_LOCAL_BIDRECT_SEND_MINIMUM ||
            neigh_rq_count < BATADV_TQ_LOCAL_BIDRECT_RECV_MINIMUM)
                tq_own = 0;
        else
                /* neigh_node->real_packet_count is never zero as we
                 * only purge old information when getting new
                 * information
                 */
                tq_own = (BATADV_TQ_MAX_VALUE * total_count) /  neigh_rq_count;

        /* 1 - ((1-x) ** 3), normalized to TQ_MAX_VALUE this does
         * affect the nearly-symmetric links only a little, but
         * punishes asymmetric links more.  This will give a value
         * between 0 and TQ_MAX_VALUE
         */
        neigh_rq_inv = BATADV_TQ_LOCAL_WINDOW_SIZE - neigh_rq_count;
        neigh_rq_inv_cube = neigh_rq_inv * neigh_rq_inv * neigh_rq_inv;
        neigh_rq_max_cube = BATADV_TQ_LOCAL_WINDOW_SIZE *
                            BATADV_TQ_LOCAL_WINDOW_SIZE *
                            BATADV_TQ_LOCAL_WINDOW_SIZE;
        inv_asym_penalty = BATADV_TQ_MAX_VALUE * neigh_rq_inv_cube;
        inv_asym_penalty /= neigh_rq_max_cube;
        tq_asym_penalty = BATADV_TQ_MAX_VALUE - inv_asym_penalty;

        /* penalize if the OGM is forwarded on the same interface. WiFi
         * interfaces and other half duplex devices suffer from throughput
         * drops as they can't send and receive at the same time.
         */
        tq_iface_penalty = BATADV_TQ_MAX_VALUE;
        if (if_outgoing && (if_incoming == if_outgoing) &&
            batadv_is_wifi_netdev(if_outgoing->net_dev))
                tq_iface_penalty = batadv_hop_penalty(BATADV_TQ_MAX_VALUE,
                                                      bat_priv);

        combined_tq = batadv_ogm_packet->tq *
                      tq_own *
                      tq_asym_penalty *
                      tq_iface_penalty;
        combined_tq /= BATADV_TQ_MAX_VALUE *
                       BATADV_TQ_MAX_VALUE *
                       BATADV_TQ_MAX_VALUE;
        batadv_ogm_packet->tq = combined_tq;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "bidirectional: orig = %-15pM neigh = %-15pM => own_bcast = %2i, real recv = %2i, local tq: %3i, asym_penalty: %3i, iface_penalty: %3i, total tq: %3i, if_incoming = %s, if_outgoing = %s\n",
                   orig_node->orig, orig_neigh_node->orig, total_count,
                   neigh_rq_count, tq_own, tq_asym_penalty, tq_iface_penalty,
                   batadv_ogm_packet->tq, if_incoming->net_dev->name,
                   if_outgoing ? if_outgoing->net_dev->name : "DEFAULT");

        /* if link has the minimum required transmission quality
         * consider it bidirectional
         */
        if (batadv_ogm_packet->tq >= BATADV_TQ_TOTAL_BIDRECT_LIMIT)
                ret = 1;

out:
        if (neigh_node)
                batadv_neigh_node_free_ref(neigh_node);
        return ret;
}

/**
 * batadv_iv_ogm_update_seqnos -  process a batman packet for all interfaces,
 *  adjust the sequence number and find out whether it is a duplicate
 * @ethhdr: ethernet header of the packet
 * @batadv_ogm_packet: OGM packet to be considered
 * @if_incoming: interface on which the OGM packet was received
 * @if_outgoing: interface for which the retransmission should be considered
 *
 * Returns duplicate status as enum batadv_dup_status
 */
static enum batadv_dup_status
batadv_iv_ogm_update_seqnos(const struct ethhdr *ethhdr,
                            const struct batadv_ogm_packet *batadv_ogm_packet,
                            const struct batadv_hard_iface *if_incoming,
                            struct batadv_hard_iface *if_outgoing)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_orig_node *orig_node;
        struct batadv_orig_ifinfo *orig_ifinfo = NULL;
        struct batadv_neigh_node *neigh_node;
        struct batadv_neigh_ifinfo *neigh_ifinfo;
        int is_dup;
        int32_t seq_diff;
        int need_update = 0;
        int set_mark;
        enum batadv_dup_status ret = BATADV_NO_DUP;
        uint32_t seqno = ntohl(batadv_ogm_packet->seqno);
        uint8_t *neigh_addr;
        uint8_t packet_count;
        unsigned long *bitmap;

