batman-adv: protect the local and the global trans-tables with rcu

The local and the global translation-tables are now lock free and rcu
protected.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Acked-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

5 files changed, 150 insertions, 128 deletions

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 3318ee27fe23..c2b06b71d574 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -84,8 +84,6 @@ int mesh_init(struct net_device *soft_iface)
 
         spin_lock_init(&bat_priv->forw_bat_list_lock);
         spin_lock_init(&bat_priv->forw_bcast_list_lock);
-        spin_lock_init(&bat_priv->tt_lhash_lock);
-        spin_lock_init(&bat_priv->tt_ghash_lock);
         spin_lock_init(&bat_priv->tt_changes_list_lock);
         spin_lock_init(&bat_priv->tt_req_list_lock);
         spin_lock_init(&bat_priv->tt_roam_list_lock);
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 05d50ca3c4db..0ce090c9fe86 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -90,9 +90,7 @@ static void update_transtable(struct bat_priv *bat_priv,
                 /* Even if we received the crc into the OGM, we prefer
                  * to recompute it to spot any possible inconsistency
                  * in the global table */
-                spin_lock_bh(&bat_priv->tt_ghash_lock);
                 orig_node->tt_crc = tt_global_crc(bat_priv, orig_node);
-                spin_unlock_bh(&bat_priv->tt_ghash_lock);
                 /* Roaming phase is over: tables are in sync again. I can
                  * unset the flag */
                 orig_node->tt_poss_change = false;
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index d516d8591cfc..5f1fcd573633 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -80,6 +80,9 @@ static struct tt_local_entry *tt_local_hash_find(struct bat_priv *bat_priv,
                 if (!compare_eth(tt_local_entry, data))
                         continue;
 
+                if (!atomic_inc_not_zero(&tt_local_entry->refcount))
+                        continue;
+
                 tt_local_entry_tmp = tt_local_entry;
                 break;
         }
@@ -109,6 +112,9 @@ static struct tt_global_entry *tt_global_hash_find(struct bat_priv *bat_priv,
                 if (!compare_eth(tt_global_entry, data))
                         continue;
 
+                if (!atomic_inc_not_zero(&tt_global_entry->refcount))
+                        continue;
+
                 tt_global_entry_tmp = tt_global_entry;
                 break;
         }
@@ -125,8 +131,20 @@ static bool is_out_of_time(unsigned long starting_time, unsigned long timeout)
         return time_after(jiffies, deadline);
 }
 
+static void tt_local_entry_free_ref(struct tt_local_entry *tt_local_entry)
+{
+        if (atomic_dec_and_test(&tt_local_entry->refcount))
+                kfree_rcu(tt_local_entry, rcu);
+}
+
+static void tt_global_entry_free_ref(struct tt_global_entry *tt_global_entry)
+{
+        if (atomic_dec_and_test(&tt_global_entry->refcount))
+                kfree_rcu(tt_global_entry, rcu);
+}
+
 static void tt_local_event(struct bat_priv *bat_priv, uint8_t op,
-                           const uint8_t *addr, uint8_t roaming)
+                           const uint8_t *addr, bool roaming)
 {
         struct tt_change_node *tt_change_node;
 
@@ -171,21 +189,19 @@ static int tt_local_init(struct bat_priv *bat_priv)
 void tt_local_add(struct net_device *soft_iface, const uint8_t *addr)
 {
         struct bat_priv *bat_priv = netdev_priv(soft_iface);
-        struct tt_local_entry *tt_local_entry;
-        struct tt_global_entry *tt_global_entry;
-        uint8_t roam_addr[ETH_ALEN];
+        struct tt_local_entry *tt_local_entry = NULL;
+        struct tt_global_entry *tt_global_entry = NULL;
 
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
         tt_local_entry = tt_local_hash_find(bat_priv, addr);
 
         if (tt_local_entry) {
                 tt_local_entry->last_seen = jiffies;
-                goto unlock;
+                goto out;
         }
 
         tt_local_entry = kmalloc(sizeof(*tt_local_entry), GFP_ATOMIC);
         if (!tt_local_entry)
-                goto unlock;
+                goto out;
 
         tt_local_event(bat_priv, NO_FLAGS, addr, false);
 
