[B.A.T.M.A.N.] [PATCH v2 14/30] batman-adv: Convert batadv_softif_vlan to kref

Sven Eckelmann
2015-12-20T13:17:54Z

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/soft-interface.c | 31 ++++++++++++++++++++++---------
net/batman-adv/sysfs.c | 3 ++-
net/batman-adv/types.h | 2 +-
3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 6c65de9..8ae61ac 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -30,6 +30,7 @@
#include <linux/if_vlan.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>
@@ -478,6 +479,24 @@ out:
}

/**
+ * batadv_softif_vlan_release - release vlan from lists and queue for free after
+ * rcu grace period
+ * @ref: kref pointer of the vlan object
+ */
+static void batadv_softif_vlan_release(struct kref *ref)
+{
+ struct batadv_softif_vlan *vlan;
+
+ vlan = container_of(ref, struct batadv_softif_vlan, refcount);
+
+ spin_lock_bh(&vlan->bat_priv->softif_vlan_list_lock);
+ hlist_del_rcu(&vlan->list);
+ spin_unlock_bh(&vlan->bat_priv->softif_vlan_list_lock);
+
+ kfree_rcu(vlan, rcu);
+}
+
+/**
* batadv_softif_vlan_free_ref - decrease the vlan object refcounter and
* possibly free it
* @vlan: the vlan object to release
@@ -487,13 +506,7 @@ void batadv_softif_vlan_free_ref(struct batadv_softif_vlan *vlan)
if (!vlan)
return;

- if (atomic_dec_and_test(&vlan->refcount)) {
- spin_lock_bh(&vlan->bat_priv->softif_vlan_list_lock);
- hlist_del_rcu(&vlan->list);
- spin_unlock_bh(&vlan->bat_priv->softif_vlan_list_lock);
-
- kfree_rcu(vlan, rcu);
- }
+ kref_put(&vlan->refcount, batadv_softif_vlan_release);
}

/**
@@ -514,7 +527,7 @@ struct batadv_softif_vlan *batadv_softif_vlan_get(struct batadv_priv *bat_priv,
if (vlan_tmp->vid != vid)
continue;

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

vlan = vlan_tmp;
@@ -549,7 +562,7 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)

vlan->bat_priv = bat_priv;
vlan->vid = vid;
- atomic_set(&vlan->refcount, 1);
+ kref_init(&vlan->refcount);

atomic_set(&vlan->ap_isolation, 0);

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index f38d7b7..4f578ac 100644
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -25,6 +25,7 @@
#include <linux/fs.h>
#include <linux/if.h>
#include <linux/if_vlan.h>
+#include <linux/kref.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/printk.h>
@@ -97,7 +98,7 @@ batadv_kobj_to_vlan(struct batadv_priv *bat_priv, struct kobject *obj)
if (vlan_tmp->kobj != obj)
continue;

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

vlan = vlan_tmp;
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 0b3cbdb..c6c3f0f 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -746,7 +746,7 @@ struct batadv_softif_vlan {
atomic_t ap_isolation; /* boolean */
struct batadv_vlan_tt tt;
struct hlist_node list;
- atomic_t refcount;
+ struct kref refcount;
struct rcu_head rcu;
};

--
2.6.4