        orig_node = batadv_iv_ogm_orig_get(bat_priv, batadv_ogm_packet->orig);
        if (!orig_node)
                return BATADV_NO_DUP;

        orig_ifinfo = batadv_orig_ifinfo_new(orig_node, if_outgoing);
        if (WARN_ON(!orig_ifinfo)) {
                batadv_orig_node_free_ref(orig_node);
                return 0;
        }

        spin_lock_bh(&orig_node->bat_iv.ogm_cnt_lock);
        seq_diff = seqno - orig_ifinfo->last_real_seqno;

        /* signalize caller that the packet is to be dropped. */
        if (!hlist_empty(&orig_node->neigh_list) &&
            batadv_window_protected(bat_priv, seq_diff,
                                    &orig_ifinfo->batman_seqno_reset)) {
                ret = BATADV_PROTECTED;
                goto out;
        }

        rcu_read_lock();
        hlist_for_each_entry_rcu(neigh_node, &orig_node->neigh_list, list) {
                neigh_ifinfo = batadv_neigh_ifinfo_new(neigh_node,
                                                       if_outgoing);
                if (!neigh_ifinfo)
                        continue;

                neigh_addr = neigh_node->addr;
                is_dup = batadv_test_bit(neigh_ifinfo->bat_iv.real_bits,
                                         orig_ifinfo->last_real_seqno,
                                         seqno);

                if (batadv_compare_eth(neigh_addr, ethhdr->h_source) &&
                    neigh_node->if_incoming == if_incoming) {
                        set_mark = 1;
                        if (is_dup)
                                ret = BATADV_NEIGH_DUP;
                } else {
                        set_mark = 0;
                        if (is_dup && (ret != BATADV_NEIGH_DUP))
                                ret = BATADV_ORIG_DUP;
                }

                /* if the window moved, set the update flag. */
                bitmap = neigh_ifinfo->bat_iv.real_bits;
                need_update |= batadv_bit_get_packet(bat_priv, bitmap,
                                                     seq_diff, set_mark);

                packet_count = bitmap_weight(bitmap,
                                             BATADV_TQ_LOCAL_WINDOW_SIZE);
                neigh_ifinfo->bat_iv.real_packet_count = packet_count;
                batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
        }
        rcu_read_unlock();

        if (need_update) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "%s updating last_seqno: old %u, new %u\n",
                           if_outgoing ? if_outgoing->net_dev->name : "DEFAULT",
                           orig_ifinfo->last_real_seqno, seqno);
                orig_ifinfo->last_real_seqno = seqno;
        }

out:
        spin_unlock_bh(&orig_node->bat_iv.ogm_cnt_lock);
        batadv_orig_node_free_ref(orig_node);
        if (orig_ifinfo)
                batadv_orig_ifinfo_free_ref(orig_ifinfo);
        return ret;
}


/**
 * batadv_iv_ogm_process_per_outif - process a batman iv OGM for an outgoing if
 * @skb: the skb containing the OGM
 * @orig_node: the (cached) orig node for the originator of this OGM
 * @if_incoming: the interface where this packet was received
 * @if_outgoing: the interface for which the packet should be considered
 */
static void
batadv_iv_ogm_process_per_outif(const struct sk_buff *skb, int ogm_offset,
                                struct batadv_orig_node *orig_node,
                                struct batadv_hard_iface *if_incoming,
                                struct batadv_hard_iface *if_outgoing)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_neigh_node *router = NULL, *router_router = NULL;
        struct batadv_orig_node *orig_neigh_node;
        struct batadv_orig_ifinfo *orig_ifinfo;
        struct batadv_neigh_node *orig_neigh_router = NULL;
        struct batadv_neigh_ifinfo *router_ifinfo = NULL;
        struct batadv_ogm_packet *ogm_packet;
        enum batadv_dup_status dup_status;
        bool is_from_best_next_hop = false;
        bool is_single_hop_neigh = false;
        bool sameseq, similar_ttl;
        struct sk_buff *skb_priv;
        struct ethhdr *ethhdr;
        uint8_t *prev_sender;
        int is_bidirect;

