diff mbox

[v2,9/9] batman-adv: Use kref_get for _batadv_update_route

Message ID 1457201124-8495-1-git-send-email-sven@narfation.org
State Accepted, archived
Delegated to: Marek Lindner
Headers show

Commit Message

Sven Eckelmann March 5, 2016, 6:05 p.m. UTC
_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

Marek Lindner April 11, 2016, 10:36 a.m. UTC | #1
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
diff mbox

Patch

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);