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>

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);

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;

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 */
 };
 

net/batman-adv/vis.c

@@ -665,11 +665,12 @@ static int generate_vis_packet(struct bat_priv *bat_priv)
 
 	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 @@ static int generate_vis_packet(struct bat_priv *bat_priv)
 			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: