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, 17 insertions, 1 deletions

diff --git a/net/batman-adv/translation-table.h b/net/batman-adv/translation-table.h
index e1285904f885..d18740d9a22b 100644
--- a/net/batman-adv/translation-table.h
+++ b/net/batman-adv/translation-table.h
@@ -9,6 +9,7 @@
 
 #include "main.h"
 
+#include <linux/kref.h>
 #include <linux/netdevice.h>
 #include <linux/netlink.h>
 #include <linux/skbuff.h>
@@ -28,7 +29,7 @@ void batadv_tt_global_del_orig(struct batadv_priv *bat_priv,
 struct batadv_tt_global_entry *
 batadv_tt_global_hash_find(struct batadv_priv *bat_priv, const u8 *addr,
 			   unsigned short vid);
-void batadv_tt_global_entry_put(struct batadv_tt_global_entry *tt_global_entry);
+void batadv_tt_global_entry_release(struct kref *ref);
 int batadv_tt_global_hash_count(struct batadv_priv *bat_priv,
 				const u8 *addr, unsigned short vid);
 struct batadv_orig_node *batadv_transtable_search(struct batadv_priv *bat_priv,
@@ -55,4 +56,19 @@ bool batadv_tt_global_is_isolated(struct batadv_priv *bat_priv,
 int batadv_tt_cache_init(void);
 void batadv_tt_cache_destroy(void);
 
+/**
+ * batadv_tt_global_entry_put() - decrement the tt_global_entry refcounter and
+ *  possibly release it
+ * @tt_global_entry: tt_global_entry to be free'd
+ */
+static inline void
+batadv_tt_global_entry_put(struct batadv_tt_global_entry *tt_global_entry)
+{
+	if (!tt_global_entry)
+		return;
+
+	kref_put(&tt_global_entry->common.refcount,
+		 batadv_tt_global_entry_release);
+}
+
 #endif /* _NET_BATMAN_ADV_TRANSLATION_TABLE_H_ */