_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 <[email protected]> --- 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
