[B.A.T.M.A.N.] [PATCH v2 12/30] batman-adv: Convert batadv_hardif_neigh_node to kref

Sven Eckelmann
2015-12-20T13:17:52Z

batman-adv uses a self-written reference implementation which is just based
on atomic_t. This is less obvious when reading the code than kref and
therefore increases the change that the reference counting will be missed.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
v2:
- split patchset into fixes and kref migration to make it easier when the
decision is made where each patch will be applied

net/batman-adv/originator.c | 22 +++++++++++++---------
net/batman-adv/types.h | 3 ++-
2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index ef82614..7e5c207 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -23,6 +23,7 @@
#include <linux/fs.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
+#include <linux/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
@@ -196,11 +197,15 @@ void batadv_neigh_ifinfo_free_ref(struct batadv_neigh_ifinfo *neigh_ifinfo)
/**
* batadv_hardif_neigh_release - release hardif neigh node from lists and
* queue for free after rcu grace period
- * @hardif_neigh: hardif neigh neighbor to free
+ * @ref: kref pointer of the neigh_node
*/
-static void
-batadv_hardif_neigh_release(struct batadv_hardif_neigh_node *hardif_neigh)
+static void batadv_hardif_neigh_release(struct kref *ref)
{
+ struct batadv_hardif_neigh_node *hardif_neigh;
+
+ hardif_neigh = container_of(ref, struct batadv_hardif_neigh_node,
+ refcount);
+
spin_lock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
hlist_del_init_rcu(&hardif_neigh->list);
spin_unlock_bh(&hardif_neigh->if_incoming->neigh_list_lock);
@@ -211,13 +216,12 @@ batadv_hardif_neigh_release(struct batadv_hardif_neigh_node *hardif_neigh)

/**
* batadv_hardif_neigh_free_ref - decrement the hardif neighbors refcounter
- * and possibly free it
+ * and possibly release it
* @hardif_neigh: hardif neigh neighbor to free
*/
void batadv_hardif_neigh_free_ref(struct batadv_hardif_neigh_node *hardif_neigh)
{
- if (atomic_dec_and_test(&hardif_neigh->refcount))
- batadv_hardif_neigh_release(hardif_neigh);
+ kref_put(&hardif_neigh->refcount, batadv_hardif_neigh_release);
}

/**
@@ -529,7 +533,7 @@ batadv_hardif_neigh_create(struct batadv_hard_iface *hard_iface,
hardif_neigh->if_incoming = hard_iface;
hardif_neigh->last_seen = jiffies;

- atomic_set(&hardif_neigh->refcount, 1);
+ kref_init(&hardif_neigh->refcount);

if (bat_priv->bat_algo_ops->bat_hardif_neigh_init)
bat_priv->bat_algo_ops->bat_hardif_neigh_init(hardif_neigh);
@@ -584,7 +588,7 @@ batadv_hardif_neigh_get(const struct batadv_hard_iface *hard_iface,
if (!batadv_compare_eth(tmp_hardif_neigh->addr, neigh_addr))
continue;

- if (!atomic_inc_not_zero(&tmp_hardif_neigh->refcount))
+ if (!kref_get_unless_zero(&tmp_hardif_neigh->refcount))
continue;

hardif_neigh = tmp_hardif_neigh;
@@ -648,7 +652,7 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node,
spin_unlock_bh(&orig_node->neigh_list_lock);

/* increment unique neighbor refcount */
- atomic_inc(&hardif_neigh->refcount);
+ kref_get(&hardif_neigh->refcount);

batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv,
"Creating new neighbor %pM for orig_node %pM on interface %s\n",
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 5e8c8df..091ad76 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -25,6 +25,7 @@
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <linux/if_ether.h>
+#include <linux/kref.h>
#include <linux/netdevice.h>
#include <linux/sched.h> /* for linux/wait.h */
#include <linux/spinlock.h>
@@ -359,7 +360,7 @@ struct batadv_hardif_neigh_node {
u8 addr[ETH_ALEN];
struct batadv_hard_iface *if_incoming;
unsigned long last_seen;
- atomic_t refcount;
+ struct kref refcount;
struct rcu_head rcu;
};

--
2.6.4