Merge tag 'for-v3.10-fixes' of git://git.infradead.org/battery-2.6

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / batman-adv / translation-table.c

/* Copyright (C) 2007-2013 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich, Antonio Quartulli
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#include "main.h"
#include "translation-table.h"
#include "soft-interface.h"
#include "hard-interface.h"
#include "send.h"
#include "hash.h"
#include "originator.h"
#include "routing.h"
#include "bridge_loop_avoidance.h"

#include <linux/crc16.h>

/* hash class keys */
static struct lock_class_key batadv_tt_local_hash_lock_class_key;
static struct lock_class_key batadv_tt_global_hash_lock_class_key;

static void batadv_send_roam_adv(struct batadv_priv *bat_priv, uint8_t *client,
                                 struct batadv_orig_node *orig_node);
static void batadv_tt_purge(struct work_struct *work);
static void
batadv_tt_global_del_orig_list(struct batadv_tt_global_entry *tt_global_entry);
static void batadv_tt_global_del(struct batadv_priv *bat_priv,
                                 struct batadv_orig_node *orig_node,
                                 const unsigned char *addr,
                                 const char *message, bool roaming);

/* returns 1 if they are the same mac addr */
static int batadv_compare_tt(const struct hlist_node *node, const void *data2)
{
        const void *data1 = container_of(node, struct batadv_tt_common_entry,
                                         hash_entry);

        return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
}

static struct batadv_tt_common_entry *
batadv_tt_hash_find(struct batadv_hashtable *hash, const void *data)
{
        struct hlist_head *head;
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_common_entry *tt_common_entry_tmp = NULL;
        uint32_t index;

        if (!hash)
                return NULL;

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

        rcu_read_lock();
        hlist_for_each_entry_rcu(tt_common_entry, head, hash_entry) {
                if (!batadv_compare_eth(tt_common_entry, data))
                        continue;

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

                tt_common_entry_tmp = tt_common_entry;
                break;
        }
        rcu_read_unlock();

        return tt_common_entry_tmp;
}

static struct batadv_tt_local_entry *
batadv_tt_local_hash_find(struct batadv_priv *bat_priv, const void *data)
{
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_local_entry *tt_local_entry = NULL;

        tt_common_entry = batadv_tt_hash_find(bat_priv->tt.local_hash, data);
        if (tt_common_entry)
                tt_local_entry = container_of(tt_common_entry,
                                              struct batadv_tt_local_entry,
                                              common);
        return tt_local_entry;
}

static struct batadv_tt_global_entry *
batadv_tt_global_hash_find(struct batadv_priv *bat_priv, const void *data)
{
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_global_entry *tt_global_entry = NULL;

        tt_common_entry = batadv_tt_hash_find(bat_priv->tt.global_hash, data);
        if (tt_common_entry)
                tt_global_entry = container_of(tt_common_entry,
                                               struct batadv_tt_global_entry,
                                               common);
        return tt_global_entry;
}

static void
batadv_tt_local_entry_free_ref(struct batadv_tt_local_entry *tt_local_entry)
{
        if (atomic_dec_and_test(&tt_local_entry->common.refcount))
                kfree_rcu(tt_local_entry, common.rcu);
}

static void batadv_tt_global_entry_free_rcu(struct rcu_head *rcu)
{
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_global_entry *tt_global_entry;

        tt_common_entry = container_of(rcu, struct batadv_tt_common_entry, rcu);
        tt_global_entry = container_of(tt_common_entry,
                                       struct batadv_tt_global_entry, common);

        kfree(tt_global_entry);
}

static void
batadv_tt_global_entry_free_ref(struct batadv_tt_global_entry *tt_global_entry)
{
        if (atomic_dec_and_test(&tt_global_entry->common.refcount)) {
                batadv_tt_global_del_orig_list(tt_global_entry);
                call_rcu(&tt_global_entry->common.rcu,
                         batadv_tt_global_entry_free_rcu);
        }
}

static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
{
        struct batadv_tt_orig_list_entry *orig_entry;

        orig_entry = container_of(rcu, struct batadv_tt_orig_list_entry, rcu);

        /* We are in an rcu callback here, therefore we cannot use
         * batadv_orig_node_free_ref() and its call_rcu():
         * An rcu_barrier() wouldn't wait for that to finish
         */
        batadv_orig_node_free_ref_now(orig_entry->orig_node);
        kfree(orig_entry);
}

static void
batadv_tt_orig_list_entry_free_ref(struct batadv_tt_orig_list_entry *orig_entry)
{
        if (!atomic_dec_and_test(&orig_entry->refcount))
                return;
        /* to avoid race conditions, immediately decrease the tt counter */
        atomic_dec(&orig_entry->orig_node->tt_size);
        call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
}

static void batadv_tt_local_event(struct batadv_priv *bat_priv,
                                  const uint8_t *addr, uint8_t flags)
{
        struct batadv_tt_change_node *tt_change_node, *entry, *safe;
        bool event_removed = false;
        bool del_op_requested, del_op_entry;

        tt_change_node = kmalloc(sizeof(*tt_change_node), GFP_ATOMIC);

        if (!tt_change_node)
                return;

        tt_change_node->change.flags = flags;
        memcpy(tt_change_node->change.addr, addr, ETH_ALEN);

        del_op_requested = flags & BATADV_TT_CLIENT_DEL;

        /* check for ADD+DEL or DEL+ADD events */
        spin_lock_bh(&bat_priv->tt.changes_list_lock);
        list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list,
                                 list) {
                if (!batadv_compare_eth(entry->change.addr, addr))
                        continue;

                /* DEL+ADD in the same orig interval have no effect and can be
                 * removed to avoid silly behaviour on the receiver side. The
                 * other way around (ADD+DEL) can happen in case of roaming of
                 * a client still in the NEW state. Roaming of NEW clients is
                 * now possible due to automatically recognition of "temporary"
                 * clients
                 */
                del_op_entry = entry->change.flags & BATADV_TT_CLIENT_DEL;
                if (!del_op_requested && del_op_entry)
                        goto del;
                if (del_op_requested && !del_op_entry)
                        goto del;
                continue;
del:
                list_del(&entry->list);
                kfree(entry);
                kfree(tt_change_node);
                event_removed = true;
                goto unlock;
        }

        /* track the change in the OGMinterval list */
        list_add_tail(&tt_change_node->list, &bat_priv->tt.changes_list);

unlock:
        spin_unlock_bh(&bat_priv->tt.changes_list_lock);

        if (event_removed)
                atomic_dec(&bat_priv->tt.local_changes);
        else
                atomic_inc(&bat_priv->tt.local_changes);
}

int batadv_tt_len(int changes_num)
{
        return changes_num * sizeof(struct batadv_tt_change);
}

static int batadv_tt_local_init(struct batadv_priv *bat_priv)
{
        if (bat_priv->tt.local_hash)
                return 0;

        bat_priv->tt.local_hash = batadv_hash_new(1024);

        if (!bat_priv->tt.local_hash)
                return -ENOMEM;

        batadv_hash_set_lock_class(bat_priv->tt.local_hash,
                                   &batadv_tt_local_hash_lock_class_key);

        return 0;
}

static void batadv_tt_global_free(struct batadv_priv *bat_priv,
                                  struct batadv_tt_global_entry *tt_global,
                                  const char *message)
{
        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Deleting global tt entry %pM: %s\n",
                   tt_global->common.addr, message);

        batadv_hash_remove(bat_priv->tt.global_hash, batadv_compare_tt,
                           batadv_choose_orig, tt_global->common.addr);
        batadv_tt_global_entry_free_ref(tt_global);
}

void batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
                         int ifindex)
{
        struct batadv_priv *bat_priv = netdev_priv(soft_iface);
        struct batadv_tt_local_entry *tt_local;
        struct batadv_tt_global_entry *tt_global;
        struct hlist_head *head;
        struct batadv_tt_orig_list_entry *orig_entry;
        int hash_added;
        bool roamed_back = false;

        tt_local = batadv_tt_local_hash_find(bat_priv, addr);
        tt_global = batadv_tt_global_hash_find(bat_priv, addr);

        if (tt_local) {
                tt_local->last_seen = jiffies;
                if (tt_local->common.flags & BATADV_TT_CLIENT_PENDING) {
                        batadv_dbg(BATADV_DBG_TT, bat_priv,
                                   "Re-adding pending client %pM\n", addr);
                        /* whatever the reason why the PENDING flag was set,
                         * this is a client which was enqueued to be removed in
                         * this orig_interval. Since it popped up again, the
                         * flag can be reset like it was never enqueued
                         */
                        tt_local->common.flags &= ~BATADV_TT_CLIENT_PENDING;
                        goto add_event;
                }

                if (tt_local->common.flags & BATADV_TT_CLIENT_ROAM) {
                        batadv_dbg(BATADV_DBG_TT, bat_priv,
                                   "Roaming client %pM came back to its original location\n",
                                   addr);
                        /* the ROAM flag is set because this client roamed away
                         * and the node got a roaming_advertisement message. Now
                         * that the client popped up again at its original
                         * location such flag can be unset
                         */
                        tt_local->common.flags &= ~BATADV_TT_CLIENT_ROAM;
                        roamed_back = true;
                }
                goto check_roaming;
        }

        tt_local = kmalloc(sizeof(*tt_local), GFP_ATOMIC);
        if (!tt_local)
                goto out;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Creating new local tt entry: %pM (ttvn: %d)\n", addr,
                   (uint8_t)atomic_read(&bat_priv->tt.vn));

        memcpy(tt_local->common.addr, addr, ETH_ALEN);
        /* The local entry has to be marked as NEW to avoid to send it in
         * a full table response going out before the next ttvn increment
         * (consistency check)
         */
        tt_local->common.flags = BATADV_TT_CLIENT_NEW;
        if (batadv_is_wifi_iface(ifindex))
                tt_local->common.flags |= BATADV_TT_CLIENT_WIFI;
        atomic_set(&tt_local->common.refcount, 2);
        tt_local->last_seen = jiffies;
        tt_local->common.added_at = tt_local->last_seen;

