Linux 4.8.3

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

/* Copyright (C) 2011-2016  B.A.T.M.A.N. contributors:
 *
 * 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 "bridge_loop_avoidance.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/compiler.h>
#include <linux/crc16.h>
#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/fs.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/jhash.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/workqueue.h>
#include <net/arp.h>

#include "hard-interface.h"
#include "hash.h"
#include "log.h"
#include "originator.h"
#include "packet.h"
#include "sysfs.h"
#include "translation-table.h"

static const u8 batadv_announce_mac[4] = {0x43, 0x05, 0x43, 0x05};

static void batadv_bla_periodic_work(struct work_struct *work);
static void
batadv_bla_send_announce(struct batadv_priv *bat_priv,
                         struct batadv_bla_backbone_gw *backbone_gw);

/**
 * batadv_choose_claim - choose the right bucket for a claim.
 * @data: data to hash
 * @size: size of the hash table
 *
 * Return: the hash index of the claim
 */
static inline u32 batadv_choose_claim(const void *data, u32 size)
{
        struct batadv_bla_claim *claim = (struct batadv_bla_claim *)data;
        u32 hash = 0;

        hash = jhash(&claim->addr, sizeof(claim->addr), hash);
        hash = jhash(&claim->vid, sizeof(claim->vid), hash);

        return hash % size;
}

/**
 * batadv_choose_backbone_gw - choose the right bucket for a backbone gateway.
 * @data: data to hash
 * @size: size of the hash table
 *
 * Return: the hash index of the backbone gateway
 */
static inline u32 batadv_choose_backbone_gw(const void *data, u32 size)
{
        const struct batadv_bla_claim *claim = (struct batadv_bla_claim *)data;
        u32 hash = 0;

        hash = jhash(&claim->addr, sizeof(claim->addr), hash);
        hash = jhash(&claim->vid, sizeof(claim->vid), hash);

        return hash % size;
}

/**
 * batadv_compare_backbone_gw - compare address and vid of two backbone gws
 * @node: list node of the first entry to compare
 * @data2: pointer to the second backbone gateway
 *
 * Return: true if the backbones have the same data, false otherwise
 */
static bool batadv_compare_backbone_gw(const struct hlist_node *node,
                                       const void *data2)
{
        const void *data1 = container_of(node, struct batadv_bla_backbone_gw,
                                         hash_entry);
        const struct batadv_bla_backbone_gw *gw1 = data1;
        const struct batadv_bla_backbone_gw *gw2 = data2;

        if (!batadv_compare_eth(gw1->orig, gw2->orig))
                return false;

        if (gw1->vid != gw2->vid)
                return false;

        return true;
}

/**
 * batadv_compare_claim - compare address and vid of two claims
 * @node: list node of the first entry to compare
 * @data2: pointer to the second claims
 *
 * Return: true if the claim have the same data, 0 otherwise
 */
static bool batadv_compare_claim(const struct hlist_node *node,
                                 const void *data2)
{
        const void *data1 = container_of(node, struct batadv_bla_claim,
                                         hash_entry);
        const struct batadv_bla_claim *cl1 = data1;
        const struct batadv_bla_claim *cl2 = data2;

        if (!batadv_compare_eth(cl1->addr, cl2->addr))
                return false;

        if (cl1->vid != cl2->vid)
                return false;

        return true;
}

/**
 * batadv_backbone_gw_release - release backbone gw from lists and queue for
 *  free after rcu grace period
 * @ref: kref pointer of the backbone gw
 */
static void batadv_backbone_gw_release(struct kref *ref)
{
        struct batadv_bla_backbone_gw *backbone_gw;

        backbone_gw = container_of(ref, struct batadv_bla_backbone_gw,
                                   refcount);

        kfree_rcu(backbone_gw, rcu);
}

/**
 * batadv_backbone_gw_put - decrement the backbone gw refcounter and possibly
 *  release it
 * @backbone_gw: backbone gateway to be free'd
 */
static void batadv_backbone_gw_put(struct batadv_bla_backbone_gw *backbone_gw)
{
        kref_put(&backbone_gw->refcount, batadv_backbone_gw_release);
}

/**
 * batadv_claim_release - release claim from lists and queue for free after rcu
 *  grace period
 * @ref: kref pointer of the claim
 */
static void batadv_claim_release(struct kref *ref)
{
        struct batadv_bla_claim *claim;
        struct batadv_bla_backbone_gw *old_backbone_gw;

        claim = container_of(ref, struct batadv_bla_claim, refcount);

        spin_lock_bh(&claim->backbone_lock);
        old_backbone_gw = claim->backbone_gw;
        claim->backbone_gw = NULL;
        spin_unlock_bh(&claim->backbone_lock);

        spin_lock_bh(&old_backbone_gw->crc_lock);
        old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
        spin_unlock_bh(&old_backbone_gw->crc_lock);

        batadv_backbone_gw_put(old_backbone_gw);

        kfree_rcu(claim, rcu);
}

/**
 * batadv_claim_put - decrement the claim refcounter and possibly
 *  release it
 * @claim: claim to be free'd
 */
static void batadv_claim_put(struct batadv_bla_claim *claim)
{
        kref_put(&claim->refcount, batadv_claim_release);
}

/**
 * batadv_claim_hash_find - looks for a claim in the claim hash
 * @bat_priv: the bat priv with all the soft interface information
 * @data: search data (may be local/static data)
 *
 * Return: claim if found or NULL otherwise.
 */
static struct batadv_bla_claim *
batadv_claim_hash_find(struct batadv_priv *bat_priv,
                       struct batadv_bla_claim *data)
{
        struct batadv_hashtable *hash = bat_priv->bla.claim_hash;
        struct hlist_head *head;
        struct batadv_bla_claim *claim;
        struct batadv_bla_claim *claim_tmp = NULL;
        int index;

        if (!hash)
                return NULL;

        index = batadv_choose_claim(data, hash->size);
        head = &hash->table[index];

        rcu_read_lock();
        hlist_for_each_entry_rcu(claim, head, hash_entry) {
                if (!batadv_compare_claim(&claim->hash_entry, data))
                        continue;

                if (!kref_get_unless_zero(&claim->refcount))
                        continue;

                claim_tmp = claim;
                break;
        }
        rcu_read_unlock();

        return claim_tmp;
}

/**
 * batadv_backbone_hash_find - looks for a backbone gateway in the hash
 * @bat_priv: the bat priv with all the soft interface information
 * @addr: the address of the originator
 * @vid: the VLAN ID
 *
 * Return: backbone gateway if found or NULL otherwise
 */
static struct batadv_bla_backbone_gw *
batadv_backbone_hash_find(struct batadv_priv *bat_priv, u8 *addr,
                          unsigned short vid)
{
        struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
        struct hlist_head *head;
        struct batadv_bla_backbone_gw search_entry, *backbone_gw;
        struct batadv_bla_backbone_gw *backbone_gw_tmp = NULL;
        int index;

        if (!hash)
                return NULL;

        ether_addr_copy(search_entry.orig, addr);
        search_entry.vid = vid;

        index = batadv_choose_backbone_gw(&search_entry, hash->size);
        head = &hash->table[index];

        rcu_read_lock();
        hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                if (!batadv_compare_backbone_gw(&backbone_gw->hash_entry,
                                                &search_entry))
                        continue;

                if (!kref_get_unless_zero(&backbone_gw->refcount))
                        continue;

                backbone_gw_tmp = backbone_gw;
                break;
        }
        rcu_read_unlock();

        return backbone_gw_tmp;
}

/**
 * batadv_bla_del_backbone_claims - delete all claims for a backbone
 * @backbone_gw: backbone gateway where the claims should be removed
 */
static void
batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw)
{
        struct batadv_hashtable *hash;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        struct batadv_bla_claim *claim;
        int i;
        spinlock_t *list_lock;  /* protects write access to the hash lists */

        hash = backbone_gw->bat_priv->bla.claim_hash;
        if (!hash)
                return;

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

                spin_lock_bh(list_lock);
                hlist_for_each_entry_safe(claim, node_tmp,
                                          head, hash_entry) {
                        if (claim->backbone_gw != backbone_gw)
                                continue;

