batman-adv: Fix consistency of update route messages

The debug messages of _batadv_update_route were printed before the actual
route change is done. At this point it is not really known which
curr_router will be replaced. Thus the messages could print the wrong
operation.

Printing the debug messages after the operation was done avoids this
problem.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 7602c001e92b0a382577cd45a8c05da7b3889456..610f2c45edcdd583ebe78c8a565bd7f1ee11a103 100644 (file)
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -74,11 +74,23 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,
        if (!orig_ifinfo)
                return;
 
-       rcu_read_lock();
-       curr_router = rcu_dereference(orig_ifinfo->router);
-       if (curr_router && !kref_get_unless_zero(&curr_router->refcount))
-               curr_router = NULL;
-       rcu_read_unlock();
+       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
+        * protected region. After the new best neighbor has replace the current
+        * best neighbor the reference counter needs to decrease. Consequently,
+        * the code needs to ensure the curr_router variable contains a pointer
+        * to the replaced best neighbor.
+        */
+       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);
 
        /* route deleted */
        if ((curr_router) && (!neigh_node)) {
@@ -100,27 +112,6 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,
                           curr_router->addr);
        }
 
-       if (curr_router)
-               batadv_neigh_node_put(curr_router);
-
-       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
-        * protected region. After the new best neighbor has replace the current
-        * best neighbor the reference counter needs to decrease. Consequently,
-        * the code needs to ensure the curr_router variable contains a pointer
-        * to the replaced best neighbor.
-        */
-       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);
-
        /* decrease refcount of previous best neighbor */
        if (curr_router)
                batadv_neigh_node_put(curr_router);