[linux-next] LinuxNextTracking branch, master, updated. next-20160118

batman at open-mesh.org batman at open-mesh.org
Tue Jan 19 00:15:46 CET 2016


The following commit has been merged in the master branch:
commit f63896928760a7c3ce9c5d3f882ba9f10ae73ad0
Author: Sven Eckelmann <sven at narfation.org>
Date:   Tue Jan 5 12:06:23 2016 +0100

    batman-adv: Drop immediate batadv_hardif_neigh_node free function
    
    It is not allowed to free the memory of an object which is part of a list
    which is protected by rcu-read-side-critical sections without making sure
    that no other context is accessing the object anymore. This usually happens
    by removing the references to this object and then waiting until the rcu
    grace period is over and no one (allowedly) accesses it anymore.
    
    But the _now functions ignore this completely. They free the object
    directly even when a different context still tries to access it. This has
    to be avoided and thus these functions must be removed and all functions
    have to use batadv_hardif_neigh_free_ref.
    
    Fixes: cef63419f7db ("batman-adv: add list of unique single hop neighbors per hard-interface")
    Signed-off-by: Sven Eckelmann <sven at narfation.org>
    Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
    Signed-off-by: Antonio Quartulli <a at unstable.cc>

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 78fd4ea..0b7ab38e 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -202,50 +202,30 @@ void batadv_neigh_ifinfo_free_ref(struct batadv_neigh_ifinfo *neigh_ifinfo)
 }
 
 /**
- * batadv_hardif_neigh_free_rcu - free the hardif neigh_node
- * @rcu: rcu pointer of the neigh_node
- */
-static void batadv_hardif_neigh_free_rcu(struct rcu_head *rcu)
-{
-	struct batadv_hardif_neigh_node *hardif_neigh;
-
-	hardif_neigh = container_of(rcu, struct batadv_hardif_neigh_node, rcu);
-
-	batadv_hardif_free_ref_now(hardif_neigh->if_incoming);
-	kfree(hardif_neigh);
-}
-
-/**
- * batadv_hardif_neigh_free_now - decrement the hardif neighbors refcounter
- *  and possibly free it (without rcu callback)
+ * 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
  */
 static void
-batadv_hardif_neigh_free_now(struct batadv_hardif_neigh_node *hardif_neigh)
+batadv_hardif_neigh_release(struct batadv_hardif_neigh_node *hardif_neigh)
 {
-	if (atomic_dec_and_test(&hardif_neigh->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);
+	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);
 
-		batadv_hardif_neigh_free_rcu(&hardif_neigh->rcu);
-	}
+	batadv_hardif_free_ref(hardif_neigh->if_incoming);
+	kfree_rcu(hardif_neigh, rcu);
 }
 
 /**
  * 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)) {
-		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);
-
-		call_rcu(&hardif_neigh->rcu, batadv_hardif_neigh_free_rcu);
-	}
+	if (atomic_dec_and_test(&hardif_neigh->refcount))
+		batadv_hardif_neigh_release(hardif_neigh);
 }
 
 /**
@@ -272,8 +252,8 @@ static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
 					       neigh_node->addr);
 	if (hardif_neigh) {
 		/* batadv_hardif_neigh_get() increases refcount too */
-		batadv_hardif_neigh_free_now(hardif_neigh);
-		batadv_hardif_neigh_free_now(hardif_neigh);
+		batadv_hardif_neigh_free_ref(hardif_neigh);
+		batadv_hardif_neigh_free_ref(hardif_neigh);
 	}
 
 	if (bao->bat_neigh_free)

-- 
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