                        batadv_claim_put(claim);
                        hlist_del_rcu(&claim->hash_entry);
                }
                spin_unlock_bh(list_lock);
        }

        /* all claims gone, initialize CRC */
        spin_lock_bh(&backbone_gw->crc_lock);
        backbone_gw->crc = BATADV_BLA_CRC_INIT;
        spin_unlock_bh(&backbone_gw->crc_lock);
}

/**
 * batadv_bla_send_claim - sends a claim frame according to the provided info
 * @bat_priv: the bat priv with all the soft interface information
 * @mac: the mac address to be announced within the claim
 * @vid: the VLAN ID
 * @claimtype: the type of the claim (CLAIM, UNCLAIM, ANNOUNCE, ...)
 */
static void batadv_bla_send_claim(struct batadv_priv *bat_priv, u8 *mac,
                                  unsigned short vid, int claimtype)
{
        struct sk_buff *skb;
        struct ethhdr *ethhdr;
        struct batadv_hard_iface *primary_if;
        struct net_device *soft_iface;
        u8 *hw_src;
        struct batadv_bla_claim_dst local_claim_dest;
        __be32 zeroip = 0;

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                return;

        memcpy(&local_claim_dest, &bat_priv->bla.claim_dest,
               sizeof(local_claim_dest));
        local_claim_dest.type = claimtype;

        soft_iface = primary_if->soft_iface;

        skb = arp_create(ARPOP_REPLY, ETH_P_ARP,
                         /* IP DST: 0.0.0.0 */
                         zeroip,
                         primary_if->soft_iface,
                         /* IP SRC: 0.0.0.0 */
                         zeroip,
                         /* Ethernet DST: Broadcast */
                         NULL,
                         /* Ethernet SRC/HW SRC:  originator mac */
                         primary_if->net_dev->dev_addr,
                         /* HW DST: FF:43:05:XX:YY:YY
                          * with XX   = claim type
                          * and YY:YY = group id
                          */
                         (u8 *)&local_claim_dest);

        if (!skb)
                goto out;

        ethhdr = (struct ethhdr *)skb->data;
        hw_src = (u8 *)ethhdr + ETH_HLEN + sizeof(struct arphdr);

        /* now we pretend that the client would have sent this ... */
        switch (claimtype) {
        case BATADV_CLAIM_TYPE_CLAIM:
                /* normal claim frame
                 * set Ethernet SRC to the clients mac
                 */
                ether_addr_copy(ethhdr->h_source, mac);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): CLAIM %pM on vid %d\n", mac,
                           BATADV_PRINT_VID(vid));
                break;
        case BATADV_CLAIM_TYPE_UNCLAIM:
                /* unclaim frame
                 * set HW SRC to the clients mac
                 */
                ether_addr_copy(hw_src, mac);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): UNCLAIM %pM on vid %d\n", mac,
                           BATADV_PRINT_VID(vid));
                break;
        case BATADV_CLAIM_TYPE_ANNOUNCE:
                /* announcement frame
                 * set HW SRC to the special mac containg the crc
                 */
                ether_addr_copy(hw_src, mac);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): ANNOUNCE of %pM on vid %d\n",
                           ethhdr->h_source, BATADV_PRINT_VID(vid));
                break;
        case BATADV_CLAIM_TYPE_REQUEST:
                /* request frame
                 * set HW SRC and header destination to the receiving backbone
                 * gws mac
                 */
                ether_addr_copy(hw_src, mac);
                ether_addr_copy(ethhdr->h_dest, mac);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): REQUEST of %pM to %pM on vid %d\n",
                           ethhdr->h_source, ethhdr->h_dest,
                           BATADV_PRINT_VID(vid));
                break;
        case BATADV_CLAIM_TYPE_LOOPDETECT:
                ether_addr_copy(ethhdr->h_source, mac);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_send_claim(): LOOPDETECT of %pM to %pM on vid %d\n",
                           ethhdr->h_source, ethhdr->h_dest,
                           BATADV_PRINT_VID(vid));

                break;
        }

        if (vid & BATADV_VLAN_HAS_TAG) {
                skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
                                      vid & VLAN_VID_MASK);
                if (!skb)
                        goto out;
        }

        skb_reset_mac_header(skb);
        skb->protocol = eth_type_trans(skb, soft_iface);
        batadv_inc_counter(bat_priv, BATADV_CNT_RX);
        batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
                           skb->len + ETH_HLEN);
        soft_iface->last_rx = jiffies;

        netif_rx(skb);
out:
        if (primary_if)
                batadv_hardif_put(primary_if);
}

/**
 * batadv_bla_loopdetect_report - worker for reporting the loop
 * @work: work queue item
 *
 * Throws an uevent, as the loopdetect check function can't do that itself
 * since the kernel may sleep while throwing uevents.
 */
static void batadv_bla_loopdetect_report(struct work_struct *work)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_priv *bat_priv;
        char vid_str[6] = { '\0' };

        backbone_gw = container_of(work, struct batadv_bla_backbone_gw,
                                   report_work);
        bat_priv = backbone_gw->bat_priv;

        batadv_info(bat_priv->soft_iface,
                    "Possible loop on VLAN %d detected which can't be handled by BLA - please check your network setup!\n",
                    BATADV_PRINT_VID(backbone_gw->vid));
        snprintf(vid_str, sizeof(vid_str), "%d",
                 BATADV_PRINT_VID(backbone_gw->vid));
        vid_str[sizeof(vid_str) - 1] = 0;

        batadv_throw_uevent(bat_priv, BATADV_UEV_BLA, BATADV_UEV_LOOPDETECT,
                            vid_str);

        batadv_backbone_gw_put(backbone_gw);
}

/**
 * batadv_bla_get_backbone_gw - finds or creates a backbone gateway
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: the mac address of the originator
 * @vid: the VLAN ID
 * @own_backbone: set if the requested backbone is local
 *
 * Return: the (possibly created) backbone gateway or NULL on error
 */
static struct batadv_bla_backbone_gw *
batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, u8 *orig,
                           unsigned short vid, bool own_backbone)
{
        struct batadv_bla_backbone_gw *entry;
        struct batadv_orig_node *orig_node;
        int hash_added;

        entry = batadv_backbone_hash_find(bat_priv, orig, vid);

        if (entry)
                return entry;

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "bla_get_backbone_gw(): not found (%pM, %d), creating new entry\n",
                   orig, BATADV_PRINT_VID(vid));

        entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
        if (!entry)
                return NULL;

        entry->vid = vid;
        entry->lasttime = jiffies;
        entry->crc = BATADV_BLA_CRC_INIT;
        entry->bat_priv = bat_priv;
        spin_lock_init(&entry->crc_lock);
        atomic_set(&entry->request_sent, 0);
        atomic_set(&entry->wait_periods, 0);
        ether_addr_copy(entry->orig, orig);
        INIT_WORK(&entry->report_work, batadv_bla_loopdetect_report);

        /* one for the hash, one for returning */
        kref_init(&entry->refcount);
        kref_get(&entry->refcount);

        hash_added = batadv_hash_add(bat_priv->bla.backbone_hash,
                                     batadv_compare_backbone_gw,
                                     batadv_choose_backbone_gw, entry,
                                     &entry->hash_entry);

        if (unlikely(hash_added != 0)) {
                /* hash failed, free the structure */
                kfree(entry);
                return NULL;
        }

        /* this is a gateway now, remove any TT entry on this VLAN */
        orig_node = batadv_orig_hash_find(bat_priv, orig);
        if (orig_node) {
                batadv_tt_global_del_orig(bat_priv, orig_node, vid,
                                          "became a backbone gateway");
                batadv_orig_node_put(orig_node);
        }

        if (own_backbone) {
                batadv_bla_send_announce(bat_priv, entry);