@@ -195,6 +211,7 @@ void tt_local_add(struct net_device *soft_iface, const uint8_t *addr)
 
         memcpy(tt_local_entry->addr, addr, ETH_ALEN);
         tt_local_entry->last_seen = jiffies;
+        atomic_set(&tt_local_entry->refcount, 2);
 
         /* the batman interface mac address should never be purged */
         if (compare_eth(addr, soft_iface->dev_addr))
@@ -204,30 +221,26 @@ void tt_local_add(struct net_device *soft_iface, const uint8_t *addr)
 
         hash_add(bat_priv->tt_local_hash, compare_ltt, choose_orig,
                  tt_local_entry, &tt_local_entry->hash_entry);
+
         atomic_inc(&bat_priv->num_local_tt);
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
 
         /* remove address from global hash if present */
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
-
         tt_global_entry = tt_global_hash_find(bat_priv, addr);
 
         /* Check whether it is a roaming! */
         if (tt_global_entry) {
-                memcpy(roam_addr, tt_global_entry->addr, ETH_ALEN);
                 /* This node is probably going to update its tt table */
                 tt_global_entry->orig_node->tt_poss_change = true;
                 _tt_global_del(bat_priv, tt_global_entry,
                                "local tt received");
-                spin_unlock_bh(&bat_priv->tt_ghash_lock);
                 send_roam_adv(bat_priv, tt_global_entry->addr,
-                        tt_global_entry->orig_node);
-        } else
-                spin_unlock_bh(&bat_priv->tt_ghash_lock);
-
-        return;
-unlock:
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
+                              tt_global_entry->orig_node);
+        }
+out:
+        if (tt_local_entry)
+                tt_local_entry_free_ref(tt_local_entry);
+        if (tt_global_entry)
+                tt_global_entry_free_ref(tt_global_entry);
 }
 
 int tt_changes_fill_buffer(struct bat_priv *bat_priv,
@@ -309,8 +322,6 @@ int tt_local_seq_print_text(struct seq_file *seq, void *offset)
                    "announced via TT (TTVN: %u):\n",
                    net_dev->name, (uint8_t)atomic_read(&bat_priv->ttvn));
 
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
-
         buf_size = 1;
         /* Estimate length for: " * xx:xx:xx:xx:xx:xx\n" */
         for (i = 0; i < hash->size; i++) {
@@ -324,7 +335,6 @@ int tt_local_seq_print_text(struct seq_file *seq, void *offset)
 
         buff = kmalloc(buf_size, GFP_ATOMIC);
         if (!buff) {
-                spin_unlock_bh(&bat_priv->tt_lhash_lock);
                 ret = -ENOMEM;
                 goto out;
         }
@@ -344,8 +354,6 @@ int tt_local_seq_print_text(struct seq_file *seq, void *offset)
                 rcu_read_unlock();
         }
 
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
-
         seq_printf(seq, "%s", buff);
         kfree(buff);
 out:
@@ -354,15 +362,6 @@ out:
         return ret;
 }
 
-static void tt_local_entry_free(struct hlist_node *node, void *arg)
-{
-        struct bat_priv *bat_priv = arg;
-        void *data = container_of(node, struct tt_local_entry, hash_entry);
-
-        kfree(data);
-        atomic_dec(&bat_priv->num_local_tt);
-}
-
 static void tt_local_del(struct bat_priv *bat_priv,
                          struct tt_local_entry *tt_local_entry,
                          const char *message)
@@ -375,23 +374,24 @@ static void tt_local_del(struct bat_priv *bat_priv,
         hash_remove(bat_priv->tt_local_hash, compare_ltt, choose_orig,
                     tt_local_entry->addr);
 
-        tt_local_entry_free(&tt_local_entry->hash_entry, bat_priv);
+        tt_local_entry_free_ref(tt_local_entry);
 }
 
 void tt_local_remove(struct bat_priv *bat_priv, const uint8_t *addr,
                      const char *message, bool roaming)
 {
-        struct tt_local_entry *tt_local_entry;
+        struct tt_local_entry *tt_local_entry = NULL;
 
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
         tt_local_entry = tt_local_hash_find(bat_priv, addr);
 
-        if (tt_local_entry) {
-                tt_local_event(bat_priv, TT_CHANGE_DEL, tt_local_entry->addr,
-                               roaming);
-                tt_local_del(bat_priv, tt_local_entry, message);
-        }
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
+        if (!tt_local_entry)
+                goto out;
+
+        tt_local_event(bat_priv, TT_CHANGE_DEL, tt_local_entry->addr, roaming);
+        tt_local_del(bat_priv, tt_local_entry, message);
+out:
+        if (tt_local_entry)
+                tt_local_entry_free_ref(tt_local_entry);
 }
 
 static void tt_local_purge(struct bat_priv *bat_priv)
@@ -400,40 +400,45 @@ static void tt_local_purge(struct bat_priv *bat_priv)
         struct tt_local_entry *tt_local_entry;
         struct hlist_node *node, *node_tmp;
         struct hlist_head *head;
+        spinlock_t *list_lock; /* protects write access to the hash lists */
         int i;
 
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
-
         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_local_entry, node, node_tmp,
                                           head, hash_entry) {
                         if (tt_local_entry->never_purge)
                                 continue;
 
                         if (!is_out_of_time(tt_local_entry->last_seen,
-                                           TT_LOCAL_TIMEOUT * 1000))
+                                            TT_LOCAL_TIMEOUT * 1000))
                                 continue;
 
                         tt_local_event(bat_priv, TT_CHANGE_DEL,
                                        tt_local_entry->addr, false);
-                        tt_local_del(bat_priv, tt_local_entry,
-                                     "address timed out");
+                        atomic_dec(&bat_priv->num_local_tt);
+                        bat_dbg(DBG_TT, bat_priv, "Deleting local "
+                                "tt entry (%pM): timed out\n",
+                                tt_local_entry->addr);
+                        hlist_del_rcu(node);
+                        tt_local_entry_free_ref(tt_local_entry);
                 }
+                spin_unlock_bh(list_lock);
         }
 
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
 }
 
 static void tt_local_table_free(struct bat_priv *bat_priv)
 {
         struct hashtable_t *hash;
-        int i;
         spinlock_t *list_lock; /* protects write access to the hash lists */
-        struct hlist_head *head;
-        struct hlist_node *node, *node_tmp;
         struct tt_local_entry *tt_local_entry;
+        struct hlist_node *node, *node_tmp;
+        struct hlist_head *head;
+        int i;
 
         if (!bat_priv->tt_local_hash)
                 return;
@@ -448,7 +453,7 @@ static void tt_local_table_free(struct bat_priv *bat_priv)
                 hlist_for_each_entry_safe(tt_local_entry, node, node_tmp,
                                           head, hash_entry) {
                         hlist_del_rcu(node);
-                        kfree(tt_local_entry);
+                        tt_local_entry_free_ref(tt_local_entry);
                 }
                 spin_unlock_bh(list_lock);
         }
@@ -492,10 +497,9 @@ int tt_global_add(struct bat_priv *bat_priv, struct orig_node *orig_node,
                   const unsigned char *tt_addr, uint8_t ttvn, bool roaming)
 {
         struct tt_global_entry *tt_global_entry;
-        struct tt_local_entry *tt_local_entry;
         struct orig_node *orig_node_tmp;
+        int ret = 0;
 
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
         tt_global_entry = tt_global_hash_find(bat_priv, tt_addr);
 
         if (!tt_global_entry) {
@@ -503,7 +507,8 @@ int tt_global_add(struct bat_priv *bat_priv, struct orig_node *orig_node,
                         kmalloc(sizeof(*tt_global_entry),
                                 GFP_ATOMIC);
                 if (!tt_global_entry)
-                        goto unlock;
+                        goto out;
+
                 memcpy(tt_global_entry->addr, tt_addr, ETH_ALEN);
                 /* Assign the new orig_node */
                 atomic_inc(&orig_node->refcount);
@@ -511,10 +516,12 @@ int tt_global_add(struct bat_priv *bat_priv, struct orig_node *orig_node,
                 tt_global_entry->ttvn = ttvn;
                 tt_global_entry->flags = NO_FLAGS;
                 tt_global_entry->roam_at = 0;
-                atomic_inc(&orig_node->tt_size);
+                atomic_set(&tt_global_entry->refcount, 2);
+
                 hash_add(bat_priv->tt_global_hash, compare_gtt,
                          choose_orig, tt_global_entry,
                          &tt_global_entry->hash_entry);
+                atomic_inc(&orig_node->tt_size);
         } else {
                 if (tt_global_entry->orig_node != orig_node) {
                         atomic_dec(&tt_global_entry->orig_node->tt_size);
@@ -529,25 +536,18 @@ int tt_global_add(struct bat_priv *bat_priv, struct orig_node *orig_node,
                 tt_global_entry->roam_at = 0;
         }
 