        /* create a private copy of the skb, as some functions change tq value
         * and/or flags.
         */
        skb_priv = skb_copy(skb, GFP_ATOMIC);
        if (!skb_priv)
                return;

        ethhdr = eth_hdr(skb_priv);
        ogm_packet = (struct batadv_ogm_packet *)(skb_priv->data + ogm_offset);

        dup_status = batadv_iv_ogm_update_seqnos(ethhdr, ogm_packet,
                                                 if_incoming, if_outgoing);
        if (batadv_compare_eth(ethhdr->h_source, ogm_packet->orig))
                is_single_hop_neigh = true;

        if (dup_status == BATADV_PROTECTED) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: packet within seqno protection time (sender: %pM)\n",
                           ethhdr->h_source);
                goto out;
        }

        if (ogm_packet->tq == 0) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: originator packet with tq equal 0\n");
                goto out;
        }

        router = batadv_orig_router_get(orig_node, if_outgoing);
        if (router) {
                router_router = batadv_orig_router_get(router->orig_node,
                                                       if_outgoing);
                router_ifinfo = batadv_neigh_ifinfo_get(router, if_outgoing);
        }

        if ((router_ifinfo && router_ifinfo->bat_iv.tq_avg != 0) &&
            (batadv_compare_eth(router->addr, ethhdr->h_source)))
                is_from_best_next_hop = true;

        prev_sender = ogm_packet->prev_sender;
        /* avoid temporary routing loops */
        if (router && router_router &&
            (batadv_compare_eth(router->addr, prev_sender)) &&
            !(batadv_compare_eth(ogm_packet->orig, prev_sender)) &&
            (batadv_compare_eth(router->addr, router_router->addr))) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: ignoring all rebroadcast packets that may make me loop (sender: %pM)\n",
                           ethhdr->h_source);
                goto out;
        }

        if (if_outgoing == BATADV_IF_DEFAULT)
                batadv_tvlv_ogm_receive(bat_priv, ogm_packet, orig_node);

        /* if sender is a direct neighbor the sender mac equals
         * originator mac
         */
        if (is_single_hop_neigh)
                orig_neigh_node = orig_node;
        else
                orig_neigh_node = batadv_iv_ogm_orig_get(bat_priv,
                                                         ethhdr->h_source);

        if (!orig_neigh_node)
                goto out;

        /* Update nc_nodes of the originator */
        batadv_nc_update_nc_node(bat_priv, orig_node, orig_neigh_node,
                                 ogm_packet, is_single_hop_neigh);

        orig_neigh_router = batadv_orig_router_get(orig_neigh_node,
                                                   if_outgoing);

        /* drop packet if sender is not a direct neighbor and if we
         * don't route towards it
         */
        if (!is_single_hop_neigh && (!orig_neigh_router)) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: OGM via unknown neighbor!\n");
                goto out_neigh;
        }

        is_bidirect = batadv_iv_ogm_calc_tq(orig_node, orig_neigh_node,
                                            ogm_packet, if_incoming,
                                            if_outgoing);

        /* update ranking if it is not a duplicate or has the same
         * seqno and similar ttl as the non-duplicate
         */
        orig_ifinfo = batadv_orig_ifinfo_new(orig_node, if_outgoing);
        if (!orig_ifinfo)
                goto out_neigh;

        sameseq = orig_ifinfo->last_real_seqno == ntohl(ogm_packet->seqno);
        similar_ttl = (orig_ifinfo->last_ttl - 3) <= ogm_packet->ttl;

        if (is_bidirect && ((dup_status == BATADV_NO_DUP) ||
                            (sameseq && similar_ttl))) {
                batadv_iv_ogm_orig_update(bat_priv, orig_node,
                                          orig_ifinfo, ethhdr,
                                          ogm_packet, if_incoming,
                                          if_outgoing, dup_status);
        }
        batadv_orig_ifinfo_free_ref(orig_ifinfo);

        /* only forward for specific interface, not for the default one. */
        if (if_outgoing == BATADV_IF_DEFAULT)
                goto out_neigh;

        /* is single hop (direct) neighbor */
        if (is_single_hop_neigh) {
                /* OGMs from secondary interfaces should only scheduled once
                 * per interface where it has been received, not multiple times
                 */
                if ((ogm_packet->ttl <= 2) &&
                    (if_incoming != if_outgoing)) {
                        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                                   "Drop packet: OGM from secondary interface and wrong outgoing interface\n");
                        goto out_neigh;
                }
                /* mark direct link on incoming interface */
                batadv_iv_ogm_forward(orig_node, ethhdr, ogm_packet,
                                      is_single_hop_neigh,
                                      is_from_best_next_hop, if_incoming,
                                      if_outgoing);

                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Forwarding packet: rebroadcast neighbor packet with direct link flag\n");
                goto out_neigh;
        }

        /* multihop originator */
        if (!is_bidirect) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: not received via bidirectional link\n");
                goto out_neigh;
        }

        if (dup_status == BATADV_NEIGH_DUP) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: duplicate packet received\n");
                goto out_neigh;
        }

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Forwarding packet: rebroadcast originator packet\n");
        batadv_iv_ogm_forward(orig_node, ethhdr, ogm_packet,
                              is_single_hop_neigh, is_from_best_next_hop,
                              if_incoming, if_outgoing);

out_neigh:
        if ((orig_neigh_node) && (!is_single_hop_neigh))
                batadv_orig_node_free_ref(orig_neigh_node);
out:
        if (router_ifinfo)
                batadv_neigh_ifinfo_free_ref(router_ifinfo);
        if (router)
                batadv_neigh_node_free_ref(router);
        if (router_router)
                batadv_neigh_node_free_ref(router_router);
        if (orig_neigh_router)
                batadv_neigh_node_free_ref(orig_neigh_router);

        kfree_skb(skb_priv);
}

/**
 * batadv_iv_ogm_process - process an incoming batman iv OGM
 * @skb: the skb containing the OGM
 * @ogm_offset: offset to the OGM which should be processed (for aggregates)
 * @if_incoming: the interface where this packet was receved
 */
static void batadv_iv_ogm_process(const struct sk_buff *skb, int ogm_offset,
                                  struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_orig_node *orig_neigh_node, *orig_node;
        struct batadv_hard_iface *hard_iface;
        struct batadv_ogm_packet *ogm_packet;
        uint32_t if_incoming_seqno;
        bool has_directlink_flag;
        struct ethhdr *ethhdr;
        bool is_my_oldorig = false;
        bool is_my_addr = false;
        bool is_my_orig = false;

        ogm_packet = (struct batadv_ogm_packet *)(skb->data + ogm_offset);
        ethhdr = eth_hdr(skb);

        /* Silently drop when the batman packet is actually not a
         * correct packet.
         *
         * This might happen if a packet is padded (e.g. Ethernet has a
         * minimum frame length of 64 byte) and the aggregation interprets
         * it as an additional length.
         *
         * TODO: A more sane solution would be to have a bit in the
         * batadv_ogm_packet to detect whether the packet is the last
         * packet in an aggregation.  Here we expect that the padding
         * is always zero (or not 0x01)
         */
        if (ogm_packet->packet_type != BATADV_IV_OGM)
                return;

        /* could be changed by schedule_own_packet() */
        if_incoming_seqno = atomic_read(&if_incoming->bat_iv.ogm_seqno);

        if (ogm_packet->flags & BATADV_DIRECTLINK)
                has_directlink_flag = true;
        else
                has_directlink_flag = false;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Received BATMAN packet via NB: %pM, IF: %s [%pM] (from OG: %pM, via prev OG: %pM, seqno %u, tq %d, TTL %d, V %d, IDF %d)\n",
                   ethhdr->h_source, if_incoming->net_dev->name,
                   if_incoming->net_dev->dev_addr, ogm_packet->orig,
                   ogm_packet->prev_sender, ntohl(ogm_packet->seqno),
                   ogm_packet->tq, ogm_packet->ttl,
                   ogm_packet->version, has_directlink_flag);

        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->if_status != BATADV_IF_ACTIVE)
                        continue;

                if (hard_iface->soft_iface != if_incoming->soft_iface)
                        continue;

                if (batadv_compare_eth(ethhdr->h_source,
                                       hard_iface->net_dev->dev_addr))
                        is_my_addr = true;

                if (batadv_compare_eth(ogm_packet->orig,
                                       hard_iface->net_dev->dev_addr))
                        is_my_orig = true;

                if (batadv_compare_eth(ogm_packet->prev_sender,
                                       hard_iface->net_dev->dev_addr))
                        is_my_oldorig = true;
        }
        rcu_read_unlock();

        if (is_my_addr) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: received my own broadcast (sender: %pM)\n",
                           ethhdr->h_source);
                return;
        }

        if (is_my_orig) {
                unsigned long *word;
                int offset;
                int32_t bit_pos;
                int16_t if_num;
                uint8_t *weight;

                orig_neigh_node = batadv_iv_ogm_orig_get(bat_priv,
                                                         ethhdr->h_source);
                if (!orig_neigh_node)
                        return;

                /* neighbor has to indicate direct link and it has to
                 * come via the corresponding interface
                 * save packet seqno for bidirectional check
                 */
                if (has_directlink_flag &&
                    batadv_compare_eth(if_incoming->net_dev->dev_addr,
                                       ogm_packet->orig)) {
                        if_num = if_incoming->if_num;
                        offset = if_num * BATADV_NUM_WORDS;

                        spin_lock_bh(&orig_neigh_node->bat_iv.ogm_cnt_lock);
                        word = &(orig_neigh_node->bat_iv.bcast_own[offset]);
                        bit_pos = if_incoming_seqno - 2;
                        bit_pos -= ntohl(ogm_packet->seqno);
                        batadv_set_bit(word, bit_pos);
                        weight = &orig_neigh_node->bat_iv.bcast_own_sum[if_num];
                        *weight = bitmap_weight(word,
                                                BATADV_TQ_LOCAL_WINDOW_SIZE);
                        spin_unlock_bh(&orig_neigh_node->bat_iv.ogm_cnt_lock);
                }

                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: originator packet from myself (via neighbor)\n");
                batadv_orig_node_free_ref(orig_neigh_node);
                return;
        }

        if (is_my_oldorig) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: ignoring all rebroadcast echos (sender: %pM)\n",
                           ethhdr->h_source);
                return;
        }

        if (ogm_packet->flags & BATADV_NOT_BEST_NEXT_HOP) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: ignoring all packets not forwarded from the best next hop (sender: %pM)\n",
                           ethhdr->h_source);
                return;
        }

        orig_node = batadv_iv_ogm_orig_get(bat_priv, ogm_packet->orig);
        if (!orig_node)
                return;

        batadv_iv_ogm_process_per_outif(skb, ogm_offset, orig_node,
                                        if_incoming, BATADV_IF_DEFAULT);

        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->if_status != BATADV_IF_ACTIVE)
                        continue;

                if (hard_iface->soft_iface != bat_priv->soft_iface)
                        continue;

                batadv_iv_ogm_process_per_outif(skb, ogm_offset, orig_node,
                                                if_incoming, hard_iface);
        }
        rcu_read_unlock();

        batadv_orig_node_free_ref(orig_node);
}

static int batadv_iv_ogm_receive(struct sk_buff *skb,
                                 struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_ogm_packet *ogm_packet;
        uint8_t *packet_pos;
        int ogm_offset;
        bool ret;

        ret = batadv_check_management_packet(skb, if_incoming, BATADV_OGM_HLEN);
        if (!ret)
                return NET_RX_DROP;

        /* did we receive a B.A.T.M.A.N. IV OGM packet on an interface
         * that does not have B.A.T.M.A.N. IV enabled ?
         */
        if (bat_priv->bat_algo_ops->bat_ogm_emit != batadv_iv_ogm_emit)
                return NET_RX_DROP;

        batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_RX);
        batadv_add_counter(bat_priv, BATADV_CNT_MGMT_RX_BYTES,
                           skb->len + ETH_HLEN);

        ogm_offset = 0;
        ogm_packet = (struct batadv_ogm_packet *)skb->data;