                /* this will be decreased in the worker thread */
                atomic_inc(&entry->request_sent);
                atomic_set(&entry->wait_periods, BATADV_BLA_WAIT_PERIODS);
                atomic_inc(&bat_priv->bla.num_requests);
        }

        return entry;
}

/**
 * batadv_bla_update_own_backbone_gw - updates the own backbone gw for a VLAN
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the selected primary interface
 * @vid: VLAN identifier
 *
 * update or add the own backbone gw to make sure we announce
 * where we receive other backbone gws
 */
static void
batadv_bla_update_own_backbone_gw(struct batadv_priv *bat_priv,
                                  struct batadv_hard_iface *primary_if,
                                  unsigned short vid)
{
        struct batadv_bla_backbone_gw *backbone_gw;

        backbone_gw = batadv_bla_get_backbone_gw(bat_priv,
                                                 primary_if->net_dev->dev_addr,
                                                 vid, true);
        if (unlikely(!backbone_gw))
                return;

        backbone_gw->lasttime = jiffies;
        batadv_backbone_gw_put(backbone_gw);
}

/**
 * batadv_bla_answer_request - answer a bla request by sending own claims
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: interface where the request came on
 * @vid: the vid where the request came on
 *
 * Repeat all of our own claims, and finally send an ANNOUNCE frame
 * to allow the requester another check if the CRC is correct now.
 */
static void batadv_bla_answer_request(struct batadv_priv *bat_priv,
                                      struct batadv_hard_iface *primary_if,
                                      unsigned short vid)
{
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        struct batadv_bla_claim *claim;
        struct batadv_bla_backbone_gw *backbone_gw;
        int i;

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "bla_answer_request(): received a claim request, send all of our own claims again\n");

        backbone_gw = batadv_backbone_hash_find(bat_priv,
                                                primary_if->net_dev->dev_addr,
                                                vid);
        if (!backbone_gw)
                return;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(claim, head, hash_entry) {
                        /* only own claims are interesting */
                        if (claim->backbone_gw != backbone_gw)
                                continue;

                        batadv_bla_send_claim(bat_priv, claim->addr, claim->vid,
                                              BATADV_CLAIM_TYPE_CLAIM);
                }
                rcu_read_unlock();
        }

        /* finally, send an announcement frame */
        batadv_bla_send_announce(bat_priv, backbone_gw);
        batadv_backbone_gw_put(backbone_gw);
}

/**
 * batadv_bla_send_request - send a request to repeat claims
 * @backbone_gw: the backbone gateway from whom we are out of sync
 *
 * When the crc is wrong, ask the backbone gateway for a full table update.
 * After the request, it will repeat all of his own claims and finally
 * send an announcement claim with which we can check again.
 */
static void batadv_bla_send_request(struct batadv_bla_backbone_gw *backbone_gw)
{
        /* first, remove all old entries */
        batadv_bla_del_backbone_claims(backbone_gw);

        batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
                   "Sending REQUEST to %pM\n", backbone_gw->orig);

        /* send request */
        batadv_bla_send_claim(backbone_gw->bat_priv, backbone_gw->orig,
                              backbone_gw->vid, BATADV_CLAIM_TYPE_REQUEST);

        /* no local broadcasts should be sent or received, for now. */
        if (!atomic_read(&backbone_gw->request_sent)) {
                atomic_inc(&backbone_gw->bat_priv->bla.num_requests);
                atomic_set(&backbone_gw->request_sent, 1);
        }
}

/**
 * batadv_bla_send_announce - Send an announcement frame
 * @bat_priv: the bat priv with all the soft interface information
 * @backbone_gw: our backbone gateway which should be announced
 */
static void batadv_bla_send_announce(struct batadv_priv *bat_priv,
                                     struct batadv_bla_backbone_gw *backbone_gw)
{
        u8 mac[ETH_ALEN];
        __be16 crc;

        memcpy(mac, batadv_announce_mac, 4);
        spin_lock_bh(&backbone_gw->crc_lock);
        crc = htons(backbone_gw->crc);
        spin_unlock_bh(&backbone_gw->crc_lock);
        memcpy(&mac[4], &crc, 2);

        batadv_bla_send_claim(bat_priv, mac, backbone_gw->vid,
                              BATADV_CLAIM_TYPE_ANNOUNCE);
}

/**
 * batadv_bla_add_claim - Adds a claim in the claim hash
 * @bat_priv: the bat priv with all the soft interface information
 * @mac: the mac address of the claim
 * @vid: the VLAN ID of the frame
 * @backbone_gw: the backbone gateway which claims it
 */
static void batadv_bla_add_claim(struct batadv_priv *bat_priv,
                                 const u8 *mac, const unsigned short vid,
                                 struct batadv_bla_backbone_gw *backbone_gw)
{
        struct batadv_bla_backbone_gw *old_backbone_gw;
        struct batadv_bla_claim *claim;
        struct batadv_bla_claim search_claim;
        bool remove_crc = false;
        int hash_added;

        ether_addr_copy(search_claim.addr, mac);
        search_claim.vid = vid;
        claim = batadv_claim_hash_find(bat_priv, &search_claim);

        /* create a new claim entry if it does not exist yet. */
        if (!claim) {
                claim = kzalloc(sizeof(*claim), GFP_ATOMIC);
                if (!claim)
                        return;

                ether_addr_copy(claim->addr, mac);
                spin_lock_init(&claim->backbone_lock);
                claim->vid = vid;
                claim->lasttime = jiffies;
                kref_get(&backbone_gw->refcount);
                claim->backbone_gw = backbone_gw;

                kref_init(&claim->refcount);
                kref_get(&claim->refcount);
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_add_claim(): adding new entry %pM, vid %d to hash ...\n",
                           mac, BATADV_PRINT_VID(vid));
                hash_added = batadv_hash_add(bat_priv->bla.claim_hash,
                                             batadv_compare_claim,
                                             batadv_choose_claim, claim,
                                             &claim->hash_entry);

                if (unlikely(hash_added != 0)) {
                        /* only local changes happened. */
                        kfree(claim);
                        return;
                }
        } else {
                claim->lasttime = jiffies;
                if (claim->backbone_gw == backbone_gw)
                        /* no need to register a new backbone */
                        goto claim_free_ref;

                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_add_claim(): changing ownership for %pM, vid %d\n",
                           mac, BATADV_PRINT_VID(vid));

                remove_crc = true;
        }

        /* replace backbone_gw atomically and adjust reference counters */
        spin_lock_bh(&claim->backbone_lock);
        old_backbone_gw = claim->backbone_gw;
        kref_get(&backbone_gw->refcount);
        claim->backbone_gw = backbone_gw;
        spin_unlock_bh(&claim->backbone_lock);

        if (remove_crc) {
                /* remove claim address from old backbone_gw */
                spin_lock_bh(&old_backbone_gw->crc_lock);
                old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
                spin_unlock_bh(&old_backbone_gw->crc_lock);
        }

        batadv_backbone_gw_put(old_backbone_gw);

        /* add claim address to new backbone_gw */
        spin_lock_bh(&backbone_gw->crc_lock);
        backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
        spin_unlock_bh(&backbone_gw->crc_lock);
        backbone_gw->lasttime = jiffies;

claim_free_ref:
        batadv_claim_put(claim);
}

/**
 * batadv_bla_claim_get_backbone_gw - Get valid reference for backbone_gw of
 *  claim
 * @claim: claim whose backbone_gw should be returned
 *
 * Return: valid reference to claim::backbone_gw
 */
static struct batadv_bla_backbone_gw *
batadv_bla_claim_get_backbone_gw(struct batadv_bla_claim *claim)
{
        struct batadv_bla_backbone_gw *backbone_gw;

        spin_lock_bh(&claim->backbone_lock);
        backbone_gw = claim->backbone_gw;
        kref_get(&backbone_gw->refcount);
        spin_unlock_bh(&claim->backbone_lock);

        return backbone_gw;
}

/**
 * batadv_bla_del_claim - delete a claim from the claim hash
 * @bat_priv: the bat priv with all the soft interface information
 * @mac: mac address of the claim to be removed
 * @vid: VLAN id for the claim to be removed
 */
static void batadv_bla_del_claim(struct batadv_priv *bat_priv,
                                 const u8 *mac, const unsigned short vid)
{
        struct batadv_bla_claim search_claim, *claim;

        ether_addr_copy(search_claim.addr, mac);
        search_claim.vid = vid;
        claim = batadv_claim_hash_find(bat_priv, &search_claim);
        if (!claim)
                return;

        batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_del_claim(): %pM, vid %d\n",
                   mac, BATADV_PRINT_VID(vid));

        batadv_hash_remove(bat_priv->bla.claim_hash, batadv_compare_claim,
                           batadv_choose_claim, claim);
        batadv_claim_put(claim); /* reference from the hash is gone */

        /* don't need the reference from hash_find() anymore */
        batadv_claim_put(claim);
}

/**
 * batadv_handle_announce - check for ANNOUNCE frame
 * @bat_priv: the bat priv with all the soft interface information
 * @an_addr: announcement mac address (ARP Sender HW address)
 * @backbone_addr: originator address of the sender (Ethernet source MAC)
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_announce(struct batadv_priv *bat_priv, u8 *an_addr,
                                   u8 *backbone_addr, unsigned short vid)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        u16 backbone_crc, crc;

        if (memcmp(an_addr, batadv_announce_mac, 4) != 0)
                return false;

        backbone_gw = batadv_bla_get_backbone_gw(bat_priv, backbone_addr, vid,
                                                 false);

        if (unlikely(!backbone_gw))
                return true;

        /* handle as ANNOUNCE frame */
        backbone_gw->lasttime = jiffies;
        crc = ntohs(*((__be16 *)(&an_addr[4])));

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "handle_announce(): ANNOUNCE vid %d (sent by %pM)... CRC = %#.4x\n",
                   BATADV_PRINT_VID(vid), backbone_gw->orig, crc);

        spin_lock_bh(&backbone_gw->crc_lock);
        backbone_crc = backbone_gw->crc;
        spin_unlock_bh(&backbone_gw->crc_lock);

        if (backbone_crc != crc) {
                batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
                           "handle_announce(): CRC FAILED for %pM/%d (my = %#.4x, sent = %#.4x)\n",
                           backbone_gw->orig,
                           BATADV_PRINT_VID(backbone_gw->vid),
                           backbone_crc, crc);

                batadv_bla_send_request(backbone_gw);
        } else {
                /* if we have sent a request and the crc was OK,
                 * we can allow traffic again.
                 */
                if (atomic_read(&backbone_gw->request_sent)) {
                        atomic_dec(&backbone_gw->bat_priv->bla.num_requests);
                        atomic_set(&backbone_gw->request_sent, 0);
                }
        }

        batadv_backbone_gw_put(backbone_gw);
        return true;
}

/**
 * batadv_handle_request - check for REQUEST frame
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the primary hard interface of this batman soft interface
 * @backbone_addr: backbone address to be requested (ARP sender HW MAC)
 * @ethhdr: ethernet header of a packet
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_request(struct batadv_priv *bat_priv,
                                  struct batadv_hard_iface *primary_if,
                                  u8 *backbone_addr, struct ethhdr *ethhdr,
                                  unsigned short vid)
{
        /* check for REQUEST frame */
        if (!batadv_compare_eth(backbone_addr, ethhdr->h_dest))
                return false;

        /* sanity check, this should not happen on a normal switch,
         * we ignore it in this case.
         */
        if (!batadv_compare_eth(ethhdr->h_dest, primary_if->net_dev->dev_addr))
                return true;

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "handle_request(): REQUEST vid %d (sent by %pM)...\n",
                   BATADV_PRINT_VID(vid), ethhdr->h_source);

        batadv_bla_answer_request(bat_priv, primary_if, vid);
        return true;
}

/**
 * batadv_handle_unclaim - check for UNCLAIM frame
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the primary hard interface of this batman soft interface
 * @backbone_addr: originator address of the backbone (Ethernet source)
 * @claim_addr: Client to be unclaimed (ARP sender HW MAC)
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_unclaim(struct batadv_priv *bat_priv,
                                  struct batadv_hard_iface *primary_if,
                                  u8 *backbone_addr, u8 *claim_addr,
                                  unsigned short vid)
{
        struct batadv_bla_backbone_gw *backbone_gw;

        /* unclaim in any case if it is our own */
        if (primary_if && batadv_compare_eth(backbone_addr,
                                             primary_if->net_dev->dev_addr))
                batadv_bla_send_claim(bat_priv, claim_addr, vid,
                                      BATADV_CLAIM_TYPE_UNCLAIM);

        backbone_gw = batadv_backbone_hash_find(bat_priv, backbone_addr, vid);

        if (!backbone_gw)
                return true;

        /* this must be an UNCLAIM frame */
        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "handle_unclaim(): UNCLAIM %pM on vid %d (sent by %pM)...\n",
                   claim_addr, BATADV_PRINT_VID(vid), backbone_gw->orig);

        batadv_bla_del_claim(bat_priv, claim_addr, vid);
        batadv_backbone_gw_put(backbone_gw);
        return true;
}

/**
 * batadv_handle_claim - check for CLAIM frame
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the primary hard interface of this batman soft interface
 * @backbone_addr: originator address of the backbone (Ethernet Source)
 * @claim_addr: client mac address to be claimed (ARP sender HW MAC)
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_claim(struct batadv_priv *bat_priv,
                                struct batadv_hard_iface *primary_if,
                                u8 *backbone_addr, u8 *claim_addr,
                                unsigned short vid)
{
        struct batadv_bla_backbone_gw *backbone_gw;

        /* register the gateway if not yet available, and add the claim. */

        backbone_gw = batadv_bla_get_backbone_gw(bat_priv, backbone_addr, vid,
                                                 false);

        if (unlikely(!backbone_gw))
                return true;

        /* this must be a CLAIM frame */
        batadv_bla_add_claim(bat_priv, claim_addr, vid, backbone_gw);
        if (batadv_compare_eth(backbone_addr, primary_if->net_dev->dev_addr))
                batadv_bla_send_claim(bat_priv, claim_addr, vid,
                                      BATADV_CLAIM_TYPE_CLAIM);

        /* TODO: we could call something like tt_local_del() here. */

        batadv_backbone_gw_put(backbone_gw);
        return true;
}

/**
 * batadv_check_claim_group - check for claim group membership
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the primary interface of this batman interface
 * @hw_src: the Hardware source in the ARP Header
 * @hw_dst: the Hardware destination in the ARP Header
 * @ethhdr: pointer to the Ethernet header of the claim frame
 *
 * checks if it is a claim packet and if its on the same group.
 * This function also applies the group ID of the sender
 * if it is in the same mesh.
 *
 * Return:
 *      2  - if it is a claim packet and on the same group
 *      1  - if is a claim packet from another group
 *      0  - if it is not a claim packet
 */
static int batadv_check_claim_group(struct batadv_priv *bat_priv,
                                    struct batadv_hard_iface *primary_if,
                                    u8 *hw_src, u8 *hw_dst,
                                    struct ethhdr *ethhdr)
{
        u8 *backbone_addr;
        struct batadv_orig_node *orig_node;
        struct batadv_bla_claim_dst *bla_dst, *bla_dst_own;

        bla_dst = (struct batadv_bla_claim_dst *)hw_dst;
        bla_dst_own = &bat_priv->bla.claim_dest;

        /* if announcement packet, use the source,
         * otherwise assume it is in the hw_src
         */
        switch (bla_dst->type) {
        case BATADV_CLAIM_TYPE_CLAIM:
                backbone_addr = hw_src;
                break;
        case BATADV_CLAIM_TYPE_REQUEST:
        case BATADV_CLAIM_TYPE_ANNOUNCE:
        case BATADV_CLAIM_TYPE_UNCLAIM:
                backbone_addr = ethhdr->h_source;
                break;
        default:
                return 0;
        }

        /* don't accept claim frames from ourselves */
        if (batadv_compare_eth(backbone_addr, primary_if->net_dev->dev_addr))
                return 0;

        /* if its already the same group, it is fine. */
        if (bla_dst->group == bla_dst_own->group)
                return 2;

        /* lets see if this originator is in our mesh */
        orig_node = batadv_orig_hash_find(bat_priv, backbone_addr);

        /* dont accept claims from gateways which are not in
         * the same mesh or group.
         */
        if (!orig_node)
                return 1;

        /* if our mesh friends mac is bigger, use it for ourselves. */
        if (ntohs(bla_dst->group) > ntohs(bla_dst_own->group)) {
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "taking other backbones claim group: %#.4x\n",
                           ntohs(bla_dst->group));
                bla_dst_own->group = bla_dst->group;
        }

        batadv_orig_node_put(orig_node);

        return 2;
}

/**
 * batadv_bla_process_claim - Check if this is a claim frame, and process it
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the primary hard interface of this batman soft interface
 * @skb: the frame to be checked
 *
 * Return: true if it was a claim frame, otherwise return false to
 * tell the callee that it can use the frame on its own.
 */
static bool batadv_bla_process_claim(struct batadv_priv *bat_priv,
                                     struct batadv_hard_iface *primary_if,
                                     struct sk_buff *skb)
{
        struct batadv_bla_claim_dst *bla_dst, *bla_dst_own;
        u8 *hw_src, *hw_dst;
        struct vlan_hdr *vhdr, vhdr_buf;
        struct ethhdr *ethhdr;
        struct arphdr *arphdr;
        unsigned short vid;
        int vlan_depth = 0;
        __be16 proto;
        int headlen;
        int ret;

        vid = batadv_get_vid(skb, 0);
        ethhdr = eth_hdr(skb);

        proto = ethhdr->h_proto;
        headlen = ETH_HLEN;
        if (vid & BATADV_VLAN_HAS_TAG) {
                /* Traverse the VLAN/Ethertypes.
                 *
                 * At this point it is known that the first protocol is a VLAN
                 * header, so start checking at the encapsulated protocol.
                 *
                 * The depth of the VLAN headers is recorded to drop BLA claim
                 * frames encapsulated into multiple VLAN headers (QinQ).
                 */
                do {
                        vhdr = skb_header_pointer(skb, headlen, VLAN_HLEN,
                                                  &vhdr_buf);
                        if (!vhdr)
                                return false;

                        proto = vhdr->h_vlan_encapsulated_proto;
                        headlen += VLAN_HLEN;
                        vlan_depth++;
                } while (proto == htons(ETH_P_8021Q));
        }

        if (proto != htons(ETH_P_ARP))
                return false; /* not a claim frame */

        /* this must be a ARP frame. check if it is a claim. */

        if (unlikely(!pskb_may_pull(skb, headlen + arp_hdr_len(skb->dev))))
                return false;

        /* pskb_may_pull() may have modified the pointers, get ethhdr again */
        ethhdr = eth_hdr(skb);
        arphdr = (struct arphdr *)((u8 *)ethhdr + headlen);

        /* Check whether the ARP frame carries a valid
         * IP information
         */
        if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
                return false;
        if (arphdr->ar_pro != htons(ETH_P_IP))
                return false;
        if (arphdr->ar_hln != ETH_ALEN)
                return false;
        if (arphdr->ar_pln != 4)
                return false;

        hw_src = (u8 *)arphdr + sizeof(struct arphdr);
        hw_dst = hw_src + ETH_ALEN + 4;
        bla_dst = (struct batadv_bla_claim_dst *)hw_dst;
        bla_dst_own = &bat_priv->bla.claim_dest;

        /* check if it is a claim frame in general */
        if (memcmp(bla_dst->magic, bla_dst_own->magic,
                   sizeof(bla_dst->magic)) != 0)
                return false;

        /* check if there is a claim frame encapsulated deeper in (QinQ) and
         * drop that, as this is not supported by BLA but should also not be
         * sent via the mesh.
         */
        if (vlan_depth > 1)
                return true;

        /* Let the loopdetect frames on the mesh in any case. */
        if (bla_dst->type == BATADV_CLAIM_TYPE_LOOPDETECT)
                return 0;

        /* check if it is a claim frame. */
        ret = batadv_check_claim_group(bat_priv, primary_if, hw_src, hw_dst,
                                       ethhdr);
        if (ret == 1)
                batadv_dbg(BATADV_DBG_BLA, bat_priv,
                           "bla_process_claim(): received a claim frame from another group. From: %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
                           ethhdr->h_source, BATADV_PRINT_VID(vid), hw_src,
                           hw_dst);

        if (ret < 2)
                return !!ret;

        /* become a backbone gw ourselves on this vlan if not happened yet */
        batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);

        /* check for the different types of claim frames ... */
        switch (bla_dst->type) {
        case BATADV_CLAIM_TYPE_CLAIM:
                if (batadv_handle_claim(bat_priv, primary_if, hw_src,
                                        ethhdr->h_source, vid))
                        return true;
                break;
        case BATADV_CLAIM_TYPE_UNCLAIM:
                if (batadv_handle_unclaim(bat_priv, primary_if,
                                          ethhdr->h_source, hw_src, vid))
                        return true;
                break;

        case BATADV_CLAIM_TYPE_ANNOUNCE:
                if (batadv_handle_announce(bat_priv, hw_src, ethhdr->h_source,
                                           vid))
                        return true;
                break;
        case BATADV_CLAIM_TYPE_REQUEST:
                if (batadv_handle_request(bat_priv, primary_if, hw_src, ethhdr,
                                          vid))
                        return true;
                break;
        }

        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                   "bla_process_claim(): ERROR - this looks like a claim frame, but is useless. eth src %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
                   ethhdr->h_source, BATADV_PRINT_VID(vid), hw_src, hw_dst);
        return true;
}

/**
 * batadv_bla_purge_backbone_gw - Remove backbone gateways after a timeout or
 *  immediately
 * @bat_priv: the bat priv with all the soft interface information
 * @now: whether the whole hash shall be wiped now
 *
 * Check when we last heard from other nodes, and remove them in case of
 * a time out, or clean all backbone gws if now is set.
 */
static void batadv_bla_purge_backbone_gw(struct batadv_priv *bat_priv, int now)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        spinlock_t *list_lock;  /* protects write access to the hash lists */
        int i;

        hash = bat_priv->bla.backbone_hash;
        if (!hash)
                return;

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

                spin_lock_bh(list_lock);
                hlist_for_each_entry_safe(backbone_gw, node_tmp,
                                          head, hash_entry) {
                        if (now)
                                goto purge_now;
                        if (!batadv_has_timed_out(backbone_gw->lasttime,
                                                  BATADV_BLA_BACKBONE_TIMEOUT))
                                continue;

                        batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
                                   "bla_purge_backbone_gw(): backbone gw %pM timed out\n",
                                   backbone_gw->orig);

purge_now:
                        /* don't wait for the pending request anymore */
                        if (atomic_read(&backbone_gw->request_sent))
                                atomic_dec(&bat_priv->bla.num_requests);

                        batadv_bla_del_backbone_claims(backbone_gw);

                        hlist_del_rcu(&backbone_gw->hash_entry);
                        batadv_backbone_gw_put(backbone_gw);
                }
                spin_unlock_bh(list_lock);
        }
}

/**
 * batadv_bla_purge_claims - Remove claims after a timeout or immediately
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the selected primary interface, may be NULL if now is set
 * @now: whether the whole hash shall be wiped now
 *
 * Check when we heard last time from our own claims, and remove them in case of
 * a time out, or clean all claims if now is set
 */
static void batadv_bla_purge_claims(struct batadv_priv *bat_priv,
                                    struct batadv_hard_iface *primary_if,
                                    int now)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_bla_claim *claim;
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        int i;

        hash = bat_priv->bla.claim_hash;
        if (!hash)
                return;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(claim, head, hash_entry) {
                        backbone_gw = batadv_bla_claim_get_backbone_gw(claim);
                        if (now)
                                goto purge_now;

                        if (!batadv_compare_eth(backbone_gw->orig,
                                                primary_if->net_dev->dev_addr))
                                goto skip;

                        if (!batadv_has_timed_out(claim->lasttime,
                                                  BATADV_BLA_CLAIM_TIMEOUT))
                                goto skip;

                        batadv_dbg(BATADV_DBG_BLA, bat_priv,
                                   "bla_purge_claims(): %pM, vid %d, time out\n",
                                   claim->addr, claim->vid);

purge_now:
                        batadv_handle_unclaim(bat_priv, primary_if,
                                              backbone_gw->orig,
                                              claim->addr, claim->vid);
skip:
                        batadv_backbone_gw_put(backbone_gw);
                }
                rcu_read_unlock();
        }
}

/**
 * batadv_bla_update_orig_address - Update the backbone gateways when the own
 *  originator address changes
 * @bat_priv: the bat priv with all the soft interface information
 * @primary_if: the new selected primary_if
 * @oldif: the old primary interface, may be NULL
 */
void batadv_bla_update_orig_address(struct batadv_priv *bat_priv,
                                    struct batadv_hard_iface *primary_if,
                                    struct batadv_hard_iface *oldif)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct hlist_head *head;
        struct batadv_hashtable *hash;
        __be16 group;
        int i;

        /* reset bridge loop avoidance group id */
        group = htons(crc16(0, primary_if->net_dev->dev_addr, ETH_ALEN));
        bat_priv->bla.claim_dest.group = group;

        /* purge everything when bridge loop avoidance is turned off */
        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                oldif = NULL;

        if (!oldif) {
                batadv_bla_purge_claims(bat_priv, NULL, 1);
                batadv_bla_purge_backbone_gw(bat_priv, 1);
                return;
        }

        hash = bat_priv->bla.backbone_hash;
        if (!hash)
                return;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        /* own orig still holds the old value. */
                        if (!batadv_compare_eth(backbone_gw->orig,
                                                oldif->net_dev->dev_addr))
                                continue;

                        ether_addr_copy(backbone_gw->orig,
                                        primary_if->net_dev->dev_addr);
                        /* send an announce frame so others will ask for our
                         * claims and update their tables.
                         */
                        batadv_bla_send_announce(bat_priv, backbone_gw);
                }
                rcu_read_unlock();
        }
}

/**
 * batadv_bla_send_loopdetect - send a loopdetect frame
 * @bat_priv: the bat priv with all the soft interface information
 * @backbone_gw: the backbone gateway for which a loop should be detected
 *
 * To detect loops that the bridge loop avoidance can't handle, send a loop
 * detection packet on the backbone. Unlike other BLA frames, this frame will
 * be allowed on the mesh by other nodes. If it is received on the mesh, this
 * indicates that there is a loop.
 */
static void
batadv_bla_send_loopdetect(struct batadv_priv *bat_priv,
                           struct batadv_bla_backbone_gw *backbone_gw)
{
        batadv_dbg(BATADV_DBG_BLA, bat_priv, "Send loopdetect frame for vid %d\n",
                   backbone_gw->vid);
        batadv_bla_send_claim(bat_priv, bat_priv->bla.loopdetect_addr,
                              backbone_gw->vid, BATADV_CLAIM_TYPE_LOOPDETECT);
}

/**
 * batadv_bla_status_update - purge bla interfaces if necessary
 * @net_dev: the soft interface net device
 */
void batadv_bla_status_update(struct net_device *net_dev)
{
        struct batadv_priv *bat_priv = netdev_priv(net_dev);
        struct batadv_hard_iface *primary_if;

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                return;

        /* this function already purges everything when bla is disabled,
         * so just call that one.
         */
        batadv_bla_update_orig_address(bat_priv, primary_if, primary_if);
        batadv_hardif_put(primary_if);
}

/**
 * batadv_bla_periodic_work - performs periodic bla work
 * @work: kernel work struct
 *
 * periodic work to do:
 *  * purge structures when they are too old
 *  * send announcements
 */
static void batadv_bla_periodic_work(struct work_struct *work)
{
        struct delayed_work *delayed_work;
        struct batadv_priv *bat_priv;
        struct batadv_priv_bla *priv_bla;
        struct hlist_head *head;
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_hashtable *hash;
        struct batadv_hard_iface *primary_if;
        bool send_loopdetect = false;
        int i;

        delayed_work = to_delayed_work(work);
        priv_bla = container_of(delayed_work, struct batadv_priv_bla, work);
        bat_priv = container_of(priv_bla, struct batadv_priv, bla);
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto out;

        batadv_bla_purge_claims(bat_priv, primary_if, 0);
        batadv_bla_purge_backbone_gw(bat_priv, 0);

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                goto out;

        if (atomic_dec_and_test(&bat_priv->bla.loopdetect_next)) {
                /* set a new random mac address for the next bridge loop
                 * detection frames. Set the locally administered bit to avoid
                 * collisions with users mac addresses.
                 */
                random_ether_addr(bat_priv->bla.loopdetect_addr);
                bat_priv->bla.loopdetect_addr[0] = 0xba;
                bat_priv->bla.loopdetect_addr[1] = 0xbe;
                bat_priv->bla.loopdetect_lasttime = jiffies;
                atomic_set(&bat_priv->bla.loopdetect_next,
                           BATADV_BLA_LOOPDETECT_PERIODS);

                /* mark for sending loop detect on all VLANs */
                send_loopdetect = true;
        }

        hash = bat_priv->bla.backbone_hash;
        if (!hash)
                goto out;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        if (!batadv_compare_eth(backbone_gw->orig,
                                                primary_if->net_dev->dev_addr))
                                continue;

                        backbone_gw->lasttime = jiffies;

                        batadv_bla_send_announce(bat_priv, backbone_gw);
                        if (send_loopdetect)
                                batadv_bla_send_loopdetect(bat_priv,
                                                           backbone_gw);

                        /* request_sent is only set after creation to avoid
                         * problems when we are not yet known as backbone gw
                         * in the backbone.
                         *
                         * We can reset this now after we waited some periods
                         * to give bridge forward delays and bla group forming
                         * some grace time.
                         */

                        if (atomic_read(&backbone_gw->request_sent) == 0)
                                continue;

                        if (!atomic_dec_and_test(&backbone_gw->wait_periods))
                                continue;

                        atomic_dec(&backbone_gw->bat_priv->bla.num_requests);
                        atomic_set(&backbone_gw->request_sent, 0);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_put(primary_if);

        queue_delayed_work(batadv_event_workqueue, &bat_priv->bla.work,
                           msecs_to_jiffies(BATADV_BLA_PERIOD_LENGTH));
}

/* The hash for claim and backbone hash receive the same key because they
 * are getting initialized by hash_new with the same key. Reinitializing
 * them with to different keys to allow nested locking without generating
 * lockdep warnings
 */
static struct lock_class_key batadv_claim_hash_lock_class_key;
static struct lock_class_key batadv_backbone_hash_lock_class_key;

/**
 * batadv_bla_init - initialize all bla structures
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: 0 on success, < 0 on error.
 */
int batadv_bla_init(struct batadv_priv *bat_priv)
{
        int i;
        u8 claim_dest[ETH_ALEN] = {0xff, 0x43, 0x05, 0x00, 0x00, 0x00};
        struct batadv_hard_iface *primary_if;
        u16 crc;
        unsigned long entrytime;

        spin_lock_init(&bat_priv->bla.bcast_duplist_lock);

        batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hash registering\n");

        /* setting claim destination address */
        memcpy(&bat_priv->bla.claim_dest.magic, claim_dest, 3);
        bat_priv->bla.claim_dest.type = 0;
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (primary_if) {
                crc = crc16(0, primary_if->net_dev->dev_addr, ETH_ALEN);
                bat_priv->bla.claim_dest.group = htons(crc);
                batadv_hardif_put(primary_if);
        } else {
                bat_priv->bla.claim_dest.group = 0; /* will be set later */
        }

        /* initialize the duplicate list */
        entrytime = jiffies - msecs_to_jiffies(BATADV_DUPLIST_TIMEOUT);
        for (i = 0; i < BATADV_DUPLIST_SIZE; i++)
                bat_priv->bla.bcast_duplist[i].entrytime = entrytime;
        bat_priv->bla.bcast_duplist_curr = 0;

        atomic_set(&bat_priv->bla.loopdetect_next,
                   BATADV_BLA_LOOPDETECT_PERIODS);

        if (bat_priv->bla.claim_hash)
                return 0;

        bat_priv->bla.claim_hash = batadv_hash_new(128);
        bat_priv->bla.backbone_hash = batadv_hash_new(32);

        if (!bat_priv->bla.claim_hash || !bat_priv->bla.backbone_hash)
                return -ENOMEM;

        batadv_hash_set_lock_class(bat_priv->bla.claim_hash,
                                   &batadv_claim_hash_lock_class_key);
        batadv_hash_set_lock_class(bat_priv->bla.backbone_hash,
                                   &batadv_backbone_hash_lock_class_key);

        batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hashes initialized\n");

        INIT_DELAYED_WORK(&bat_priv->bla.work, batadv_bla_periodic_work);

        queue_delayed_work(batadv_event_workqueue, &bat_priv->bla.work,
                           msecs_to_jiffies(BATADV_BLA_PERIOD_LENGTH));
        return 0;
}

/**
 * batadv_bla_check_bcast_duplist - Check if a frame is in the broadcast dup.
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: contains the bcast_packet to be checked
 *
 * check if it is on our broadcast list. Another gateway might
 * have sent the same packet because it is connected to the same backbone,
 * so we have to remove this duplicate.
 *
 * This is performed by checking the CRC, which will tell us
 * with a good chance that it is the same packet. If it is furthermore
 * sent by another host, drop it. We allow equal packets from
 * the same host however as this might be intended.
 *
 * Return: true if a packet is in the duplicate list, false otherwise.
 */
bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
                                    struct sk_buff *skb)
{
        int i, curr;
        __be32 crc;
        struct batadv_bcast_packet *bcast_packet;
        struct batadv_bcast_duplist_entry *entry;
        bool ret = false;

        bcast_packet = (struct batadv_bcast_packet *)skb->data;

        /* calculate the crc ... */
        crc = batadv_skb_crc32(skb, (u8 *)(bcast_packet + 1));

        spin_lock_bh(&bat_priv->bla.bcast_duplist_lock);

        for (i = 0; i < BATADV_DUPLIST_SIZE; i++) {
                curr = (bat_priv->bla.bcast_duplist_curr + i);
                curr %= BATADV_DUPLIST_SIZE;
                entry = &bat_priv->bla.bcast_duplist[curr];

                /* we can stop searching if the entry is too old ;
                 * later entries will be even older
                 */
                if (batadv_has_timed_out(entry->entrytime,
                                         BATADV_DUPLIST_TIMEOUT))
                        break;

                if (entry->crc != crc)
                        continue;

                if (batadv_compare_eth(entry->orig, bcast_packet->orig))
                        continue;

                /* this entry seems to match: same crc, not too old,
                 * and from another gw. therefore return true to forbid it.
                 */
                ret = true;
                goto out;
        }
        /* not found, add a new entry (overwrite the oldest entry)
         * and allow it, its the first occurrence.
         */
        curr = (bat_priv->bla.bcast_duplist_curr + BATADV_DUPLIST_SIZE - 1);
        curr %= BATADV_DUPLIST_SIZE;
        entry = &bat_priv->bla.bcast_duplist[curr];
        entry->crc = crc;
        entry->entrytime = jiffies;
        ether_addr_copy(entry->orig, bcast_packet->orig);
        bat_priv->bla.bcast_duplist_curr = curr;

out:
        spin_unlock_bh(&bat_priv->bla.bcast_duplist_lock);

        return ret;
}

/**
 * batadv_bla_is_backbone_gw_orig - Check if the originator is a gateway for
 *  the VLAN identified by vid.
 * @bat_priv: the bat priv with all the soft interface information
 * @orig: originator mac address
 * @vid: VLAN identifier
 *
 * Return: true if orig is a backbone for this vid, false otherwise.
 */
bool batadv_bla_is_backbone_gw_orig(struct batadv_priv *bat_priv, u8 *orig,
                                    unsigned short vid)
{
        struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
        struct hlist_head *head;
        struct batadv_bla_backbone_gw *backbone_gw;
        int i;

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                return false;

        if (!hash)
                return false;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        if (batadv_compare_eth(backbone_gw->orig, orig) &&
                            backbone_gw->vid == vid) {
                                rcu_read_unlock();
                                return true;
                        }
                }
                rcu_read_unlock();
        }

        return false;
}

/**
 * batadv_bla_is_backbone_gw - check if originator is a backbone gw for a VLAN.
 * @skb: the frame to be checked
 * @orig_node: the orig_node of the frame
 * @hdr_size: maximum length of the frame
 *
 * Return: true if the orig_node is also a gateway on the soft interface,
 * otherwise it returns false.
 */
bool batadv_bla_is_backbone_gw(struct sk_buff *skb,
                               struct batadv_orig_node *orig_node, int hdr_size)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        unsigned short vid;

        if (!atomic_read(&orig_node->bat_priv->bridge_loop_avoidance))
                return false;

        /* first, find out the vid. */
        if (!pskb_may_pull(skb, hdr_size + ETH_HLEN))
                return false;

        vid = batadv_get_vid(skb, hdr_size);

        /* see if this originator is a backbone gw for this VLAN */
        backbone_gw = batadv_backbone_hash_find(orig_node->bat_priv,
                                                orig_node->orig, vid);
        if (!backbone_gw)
                return false;

        batadv_backbone_gw_put(backbone_gw);
        return true;
}

/**
 * batadv_bla_free - free all bla structures
 * @bat_priv: the bat priv with all the soft interface information
 *
 * for softinterface free or module unload
 */
void batadv_bla_free(struct batadv_priv *bat_priv)
{
        struct batadv_hard_iface *primary_if;

        cancel_delayed_work_sync(&bat_priv->bla.work);
        primary_if = batadv_primary_if_get_selected(bat_priv);

        if (bat_priv->bla.claim_hash) {
                batadv_bla_purge_claims(bat_priv, primary_if, 1);
                batadv_hash_destroy(bat_priv->bla.claim_hash);
                bat_priv->bla.claim_hash = NULL;
        }
        if (bat_priv->bla.backbone_hash) {
                batadv_bla_purge_backbone_gw(bat_priv, 1);
                batadv_hash_destroy(bat_priv->bla.backbone_hash);
                bat_priv->bla.backbone_hash = NULL;
        }
        if (primary_if)
                batadv_hardif_put(primary_if);
}

/**
 * batadv_bla_loopdetect_check - check and handle a detected loop
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the packet to check
 * @primary_if: interface where the request came on
 * @vid: the VLAN ID of the frame
 *
 * Checks if this packet is a loop detect frame which has been sent by us,
 * throw an uevent and log the event if that is the case.
 *
 * Return: true if it is a loop detect frame which is to be dropped, false
 * otherwise.
 */
static bool
batadv_bla_loopdetect_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
                            struct batadv_hard_iface *primary_if,
                            unsigned short vid)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct ethhdr *ethhdr;

        ethhdr = eth_hdr(skb);

        /* Only check for the MAC address and skip more checks here for
         * performance reasons - this function is on the hotpath, after all.
         */
        if (!batadv_compare_eth(ethhdr->h_source,
                                bat_priv->bla.loopdetect_addr))
                return false;

        /* If the packet came too late, don't forward it on the mesh
         * but don't consider that as loop. It might be a coincidence.
         */
        if (batadv_has_timed_out(bat_priv->bla.loopdetect_lasttime,
                                 BATADV_BLA_LOOPDETECT_TIMEOUT))
                return true;

        backbone_gw = batadv_bla_get_backbone_gw(bat_priv,
                                                 primary_if->net_dev->dev_addr,
                                                 vid, true);
        if (unlikely(!backbone_gw))
                return true;

        queue_work(batadv_event_workqueue, &backbone_gw->report_work);
        /* backbone_gw is unreferenced in the report work function function */

        return true;
}

/**
 * batadv_bla_rx - check packets coming from the mesh.
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 * @is_bcast: the packet came in a broadcast packet type.
 *
 * batadv_bla_rx avoidance checks if:
 *  * we have to race for a claim
 *  * if the frame is allowed on the LAN
 *
 * in these cases, the skb is further handled by this function
 *
 * Return: true if handled, otherwise it returns false and the caller shall
 * further process the skb.
 */
bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
                   unsigned short vid, bool is_bcast)
{
        struct batadv_bla_backbone_gw *backbone_gw;
        struct ethhdr *ethhdr;
        struct batadv_bla_claim search_claim, *claim = NULL;
        struct batadv_hard_iface *primary_if;
        bool own_claim;
        bool ret;

        ethhdr = eth_hdr(skb);

