batman-adv: do not silently ignore wrong condition

Only one neigh_node per orig_node should match a given
neighbor address, therefore, if more than one matching
neigh_node is found, a WARNING has to be triggered to let
the user know that something is wrong in the originator
state instead of silently skipping the error.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

net/batman-adv/bat_iv_ogm.c

@@ -669,7 +669,7 @@ batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv,
 		if (batadv_compare_eth(neigh_addr, ethhdr->h_source) &&
 		    tmp_neigh_node->if_incoming == if_incoming &&
 		    atomic_inc_not_zero(&tmp_neigh_node->refcount)) {
-			if (neigh_node)
+			if (WARN(neigh_node, "too many matching neigh_nodes"))
 				batadv_neigh_node_free_ref(neigh_node);
 			neigh_node = tmp_neigh_node;
 			continue;