batman-adv: Check ptr for NULL before reducing its refcnt

The commit b37a46683739 ("netdevice: add the case if dev is NULL") changed
the way how the NULL check for net_devices have to be handled when trying
to reduce its reference counter. Before this commit, it was the
responsibility of the caller to check whether the object is NULL or not.
But it was changed to behave more like kfree. Now the callee has to handle
the NULL-case.

The batman-adv code was scanned via cocinelle for similar places. These
were changed to use the paradigm

  @@
  identifier E, T, R, C;
  identifier put;
  @@
   void put(struct T *E)
   {
  +	if (!E)
  +		return;
  	kref_put(&E->C, R);
   }

Functions which were used in other sources files were moved to the header
to allow the compiler to inline the NULL check and the kref_put call.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

1 files changed, 15 insertions, 1 deletions

diff --git a/net/batman-adv/soft-interface.h b/net/batman-adv/soft-interface.h
index 67a2ddd6832f..9f2003f1a497 100644
--- a/net/batman-adv/soft-interface.h
+++ b/net/batman-adv/soft-interface.h
@@ -9,6 +9,7 @@
 
 #include "main.h"
 
+#include <linux/kref.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/types.h>
@@ -21,8 +22,21 @@ void batadv_interface_rx(struct net_device *soft_iface,
 bool batadv_softif_is_valid(const struct net_device *net_dev);
 extern struct rtnl_link_ops batadv_link_ops;
 int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid);
-void batadv_softif_vlan_put(struct batadv_softif_vlan *softif_vlan);
+void batadv_softif_vlan_release(struct kref *ref);
 struct batadv_softif_vlan *batadv_softif_vlan_get(struct batadv_priv *bat_priv,
 						  unsigned short vid);
 
+/**
+ * batadv_softif_vlan_put() - decrease the vlan object refcounter and
+ *  possibly release it
+ * @vlan: the vlan object to release
+ */
+static inline void batadv_softif_vlan_put(struct batadv_softif_vlan *vlan)
+{
+	if (!vlan)
+		return;
+
+	kref_put(&vlan->refcount, batadv_softif_vlan_release);
+}
+
 #endif /* _NET_BATMAN_ADV_SOFT_INTERFACE_H_ */