batman-adv: Use kref_get for _batadv_update_route

_batadv_update_route requires that the caller already has a valid reference
for neigh_node. It is therefore not possible that it has an reference
counter of 0 and was still given to this function

The kref_get function instead WARNs (with debug information) when the
reference counter would still be 0. This makes a bug in batman-adv better
visible because kref_get_unless_zero would have ignored this problem.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 2ecfca2..b494e43 100644 (file)
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -100,10 +100,6 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,
        if (curr_router)
                batadv_neigh_node_put(curr_router);
 
-       /* increase refcount of new best neighbor */
-       if (neigh_node && !kref_get_unless_zero(&neigh_node->refcount))
-               neigh_node = NULL;
-
        spin_lock_bh(&orig_node->neigh_list_lock);
        /* curr_router used earlier may not be the current orig_ifinfo->router
         * anymore because it was dereferenced outside of the neigh_list_lock
@@ -114,6 +110,10 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,
         */
        curr_router = rcu_dereference_protected(orig_ifinfo->router, true);
 
+       /* increase refcount of new best neighbor */
+       if (neigh_node)
+               kref_get(&neigh_node->refcount);
+
        rcu_assign_pointer(orig_ifinfo->router, neigh_node);
        spin_unlock_bh(&orig_node->neigh_list_lock);
        batadv_orig_ifinfo_put(orig_ifinfo);