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
-
         bat_dbg(DBG_TT, bat_priv,
                 "Creating new global tt entry: %pM (via %pM)\n",
                 tt_global_entry->addr, orig_node->orig);
 
         /* remove address from local hash if present */
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
-        tt_local_entry = tt_local_hash_find(bat_priv, tt_addr);
-
-        if (tt_local_entry)
-                tt_local_remove(bat_priv, tt_global_entry->addr,
-                                "global tt received", roaming);
-
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
-        return 1;
-unlock:
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
-        return 0;
+        tt_local_remove(bat_priv, tt_global_entry->addr,
+                        "global tt received", roaming);
+        ret = 1;
+out:
+        if (tt_global_entry)
+                tt_global_entry_free_ref(tt_global_entry);
+        return ret;
 }
 
 int tt_global_seq_print_text(struct seq_file *seq, void *offset)
@@ -584,8 +584,6 @@ int tt_global_seq_print_text(struct seq_file *seq, void *offset)
         seq_printf(seq, "       %-13s %s       %-15s %s\n",
                    "Client", "(TTVN)", "Originator", "(Curr TTVN)");
 
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
-
         buf_size = 1;
         /* Estimate length for: " * xx:xx:xx:xx:xx:xx (ttvn) via
          * xx:xx:xx:xx:xx:xx (cur_ttvn)\n"*/
@@ -600,10 +598,10 @@ int tt_global_seq_print_text(struct seq_file *seq, void *offset)
 
         buff = kmalloc(buf_size, GFP_ATOMIC);
         if (!buff) {
-                spin_unlock_bh(&bat_priv->tt_ghash_lock);
                 ret = -ENOMEM;
                 goto out;
         }
+
         buff[0] = '\0';
         pos = 0;
 
@@ -625,8 +623,6 @@ int tt_global_seq_print_text(struct seq_file *seq, void *offset)
                 rcu_read_unlock();
         }
 
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
-
         seq_printf(seq, "%s", buff);
         kfree(buff);
 out:
@@ -640,7 +636,7 @@ static void _tt_global_del(struct bat_priv *bat_priv,
                            const char *message)
 {
         if (!tt_global_entry)
-                return;
+                goto out;
 
         bat_dbg(DBG_TT, bat_priv,
                 "Deleting global tt entry %pM (via %pM): %s\n",
@@ -648,31 +644,35 @@ static void _tt_global_del(struct bat_priv *bat_priv,
                 message);
 
         atomic_dec(&tt_global_entry->orig_node->tt_size);
+
         hash_remove(bat_priv->tt_global_hash, compare_gtt, choose_orig,
                     tt_global_entry->addr);
-        kfree(tt_global_entry);
+out:
+        if (tt_global_entry)
+                tt_global_entry_free_ref(tt_global_entry);
 }
 
 void tt_global_del(struct bat_priv *bat_priv,
                    struct orig_node *orig_node, const unsigned char *addr,
                    const char *message, bool roaming)
 {
-        struct tt_global_entry *tt_global_entry;
+        struct tt_global_entry *tt_global_entry = NULL;
 
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
         tt_global_entry = tt_global_hash_find(bat_priv, addr);
+        if (!tt_global_entry)
+                goto out;
 
-        if (tt_global_entry && tt_global_entry->orig_node == orig_node) {
+        if (tt_global_entry->orig_node == orig_node) {
                 if (roaming) {
                         tt_global_entry->flags |= TT_CLIENT_ROAM;
                         tt_global_entry->roam_at = jiffies;
                         goto out;
                 }
-                atomic_dec(&orig_node->tt_size);
                 _tt_global_del(bat_priv, tt_global_entry, message);
         }
 out:
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
+        if (tt_global_entry)
+                tt_global_entry_free_ref(tt_global_entry);
 }
 
 void tt_global_del_orig(struct bat_priv *bat_priv,
@@ -683,30 +683,28 @@ void tt_global_del_orig(struct bat_priv *bat_priv,
         struct hashtable_t *hash = bat_priv->tt_global_hash;
         struct hlist_node *node, *safe;
         struct hlist_head *head;
+        spinlock_t *list_lock; /* protects write access to the hash lists */
 
