[B.A.T.M.A.N.] [PATCH v2 9/9] batman-adv: Use kref_get for _batadv_update_route

[Sven Eckelmann <sven@narfation.org>]

_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>
---
This patch requires https://patchwork.open-mesh.org/patch/15888/

v2:
 - 	Remove one of the empty lines around the removed block

 net/batman-adv/routing.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index ffc4c09..06581af 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -100,13 +100,11 @@ 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 = rcu_dereference_protected(orig_ifinfo->router, true);
 
+	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);
-- 
2.7.0