        /* the batman interface mac address should never be purged */
        if (batadv_compare_eth(addr, soft_iface->dev_addr))
                tt_local->common.flags |= BATADV_TT_CLIENT_NOPURGE;

        hash_added = batadv_hash_add(bat_priv->tt.local_hash, batadv_compare_tt,
                                     batadv_choose_orig, &tt_local->common,
                                     &tt_local->common.hash_entry);

        if (unlikely(hash_added != 0)) {
                /* remove the reference for the hash */
                batadv_tt_local_entry_free_ref(tt_local);
                goto out;
        }

add_event:
        batadv_tt_local_event(bat_priv, addr, tt_local->common.flags);

check_roaming:
        /* Check whether it is a roaming, but don't do anything if the roaming
         * process has already been handled
         */
        if (tt_global && !(tt_global->common.flags & BATADV_TT_CLIENT_ROAM)) {
                /* These node are probably going to update their tt table */
                head = &tt_global->orig_list;
                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_entry, head, list) {
                        batadv_send_roam_adv(bat_priv, tt_global->common.addr,
                                             orig_entry->orig_node);
                }
                rcu_read_unlock();
                if (roamed_back) {
                        batadv_tt_global_free(bat_priv, tt_global,
                                              "Roaming canceled");
                        tt_global = NULL;
                } else {
                        /* The global entry has to be marked as ROAMING and
                         * has to be kept for consistency purpose
                         */
                        tt_global->common.flags |= BATADV_TT_CLIENT_ROAM;
                        tt_global->roam_at = jiffies;
                }
        }

out:
        if (tt_local)
                batadv_tt_local_entry_free_ref(tt_local);
        if (tt_global)
                batadv_tt_global_entry_free_ref(tt_global);
}

static void batadv_tt_realloc_packet_buff(unsigned char **packet_buff,
                                          int *packet_buff_len,
                                          int min_packet_len,
                                          int new_packet_len)
{
        unsigned char *new_buff;

        new_buff = kmalloc(new_packet_len, GFP_ATOMIC);

        /* keep old buffer if kmalloc should fail */
        if (new_buff) {
                memcpy(new_buff, *packet_buff, min_packet_len);
                kfree(*packet_buff);
                *packet_buff = new_buff;
                *packet_buff_len = new_packet_len;
        }
}

static void batadv_tt_prepare_packet_buff(struct batadv_priv *bat_priv,
                                          unsigned char **packet_buff,
                                          int *packet_buff_len,
                                          int min_packet_len)
{
        int req_len;

        req_len = min_packet_len;
        req_len += batadv_tt_len(atomic_read(&bat_priv->tt.local_changes));

        /* if we have too many changes for one packet don't send any
         * and wait for the tt table request which will be fragmented
         */
        if (req_len > bat_priv->soft_iface->mtu)
                req_len = min_packet_len;

        batadv_tt_realloc_packet_buff(packet_buff, packet_buff_len,
                                      min_packet_len, req_len);
}

static int batadv_tt_changes_fill_buff(struct batadv_priv *bat_priv,
                                       unsigned char **packet_buff,
                                       int *packet_buff_len,
                                       int min_packet_len)
{
        struct batadv_tt_change_node *entry, *safe;
        int count = 0, tot_changes = 0, new_len;
        unsigned char *tt_buff;

        batadv_tt_prepare_packet_buff(bat_priv, packet_buff,
                                      packet_buff_len, min_packet_len);

        new_len = *packet_buff_len - min_packet_len;
        tt_buff = *packet_buff + min_packet_len;

        if (new_len > 0)
                tot_changes = new_len / batadv_tt_len(1);

        spin_lock_bh(&bat_priv->tt.changes_list_lock);
        atomic_set(&bat_priv->tt.local_changes, 0);

        list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list,
                                 list) {
                if (count < tot_changes) {
                        memcpy(tt_buff + batadv_tt_len(count),
                               &entry->change, sizeof(struct batadv_tt_change));
                        count++;
                }
                list_del(&entry->list);
                kfree(entry);
        }
        spin_unlock_bh(&bat_priv->tt.changes_list_lock);

        /* Keep the buffer for possible tt_request */
        spin_lock_bh(&bat_priv->tt.last_changeset_lock);
        kfree(bat_priv->tt.last_changeset);
        bat_priv->tt.last_changeset_len = 0;
        bat_priv->tt.last_changeset = NULL;
        /* check whether this new OGM has no changes due to size problems */
        if (new_len > 0) {
                /* if kmalloc() fails we will reply with the full table
                 * instead of providing the diff
                 */
                bat_priv->tt.last_changeset = kmalloc(new_len, GFP_ATOMIC);
                if (bat_priv->tt.last_changeset) {
                        memcpy(bat_priv->tt.last_changeset, tt_buff, new_len);
                        bat_priv->tt.last_changeset_len = new_len;
                }
        }
        spin_unlock_bh(&bat_priv->tt.last_changeset_lock);

        return count;
}

int batadv_tt_local_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->tt.local_hash;
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_local_entry *tt_local;
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        uint32_t i;
        int last_seen_secs;
        int last_seen_msecs;
        unsigned long last_seen_jiffies;
        bool no_purge;
        uint16_t np_flag = BATADV_TT_CLIENT_NOPURGE;

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

        seq_printf(seq,
                   "Locally retrieved addresses (from %s) announced via TT (TTVN: %u CRC: %#.4x):\n",
                   net_dev->name, (uint8_t)atomic_read(&bat_priv->tt.vn),
                   bat_priv->tt.local_crc);
        seq_printf(seq, "       %-13s %-7s %-10s\n", "Client", "Flags",
                   "Last seen");

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(tt_common_entry,
                                         head, hash_entry) {
                        tt_local = container_of(tt_common_entry,
                                                struct batadv_tt_local_entry,
                                                common);
                        last_seen_jiffies = jiffies - tt_local->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;

                        no_purge = tt_common_entry->flags & np_flag;

                        seq_printf(seq, " * %pM [%c%c%c%c%c] %3u.%03u\n",
                                   tt_common_entry->addr,
                                   (tt_common_entry->flags &
                                    BATADV_TT_CLIENT_ROAM ? 'R' : '.'),
                                   no_purge ? 'P' : '.',
                                   (tt_common_entry->flags &
                                    BATADV_TT_CLIENT_NEW ? 'N' : '.'),
                                   (tt_common_entry->flags &
                                    BATADV_TT_CLIENT_PENDING ? 'X' : '.'),
                                   (tt_common_entry->flags &
                                    BATADV_TT_CLIENT_WIFI ? 'W' : '.'),
                                   no_purge ? 0 : last_seen_secs,
                                   no_purge ? 0 : last_seen_msecs);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return 0;
}

static void
batadv_tt_local_set_pending(struct batadv_priv *bat_priv,
                            struct batadv_tt_local_entry *tt_local_entry,
                            uint16_t flags, const char *message)
{
        batadv_tt_local_event(bat_priv, tt_local_entry->common.addr,
                              tt_local_entry->common.flags | flags);

        /* The local client has to be marked as "pending to be removed" but has
         * to be kept in the table in order to send it in a full table
         * response issued before the net ttvn increment (consistency check)
         */
        tt_local_entry->common.flags |= BATADV_TT_CLIENT_PENDING;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Local tt entry (%pM) pending to be removed: %s\n",
                   tt_local_entry->common.addr, message);
}

/**
 * batadv_tt_local_remove - logically remove an entry from the local table
 * @bat_priv: the bat priv with all the soft interface information
 * @addr: the MAC address of the client to remove
 * @message: message to append to the log on deletion
 * @roaming: true if the deletion is due to a roaming event
 *
 * Returns the flags assigned to the local entry before being deleted
 */
uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
                                const uint8_t *addr, const char *message,
                                bool roaming)
{
        struct batadv_tt_local_entry *tt_local_entry;
        uint16_t flags, curr_flags = BATADV_NO_FLAGS;

        tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr);
        if (!tt_local_entry)
                goto out;

        curr_flags = tt_local_entry->common.flags;

        flags = BATADV_TT_CLIENT_DEL;
        /* if this global entry addition is due to a roaming, the node has to
         * mark the local entry as "roamed" in order to correctly reroute
         * packets later
         */
        if (roaming) {
                flags |= BATADV_TT_CLIENT_ROAM;
                /* mark the local client as ROAMed */
                tt_local_entry->common.flags |= BATADV_TT_CLIENT_ROAM;
        }

        if (!(tt_local_entry->common.flags & BATADV_TT_CLIENT_NEW)) {
                batadv_tt_local_set_pending(bat_priv, tt_local_entry, flags,
                                            message);
                goto out;
        }
        /* if this client has been added right now, it is possible to
         * immediately purge it
         */
        batadv_tt_local_event(bat_priv, tt_local_entry->common.addr,
                              curr_flags | BATADV_TT_CLIENT_DEL);
        hlist_del_rcu(&tt_local_entry->common.hash_entry);
        batadv_tt_local_entry_free_ref(tt_local_entry);

out:
        if (tt_local_entry)
                batadv_tt_local_entry_free_ref(tt_local_entry);

        return curr_flags;
}

static void batadv_tt_local_purge_list(struct batadv_priv *bat_priv,
                                       struct hlist_head *head)
{
        struct batadv_tt_local_entry *tt_local_entry;
        struct batadv_tt_common_entry *tt_common_entry;
        struct hlist_node *node_tmp;

        hlist_for_each_entry_safe(tt_common_entry, node_tmp, head,
                                  hash_entry) {
                tt_local_entry = container_of(tt_common_entry,
                                              struct batadv_tt_local_entry,
                                              common);
                if (tt_local_entry->common.flags & BATADV_TT_CLIENT_NOPURGE)
                        continue;

                /* entry already marked for deletion */
                if (tt_local_entry->common.flags & BATADV_TT_CLIENT_PENDING)
                        continue;

                if (!batadv_has_timed_out(tt_local_entry->last_seen,
                                          BATADV_TT_LOCAL_TIMEOUT))
                        continue;

                batadv_tt_local_set_pending(bat_priv, tt_local_entry,
                                            BATADV_TT_CLIENT_DEL, "timed out");
        }
}

static void batadv_tt_local_purge(struct batadv_priv *bat_priv)
{
        struct batadv_hashtable *hash = bat_priv->tt.local_hash;
        struct hlist_head *head;
        spinlock_t *list_lock; /* protects write access to the hash lists */
        uint32_t i;

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

                spin_lock_bh(list_lock);
                batadv_tt_local_purge_list(bat_priv, head);
                spin_unlock_bh(list_lock);
        }
}

static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
{
        struct batadv_hashtable *hash;
        spinlock_t *list_lock; /* protects write access to the hash lists */
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_local_entry *tt_local;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        uint32_t i;

        if (!bat_priv->tt.local_hash)
                return;

        hash = bat_priv->tt.local_hash;