-        if (!bat_priv->tt_global_hash)
-                return;
-
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
         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_global_entry, node, safe,
                                          head, hash_entry) {
-                        if (tt_global_entry->orig_node == orig_node)
-                                _tt_global_del(bat_priv, tt_global_entry,
-                                               message);
+                        if (tt_global_entry->orig_node == orig_node) {
+                                bat_dbg(DBG_TT, bat_priv,
+                                        "Deleting global tt entry %pM "
+                                        "(via %pM): originator time out\n",
+                                        tt_global_entry->addr,
+                                        tt_global_entry->orig_node->orig);
+                                hlist_del_rcu(node);
+                                tt_global_entry_free_ref(tt_global_entry);
+                        }
                 }
+                spin_unlock_bh(list_lock);
         }
         atomic_set(&orig_node->tt_size, 0);
-
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
-}
-
-static void tt_global_entry_free(struct hlist_node *node, void *arg)
-{
-        void *data = container_of(node, struct tt_global_entry, hash_entry);
-        kfree(data);
 }
 
 static void tt_global_roam_purge(struct bat_priv *bat_priv)
@@ -715,13 +713,14 @@ static void tt_global_roam_purge(struct bat_priv *bat_priv)
         struct tt_global_entry *tt_global_entry;
         struct hlist_node *node, *node_tmp;
         struct hlist_head *head;
+        spinlock_t *list_lock; /* protects write access to the hash lists */
         int i;
 
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
-
         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_global_entry, node, node_tmp,
                                           head, hash_entry) {
                         if (!(tt_global_entry->flags & TT_CLIENT_ROAM))
@@ -730,20 +729,47 @@ static void tt_global_roam_purge(struct bat_priv *bat_priv)
                                             TT_CLIENT_ROAM_TIMEOUT * 1000))
                                 continue;
 
-                        _tt_global_del(bat_priv, tt_global_entry,
-                                       "Roaming timeout");
+                        bat_dbg(DBG_TT, bat_priv, "Deleting global "
+                                "tt entry (%pM): Roaming timeout\n",
+                                tt_global_entry->addr);
+                        atomic_dec(&tt_global_entry->orig_node->tt_size);
+                        hlist_del_rcu(node);
+                        tt_global_entry_free_ref(tt_global_entry);
                 }
+                spin_unlock_bh(list_lock);
         }
 
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
 }
 
 static void tt_global_table_free(struct bat_priv *bat_priv)
 {
+        struct hashtable_t *hash;
+        spinlock_t *list_lock; /* protects write access to the hash lists */
+        struct tt_global_entry *tt_global_entry;
+        struct hlist_node *node, *node_tmp;
+        struct hlist_head *head;
+        int i;
+
         if (!bat_priv->tt_global_hash)
                 return;
 
-        hash_delete(bat_priv->tt_global_hash, tt_global_entry_free, NULL);
+        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_global_entry, node, node_tmp,
+                                          head, hash_entry) {
+                        hlist_del_rcu(node);
+                        tt_global_entry_free_ref(tt_global_entry);
+                }
+                spin_unlock_bh(list_lock);
+        }
+
+        hash_destroy(hash);
+
         bat_priv->tt_global_hash = NULL;
 }
 
@@ -753,19 +779,19 @@ struct orig_node *transtable_search(struct bat_priv *bat_priv,
         struct tt_global_entry *tt_global_entry;
         struct orig_node *orig_node = NULL;
 
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
         tt_global_entry = tt_global_hash_find(bat_priv, addr);
 
         if (!tt_global_entry)
                 goto out;
 
         if (!atomic_inc_not_zero(&tt_global_entry->orig_node->refcount))
-                goto out;
+                goto free_tt;
 
         orig_node = tt_global_entry->orig_node;
 
+free_tt:
+        tt_global_entry_free_ref(tt_global_entry);
 out:
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
         return orig_node;
 }
 
