[v2,9/9] batman-adv: Use kref_get for _batadv_update_route
Commit Message
_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(-)
Comments
On Saturday, March 05, 2016 19:05:24 Sven Eckelmann wrote:
> _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(-)
Applied in revision 4390308.
Thanks,
Marek
@@ -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);