        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(tt_common_entry, node_tmp,
                                          head, hash_entry) {
                        hlist_del_rcu(&tt_common_entry->hash_entry);
                        tt_local = container_of(tt_common_entry,
                                                struct batadv_tt_local_entry,
                                                common);
                        batadv_tt_local_entry_free_ref(tt_local);
                }
                spin_unlock_bh(list_lock);
        }

        batadv_hash_destroy(hash);

        bat_priv->tt.local_hash = NULL;
}

static int batadv_tt_global_init(struct batadv_priv *bat_priv)
{
        if (bat_priv->tt.global_hash)
                return 0;

        bat_priv->tt.global_hash = batadv_hash_new(1024);

        if (!bat_priv->tt.global_hash)
                return -ENOMEM;

        batadv_hash_set_lock_class(bat_priv->tt.global_hash,
                                   &batadv_tt_global_hash_lock_class_key);

        return 0;
}

static void batadv_tt_changes_list_free(struct batadv_priv *bat_priv)
{
        struct batadv_tt_change_node *entry, *safe;

        spin_lock_bh(&bat_priv->tt.changes_list_lock);

        list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list,
                                 list) {
                list_del(&entry->list);
                kfree(entry);
        }

        atomic_set(&bat_priv->tt.local_changes, 0);
        spin_unlock_bh(&bat_priv->tt.changes_list_lock);
}

/* retrieves the orig_tt_list_entry belonging to orig_node from the
 * batadv_tt_global_entry list
 *
 * returns it with an increased refcounter, NULL if not found
 */
static struct batadv_tt_orig_list_entry *
batadv_tt_global_orig_entry_find(const struct batadv_tt_global_entry *entry,
                                 const struct batadv_orig_node *orig_node)
{
        struct batadv_tt_orig_list_entry *tmp_orig_entry, *orig_entry = NULL;
        const struct hlist_head *head;

        rcu_read_lock();
        head = &entry->orig_list;
        hlist_for_each_entry_rcu(tmp_orig_entry, head, list) {
                if (tmp_orig_entry->orig_node != orig_node)
                        continue;
                if (!atomic_inc_not_zero(&tmp_orig_entry->refcount))
                        continue;

                orig_entry = tmp_orig_entry;
                break;
        }
        rcu_read_unlock();

        return orig_entry;
}

/* find out if an orig_node is already in the list of a tt_global_entry.
 * returns true if found, false otherwise
 */
static bool
batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
                                const struct batadv_orig_node *orig_node)
{
        struct batadv_tt_orig_list_entry *orig_entry;
        bool found = false;

        orig_entry = batadv_tt_global_orig_entry_find(entry, orig_node);
        if (orig_entry) {
                found = true;
                batadv_tt_orig_list_entry_free_ref(orig_entry);
        }

        return found;
}

static void
batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global,
                                struct batadv_orig_node *orig_node, int ttvn)
{
        struct batadv_tt_orig_list_entry *orig_entry;

        orig_entry = batadv_tt_global_orig_entry_find(tt_global, orig_node);
        if (orig_entry) {
                /* refresh the ttvn: the current value could be a bogus one that
                 * was added during a "temporary client detection"
                 */
                orig_entry->ttvn = ttvn;
                goto out;
        }

        orig_entry = kzalloc(sizeof(*orig_entry), GFP_ATOMIC);
        if (!orig_entry)
                goto out;

        INIT_HLIST_NODE(&orig_entry->list);
        atomic_inc(&orig_node->refcount);
        atomic_inc(&orig_node->tt_size);
        orig_entry->orig_node = orig_node;
        orig_entry->ttvn = ttvn;
        atomic_set(&orig_entry->refcount, 2);

        spin_lock_bh(&tt_global->list_lock);
        hlist_add_head_rcu(&orig_entry->list,
                           &tt_global->orig_list);
        spin_unlock_bh(&tt_global->list_lock);
out:
        if (orig_entry)
                batadv_tt_orig_list_entry_free_ref(orig_entry);
}

/* caller must hold orig_node refcount */
int batadv_tt_global_add(struct batadv_priv *bat_priv,
                         struct batadv_orig_node *orig_node,
                         const unsigned char *tt_addr, uint8_t flags,
                         uint8_t ttvn)
{
        struct batadv_tt_global_entry *tt_global_entry;
        struct batadv_tt_local_entry *tt_local_entry;
        int ret = 0;
        int hash_added;
        struct batadv_tt_common_entry *common;
        uint16_t local_flags;

        tt_global_entry = batadv_tt_global_hash_find(bat_priv, tt_addr);
        tt_local_entry = batadv_tt_local_hash_find(bat_priv, tt_addr);

        /* if the node already has a local client for this entry, it has to wait
         * for a roaming advertisement instead of manually messing up the global
         * table
         */
        if ((flags & BATADV_TT_CLIENT_TEMP) && tt_local_entry &&
            !(tt_local_entry->common.flags & BATADV_TT_CLIENT_NEW))
                goto out;

        if (!tt_global_entry) {
                tt_global_entry = kzalloc(sizeof(*tt_global_entry), GFP_ATOMIC);
                if (!tt_global_entry)
                        goto out;

                common = &tt_global_entry->common;
                memcpy(common->addr, tt_addr, ETH_ALEN);

                common->flags = flags;
                tt_global_entry->roam_at = 0;
                /* node must store current time in case of roaming. This is
                 * needed to purge this entry out on timeout (if nobody claims
                 * it)
                 */
                if (flags & BATADV_TT_CLIENT_ROAM)
                        tt_global_entry->roam_at = jiffies;
                atomic_set(&common->refcount, 2);
                common->added_at = jiffies;

                INIT_HLIST_HEAD(&tt_global_entry->orig_list);
                spin_lock_init(&tt_global_entry->list_lock);

                hash_added = batadv_hash_add(bat_priv->tt.global_hash,
                                             batadv_compare_tt,
                                             batadv_choose_orig, common,
                                             &common->hash_entry);

                if (unlikely(hash_added != 0)) {
                        /* remove the reference for the hash */
                        batadv_tt_global_entry_free_ref(tt_global_entry);
                        goto out_remove;
                }
        } else {
                common = &tt_global_entry->common;
                /* If there is already a global entry, we can use this one for
                 * our processing.
                 * But if we are trying to add a temporary client then here are
                 * two options at this point:
                 * 1) the global client is not a temporary client: the global
                 *    client has to be left as it is, temporary information
                 *    should never override any already known client state
                 * 2) the global client is a temporary client: purge the
                 *    originator list and add the new one orig_entry
                 */
                if (flags & BATADV_TT_CLIENT_TEMP) {
                        if (!(common->flags & BATADV_TT_CLIENT_TEMP))
                                goto out;
                        if (batadv_tt_global_entry_has_orig(tt_global_entry,
                                                            orig_node))
                                goto out_remove;
                        batadv_tt_global_del_orig_list(tt_global_entry);
                        goto add_orig_entry;
                }

                /* if the client was temporary added before receiving the first
                 * OGM announcing it, we have to clear the TEMP flag
                 */
                common->flags &= ~BATADV_TT_CLIENT_TEMP;

                /* the change can carry possible "attribute" flags like the
                 * TT_CLIENT_WIFI, therefore they have to be copied in the
                 * client entry
                 */
                tt_global_entry->common.flags |= flags;

                /* If there is the BATADV_TT_CLIENT_ROAM flag set, there is only
                 * one originator left in the list and we previously received a
                 * delete + roaming change for this originator.
                 *
                 * We should first delete the old originator before adding the
                 * new one.
                 */
                if (common->flags & BATADV_TT_CLIENT_ROAM) {
                        batadv_tt_global_del_orig_list(tt_global_entry);
                        common->flags &= ~BATADV_TT_CLIENT_ROAM;
                        tt_global_entry->roam_at = 0;
                }
        }
add_orig_entry:
        /* add the new orig_entry (if needed) or update it */
        batadv_tt_global_orig_entry_add(tt_global_entry, orig_node, ttvn);

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Creating new global tt entry: %pM (via %pM)\n",
                   common->addr, orig_node->orig);
        ret = 1;

out_remove:

        /* remove address from local hash if present */
        local_flags = batadv_tt_local_remove(bat_priv, tt_addr,
                                             "global tt received",
                                             flags & BATADV_TT_CLIENT_ROAM);
        tt_global_entry->common.flags |= local_flags & BATADV_TT_CLIENT_WIFI;

        if (!(flags & BATADV_TT_CLIENT_ROAM))
                /* this is a normal global add. Therefore the client is not in a
                 * roaming state anymore.
                 */
                tt_global_entry->common.flags &= ~BATADV_TT_CLIENT_ROAM;

out:
        if (tt_global_entry)
                batadv_tt_global_entry_free_ref(tt_global_entry);
        if (tt_local_entry)
                batadv_tt_local_entry_free_ref(tt_local_entry);
        return ret;
}

/* batadv_transtable_best_orig - Get best originator list entry from tt entry
 * @tt_global_entry: global translation table entry to be analyzed
 *
 * This functon assumes the caller holds rcu_read_lock().
 * Returns best originator list entry or NULL on errors.
 */
static struct batadv_tt_orig_list_entry *
batadv_transtable_best_orig(struct batadv_tt_global_entry *tt_global_entry)
{
        struct batadv_neigh_node *router = NULL;
        struct hlist_head *head;
        struct batadv_tt_orig_list_entry *orig_entry, *best_entry = NULL;
        int best_tq = 0;

        head = &tt_global_entry->orig_list;
        hlist_for_each_entry_rcu(orig_entry, head, list) {
                router = batadv_orig_node_get_router(orig_entry->orig_node);
                if (!router)
                        continue;

                if (router->tq_avg > best_tq) {
                        best_entry = orig_entry;
                        best_tq = router->tq_avg;
                }

                batadv_neigh_node_free_ref(router);
        }

        return best_entry;
}

/* batadv_tt_global_print_entry - print all orig nodes who announce the address
 * for this global entry
 * @tt_global_entry: global translation table entry to be printed
 * @seq: debugfs table seq_file struct
 *
 * This functon assumes the caller holds rcu_read_lock().
 */
static void
batadv_tt_global_print_entry(struct batadv_tt_global_entry *tt_global_entry,
                             struct seq_file *seq)
{
        struct hlist_head *head;
        struct batadv_tt_orig_list_entry *orig_entry, *best_entry;
        struct batadv_tt_common_entry *tt_common_entry;
        uint16_t flags;
        uint8_t last_ttvn;

        tt_common_entry = &tt_global_entry->common;
        flags = tt_common_entry->flags;

        best_entry = batadv_transtable_best_orig(tt_global_entry);
        if (best_entry) {
                last_ttvn = atomic_read(&best_entry->orig_node->last_ttvn);
                seq_printf(seq,
                           " %c %pM  (%3u) via %pM     (%3u)   (%#.4x) [%c%c%c]\n",
                           '*', tt_global_entry->common.addr,
                           best_entry->ttvn, best_entry->orig_node->orig,
                           last_ttvn, best_entry->orig_node->tt_crc,
                           (flags & BATADV_TT_CLIENT_ROAM ? 'R' : '.'),
                           (flags & BATADV_TT_CLIENT_WIFI ? 'W' : '.'),
                           (flags & BATADV_TT_CLIENT_TEMP ? 'T' : '.'));
        }

        head = &tt_global_entry->orig_list;

        hlist_for_each_entry_rcu(orig_entry, head, list) {
                if (best_entry == orig_entry)
                        continue;

                last_ttvn = atomic_read(&orig_entry->orig_node->last_ttvn);
                seq_printf(seq, " %c %pM  (%3u) via %pM     (%3u)   [%c%c%c]\n",
                           '+', tt_global_entry->common.addr,
                           orig_entry->ttvn, orig_entry->orig_node->orig,
                           last_ttvn,
                           (flags & BATADV_TT_CLIENT_ROAM ? 'R' : '.'),
                           (flags & BATADV_TT_CLIENT_WIFI ? 'W' : '.'),
                           (flags & BATADV_TT_CLIENT_TEMP ? 'T' : '.'));
        }
}

int batadv_tt_global_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->tt.global_hash;
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_global_entry *tt_global;
        struct batadv_hard_iface *primary_if;
        struct hlist_head *head;
        uint32_t i;

