[PATCH 3.16 217/328] batman-adv: Place kref_get for softif_vlan near use

Ben Hutchings
2018-12-09T21:58:25Z

From: Sven Eckelmann <sven@narfation.org>

commit df28ca6bb3282a4c8dc5b65f60b0136fc190ee52 upstream.

It is hard to understand why the refcnt is increased when it isn't done
near the actual place the new reference is used. So using kref_get right
before the place which requires the reference and in the same function
helps to avoid accidental problems caused by incorrect reference counting.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
[bwh: Backported to 3.16:
- s/kref_get/atomic_inc/
- s/_put/_free_ref/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/batman-adv/soft-interface.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -529,6 +529,7 @@ int batadv_softif_create_vlan(struct bat
}

spin_lock_bh(&bat_priv->softif_vlan_list_lock);
+ atomic_inc(&vlan->refcount);
hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list);
spin_unlock_bh(&bat_priv->softif_vlan_list_lock);

@@ -539,6 +540,9 @@ int batadv_softif_create_vlan(struct bat
bat_priv->soft_iface->dev_addr, vid,
BATADV_NULL_IFINDEX, BATADV_NO_MARK);

+ /* don't return reference to new softif_vlan */
+ batadv_softif_vlan_free_ref(vlan);
+
return 0;
}