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, 89 insertions, 7 deletions

diff --git a/net/batman-adv/originator.h b/net/batman-adv/originator.h
index 805be87d55b8..ea3d69e4e670 100644
--- a/net/batman-adv/originator.h
+++ b/net/batman-adv/originator.h
@@ -12,6 +12,7 @@
 #include <linux/compiler.h>
 #include <linux/if_ether.h>
 #include <linux/jhash.h>
+#include <linux/kref.h>
 #include <linux/netlink.h>
 #include <linux/skbuff.h>
 #include <linux/types.h>
@@ -20,19 +21,18 @@ bool batadv_compare_orig(const struct hlist_node *node, const void *data2);
 int batadv_originator_init(struct batadv_priv *bat_priv);
 void batadv_originator_free(struct batadv_priv *bat_priv);
 void batadv_purge_orig_ref(struct batadv_priv *bat_priv);
-void batadv_orig_node_put(struct batadv_orig_node *orig_node);
+void batadv_orig_node_release(struct kref *ref);
 struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
 					      const u8 *addr);
 struct batadv_hardif_neigh_node *
 batadv_hardif_neigh_get(const struct batadv_hard_iface *hard_iface,
 			const u8 *neigh_addr);
-void
-batadv_hardif_neigh_put(struct batadv_hardif_neigh_node *hardif_neigh);
+void batadv_hardif_neigh_release(struct kref *ref);
 struct batadv_neigh_node *
 batadv_neigh_node_get_or_create(struct batadv_orig_node *orig_node,
 				struct batadv_hard_iface *hard_iface,
 				const u8 *neigh_addr);
-void batadv_neigh_node_put(struct batadv_neigh_node *neigh_node);
+void batadv_neigh_node_release(struct kref *ref);
 struct batadv_neigh_node *
 batadv_orig_router_get(struct batadv_orig_node *orig_node,
 		       const struct batadv_hard_iface *if_outgoing);
@@ -42,7 +42,7 @@ batadv_neigh_ifinfo_new(struct batadv_neigh_node *neigh,
 struct batadv_neigh_ifinfo *
 batadv_neigh_ifinfo_get(struct batadv_neigh_node *neigh,
 			struct batadv_hard_iface *if_outgoing);
-void batadv_neigh_ifinfo_put(struct batadv_neigh_ifinfo *neigh_ifinfo);
+void batadv_neigh_ifinfo_release(struct kref *ref);
 
 int batadv_hardif_neigh_dump(struct sk_buff *msg, struct netlink_callback *cb);
 
@@ -52,7 +52,7 @@ batadv_orig_ifinfo_get(struct batadv_orig_node *orig_node,
 struct batadv_orig_ifinfo *
 batadv_orig_ifinfo_new(struct batadv_orig_node *orig_node,
 		       struct batadv_hard_iface *if_outgoing);
-void batadv_orig_ifinfo_put(struct batadv_orig_ifinfo *orig_ifinfo);
+void batadv_orig_ifinfo_release(struct kref *ref);
 
 int batadv_orig_dump(struct sk_buff *msg, struct netlink_callback *cb);
 struct batadv_orig_node_vlan *
@@ -61,7 +61,7 @@ batadv_orig_node_vlan_new(struct batadv_orig_node *orig_node,
 struct batadv_orig_node_vlan *
 batadv_orig_node_vlan_get(struct batadv_orig_node *orig_node,
 			  unsigned short vid);
-void batadv_orig_node_vlan_put(struct batadv_orig_node_vlan *orig_vlan);
+void batadv_orig_node_vlan_release(struct kref *ref);
 
 /**
  * batadv_choose_orig() - Return the index of the orig entry in the hash table
@@ -82,4 +82,86 @@ static inline u32 batadv_choose_orig(const void *data, u32 size)
 struct batadv_orig_node *
 batadv_orig_hash_find(struct batadv_priv *bat_priv, const void *data);
 
+/**
+ * batadv_orig_node_vlan_put() - decrement the refcounter and possibly release
+ *  the originator-vlan object
+ * @orig_vlan: the originator-vlan object to release
+ */
+static inline void
+batadv_orig_node_vlan_put(struct batadv_orig_node_vlan *orig_vlan)
+{
+	if (!orig_vlan)
+		return;
+
+	kref_put(&orig_vlan->refcount, batadv_orig_node_vlan_release);
+}
+
+/**
+ * batadv_neigh_ifinfo_put() - decrement the refcounter and possibly release
+ *  the neigh_ifinfo
+ * @neigh_ifinfo: the neigh_ifinfo object to release
+ */
+static inline void
+batadv_neigh_ifinfo_put(struct batadv_neigh_ifinfo *neigh_ifinfo)
+{
+	if (!neigh_ifinfo)
+		return;
+
+	kref_put(&neigh_ifinfo->refcount, batadv_neigh_ifinfo_release);
+}
+
+/**
+ * batadv_hardif_neigh_put() - decrement the hardif neighbors refcounter
+ *  and possibly release it
+ * @hardif_neigh: hardif neigh neighbor to free
+ */
+static inline void
+batadv_hardif_neigh_put(struct batadv_hardif_neigh_node *hardif_neigh)
+{
+	if (!hardif_neigh)
+		return;
+
+	kref_put(&hardif_neigh->refcount, batadv_hardif_neigh_release);
+}
+
+/**
+ * batadv_neigh_node_put() - decrement the neighbors refcounter and possibly
+ *  release it
+ * @neigh_node: neigh neighbor to free
+ */
+static inline void batadv_neigh_node_put(struct batadv_neigh_node *neigh_node)
+{
+	if (!neigh_node)
+		return;
+
+	kref_put(&neigh_node->refcount, batadv_neigh_node_release);
+}
+
+/**
+ * batadv_orig_ifinfo_put() - decrement the refcounter and possibly release
+ *  the orig_ifinfo
+ * @orig_ifinfo: the orig_ifinfo object to release
+ */
+static inline void
+batadv_orig_ifinfo_put(struct batadv_orig_ifinfo *orig_ifinfo)
+{
+	if (!orig_ifinfo)
+		return;
+
+	kref_put(&orig_ifinfo->refcount, batadv_orig_ifinfo_release);
+}
+
+/**
+ * batadv_orig_node_put() - decrement the orig node refcounter and possibly
+ *  release it
+ * @orig_node: the orig node to free
+ */
+static inline void batadv_orig_node_put(struct batadv_orig_node *orig_node)
+{
+	if (!orig_node)
+		return;
+
+	kref_put(&orig_node->refcount, batadv_orig_node_release);
+}
+
 #endif /* _NET_BATMAN_ADV_ORIGINATOR_H_ */