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

        seq_printf(seq,
                   "Globally announced TT entries received via the mesh %s\n",
                   net_dev->name);
        seq_printf(seq, "       %-13s %s       %-15s %s (%-6s) %s\n",
                   "Client", "(TTVN)", "Originator", "(Curr TTVN)", "CRC",
                   "Flags");

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(tt_common_entry,
                                         head, hash_entry) {
                        tt_global = container_of(tt_common_entry,
                                                 struct batadv_tt_global_entry,
                                                 common);
                        batadv_tt_global_print_entry(tt_global, seq);
                }
                rcu_read_unlock();
        }
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return 0;
}

/* deletes the orig list of a tt_global_entry */
static void
batadv_tt_global_del_orig_list(struct batadv_tt_global_entry *tt_global_entry)
{
        struct hlist_head *head;
        struct hlist_node *safe;
        struct batadv_tt_orig_list_entry *orig_entry;

        spin_lock_bh(&tt_global_entry->list_lock);
        head = &tt_global_entry->orig_list;
        hlist_for_each_entry_safe(orig_entry, safe, head, list) {
                hlist_del_rcu(&orig_entry->list);
                batadv_tt_orig_list_entry_free_ref(orig_entry);
        }
        spin_unlock_bh(&tt_global_entry->list_lock);
}

static void
batadv_tt_global_del_orig_entry(struct batadv_priv *bat_priv,
                                struct batadv_tt_global_entry *tt_global_entry,
                                struct batadv_orig_node *orig_node,
                                const char *message)
{
        struct hlist_head *head;
        struct hlist_node *safe;
        struct batadv_tt_orig_list_entry *orig_entry;

        spin_lock_bh(&tt_global_entry->list_lock);
        head = &tt_global_entry->orig_list;
        hlist_for_each_entry_safe(orig_entry, safe, head, list) {
                if (orig_entry->orig_node == orig_node) {
                        batadv_dbg(BATADV_DBG_TT, bat_priv,
                                   "Deleting %pM from global tt entry %pM: %s\n",
                                   orig_node->orig,
                                   tt_global_entry->common.addr, message);
                        hlist_del_rcu(&orig_entry->list);
                        batadv_tt_orig_list_entry_free_ref(orig_entry);
                }
        }
        spin_unlock_bh(&tt_global_entry->list_lock);
}

/* If the client is to be deleted, we check if it is the last origantor entry
 * within tt_global entry. If yes, we set the BATADV_TT_CLIENT_ROAM flag and the
 * timer, otherwise we simply remove the originator scheduled for deletion.
 */
static void
batadv_tt_global_del_roaming(struct batadv_priv *bat_priv,
                             struct batadv_tt_global_entry *tt_global_entry,
                             struct batadv_orig_node *orig_node,
                             const char *message)
{
        bool last_entry = true;
        struct hlist_head *head;
        struct batadv_tt_orig_list_entry *orig_entry;

        /* no local entry exists, case 1:
         * Check if this is the last one or if other entries exist.
         */

        rcu_read_lock();
        head = &tt_global_entry->orig_list;
        hlist_for_each_entry_rcu(orig_entry, head, list) {
                if (orig_entry->orig_node != orig_node) {
                        last_entry = false;
                        break;
                }
        }
        rcu_read_unlock();

        if (last_entry) {
                /* its the last one, mark for roaming. */
                tt_global_entry->common.flags |= BATADV_TT_CLIENT_ROAM;
                tt_global_entry->roam_at = jiffies;
        } else
                /* there is another entry, we can simply delete this
                 * one and can still use the other one.
                 */
                batadv_tt_global_del_orig_entry(bat_priv, tt_global_entry,
                                                orig_node, message);
}



static void batadv_tt_global_del(struct batadv_priv *bat_priv,
                                 struct batadv_orig_node *orig_node,
                                 const unsigned char *addr,
                                 const char *message, bool roaming)
{
        struct batadv_tt_global_entry *tt_global_entry;
        struct batadv_tt_local_entry *local_entry = NULL;

        tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);
        if (!tt_global_entry)
                goto out;

        if (!roaming) {
                batadv_tt_global_del_orig_entry(bat_priv, tt_global_entry,
                                                orig_node, message);

                if (hlist_empty(&tt_global_entry->orig_list))
                        batadv_tt_global_free(bat_priv, tt_global_entry,
                                              message);

                goto out;
        }

        /* if we are deleting a global entry due to a roam
         * event, there are two possibilities:
         * 1) the client roamed from node A to node B => if there
         *    is only one originator left for this client, we mark
         *    it with BATADV_TT_CLIENT_ROAM, we start a timer and we
         *    wait for node B to claim it. In case of timeout
         *    the entry is purged.
         *
         *    If there are other originators left, we directly delete
         *    the originator.
         * 2) the client roamed to us => we can directly delete
         *    the global entry, since it is useless now.
         */
        local_entry = batadv_tt_local_hash_find(bat_priv,
                                                tt_global_entry->common.addr);
        if (local_entry) {
                /* local entry exists, case 2: client roamed to us. */
                batadv_tt_global_del_orig_list(tt_global_entry);
                batadv_tt_global_free(bat_priv, tt_global_entry, message);
        } else
                /* no local entry exists, case 1: check for roaming */
                batadv_tt_global_del_roaming(bat_priv, tt_global_entry,
                                             orig_node, message);


out:
        if (tt_global_entry)
                batadv_tt_global_entry_free_ref(tt_global_entry);
        if (local_entry)
                batadv_tt_local_entry_free_ref(local_entry);
}

void batadv_tt_global_del_orig(struct batadv_priv *bat_priv,
                               struct batadv_orig_node *orig_node,
                               const char *message)
{
        struct batadv_tt_global_entry *tt_global;
        struct batadv_tt_common_entry *tt_common_entry;
        uint32_t i;
        struct batadv_hashtable *hash = bat_priv->tt.global_hash;
        struct hlist_node *safe;
        struct hlist_head *head;
        spinlock_t *list_lock; /* protects write access to the hash lists */

        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(tt_common_entry, safe,
                                          head, hash_entry) {
                        tt_global = container_of(tt_common_entry,
                                                 struct batadv_tt_global_entry,
                                                 common);

                        batadv_tt_global_del_orig_entry(bat_priv, tt_global,
                                                        orig_node, message);

                        if (hlist_empty(&tt_global->orig_list)) {
                                batadv_dbg(BATADV_DBG_TT, bat_priv,
                                           "Deleting global tt entry %pM: %s\n",
                                           tt_global->common.addr, message);
                                hlist_del_rcu(&tt_common_entry->hash_entry);
                                batadv_tt_global_entry_free_ref(tt_global);
                        }
                }
                spin_unlock_bh(list_lock);
        }
        orig_node->tt_initialised = false;
}

static bool batadv_tt_global_to_purge(struct batadv_tt_global_entry *tt_global,
                                      char **msg)
{
        bool purge = false;
        unsigned long roam_timeout = BATADV_TT_CLIENT_ROAM_TIMEOUT;
        unsigned long temp_timeout = BATADV_TT_CLIENT_TEMP_TIMEOUT;

        if ((tt_global->common.flags & BATADV_TT_CLIENT_ROAM) &&
            batadv_has_timed_out(tt_global->roam_at, roam_timeout)) {
                purge = true;
                *msg = "Roaming timeout\n";
        }

        if ((tt_global->common.flags & BATADV_TT_CLIENT_TEMP) &&
            batadv_has_timed_out(tt_global->common.added_at, temp_timeout)) {
                purge = true;
                *msg = "Temporary client timeout\n";
        }

        return purge;
}

static void batadv_tt_global_purge(struct batadv_priv *bat_priv)
{
        struct batadv_hashtable *hash = bat_priv->tt.global_hash;
        struct hlist_head *head;
        struct hlist_node *node_tmp;
        spinlock_t *list_lock; /* protects write access to the hash lists */
        uint32_t i;
        char *msg = NULL;
        struct batadv_tt_common_entry *tt_common;
        struct batadv_tt_global_entry *tt_global;

        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(tt_common, node_tmp, head,
                                          hash_entry) {
                        tt_global = container_of(tt_common,
                                                 struct batadv_tt_global_entry,
                                                 common);

                        if (!batadv_tt_global_to_purge(tt_global, &msg))
                                continue;

                        batadv_dbg(BATADV_DBG_TT, bat_priv,
                                   "Deleting global tt entry (%pM): %s\n",
                                   tt_global->common.addr, msg);

                        hlist_del_rcu(&tt_common->hash_entry);

                        batadv_tt_global_entry_free_ref(tt_global);
                }
                spin_unlock_bh(list_lock);
        }
}

static void batadv_tt_global_table_free(struct batadv_priv *bat_priv)
{
        struct batadv_hashtable *hash;
        spinlock_t *list_lock; /* protects write access to the hash lists */
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_global_entry *tt_global;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        uint32_t i;

        if (!bat_priv->tt.global_hash)
                return;

        hash = bat_priv->tt.global_hash;

        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(tt_common_entry, node_tmp,
                                          head, hash_entry) {
                        hlist_del_rcu(&tt_common_entry->hash_entry);
                        tt_global = container_of(tt_common_entry,
                                                 struct batadv_tt_global_entry,
                                                 common);
                        batadv_tt_global_entry_free_ref(tt_global);
                }
                spin_unlock_bh(list_lock);
        }

        batadv_hash_destroy(hash);

        bat_priv->tt.global_hash = NULL;
}

static bool
_batadv_is_ap_isolated(struct batadv_tt_local_entry *tt_local_entry,
                       struct batadv_tt_global_entry *tt_global_entry)
{
        bool ret = false;

        if (tt_local_entry->common.flags & BATADV_TT_CLIENT_WIFI &&
            tt_global_entry->common.flags & BATADV_TT_CLIENT_WIFI)
                ret = true;

        return ret;
}

struct batadv_orig_node *batadv_transtable_search(struct batadv_priv *bat_priv,
                                                  const uint8_t *src,
                                                  const uint8_t *addr)
{
        struct batadv_tt_local_entry *tt_local_entry = NULL;
        struct batadv_tt_global_entry *tt_global_entry = NULL;
        struct batadv_orig_node *orig_node = NULL;
        struct batadv_tt_orig_list_entry *best_entry;

        if (src && atomic_read(&bat_priv->ap_isolation)) {
                tt_local_entry = batadv_tt_local_hash_find(bat_priv, src);
                if (!tt_local_entry ||
                    (tt_local_entry->common.flags & BATADV_TT_CLIENT_PENDING))
                        goto out;
        }

        tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);
        if (!tt_global_entry)
                goto out;