        /* unpack the aggregated packets and process them one by one */
        while (batadv_iv_ogm_aggr_packet(ogm_offset, skb_headlen(skb),
                                         ogm_packet->tvlv_len)) {
                batadv_iv_ogm_process(skb, ogm_offset, if_incoming);

                ogm_offset += BATADV_OGM_HLEN;
                ogm_offset += ntohs(ogm_packet->tvlv_len);

                packet_pos = skb->data + ogm_offset;
                ogm_packet = (struct batadv_ogm_packet *)packet_pos;
        }

        kfree_skb(skb);
        return NET_RX_SUCCESS;
}

/**
 * batadv_iv_ogm_orig_print_neigh - print neighbors for the originator table
 * @orig_node: the orig_node for which the neighbors are printed
 * @if_outgoing: outgoing interface for these entries
 * @seq: debugfs table seq_file struct
 *
 * Must be called while holding an rcu lock.
 */
static void
batadv_iv_ogm_orig_print_neigh(struct batadv_orig_node *orig_node,
                               struct batadv_hard_iface *if_outgoing,
                               struct seq_file *seq)
{
        struct batadv_neigh_node *neigh_node;
        struct batadv_neigh_ifinfo *n_ifinfo;

        hlist_for_each_entry_rcu(neigh_node, &orig_node->neigh_list, list) {
                n_ifinfo = batadv_neigh_ifinfo_get(neigh_node, if_outgoing);
                if (!n_ifinfo)
                        continue;

                seq_printf(seq, " %pM (%3i)",
                           neigh_node->addr,
                           n_ifinfo->bat_iv.tq_avg);

                batadv_neigh_ifinfo_free_ref(n_ifinfo);
        }
}

/**
 * batadv_iv_ogm_orig_print - print the originator table
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: debugfs table seq_file struct
 * @if_outgoing: the outgoing interface for which this should be printed
 */
static void batadv_iv_ogm_orig_print(struct batadv_priv *bat_priv,
                                     struct seq_file *seq,
                                     struct batadv_hard_iface *if_outgoing)
{
        struct batadv_neigh_node *neigh_node;
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        int last_seen_msecs, last_seen_secs;
        struct batadv_orig_node *orig_node;
        struct batadv_neigh_ifinfo *n_ifinfo;
        unsigned long last_seen_jiffies;
        struct hlist_head *head;
        int batman_count = 0;
        uint32_t i;

        seq_printf(seq, "  %-15s %s (%s/%i) %17s [%10s]: %20s ...\n",
                   "Originator", "last-seen", "#", BATADV_TQ_MAX_VALUE,
                   "Nexthop", "outgoingIF", "Potential nexthops");

        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        neigh_node = batadv_orig_router_get(orig_node,
                                                            if_outgoing);
                        if (!neigh_node)
                                continue;

                        n_ifinfo = batadv_neigh_ifinfo_get(neigh_node,
                                                           if_outgoing);
                        if (!n_ifinfo)
                                goto next;

                        if (n_ifinfo->bat_iv.tq_avg == 0)
                                goto next;

                        last_seen_jiffies = jiffies - orig_node->last_seen;
                        last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
                        last_seen_secs = last_seen_msecs / 1000;
                        last_seen_msecs = last_seen_msecs % 1000;

                        seq_printf(seq, "%pM %4i.%03is   (%3i) %pM [%10s]:",
                                   orig_node->orig, last_seen_secs,
                                   last_seen_msecs, n_ifinfo->bat_iv.tq_avg,
                                   neigh_node->addr,
                                   neigh_node->if_incoming->net_dev->name);

                        batadv_iv_ogm_orig_print_neigh(orig_node, if_outgoing,
                                                       seq);
                        seq_puts(seq, "\n");
                        batman_count++;

next:
                        batadv_neigh_node_free_ref(neigh_node);
                        if (n_ifinfo)
                                batadv_neigh_ifinfo_free_ref(n_ifinfo);
                }
                rcu_read_unlock();
        }

        if (batman_count == 0)
                seq_puts(seq, "No batman nodes in range ...\n");
}

