batman-adv: Convert batadv_gw_node to kref

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>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 5950974..1f3847c 100644 (file)
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -28,6 +28,7 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/kernel.h>
+#include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/netdevice.h>
 #include <linux/rculist.h>
@@ -59,12 +60,29 @@
  */
 #define BATADV_DHCP_CHADDR_OFFSET      28
 
+/**
+ * batadv_gw_node_release - release gw_node from lists and queue for free after
+ *  rcu grace period
+ * @ref: kref pointer of the gw_node
+ */
+static void batadv_gw_node_release(struct kref *ref)
+{
+       struct batadv_gw_node *gw_node;
+
+       gw_node = container_of(ref, struct batadv_gw_node, refcount);
+
+       batadv_orig_node_free_ref(gw_node->orig_node);
+       kfree_rcu(gw_node, rcu);
+}
+
+/**
+ * batadv_gw_node_free_ref - decrement the gw_node refcounter and possibly
+ *  release it
+ * @gw_node: gateway node to free
+ */
 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
 {
-       if (atomic_dec_and_test(&gw_node->refcount)) {
-               batadv_orig_node_free_ref(gw_node->orig_node);
-               kfree_rcu(gw_node, rcu);
-       }
+       kref_put(&gw_node->refcount, batadv_gw_node_release);
 }
 
 static struct batadv_gw_node *
@@ -77,7 +95,7 @@ batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
        if (!gw_node)
                goto out;
 
-       if (!atomic_inc_not_zero(&gw_node->refcount))
+       if (!kref_get_unless_zero(&gw_node->refcount))
                gw_node = NULL;
 
 out:
@@ -118,7 +136,7 @@ static void batadv_gw_select(struct batadv_priv *bat_priv,
 
        spin_lock_bh(&bat_priv->gw.list_lock);
 
-       if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
+       if (new_gw_node && !kref_get_unless_zero(&new_gw_node->refcount))
                new_gw_node = NULL;
 
        curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
@@ -170,7 +188,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
                if (!router_ifinfo)
                        goto next;
 
-               if (!atomic_inc_not_zero(&gw_node->refcount))
+               if (!kref_get_unless_zero(&gw_node->refcount))
                        goto next;
 
                tq_avg = router_ifinfo->bat_iv.tq_avg;
@@ -188,7 +206,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
                                if (curr_gw)
                                        batadv_gw_node_free_ref(curr_gw);
                                curr_gw = gw_node;
-                               atomic_inc(&curr_gw->refcount);
+                               kref_get(&curr_gw->refcount);
                        }
                        break;
 
@@ -203,7 +221,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
                                if (curr_gw)
                                        batadv_gw_node_free_ref(curr_gw);
                                curr_gw = gw_node;
-                               atomic_inc(&curr_gw->refcount);
+                               kref_get(&curr_gw->refcount);
                        }
                        break;
                }
@@ -436,7 +454,7 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
        gw_node->orig_node = orig_node;
        gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
        gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
-       atomic_set(&gw_node->refcount, 1);
+       kref_init(&gw_node->refcount);
 
        spin_lock_bh(&bat_priv->gw.list_lock);
        hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
@@ -469,7 +487,7 @@ batadv_gw_node_get(struct batadv_priv *bat_priv,
                if (gw_node_tmp->orig_node != orig_node)
                        continue;
 
-               if (!atomic_inc_not_zero(&gw_node_tmp->refcount))
+               if (!kref_get_unless_zero(&gw_node_tmp->refcount))
                        continue;
 
                gw_node = gw_node_tmp;

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index ace7900..06c3888 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -342,7 +342,7 @@ struct batadv_gw_node {
        struct batadv_orig_node *orig_node;
        u32 bandwidth_down;
        u32 bandwidth_up;
-       atomic_t refcount;
+       struct kref refcount;
        struct rcu_head rcu;
 };