        /* check whether the clients should not communicate due to AP
         * isolation
         */
        if (tt_local_entry &&
            _batadv_is_ap_isolated(tt_local_entry, tt_global_entry))
                goto out;

        rcu_read_lock();
        best_entry = batadv_transtable_best_orig(tt_global_entry);
        /* found anything? */
        if (best_entry)
                orig_node = best_entry->orig_node;
        if (orig_node && !atomic_inc_not_zero(&orig_node->refcount))
                orig_node = NULL;
        rcu_read_unlock();

out:
        if (tt_global_entry)
                batadv_tt_global_entry_free_ref(tt_global_entry);
        if (tt_local_entry)
                batadv_tt_local_entry_free_ref(tt_local_entry);

        return orig_node;
}

/* Calculates the checksum of the local table of a given orig_node */
static uint16_t batadv_tt_global_crc(struct batadv_priv *bat_priv,
                                     struct batadv_orig_node *orig_node)
{
        uint16_t total = 0, total_one;
        struct batadv_hashtable *hash = bat_priv->tt.global_hash;
        struct batadv_tt_common_entry *tt_common;
        struct batadv_tt_global_entry *tt_global;
        struct hlist_head *head;
        uint32_t i;
        int j;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(tt_common, head, hash_entry) {
                        tt_global = container_of(tt_common,
                                                 struct batadv_tt_global_entry,
                                                 common);
                        /* Roaming clients are in the global table for
                         * consistency only. They don't have to be
                         * taken into account while computing the
                         * global crc
                         */
                        if (tt_common->flags & BATADV_TT_CLIENT_ROAM)
                                continue;
                        /* Temporary clients have not been announced yet, so
                         * they have to be skipped while computing the global
                         * crc
                         */
                        if (tt_common->flags & BATADV_TT_CLIENT_TEMP)
                                continue;

                        /* find out if this global entry is announced by this
                         * originator
                         */
                        if (!batadv_tt_global_entry_has_orig(tt_global,
                                                             orig_node))
                                continue;

                        total_one = 0;
                        for (j = 0; j < ETH_ALEN; j++)
                                total_one = crc16_byte(total_one,
                                                       tt_common->addr[j]);
                        total ^= total_one;
                }
                rcu_read_unlock();
        }

        return total;
}

/* Calculates the checksum of the local table */
static uint16_t batadv_tt_local_crc(struct batadv_priv *bat_priv)
{
        uint16_t total = 0, total_one;
        struct batadv_hashtable *hash = bat_priv->tt.local_hash;
        struct batadv_tt_common_entry *tt_common;
        struct hlist_head *head;
        uint32_t i;
        int j;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(tt_common, head, hash_entry) {
                        /* not yet committed clients have not to be taken into
                         * account while computing the CRC
                         */
                        if (tt_common->flags & BATADV_TT_CLIENT_NEW)
                                continue;
                        total_one = 0;
                        for (j = 0; j < ETH_ALEN; j++)
                                total_one = crc16_byte(total_one,
                                                       tt_common->addr[j]);
                        total ^= total_one;
                }
                rcu_read_unlock();
        }

        return total;
}

static void batadv_tt_req_list_free(struct batadv_priv *bat_priv)
{
        struct batadv_tt_req_node *node, *safe;

        spin_lock_bh(&bat_priv->tt.req_list_lock);

        list_for_each_entry_safe(node, safe, &bat_priv->tt.req_list, list) {
                list_del(&node->list);
                kfree(node);
        }

        spin_unlock_bh(&bat_priv->tt.req_list_lock);
}

static void batadv_tt_save_orig_buffer(struct batadv_priv *bat_priv,
                                       struct batadv_orig_node *orig_node,
                                       const unsigned char *tt_buff,
                                       uint8_t tt_num_changes)
{
        uint16_t tt_buff_len = batadv_tt_len(tt_num_changes);

        /* Replace the old buffer only if I received something in the
         * last OGM (the OGM could carry no changes)
         */
        spin_lock_bh(&orig_node->tt_buff_lock);
        if (tt_buff_len > 0) {
                kfree(orig_node->tt_buff);
                orig_node->tt_buff_len = 0;
                orig_node->tt_buff = kmalloc(tt_buff_len, GFP_ATOMIC);
                if (orig_node->tt_buff) {
                        memcpy(orig_node->tt_buff, tt_buff, tt_buff_len);
                        orig_node->tt_buff_len = tt_buff_len;
                }
        }
        spin_unlock_bh(&orig_node->tt_buff_lock);
}

static void batadv_tt_req_purge(struct batadv_priv *bat_priv)
{
        struct batadv_tt_req_node *node, *safe;

        spin_lock_bh(&bat_priv->tt.req_list_lock);
        list_for_each_entry_safe(node, safe, &bat_priv->tt.req_list, list) {
                if (batadv_has_timed_out(node->issued_at,
                                         BATADV_TT_REQUEST_TIMEOUT)) {
                        list_del(&node->list);
                        kfree(node);
                }
        }
        spin_unlock_bh(&bat_priv->tt.req_list_lock);
}

/* returns the pointer to the new tt_req_node struct if no request
 * has already been issued for this orig_node, NULL otherwise
 */
static struct batadv_tt_req_node *
batadv_new_tt_req_node(struct batadv_priv *bat_priv,
                       struct batadv_orig_node *orig_node)
{
        struct batadv_tt_req_node *tt_req_node_tmp, *tt_req_node = NULL;

        spin_lock_bh(&bat_priv->tt.req_list_lock);
        list_for_each_entry(tt_req_node_tmp, &bat_priv->tt.req_list, list) {
                if (batadv_compare_eth(tt_req_node_tmp, orig_node) &&
                    !batadv_has_timed_out(tt_req_node_tmp->issued_at,
                                          BATADV_TT_REQUEST_TIMEOUT))
                        goto unlock;
        }

        tt_req_node = kmalloc(sizeof(*tt_req_node), GFP_ATOMIC);
        if (!tt_req_node)
                goto unlock;

        memcpy(tt_req_node->addr, orig_node->orig, ETH_ALEN);
        tt_req_node->issued_at = jiffies;

        list_add(&tt_req_node->list, &bat_priv->tt.req_list);
unlock:
        spin_unlock_bh(&bat_priv->tt.req_list_lock);
        return tt_req_node;
}

/* data_ptr is useless here, but has to be kept to respect the prototype */
static int batadv_tt_local_valid_entry(const void *entry_ptr,
                                       const void *data_ptr)
{
        const struct batadv_tt_common_entry *tt_common_entry = entry_ptr;

        if (tt_common_entry->flags & BATADV_TT_CLIENT_NEW)
                return 0;
        return 1;
}

static int batadv_tt_global_valid(const void *entry_ptr,
                                  const void *data_ptr)
{
        const struct batadv_tt_common_entry *tt_common_entry = entry_ptr;
        const struct batadv_tt_global_entry *tt_global_entry;
        const struct batadv_orig_node *orig_node = data_ptr;

        if (tt_common_entry->flags & BATADV_TT_CLIENT_ROAM ||
            tt_common_entry->flags & BATADV_TT_CLIENT_TEMP)
                return 0;

        tt_global_entry = container_of(tt_common_entry,
                                       struct batadv_tt_global_entry,
                                       common);

        return batadv_tt_global_entry_has_orig(tt_global_entry, orig_node);
}

static struct sk_buff *
batadv_tt_response_fill_table(uint16_t tt_len, uint8_t ttvn,
                              struct batadv_hashtable *hash,
                              struct batadv_priv *bat_priv,
                              int (*valid_cb)(const void *, const void *),
                              void *cb_data)
{
        struct batadv_tt_common_entry *tt_common_entry;
        struct batadv_tt_query_packet *tt_response;
        struct batadv_tt_change *tt_change;
        struct hlist_head *head;
        struct sk_buff *skb = NULL;
        uint16_t tt_tot, tt_count;
        ssize_t tt_query_size = sizeof(struct batadv_tt_query_packet);
        uint32_t i;
        size_t len;

        if (tt_query_size + tt_len > bat_priv->soft_iface->mtu) {
                tt_len = bat_priv->soft_iface->mtu - tt_query_size;
                tt_len -= tt_len % sizeof(struct batadv_tt_change);
        }
        tt_tot = tt_len / sizeof(struct batadv_tt_change);

        len = tt_query_size + tt_len;
        skb = dev_alloc_skb(len + ETH_HLEN + NET_IP_ALIGN);
        if (!skb)
                goto out;

        skb_reserve(skb, ETH_HLEN + NET_IP_ALIGN);
        tt_response = (struct batadv_tt_query_packet *)skb_put(skb, len);
        tt_response->ttvn = ttvn;

        tt_change = (struct batadv_tt_change *)(skb->data + tt_query_size);
        tt_count = 0;

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

                hlist_for_each_entry_rcu(tt_common_entry,
                                         head, hash_entry) {
                        if (tt_count == tt_tot)
                                break;

                        if ((valid_cb) && (!valid_cb(tt_common_entry, cb_data)))
                                continue;

                        memcpy(tt_change->addr, tt_common_entry->addr,
                               ETH_ALEN);
                        tt_change->flags = tt_common_entry->flags;

                        tt_count++;
                        tt_change++;
                }
        }
        rcu_read_unlock();

        /* store in the message the number of entries we have successfully
         * copied
         */
        tt_response->tt_data = htons(tt_count);

out:
        return skb;
}

static int batadv_send_tt_request(struct batadv_priv *bat_priv,
                                  struct batadv_orig_node *dst_orig_node,
                                  uint8_t ttvn, uint16_t tt_crc,
                                  bool full_table)
{
        struct sk_buff *skb = NULL;
        struct batadv_tt_query_packet *tt_request;
        struct batadv_hard_iface *primary_if;
        struct batadv_tt_req_node *tt_req_node = NULL;
        int ret = 1;
        size_t tt_req_len;