/**
 * batadv_iv_ogm_neigh_cmp - compare the metrics of two neighbors
 * @neigh1: the first neighbor object of the comparison
 * @if_outgoing1: outgoing interface for the first neighbor
 * @neigh2: the second neighbor object of the comparison
 * @if_outgoing2: outgoing interface for the second neighbor
 *
 * Returns a value less, equal to or greater than 0 if the metric via neigh1 is
 * lower, the same as or higher than the metric via neigh2
 */
static int batadv_iv_ogm_neigh_cmp(struct batadv_neigh_node *neigh1,
                                   struct batadv_hard_iface *if_outgoing1,
                                   struct batadv_neigh_node *neigh2,
                                   struct batadv_hard_iface *if_outgoing2)
{
        struct batadv_neigh_ifinfo *neigh1_ifinfo, *neigh2_ifinfo;
        uint8_t tq1, tq2;
        int diff;

        neigh1_ifinfo = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
        neigh2_ifinfo = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);

        if (!neigh1_ifinfo || !neigh2_ifinfo) {
                diff = 0;
                goto out;
        }

        tq1 = neigh1_ifinfo->bat_iv.tq_avg;
        tq2 = neigh2_ifinfo->bat_iv.tq_avg;
        diff = tq1 - tq2;

out:
        if (neigh1_ifinfo)
                batadv_neigh_ifinfo_free_ref(neigh1_ifinfo);
        if (neigh2_ifinfo)
                batadv_neigh_ifinfo_free_ref(neigh2_ifinfo);

        return diff;
}

/**
 * batadv_iv_ogm_neigh_is_eob - check if neigh1 is equally good or better than
 *  neigh2 from the metric prospective
 * @neigh1: the first neighbor object of the comparison
 * @if_outgoing: outgoing interface for the first neighbor
 * @neigh2: the second neighbor object of the comparison
 * @if_outgoing2: outgoing interface for the second neighbor

 * Returns true if the metric via neigh1 is equally good or better than
 * the metric via neigh2, false otherwise.
 */
static bool
batadv_iv_ogm_neigh_is_eob(struct batadv_neigh_node *neigh1,
                           struct batadv_hard_iface *if_outgoing1,
                           struct batadv_neigh_node *neigh2,
                           struct batadv_hard_iface *if_outgoing2)
{
        struct batadv_neigh_ifinfo *neigh1_ifinfo, *neigh2_ifinfo;
        uint8_t tq1, tq2;
        bool ret;

        neigh1_ifinfo = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
        neigh2_ifinfo = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);

        /* we can't say that the metric is better */
        if (!neigh1_ifinfo || !neigh2_ifinfo) {
                ret = false;
                goto out;
        }

        tq1 = neigh1_ifinfo->bat_iv.tq_avg;
        tq2 = neigh2_ifinfo->bat_iv.tq_avg;
        ret = (tq1 - tq2) > -BATADV_TQ_SIMILARITY_THRESHOLD;

out:
        if (neigh1_ifinfo)
                batadv_neigh_ifinfo_free_ref(neigh1_ifinfo);
        if (neigh2_ifinfo)
                batadv_neigh_ifinfo_free_ref(neigh2_ifinfo);

        return ret;
}

static struct batadv_algo_ops batadv_batman_iv __read_mostly = {
        .name = "BATMAN_IV",
        .bat_iface_enable = batadv_iv_ogm_iface_enable,
        .bat_iface_disable = batadv_iv_ogm_iface_disable,
        .bat_iface_update_mac = batadv_iv_ogm_iface_update_mac,
        .bat_primary_iface_set = batadv_iv_ogm_primary_iface_set,
        .bat_ogm_schedule = batadv_iv_ogm_schedule,
        .bat_ogm_emit = batadv_iv_ogm_emit,
        .bat_neigh_cmp = batadv_iv_ogm_neigh_cmp,
        .bat_neigh_is_equiv_or_better = batadv_iv_ogm_neigh_is_eob,
        .bat_orig_print = batadv_iv_ogm_orig_print,
        .bat_orig_free = batadv_iv_ogm_orig_free,
        .bat_orig_add_if = batadv_iv_ogm_orig_add_if,
        .bat_orig_del_if = batadv_iv_ogm_orig_del_if,
};

int __init batadv_iv_init(void)
{
        int ret;

        /* batman originator packet */
        ret = batadv_recv_handler_register(BATADV_IV_OGM,
                                           batadv_iv_ogm_receive);
        if (ret < 0)
                goto out;

        ret = batadv_algo_register(&batadv_batman_iv);
        if (ret < 0)
                goto handler_unregister;

        goto out;

handler_unregister:
        batadv_recv_handler_unregister(BATADV_IV_OGM);
out:
        return ret;
}