@@ -828,7 +854,6 @@ uint16_t tt_local_crc(struct bat_priv *bat_priv)
                                                    tt_local_entry->addr[j]);
                         total ^= total_one;
                 }
-
                 rcu_read_unlock();
         }
 
@@ -1371,15 +1396,17 @@ void tt_update_changes(struct bat_priv *bat_priv, struct orig_node *orig_node,
 
 bool is_my_client(struct bat_priv *bat_priv, const uint8_t *addr)
 {
-        struct tt_local_entry *tt_local_entry;
+        struct tt_local_entry *tt_local_entry = NULL;
+        bool ret = false;
 
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
         tt_local_entry = tt_local_hash_find(bat_priv, addr);
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
-
+        if (!tt_local_entry)
+                goto out;
+        ret = true;
+out:
         if (tt_local_entry)
-                return true;
-        return false;
+                tt_local_entry_free_ref(tt_local_entry);
+        return ret;
 }
 
 void handle_tt_response(struct bat_priv *bat_priv,
@@ -1416,9 +1443,7 @@ void handle_tt_response(struct bat_priv *bat_priv,
         spin_unlock_bh(&bat_priv->tt_req_list_lock);
 
         /* Recalculate the CRC for this orig_node and store it */
-        spin_lock_bh(&bat_priv->tt_ghash_lock);
         orig_node->tt_crc = tt_global_crc(bat_priv, orig_node);
-        spin_unlock_bh(&bat_priv->tt_ghash_lock);
         /* Roaming phase is over: tables are in sync again. I can
          * unset the flag */
         orig_node->tt_poss_change = false;
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 9c84fa9f0968..11e8569a8ca7 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -184,8 +184,6 @@ struct bat_priv {
         spinlock_t forw_bat_list_lock; /* protects forw_bat_list */
         spinlock_t forw_bcast_list_lock; /* protects  */
         spinlock_t tt_changes_list_lock; /* protects tt_changes */
-        spinlock_t tt_lhash_lock; /* protects tt_local_hash */
-        spinlock_t tt_ghash_lock; /* protects tt_global_hash */
         spinlock_t tt_req_list_lock; /* protects tt_req_list */
         spinlock_t tt_roam_list_lock; /* protects tt_roam_list */
         spinlock_t gw_list_lock; /* protects gw_list and curr_gw */
@@ -226,6 +224,8 @@ struct tt_local_entry {
         uint8_t addr[ETH_ALEN];
         unsigned long last_seen;
         char never_purge;
+        atomic_t refcount;
+        struct rcu_head rcu;
         struct hlist_node hash_entry;
 };
 
@@ -235,6 +235,8 @@ struct tt_global_entry {
         uint8_t ttvn;
         uint8_t flags; /* only TT_GLOBAL_ROAM is used */
         unsigned long roam_at; /* time at which TT_GLOBAL_ROAM was set */
+        atomic_t refcount;
+        struct rcu_head rcu;
         struct hlist_node hash_entry; /* entry in the global table */
 };
 
diff --git a/net/batman-adv/vis.c b/net/batman-adv/vis.c
index 355c6e590b0c..8a1b98589d76 100644
--- a/net/batman-adv/vis.c
+++ b/net/batman-adv/vis.c
@@ -665,11 +665,12 @@ next:
 
         hash = bat_priv->tt_local_hash;
 
-        spin_lock_bh(&bat_priv->tt_lhash_lock);
         for (i = 0; i < hash->size; i++) {
                 head = &hash->table[i];
 
-                hlist_for_each_entry(tt_local_entry, node, head, hash_entry) {
+                rcu_read_lock();
+                hlist_for_each_entry_rcu(tt_local_entry, node, head,
+                                         hash_entry) {
                         entry = (struct vis_info_entry *)
                                         skb_put(info->skb_packet,
                                                 sizeof(*entry));
@@ -678,14 +679,12 @@ next:
                         entry->quality = 0; /* 0 means TT */
                         packet->entries++;
 
-                        if (vis_packet_full(info)) {
-                                spin_unlock_bh(&bat_priv->tt_lhash_lock);
-                                return 0;
-                        }
+                        if (vis_packet_full(info))
+                                goto unlock;
                 }
+                rcu_read_unlock();
         }
 
-        spin_unlock_bh(&bat_priv->tt_lhash_lock);
         return 0;
 
 unlock: