Patch "batman-adv: Drop immediate batadv_hard_iface free function" has been added to the 4.1-stable tree

Patch "batman-adv: Drop immediate batadv_hard_iface free function" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    batman-adv: Drop immediate batadv_hard_iface free function

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     batman-adv-drop-immediate-batadv_hard_iface-free-function.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Jan 26 21:37:04 PST 2016
From: Sven Eckelmann <sven@narfation.org>
Date: Tue, 5 Jan 2016 12:06:25 +0100
Subject: batman-adv: Drop immediate batadv_hard_iface free function

From: Sven Eckelmann <sven@narfation.org>

[ Upstream commit b4d922cfc9c08318eeb77d53b7633740e6b0efb0 ]

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_free_ref.

Fixes: 89652331c00f ("batman-adv: split tq information in neigh_node struct")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/batman-adv/hard-interface.h |   12 ------------
 net/batman-adv/originator.c     |   16 +++++++---------
 2 files changed, 7 insertions(+), 21 deletions(-)

--- a/net/batman-adv/hard-interface.h
+++ b/net/batman-adv/hard-interface.h
@@ -64,18 +64,6 @@ batadv_hardif_free_ref(struct batadv_har
 		call_rcu(&hard_iface->rcu, batadv_hardif_free_rcu);
 }
 
-/**
- * batadv_hardif_free_ref_now - decrement the hard interface refcounter and
- *  possibly free it (without rcu callback)
- * @hard_iface: the hard interface to free
- */
-static inline void
-batadv_hardif_free_ref_now(struct batadv_hard_iface *hard_iface)
-{
-	if (atomic_dec_and_test(&hard_iface->refcount))
-		batadv_hardif_free_rcu(&hard_iface->rcu);
-}
-
 static inline struct batadv_hard_iface *
 batadv_primary_if_get_selected(struct batadv_priv *bat_priv)
 {
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -175,24 +175,22 @@ void batadv_neigh_ifinfo_free_ref(struct
 }
 
 /**
- * batadv_neigh_node_free_rcu - free the neigh_node
- * @rcu: rcu pointer of the neigh_node
+ * batadv_neigh_node_release - release neigh_node from lists and queue for
+ *  free after rcu grace period
+ * @neigh_node: neigh neighbor to free
  */
-static void batadv_neigh_node_free_rcu(struct rcu_head *rcu)
+static void batadv_neigh_node_release(struct batadv_neigh_node *neigh_node)
 {
 	struct hlist_node *node_tmp;
-	struct batadv_neigh_node *neigh_node;
 	struct batadv_neigh_ifinfo *neigh_ifinfo;
 
-	neigh_node = container_of(rcu, struct batadv_neigh_node, rcu);
-
 	hlist_for_each_entry_safe(neigh_ifinfo, node_tmp,
 				  &neigh_node->ifinfo_list, list) {
 		batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
 	}
-	batadv_hardif_free_ref_now(neigh_node->if_incoming);
+	batadv_hardif_free_ref(neigh_node->if_incoming);
 
-	kfree(neigh_node);
+	kfree_rcu(neigh_node, rcu);
 }
 
 /**
@@ -203,7 +201,7 @@ static void batadv_neigh_node_free_rcu(s
 void batadv_neigh_node_free_ref(struct batadv_neigh_node *neigh_node)
 {
 	if (atomic_dec_and_test(&neigh_node->refcount))
-		call_rcu(&neigh_node->rcu, batadv_neigh_node_free_rcu);
+		batadv_neigh_node_release(neigh_node);
 }
 
 /**


Patches currently in stable-queue which might be from sven@narfation.org are

queue-4.1/batman-adv-drop-immediate-batadv_neigh_node-free-function.patch
queue-4.1/batman-adv-drop-immediate-neigh_ifinfo-free-function.patch
queue-4.1/batman-adv-drop-immediate-orig_node-free-function.patch
queue-4.1/batman-adv-drop-immediate-batadv_orig_ifinfo-free-function.patch
queue-4.1/batman-adv-avoid-recursive-call_rcu-for-batadv_nc_node.patch
queue-4.1/batman-adv-drop-immediate-batadv_hard_iface-free-function.patch
queue-4.1/batman-adv-avoid-recursive-call_rcu-for-batadv_bla_claim.patch