batman-adv: protect bonding with rcu locks

bonding / alternating candidates need to be secured by rcu locks
as well. This patch therefore converts the bonding list
from a plain pointer list to a rcu securable lists and references
the bonding candidates.
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

net/batman-adv/originator.c

@@ -75,6 +75,14 @@ static void neigh_node_free_rcu(struct rcu_head *rcu)
 	kref_put(&neigh_node->refcount, neigh_node_free_ref);
 }
 
+void neigh_node_free_rcu_bond(struct rcu_head *rcu)
+{
+	struct neigh_node *neigh_node;
+
+	neigh_node = container_of(rcu, struct neigh_node, rcu_bond);
+	kref_put(&neigh_node->refcount, neigh_node_free_ref);
+}
+
 struct neigh_node *create_neighbor(struct orig_node *orig_node,
 				   struct orig_node *orig_neigh_node,
 				   uint8_t *neigh,
@@ -91,6 +99,7 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node,
 		return NULL;
 
 	INIT_HLIST_NODE(&neigh_node->list);
+	INIT_LIST_HEAD(&neigh_node->bonding_list);
 
 	memcpy(neigh_node->addr, neigh, ETH_ALEN);
 	neigh_node->orig_node = orig_neigh_node;
@@ -106,13 +115,20 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node,
 void orig_node_free_ref(struct kref *refcount)
 {
 	struct hlist_node *node, *node_tmp;
-	struct neigh_node *neigh_node;
+	struct neigh_node *neigh_node, *tmp_neigh_node;
 	struct orig_node *orig_node;
 
 	orig_node = container_of(refcount, struct orig_node, refcount);
 
 	spin_lock_bh(&orig_node->neigh_list_lock);
 
+	/* for all bonding members ... */
+	list_for_each_entry_safe(neigh_node, tmp_neigh_node,
+				 &orig_node->bond_list, bonding_list) {
+		list_del_rcu(&neigh_node->bonding_list);
+		call_rcu(&neigh_node->rcu_bond, neigh_node_free_rcu_bond);
+	}
+
 	/* for all neighbors towards this originator ... */
 	hlist_for_each_entry_safe(neigh_node, node, node_tmp,
 				  &orig_node->neigh_list, list) {
@@ -207,6 +223,7 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
 		return NULL;
 
 	INIT_HLIST_HEAD(&orig_node->neigh_list);
+	INIT_LIST_HEAD(&orig_node->bond_list);
 	spin_lock_init(&orig_node->ogm_cnt_lock);
 	spin_lock_init(&orig_node->neigh_list_lock);
 	kref_init(&orig_node->refcount);
@@ -220,6 +237,8 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
 	orig_node->batman_seqno_reset = jiffies - 1
 					- msecs_to_jiffies(RESET_PROTECTION_MS);
 
+	atomic_set(&orig_node->bond_candidates, 0);
+
 	size = bat_priv->num_ifaces * sizeof(unsigned long) * NUM_WORDS;
 
 	orig_node->bcast_own = kzalloc(size, GFP_ATOMIC);
@@ -295,6 +314,7 @@ static bool purge_orig_neighbors(struct bat_priv *bat_priv,
 			neigh_purged = true;
 
 			hlist_del_rcu(&neigh_node->list);
+			bonding_candidate_del(orig_node, neigh_node);
 			call_rcu(&neigh_node->rcu, neigh_node_free_rcu);
 		} else {
 			if ((!*best_neigh_node) ||
@@ -326,9 +346,6 @@ static bool purge_orig_node(struct bat_priv *bat_priv,
 				      best_neigh_node,
 				      orig_node->hna_buff,
 				      orig_node->hna_buff_len);
-			/* update bonding candidates, we could have lost
-			 * some candidates. */
-			update_bonding_candidates(orig_node);
 		}
 	}
 

net/batman-adv/originator.h

@@ -26,6 +26,7 @@ int originator_init(struct bat_priv *bat_priv);
 void originator_free(struct bat_priv *bat_priv);
 void purge_orig_ref(struct bat_priv *bat_priv);
 void orig_node_free_ref(struct kref *refcount);
+void neigh_node_free_rcu_bond(struct rcu_head *rcu);
 struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr);
 struct neigh_node *create_neighbor(struct orig_node *orig_node,
 				   struct orig_node *orig_neigh_node,

net/batman-adv/routing.h

@@ -39,7 +39,9 @@ int recv_bcast_packet(struct sk_buff *skb, struct batman_if *recv_if);
 int recv_vis_packet(struct sk_buff *skb, struct batman_if *recv_if);
 int recv_bat_packet(struct sk_buff *skb, struct batman_if *recv_if);
 struct neigh_node *find_router(struct bat_priv *bat_priv,
-		struct orig_node *orig_node, struct batman_if *recv_if);
-void update_bonding_candidates(struct orig_node *orig_node);
+			       struct orig_node *orig_node,
+			       struct batman_if *recv_if);
+void bonding_candidate_del(struct orig_node *orig_node,
+			   struct neigh_node *neigh_node);
 
 #endif /* _NET_BATMAN_ADV_ROUTING_H_ */

net/batman-adv/types.h

@@ -90,10 +90,8 @@ struct orig_node {
 	struct bat_priv *bat_priv;
 	unsigned long last_frag_packet;
 	spinlock_t ogm_cnt_lock; /* protects ogm counter */
-	struct {
-		uint8_t candidates;
-		struct neigh_node *selected;
-	} bond;
+	atomic_t bond_candidates;
+	struct list_head bond_list;
 };
 
 struct gw_node {
@@ -116,11 +114,12 @@ struct neigh_node {
 	uint8_t tq_index;
 	uint8_t tq_avg;
 	uint8_t last_ttl;
-	struct neigh_node *next_bond_candidate;
+	struct list_head bonding_list;
 	unsigned long last_valid;
 	unsigned long real_bits[NUM_WORDS];
 	struct kref refcount;
 	struct rcu_head rcu;
+	struct rcu_head rcu_bond;
 	struct orig_node *orig_node;
 	struct batman_if *if_incoming;
 };

net/batman-adv/unicast.c

@@ -299,6 +299,7 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 	if (!orig_node)
 		orig_node = transtable_search(bat_priv, ethhdr->h_dest);
 
+	/* find_router() increases neigh_nodes refcount if found. */
 	router = find_router(bat_priv, orig_node, NULL);
 
 	if (!router)
@@ -306,7 +307,6 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 
 	/* don't lock while sending the packets ... we therefore
 		* copy the required data before sending */
-
 	batman_if = router->if_incoming;
 	memcpy(dstaddr, router->addr, ETH_ALEN);