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

        /* The new tt_req will be issued only if I'm not waiting for a
         * reply from the same orig_node yet
         */
        tt_req_node = batadv_new_tt_req_node(bat_priv, dst_orig_node);
        if (!tt_req_node)
                goto out;

        skb = dev_alloc_skb(sizeof(*tt_request) + ETH_HLEN + NET_IP_ALIGN);
        if (!skb)
                goto out;

        skb_reserve(skb, ETH_HLEN + NET_IP_ALIGN);

        tt_req_len = sizeof(*tt_request);
        tt_request = (struct batadv_tt_query_packet *)skb_put(skb, tt_req_len);

        tt_request->header.packet_type = BATADV_TT_QUERY;
        tt_request->header.version = BATADV_COMPAT_VERSION;
        memcpy(tt_request->src, primary_if->net_dev->dev_addr, ETH_ALEN);
        memcpy(tt_request->dst, dst_orig_node->orig, ETH_ALEN);
        tt_request->header.ttl = BATADV_TTL;
        tt_request->ttvn = ttvn;
        tt_request->tt_data = htons(tt_crc);
        tt_request->flags = BATADV_TT_REQUEST;

        if (full_table)
                tt_request->flags |= BATADV_TT_FULL_TABLE;

        batadv_dbg(BATADV_DBG_TT, bat_priv, "Sending TT_REQUEST to %pM [%c]\n",
                   dst_orig_node->orig, (full_table ? 'F' : '.'));

        batadv_inc_counter(bat_priv, BATADV_CNT_TT_REQUEST_TX);

        if (batadv_send_skb_to_orig(skb, dst_orig_node, NULL))
                ret = 0;

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        if (ret)
                kfree_skb(skb);
        if (ret && tt_req_node) {
                spin_lock_bh(&bat_priv->tt.req_list_lock);
                list_del(&tt_req_node->list);
                spin_unlock_bh(&bat_priv->tt.req_list_lock);
                kfree(tt_req_node);
        }
        return ret;
}

static bool
batadv_send_other_tt_response(struct batadv_priv *bat_priv,
                              struct batadv_tt_query_packet *tt_request)
{
        struct batadv_orig_node *req_dst_orig_node;
        struct batadv_orig_node *res_dst_orig_node = NULL;
        uint8_t orig_ttvn, req_ttvn, ttvn;
        int ret = false;
        unsigned char *tt_buff;
        bool full_table;
        uint16_t tt_len, tt_tot;
        struct sk_buff *skb = NULL;
        struct batadv_tt_query_packet *tt_response;
        uint8_t *packet_pos;
        size_t len;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Received TT_REQUEST from %pM for ttvn: %u (%pM) [%c]\n",
                   tt_request->src, tt_request->ttvn, tt_request->dst,
                   (tt_request->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));

        /* Let's get the orig node of the REAL destination */
        req_dst_orig_node = batadv_orig_hash_find(bat_priv, tt_request->dst);
        if (!req_dst_orig_node)
                goto out;

        res_dst_orig_node = batadv_orig_hash_find(bat_priv, tt_request->src);
        if (!res_dst_orig_node)
                goto out;

        orig_ttvn = (uint8_t)atomic_read(&req_dst_orig_node->last_ttvn);
        req_ttvn = tt_request->ttvn;

        /* I don't have the requested data */
        if (orig_ttvn != req_ttvn ||
            tt_request->tt_data != htons(req_dst_orig_node->tt_crc))
                goto out;

        /* If the full table has been explicitly requested */
        if (tt_request->flags & BATADV_TT_FULL_TABLE ||
            !req_dst_orig_node->tt_buff)
                full_table = true;
        else
                full_table = false;

        /* In this version, fragmentation is not implemented, then
         * I'll send only one packet with as much TT entries as I can
         */
        if (!full_table) {
                spin_lock_bh(&req_dst_orig_node->tt_buff_lock);
                tt_len = req_dst_orig_node->tt_buff_len;
                tt_tot = tt_len / sizeof(struct batadv_tt_change);

                len = sizeof(*tt_response) + tt_len;
                skb = dev_alloc_skb(len + ETH_HLEN + NET_IP_ALIGN);
                if (!skb)
                        goto unlock;

                skb_reserve(skb, ETH_HLEN + NET_IP_ALIGN);
                packet_pos = skb_put(skb, len);
                tt_response = (struct batadv_tt_query_packet *)packet_pos;
                tt_response->ttvn = req_ttvn;
                tt_response->tt_data = htons(tt_tot);

                tt_buff = skb->data + sizeof(*tt_response);
                /* Copy the last orig_node's OGM buffer */
                memcpy(tt_buff, req_dst_orig_node->tt_buff,
                       req_dst_orig_node->tt_buff_len);

                spin_unlock_bh(&req_dst_orig_node->tt_buff_lock);
        } else {
                tt_len = (uint16_t)atomic_read(&req_dst_orig_node->tt_size);
                tt_len *= sizeof(struct batadv_tt_change);
                ttvn = (uint8_t)atomic_read(&req_dst_orig_node->last_ttvn);

                skb = batadv_tt_response_fill_table(tt_len, ttvn,
                                                    bat_priv->tt.global_hash,
                                                    bat_priv,
                                                    batadv_tt_global_valid,
                                                    req_dst_orig_node);
                if (!skb)
                        goto out;

                tt_response = (struct batadv_tt_query_packet *)skb->data;
        }

        tt_response->header.packet_type = BATADV_TT_QUERY;
        tt_response->header.version = BATADV_COMPAT_VERSION;
        tt_response->header.ttl = BATADV_TTL;
        memcpy(tt_response->src, req_dst_orig_node->orig, ETH_ALEN);
        memcpy(tt_response->dst, tt_request->src, ETH_ALEN);
        tt_response->flags = BATADV_TT_RESPONSE;

        if (full_table)
                tt_response->flags |= BATADV_TT_FULL_TABLE;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Sending TT_RESPONSE %pM for %pM (ttvn: %u)\n",
                   res_dst_orig_node->orig, req_dst_orig_node->orig, req_ttvn);

        batadv_inc_counter(bat_priv, BATADV_CNT_TT_RESPONSE_TX);

        if (batadv_send_skb_to_orig(skb, res_dst_orig_node, NULL))
                ret = true;
        goto out;

unlock:
        spin_unlock_bh(&req_dst_orig_node->tt_buff_lock);

out:
        if (res_dst_orig_node)
                batadv_orig_node_free_ref(res_dst_orig_node);
        if (req_dst_orig_node)
                batadv_orig_node_free_ref(req_dst_orig_node);
        if (!ret)
                kfree_skb(skb);
        return ret;
}

static bool
batadv_send_my_tt_response(struct batadv_priv *bat_priv,
                           struct batadv_tt_query_packet *tt_request)
{
        struct batadv_orig_node *orig_node;
        struct batadv_hard_iface *primary_if = NULL;
        uint8_t my_ttvn, req_ttvn, ttvn;
        int ret = false;
        unsigned char *tt_buff;
        bool full_table;
        uint16_t tt_len, tt_tot;
        struct sk_buff *skb = NULL;
        struct batadv_tt_query_packet *tt_response;
        uint8_t *packet_pos;
        size_t len;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Received TT_REQUEST from %pM for ttvn: %u (me) [%c]\n",
                   tt_request->src, tt_request->ttvn,
                   (tt_request->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));


        my_ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);
        req_ttvn = tt_request->ttvn;

        orig_node = batadv_orig_hash_find(bat_priv, tt_request->src);
        if (!orig_node)
                goto out;

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

        /* If the full table has been explicitly requested or the gap
         * is too big send the whole local translation table
         */
        if (tt_request->flags & BATADV_TT_FULL_TABLE || my_ttvn != req_ttvn ||
            !bat_priv->tt.last_changeset)
                full_table = true;
        else
                full_table = false;

        /* In this version, fragmentation is not implemented, then
         * I'll send only one packet with as much TT entries as I can
         */
        if (!full_table) {
                spin_lock_bh(&bat_priv->tt.last_changeset_lock);
                tt_len = bat_priv->tt.last_changeset_len;
                tt_tot = tt_len / sizeof(struct batadv_tt_change);

                len = sizeof(*tt_response) + tt_len;
                skb = dev_alloc_skb(len + ETH_HLEN + NET_IP_ALIGN);
                if (!skb)
                        goto unlock;

                skb_reserve(skb, ETH_HLEN + NET_IP_ALIGN);
                packet_pos = skb_put(skb, len);
                tt_response = (struct batadv_tt_query_packet *)packet_pos;
                tt_response->ttvn = req_ttvn;
                tt_response->tt_data = htons(tt_tot);

                tt_buff = skb->data + sizeof(*tt_response);
                memcpy(tt_buff, bat_priv->tt.last_changeset,
                       bat_priv->tt.last_changeset_len);
                spin_unlock_bh(&bat_priv->tt.last_changeset_lock);
        } else {
                tt_len = (uint16_t)atomic_read(&bat_priv->tt.local_entry_num);
                tt_len *= sizeof(struct batadv_tt_change);
                ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);

                skb = batadv_tt_response_fill_table(tt_len, ttvn,
                                                    bat_priv->tt.local_hash,
                                                    bat_priv,
                                                    batadv_tt_local_valid_entry,
                                                    NULL);
                if (!skb)
                        goto out;

                tt_response = (struct batadv_tt_query_packet *)skb->data;
        }

        tt_response->header.packet_type = BATADV_TT_QUERY;
        tt_response->header.version = BATADV_COMPAT_VERSION;
        tt_response->header.ttl = BATADV_TTL;
        memcpy(tt_response->src, primary_if->net_dev->dev_addr, ETH_ALEN);
        memcpy(tt_response->dst, tt_request->src, ETH_ALEN);
        tt_response->flags = BATADV_TT_RESPONSE;

        if (full_table)
                tt_response->flags |= BATADV_TT_FULL_TABLE;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Sending TT_RESPONSE to %pM [%c]\n",
                   orig_node->orig,
                   (tt_response->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));

        batadv_inc_counter(bat_priv, BATADV_CNT_TT_RESPONSE_TX);

        if (batadv_send_skb_to_orig(skb, orig_node, NULL))
                ret = true;
        goto out;

unlock:
        spin_unlock_bh(&bat_priv->tt.last_changeset_lock);
out:
        if (orig_node)
                batadv_orig_node_free_ref(orig_node);
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        if (!ret)
                kfree_skb(skb);
        /* This packet was for me, so it doesn't need to be re-routed */
        return true;
}

bool batadv_send_tt_response(struct batadv_priv *bat_priv,
                             struct batadv_tt_query_packet *tt_request)
{
        if (batadv_is_my_mac(bat_priv, tt_request->dst)) {
                /* don't answer backbone gws! */
                if (batadv_bla_is_backbone_gw_orig(bat_priv, tt_request->src))
                        return true;

                return batadv_send_my_tt_response(bat_priv, tt_request);
        } else {
                return batadv_send_other_tt_response(bat_priv, tt_request);
        }
}

static void _batadv_tt_update_changes(struct batadv_priv *bat_priv,
                                      struct batadv_orig_node *orig_node,
                                      struct batadv_tt_change *tt_change,
                                      uint16_t tt_num_changes, uint8_t ttvn)
{
        int i;
        int roams;

        for (i = 0; i < tt_num_changes; i++) {
                if ((tt_change + i)->flags & BATADV_TT_CLIENT_DEL) {
                        roams = (tt_change + i)->flags & BATADV_TT_CLIENT_ROAM;
                        batadv_tt_global_del(bat_priv, orig_node,
                                             (tt_change + i)->addr,
                                             "tt removed by changes",
                                             roams);
                } else {
                        if (!batadv_tt_global_add(bat_priv, orig_node,
                                                  (tt_change + i)->addr,
                                                  (tt_change + i)->flags, ttvn))
                                /* In case of problem while storing a
                                 * global_entry, we stop the updating
                                 * procedure without committing the
                                 * ttvn change. This will avoid to send
                                 * corrupted data on tt_request
                                 */
                                return;
                }
        }
        orig_node->tt_initialised = true;
}

static void batadv_tt_fill_gtable(struct batadv_priv *bat_priv,
                                  struct batadv_tt_query_packet *tt_response)
{
        struct batadv_orig_node *orig_node;

        orig_node = batadv_orig_hash_find(bat_priv, tt_response->src);
        if (!orig_node)
                goto out;

        /* Purge the old table first.. */
        batadv_tt_global_del_orig(bat_priv, orig_node, "Received full table");

        _batadv_tt_update_changes(bat_priv, orig_node,
                                  (struct batadv_tt_change *)(tt_response + 1),
                                  ntohs(tt_response->tt_data),
                                  tt_response->ttvn);

        spin_lock_bh(&orig_node->tt_buff_lock);
        kfree(orig_node->tt_buff);
        orig_node->tt_buff_len = 0;
        orig_node->tt_buff = NULL;
        spin_unlock_bh(&orig_node->tt_buff_lock);

        atomic_set(&orig_node->last_ttvn, tt_response->ttvn);

out:
        if (orig_node)
                batadv_orig_node_free_ref(orig_node);
}

static void batadv_tt_update_changes(struct batadv_priv *bat_priv,
                                     struct batadv_orig_node *orig_node,
                                     uint16_t tt_num_changes, uint8_t ttvn,
                                     struct batadv_tt_change *tt_change)
{
        _batadv_tt_update_changes(bat_priv, orig_node, tt_change,
                                  tt_num_changes, ttvn);

        batadv_tt_save_orig_buffer(bat_priv, orig_node,
                                   (unsigned char *)tt_change, tt_num_changes);
        atomic_set(&orig_node->last_ttvn, ttvn);
}

bool batadv_is_my_client(struct batadv_priv *bat_priv, const uint8_t *addr)
{
        struct batadv_tt_local_entry *tt_local_entry;
        bool ret = false;

        tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr);
        if (!tt_local_entry)
                goto out;
        /* Check if the client has been logically deleted (but is kept for
         * consistency purpose)
         */
        if ((tt_local_entry->common.flags & BATADV_TT_CLIENT_PENDING) ||
            (tt_local_entry->common.flags & BATADV_TT_CLIENT_ROAM))
                goto out;
        ret = true;
out:
        if (tt_local_entry)
                batadv_tt_local_entry_free_ref(tt_local_entry);
        return ret;
}

void batadv_handle_tt_response(struct batadv_priv *bat_priv,
                               struct batadv_tt_query_packet *tt_response)
{
        struct batadv_tt_req_node *node, *safe;
        struct batadv_orig_node *orig_node = NULL;
        struct batadv_tt_change *tt_change;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Received TT_RESPONSE from %pM for ttvn %d t_size: %d [%c]\n",
                   tt_response->src, tt_response->ttvn,
                   ntohs(tt_response->tt_data),
                   (tt_response->flags & BATADV_TT_FULL_TABLE ? 'F' : '.'));

        /* we should have never asked a backbone gw */
        if (batadv_bla_is_backbone_gw_orig(bat_priv, tt_response->src))
                goto out;

        orig_node = batadv_orig_hash_find(bat_priv, tt_response->src);
        if (!orig_node)
                goto out;

        if (tt_response->flags & BATADV_TT_FULL_TABLE) {
                batadv_tt_fill_gtable(bat_priv, tt_response);
        } else {
                tt_change = (struct batadv_tt_change *)(tt_response + 1);
                batadv_tt_update_changes(bat_priv, orig_node,
                                         ntohs(tt_response->tt_data),
                                         tt_response->ttvn, tt_change);
        }

        /* Delete the tt_req_node from pending tt_requests list */
        spin_lock_bh(&bat_priv->tt.req_list_lock);
        list_for_each_entry_safe(node, safe, &bat_priv->tt.req_list, list) {
                if (!batadv_compare_eth(node->addr, tt_response->src))
                        continue;
                list_del(&node->list);
                kfree(node);
        }
        spin_unlock_bh(&bat_priv->tt.req_list_lock);

        /* Recalculate the CRC for this orig_node and store it */
        orig_node->tt_crc = batadv_tt_global_crc(bat_priv, orig_node);
out:
        if (orig_node)
                batadv_orig_node_free_ref(orig_node);
}

int batadv_tt_init(struct batadv_priv *bat_priv)
{
        int ret;

        ret = batadv_tt_local_init(bat_priv);
        if (ret < 0)
                return ret;

        ret = batadv_tt_global_init(bat_priv);
        if (ret < 0)
                return ret;

        INIT_DELAYED_WORK(&bat_priv->tt.work, batadv_tt_purge);
        queue_delayed_work(batadv_event_workqueue, &bat_priv->tt.work,
                           msecs_to_jiffies(BATADV_TT_WORK_PERIOD));

        return 1;
}

static void batadv_tt_roam_list_free(struct batadv_priv *bat_priv)
{
        struct batadv_tt_roam_node *node, *safe;

        spin_lock_bh(&bat_priv->tt.roam_list_lock);

        list_for_each_entry_safe(node, safe, &bat_priv->tt.roam_list, list) {
                list_del(&node->list);
                kfree(node);
        }

        spin_unlock_bh(&bat_priv->tt.roam_list_lock);
}

static void batadv_tt_roam_purge(struct batadv_priv *bat_priv)
{
        struct batadv_tt_roam_node *node, *safe;

        spin_lock_bh(&bat_priv->tt.roam_list_lock);
        list_for_each_entry_safe(node, safe, &bat_priv->tt.roam_list, list) {
                if (!batadv_has_timed_out(node->first_time,
                                          BATADV_ROAMING_MAX_TIME))
                        continue;

                list_del(&node->list);
                kfree(node);
        }
        spin_unlock_bh(&bat_priv->tt.roam_list_lock);
}

/* This function checks whether the client already reached the
 * maximum number of possible roaming phases. In this case the ROAMING_ADV
 * will not be sent.
 *
 * returns true if the ROAMING_ADV can be sent, false otherwise
 */
static bool batadv_tt_check_roam_count(struct batadv_priv *bat_priv,
                                       uint8_t *client)
{
        struct batadv_tt_roam_node *tt_roam_node;
        bool ret = false;

        spin_lock_bh(&bat_priv->tt.roam_list_lock);
        /* The new tt_req will be issued only if I'm not waiting for a
         * reply from the same orig_node yet
         */
        list_for_each_entry(tt_roam_node, &bat_priv->tt.roam_list, list) {
                if (!batadv_compare_eth(tt_roam_node->addr, client))
                        continue;

                if (batadv_has_timed_out(tt_roam_node->first_time,
                                         BATADV_ROAMING_MAX_TIME))
                        continue;

                if (!batadv_atomic_dec_not_zero(&tt_roam_node->counter))
                        /* Sorry, you roamed too many times! */
                        goto unlock;
                ret = true;
                break;
        }

        if (!ret) {
                tt_roam_node = kmalloc(sizeof(*tt_roam_node), GFP_ATOMIC);
                if (!tt_roam_node)
                        goto unlock;

                tt_roam_node->first_time = jiffies;
                atomic_set(&tt_roam_node->counter,
                           BATADV_ROAMING_MAX_COUNT - 1);
                memcpy(tt_roam_node->addr, client, ETH_ALEN);

                list_add(&tt_roam_node->list, &bat_priv->tt.roam_list);
                ret = true;
        }

unlock:
        spin_unlock_bh(&bat_priv->tt.roam_list_lock);
        return ret;
}

static void batadv_send_roam_adv(struct batadv_priv *bat_priv, uint8_t *client,
                                 struct batadv_orig_node *orig_node)
{
        struct sk_buff *skb = NULL;
        struct batadv_roam_adv_packet *roam_adv_packet;
        int ret = 1;
        struct batadv_hard_iface *primary_if;
        size_t len = sizeof(*roam_adv_packet);

        /* before going on we have to check whether the client has
         * already roamed to us too many times
         */
        if (!batadv_tt_check_roam_count(bat_priv, client))
                goto out;

        skb = dev_alloc_skb(sizeof(*roam_adv_packet) + ETH_HLEN + NET_IP_ALIGN);
        if (!skb)
                goto out;

        skb_reserve(skb, ETH_HLEN + NET_IP_ALIGN);

        roam_adv_packet = (struct batadv_roam_adv_packet *)skb_put(skb, len);

        roam_adv_packet->header.packet_type = BATADV_ROAM_ADV;
        roam_adv_packet->header.version = BATADV_COMPAT_VERSION;
        roam_adv_packet->header.ttl = BATADV_TTL;
        roam_adv_packet->reserved = 0;
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto out;
        memcpy(roam_adv_packet->src, primary_if->net_dev->dev_addr, ETH_ALEN);
        batadv_hardif_free_ref(primary_if);
        memcpy(roam_adv_packet->dst, orig_node->orig, ETH_ALEN);
        memcpy(roam_adv_packet->client, client, ETH_ALEN);

