diff mbox

[2/4] batman-adv: Correct rcu refcounting for softif_neigh

Message ID 1296352379-1546-3-git-send-email-sven@narfation.org (mailing list archive)
State RFC, archived
Headers

Commit Message

Sven Eckelmann Jan. 30, 2011, 1:52 a.m. UTC 
  <TODO: write a long monologue about every problem we have or could have or
maybe never had and would have when we not have it>

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 batman-adv/soft-interface.c |   34 ++++++++++++++++------------------
 batman-adv/types.h          |    2 +-
 2 files changed, 17 insertions(+), 19 deletions(-)
diff mbox

Patch

diff --git a/batman-adv/soft-interface.c b/batman-adv/soft-interface.c
index 145e0f7..9fb8a6a 100644
--- a/batman-adv/soft-interface.c
+++ b/batman-adv/soft-interface.c
@@ -79,20 +79,18 @@  int my_skb_head_push(struct sk_buff *skb, unsigned int len)
 	return 0;
 }
 
-static void softif_neigh_free_ref(struct kref *refcount)
-{
-	struct softif_neigh *softif_neigh;
-
-	softif_neigh = container_of(refcount, struct softif_neigh, refcount);
-	kfree(softif_neigh);
-}
-
 static void softif_neigh_free_rcu(struct rcu_head *rcu)
 {
 	struct softif_neigh *softif_neigh;
 
 	softif_neigh = container_of(rcu, struct softif_neigh, rcu);
-	kref_put(&softif_neigh->refcount, softif_neigh_free_ref);
+	kfree(softif_neigh);
+}
+
+static void softif_neigh_free_ref(struct softif_neigh *softif_neigh)
+{
+	if (atomic_dec_and_test(&softif_neigh->refcount))
+		call_rcu(&softif_neigh->rcu, softif_neigh_free_rcu);
 }
 
 void softif_neigh_purge(struct bat_priv *bat_priv)
@@ -119,11 +117,10 @@  void softif_neigh_purge(struct bat_priv *bat_priv)
 				 softif_neigh->addr, softif_neigh->vid);
 			softif_neigh_tmp = bat_priv->softif_neigh;
 			bat_priv->softif_neigh = NULL;
-			kref_put(&softif_neigh_tmp->refcount,
-				 softif_neigh_free_ref);
+			softif_neigh_free_ref(softif_neigh_tmp);
 		}
 
-		call_rcu(&softif_neigh->rcu, softif_neigh_free_rcu);
+		softif_neigh_free_ref(softif_neigh);
 	}
 
 	spin_unlock_bh(&bat_priv->softif_neigh_lock);
@@ -144,8 +141,11 @@  static struct softif_neigh *softif_neigh_get(struct bat_priv *bat_priv,
 		if (softif_neigh->vid != vid)
 			continue;
 
+		if (!atomic_inc_not_zero(&softif_neigh->refcount))
+			continue;
+
 		softif_neigh->last_seen = jiffies;
-		goto found;
+		goto out;
 	}
 
 	softif_neigh = kzalloc(sizeof(struct softif_neigh), GFP_ATOMIC);
@@ -155,15 +155,13 @@  static struct softif_neigh *softif_neigh_get(struct bat_priv *bat_priv,
 	memcpy(softif_neigh->addr, addr, ETH_ALEN);
 	softif_neigh->vid = vid;
 	softif_neigh->last_seen = jiffies;
-	kref_init(&softif_neigh->refcount);
+	atomic_set(&softif_neigh->refcount, 1);
 
 	INIT_HLIST_NODE(&softif_neigh->list);
 	spin_lock_bh(&bat_priv->softif_neigh_lock);
 	hlist_add_head_rcu(&softif_neigh->list, &bat_priv->softif_neigh_list);
 	spin_unlock_bh(&bat_priv->softif_neigh_lock);
 
-found:
-	kref_get(&softif_neigh->refcount);
 out:
 	rcu_read_unlock();
 	return softif_neigh;
@@ -267,7 +265,7 @@  static void softif_batman_recv(struct sk_buff *skb, struct net_device *dev,
 			 softif_neigh->addr, softif_neigh->vid);
 		softif_neigh_tmp = bat_priv->softif_neigh;
 		bat_priv->softif_neigh = softif_neigh;
-		kref_put(&softif_neigh_tmp->refcount, softif_neigh_free_ref);
+		softif_neigh_free_ref(softif_neigh_tmp);
 		/* we need to hold the additional reference */
 		goto err;
 	}
@@ -285,7 +283,7 @@  static void softif_batman_recv(struct sk_buff *skb, struct net_device *dev,
 	}
 
 out:
-	kref_put(&softif_neigh->refcount, softif_neigh_free_ref);
+	softif_neigh_free_ref(softif_neigh);
 err:
 	kfree_skb(skb);
 	return;
diff --git a/batman-adv/types.h b/batman-adv/types.h
index ca5f20a..8df6d9d 100644
--- a/batman-adv/types.h
+++ b/batman-adv/types.h
@@ -270,7 +270,7 @@  struct softif_neigh {
 	uint8_t addr[ETH_ALEN];
 	unsigned long last_seen;
 	short vid;
-	struct kref refcount;
+	atomic_t refcount;
 	struct rcu_head rcu;
 };