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

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                goto allow;

        if (batadv_bla_loopdetect_check(bat_priv, skb, primary_if, vid))
                goto handled;

        if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
                /* don't allow broadcasts while requests are in flight */
                if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast)
                        goto handled;

        ether_addr_copy(search_claim.addr, ethhdr->h_source);
        search_claim.vid = vid;
        claim = batadv_claim_hash_find(bat_priv, &search_claim);

        if (!claim) {
                /* possible optimization: race for a claim */
                /* No claim exists yet, claim it for us!
                 */
                batadv_handle_claim(bat_priv, primary_if,
                                    primary_if->net_dev->dev_addr,
                                    ethhdr->h_source, vid);
                goto allow;
        }

        /* if it is our own claim ... */
        backbone_gw = batadv_bla_claim_get_backbone_gw(claim);
        own_claim = batadv_compare_eth(backbone_gw->orig,
                                       primary_if->net_dev->dev_addr);
        batadv_backbone_gw_put(backbone_gw);

        if (own_claim) {
                /* ... allow it in any case */
                claim->lasttime = jiffies;
                goto allow;
        }

        /* if it is a broadcast ... */
        if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast) {
                /* ... drop it. the responsible gateway is in charge.
                 *
                 * We need to check is_bcast because with the gateway
                 * feature, broadcasts (like DHCP requests) may be sent
                 * using a unicast packet type.
                 */
                goto handled;
        } else {
                /* seems the client considers us as its best gateway.
                 * send a claim and update the claim table
                 * immediately.
                 */
                batadv_handle_claim(bat_priv, primary_if,
                                    primary_if->net_dev->dev_addr,
                                    ethhdr->h_source, vid);
                goto allow;
        }
allow:
        batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);
        ret = false;
        goto out;

handled:
        kfree_skb(skb);
        ret = true;

out:
        if (primary_if)
                batadv_hardif_put(primary_if);
        if (claim)
                batadv_claim_put(claim);
        return ret;
}

/**
 * batadv_bla_tx - check packets going into the mesh
 * @bat_priv: the bat priv with all the soft interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 *
 * batadv_bla_tx checks if:
 *  * a claim was received which has to be processed
 *  * the frame is allowed on the mesh
 *
 * in these cases, the skb is further handled by this function.
 *
 * This call might reallocate skb data.
 *
 * Return: true if handled, otherwise it returns false and the caller shall
 * further process the skb.
 */
bool batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
                   unsigned short vid)
{
        struct ethhdr *ethhdr;
        struct batadv_bla_claim search_claim, *claim = NULL;
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_hard_iface *primary_if;
        bool client_roamed;
        bool ret = false;

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

        if (!atomic_read(&bat_priv->bridge_loop_avoidance))
                goto allow;

        if (batadv_bla_process_claim(bat_priv, primary_if, skb))
                goto handled;

        ethhdr = eth_hdr(skb);

        if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
                /* don't allow broadcasts while requests are in flight */
                if (is_multicast_ether_addr(ethhdr->h_dest))
                        goto handled;

        ether_addr_copy(search_claim.addr, ethhdr->h_source);
        search_claim.vid = vid;

        claim = batadv_claim_hash_find(bat_priv, &search_claim);

        /* if no claim exists, allow it. */
        if (!claim)
                goto allow;

        /* check if we are responsible. */
        backbone_gw = batadv_bla_claim_get_backbone_gw(claim);
        client_roamed = batadv_compare_eth(backbone_gw->orig,
                                           primary_if->net_dev->dev_addr);
        batadv_backbone_gw_put(backbone_gw);

        if (client_roamed) {
                /* if yes, the client has roamed and we have
                 * to unclaim it.
                 */
                batadv_handle_unclaim(bat_priv, primary_if,
                                      primary_if->net_dev->dev_addr,
                                      ethhdr->h_source, vid);
                goto allow;
        }

        /* check if it is a multicast/broadcast frame */
        if (is_multicast_ether_addr(ethhdr->h_dest)) {
                /* drop it. the responsible gateway has forwarded it into
                 * the backbone network.
                 */
                goto handled;
        } else {
                /* we must allow it. at least if we are
                 * responsible for the DESTINATION.
                 */
                goto allow;
        }
allow:
        batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);
        ret = false;
        goto out;
handled:
        ret = true;
out:
        if (primary_if)
                batadv_hardif_put(primary_if);
        if (claim)
                batadv_claim_put(claim);
        return ret;
}

/**
 * batadv_bla_claim_table_seq_print_text - print the claim table in a seq file
 * @seq: seq file to print on
 * @offset: not used
 *
 * Return: always 0
 */
int batadv_bla_claim_table_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->bla.claim_hash;
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_bla_claim *claim;
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        u16 backbone_crc;
        u32 i;
        bool is_own;
        u8 *primary_addr;

        primary_if = batadv_seq_print_text_primary_if_get(seq);
        if (!primary_if)
                goto out;

        primary_addr = primary_if->net_dev->dev_addr;
        seq_printf(seq,
                   "Claims announced for the mesh %s (orig %pM, group id %#.4x)\n",
                   net_dev->name, primary_addr,
                   ntohs(bat_priv->bla.claim_dest.group));
        seq_puts(seq,
                 "   Client               VID      Originator        [o] (CRC   )\n");
        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(claim, head, hash_entry) {
                        backbone_gw = batadv_bla_claim_get_backbone_gw(claim);

                        is_own = batadv_compare_eth(backbone_gw->orig,
                                                    primary_addr);

                        spin_lock_bh(&backbone_gw->crc_lock);
                        backbone_crc = backbone_gw->crc;
                        spin_unlock_bh(&backbone_gw->crc_lock);
                        seq_printf(seq, " * %pM on %5d by %pM [%c] (%#.4x)\n",
                                   claim->addr, BATADV_PRINT_VID(claim->vid),
                                   backbone_gw->orig,
                                   (is_own ? 'x' : ' '),
                                   backbone_crc);

                        batadv_backbone_gw_put(backbone_gw);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_put(primary_if);
        return 0;
}

/**
 * batadv_bla_backbone_table_seq_print_text - print the backbone table in a seq
 *  file
 * @seq: seq file to print on
 * @offset: not used
 *
 * Return: always 0
 */
int batadv_bla_backbone_table_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->bla.backbone_hash;
        struct batadv_bla_backbone_gw *backbone_gw;
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        int secs, msecs;
        u16 backbone_crc;
        u32 i;
        bool is_own;
        u8 *primary_addr;

        primary_if = batadv_seq_print_text_primary_if_get(seq);
        if (!primary_if)
                goto out;

        primary_addr = primary_if->net_dev->dev_addr;
        seq_printf(seq,
                   "Backbones announced for the mesh %s (orig %pM, group id %#.4x)\n",
                   net_dev->name, primary_addr,
                   ntohs(bat_priv->bla.claim_dest.group));
        seq_puts(seq, "   Originator           VID   last seen (CRC   )\n");
        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                        msecs = jiffies_to_msecs(jiffies -
                                                 backbone_gw->lasttime);
                        secs = msecs / 1000;
                        msecs = msecs % 1000;

                        is_own = batadv_compare_eth(backbone_gw->orig,
                                                    primary_addr);
                        if (is_own)
                                continue;

                        spin_lock_bh(&backbone_gw->crc_lock);
                        backbone_crc = backbone_gw->crc;
                        spin_unlock_bh(&backbone_gw->crc_lock);

                        seq_printf(seq, " * %pM on %5d %4i.%03is (%#.4x)\n",
                                   backbone_gw->orig,
                                   BATADV_PRINT_VID(backbone_gw->vid), secs,
                                   msecs, backbone_crc);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_put(primary_if);
        return 0;
}