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Sending ROAMING_ADV to %pM (client %pM)\n",
                   orig_node->orig, client);

        batadv_inc_counter(bat_priv, BATADV_CNT_TT_ROAM_ADV_TX);

        if (batadv_send_skb_to_orig(skb, orig_node, NULL))
                ret = 0;

out:
        if (ret && skb)
                kfree_skb(skb);
        return;
}

static void batadv_tt_purge(struct work_struct *work)
{
        struct delayed_work *delayed_work;
        struct batadv_priv_tt *priv_tt;
        struct batadv_priv *bat_priv;

        delayed_work = container_of(work, struct delayed_work, work);
        priv_tt = container_of(delayed_work, struct batadv_priv_tt, work);
        bat_priv = container_of(priv_tt, struct batadv_priv, tt);

        batadv_tt_local_purge(bat_priv);
        batadv_tt_global_purge(bat_priv);
        batadv_tt_req_purge(bat_priv);
        batadv_tt_roam_purge(bat_priv);

        queue_delayed_work(batadv_event_workqueue, &bat_priv->tt.work,
                           msecs_to_jiffies(BATADV_TT_WORK_PERIOD));
}

void batadv_tt_free(struct batadv_priv *bat_priv)
{
        cancel_delayed_work_sync(&bat_priv->tt.work);

        batadv_tt_local_table_free(bat_priv);
        batadv_tt_global_table_free(bat_priv);
        batadv_tt_req_list_free(bat_priv);
        batadv_tt_changes_list_free(bat_priv);
        batadv_tt_roam_list_free(bat_priv);

        kfree(bat_priv->tt.last_changeset);
}

/* This function will enable or disable the specified flags for all the entries
 * in the given hash table and returns the number of modified entries
 */
static uint16_t batadv_tt_set_flags(struct batadv_hashtable *hash,
                                    uint16_t flags, bool enable)
{
        uint32_t i;
        uint16_t changed_num = 0;
        struct hlist_head *head;
        struct batadv_tt_common_entry *tt_common_entry;

        if (!hash)
                goto out;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(tt_common_entry,
                                         head, hash_entry) {
                        if (enable) {
                                if ((tt_common_entry->flags & flags) == flags)
                                        continue;
                                tt_common_entry->flags |= flags;
                        } else {
                                if (!(tt_common_entry->flags & flags))
                                        continue;
                                tt_common_entry->flags &= ~flags;
                        }
                        changed_num++;
                }
                rcu_read_unlock();
        }
out:
        return changed_num;
}

/* Purge out all the tt local entries marked with BATADV_TT_CLIENT_PENDING */
static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
{
        struct batadv_hashtable *hash = bat_priv->tt.local_hash;
        struct batadv_tt_common_entry *tt_common;
        struct batadv_tt_local_entry *tt_local;
        struct hlist_node *node_tmp;
        struct hlist_head *head;
        spinlock_t *list_lock; /* protects write access to the hash lists */
        uint32_t i;

        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(tt_common, node_tmp, head,
                                          hash_entry) {
                        if (!(tt_common->flags & BATADV_TT_CLIENT_PENDING))
                                continue;

                        batadv_dbg(BATADV_DBG_TT, bat_priv,
                                   "Deleting local tt entry (%pM): pending\n",
                                   tt_common->addr);

                        atomic_dec(&bat_priv->tt.local_entry_num);
                        hlist_del_rcu(&tt_common->hash_entry);
                        tt_local = container_of(tt_common,
                                                struct batadv_tt_local_entry,
                                                common);
                        batadv_tt_local_entry_free_ref(tt_local);
                }
                spin_unlock_bh(list_lock);
        }
}

static int batadv_tt_commit_changes(struct batadv_priv *bat_priv,
                                    unsigned char **packet_buff,
                                    int *packet_buff_len, int packet_min_len)
{
        uint16_t changed_num = 0;

        if (atomic_read(&bat_priv->tt.local_changes) < 1)
                return -ENOENT;

        changed_num = batadv_tt_set_flags(bat_priv->tt.local_hash,
                                          BATADV_TT_CLIENT_NEW, false);

        /* all reset entries have to be counted as local entries */
        atomic_add(changed_num, &bat_priv->tt.local_entry_num);
        batadv_tt_local_purge_pending_clients(bat_priv);
        bat_priv->tt.local_crc = batadv_tt_local_crc(bat_priv);

        /* Increment the TTVN only once per OGM interval */
        atomic_inc(&bat_priv->tt.vn);
        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Local changes committed, updating to ttvn %u\n",
                   (uint8_t)atomic_read(&bat_priv->tt.vn));

        /* reset the sending counter */
        atomic_set(&bat_priv->tt.ogm_append_cnt, BATADV_TT_OGM_APPEND_MAX);

        return batadv_tt_changes_fill_buff(bat_priv, packet_buff,
                                           packet_buff_len, packet_min_len);
}

/* when calling this function (hard_iface == primary_if) has to be true */
int batadv_tt_append_diff(struct batadv_priv *bat_priv,
                          unsigned char **packet_buff, int *packet_buff_len,
                          int packet_min_len)
{
        int tt_num_changes;

        /* if at least one change happened */
        tt_num_changes = batadv_tt_commit_changes(bat_priv, packet_buff,
                                                  packet_buff_len,
                                                  packet_min_len);

        /* if the changes have been sent often enough */
        if ((tt_num_changes < 0) &&
            (!batadv_atomic_dec_not_zero(&bat_priv->tt.ogm_append_cnt))) {
                batadv_tt_realloc_packet_buff(packet_buff, packet_buff_len,
                                              packet_min_len, packet_min_len);
                tt_num_changes = 0;
        }

        return tt_num_changes;
}

bool batadv_is_ap_isolated(struct batadv_priv *bat_priv, uint8_t *src,
                           uint8_t *dst)
{
        struct batadv_tt_local_entry *tt_local_entry = NULL;
        struct batadv_tt_global_entry *tt_global_entry = NULL;
        bool ret = false;

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

        tt_local_entry = batadv_tt_local_hash_find(bat_priv, dst);
        if (!tt_local_entry)
                goto out;

        tt_global_entry = batadv_tt_global_hash_find(bat_priv, src);
        if (!tt_global_entry)
                goto out;

        if (!_batadv_is_ap_isolated(tt_local_entry, tt_global_entry))
                goto out;

        ret = true;

out:
        if (tt_global_entry)
                batadv_tt_global_entry_free_ref(tt_global_entry);
        if (tt_local_entry)
                batadv_tt_local_entry_free_ref(tt_local_entry);
        return ret;
}

void batadv_tt_update_orig(struct batadv_priv *bat_priv,
                           struct batadv_orig_node *orig_node,
                           const unsigned char *tt_buff, uint8_t tt_num_changes,
                           uint8_t ttvn, uint16_t tt_crc)
{
        uint8_t orig_ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
        bool full_table = true;
        struct batadv_tt_change *tt_change;

        /* don't care about a backbone gateways updates. */
        if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig))
                return;

        /* orig table not initialised AND first diff is in the OGM OR the ttvn
         * increased by one -> we can apply the attached changes
         */
        if ((!orig_node->tt_initialised && ttvn == 1) ||
            ttvn - orig_ttvn == 1) {
                /* the OGM could not contain the changes due to their size or
                 * because they have already been sent BATADV_TT_OGM_APPEND_MAX
                 * times.
                 * In this case send a tt request
                 */
                if (!tt_num_changes) {
                        full_table = false;
                        goto request_table;
                }

                tt_change = (struct batadv_tt_change *)tt_buff;
                batadv_tt_update_changes(bat_priv, orig_node, tt_num_changes,
                                         ttvn, tt_change);

                /* Even if we received the precomputed crc with the OGM, we
                 * prefer to recompute it to spot any possible inconsistency
                 * in the global table
                 */
                orig_node->tt_crc = batadv_tt_global_crc(bat_priv, orig_node);

                /* The ttvn alone is not enough to guarantee consistency
                 * because a single value could represent different states
                 * (due to the wrap around). Thus a node has to check whether
                 * the resulting table (after applying the changes) is still
                 * consistent or not. E.g. a node could disconnect while its
                 * ttvn is X and reconnect on ttvn = X + TTVN_MAX: in this case
                 * checking the CRC value is mandatory to detect the
                 * inconsistency
                 */
                if (orig_node->tt_crc != tt_crc)
                        goto request_table;
        } else {
                /* if we missed more than one change or our tables are not
                 * in sync anymore -> request fresh tt data
                 */
                if (!orig_node->tt_initialised || ttvn != orig_ttvn ||
                    orig_node->tt_crc != tt_crc) {
request_table:
                        batadv_dbg(BATADV_DBG_TT, bat_priv,
                                   "TT inconsistency for %pM. Need to retrieve the correct information (ttvn: %u last_ttvn: %u crc: %#.4x last_crc: %#.4x num_changes: %u)\n",
                                   orig_node->orig, ttvn, orig_ttvn, tt_crc,
                                   orig_node->tt_crc, tt_num_changes);
                        batadv_send_tt_request(bat_priv, orig_node, ttvn,
                                               tt_crc, full_table);
                        return;
                }
        }
}

/* returns true whether we know that the client has moved from its old
 * originator to another one. This entry is kept is still kept for consistency
 * purposes
 */
bool batadv_tt_global_client_is_roaming(struct batadv_priv *bat_priv,
                                        uint8_t *addr)
{
        struct batadv_tt_global_entry *tt_global_entry;
        bool ret = false;

        tt_global_entry = batadv_tt_global_hash_find(bat_priv, addr);
        if (!tt_global_entry)
                goto out;

        ret = tt_global_entry->common.flags & BATADV_TT_CLIENT_ROAM;
        batadv_tt_global_entry_free_ref(tt_global_entry);
out:
        return ret;
}

/**
 * batadv_tt_local_client_is_roaming - tells whether the client is roaming
 * @bat_priv: the bat priv with all the soft interface information
 * @addr: the MAC address of the local client to query
 *
 * Returns true if the local client is known to be roaming (it is not served by
 * this node anymore) or not. If yes, the client is still present in the table
 * to keep the latter consistent with the node TTVN
 */
bool batadv_tt_local_client_is_roaming(struct batadv_priv *bat_priv,
                                       uint8_t *addr)
{
        struct batadv_tt_local_entry *tt_local_entry;
        bool ret = false;

        tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr);
        if (!tt_local_entry)
                goto out;

        ret = tt_local_entry->common.flags & BATADV_TT_CLIENT_ROAM;
        batadv_tt_local_entry_free_ref(tt_local_entry);
out:
        return ret;
}

bool batadv_tt_add_temporary_global_entry(struct batadv_priv *bat_priv,
                                          struct batadv_orig_node *orig_node,
                                          const unsigned char *addr)
{
        bool ret = false;

        /* if the originator is a backbone node (meaning it belongs to the same
         * LAN of this node) the temporary client must not be added because to
         * reach such destination the node must use the LAN instead of the mesh
         */
        if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig))
                goto out;

        if (!batadv_tt_global_add(bat_priv, orig_node, addr,
                                  BATADV_TT_CLIENT_TEMP,
                                  atomic_read(&orig_node->last_ttvn)))
                goto out;

        batadv_dbg(BATADV_DBG_TT, bat_priv,
                   "Added temporary global client (addr: %pM orig: %pM)\n",
                   addr, orig_node->orig);
        ret = true;
out:
        return ret;
}