Merge tag 'batman-adv-fix-for-davem' of git://git.open-mesh.org/linux-merge

Included changes:
- properly release neigh_ifinfo in batadv_iv_ogm_process_per_outif()
- properly release orig_ifinfo->router when freeing orig_ifinfo
- properly release neigh_node objects during periodic check
- properly release neigh_info objects when the related hard_iface
  is free'd

These changes are all very important because they fix some
reference counting imbalances that lead to the
impossibility of releasing the netdev object used by
batman-adv on shutdown.
The consequence is that such object cannot be destroyed by
the networking stack (the refcounter does not reach zero)
thus bringing the system in hanging state during a normal
reboot operation or a network reconfiguration.

2 files changed, 57 insertions, 4 deletions

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index b3bd4ec3fd94..f04224c32005 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -1545,6 +1545,8 @@ out_neigh:
         if ((orig_neigh_node) && (!is_single_hop_neigh))
                 batadv_orig_node_free_ref(orig_neigh_node);
 out:
+        if (router_ifinfo)
+                batadv_neigh_ifinfo_free_ref(router_ifinfo);
         if (router)
                 batadv_neigh_node_free_ref(router);
         if (router_router)
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index ffd9dfbd9b0e..1785da37b82c 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -501,12 +501,17 @@ batadv_neigh_node_get(const struct batadv_orig_node *orig_node,
 static void batadv_orig_ifinfo_free_rcu(struct rcu_head *rcu)
 {
         struct batadv_orig_ifinfo *orig_ifinfo;
+        struct batadv_neigh_node *router;
 
         orig_ifinfo = container_of(rcu, struct batadv_orig_ifinfo, rcu);
 
         if (orig_ifinfo->if_outgoing != BATADV_IF_DEFAULT)
                 batadv_hardif_free_ref_now(orig_ifinfo->if_outgoing);
 
+        /* this is the last reference to this object */
+        router = rcu_dereference_protected(orig_ifinfo->router, true);
+        if (router)
+                batadv_neigh_node_free_ref_now(router);
         kfree(orig_ifinfo);
 }
 
@@ -702,6 +707,47 @@ free_orig_node:
 }
 
 /**
+ * batadv_purge_neigh_ifinfo - purge obsolete ifinfo entries from neighbor
+ * @bat_priv: the bat priv with all the soft interface information
+ * @neigh: orig node which is to be checked
+ */
+static void
+batadv_purge_neigh_ifinfo(struct batadv_priv *bat_priv,
+                          struct batadv_neigh_node *neigh)
+{
+        struct batadv_neigh_ifinfo *neigh_ifinfo;
+        struct batadv_hard_iface *if_outgoing;
+        struct hlist_node *node_tmp;
+
+        spin_lock_bh(&neigh->ifinfo_lock);
+
+        /* for all ifinfo objects for this neighinator */
+        hlist_for_each_entry_safe(neigh_ifinfo, node_tmp,
+                                  &neigh->ifinfo_list, list) {
+                if_outgoing = neigh_ifinfo->if_outgoing;
+
+                /* always keep the default interface */
+                if (if_outgoing == BATADV_IF_DEFAULT)
+                        continue;
+
+                /* don't purge if the interface is not (going) down */
+                if ((if_outgoing->if_status != BATADV_IF_INACTIVE) &&
+                    (if_outgoing->if_status != BATADV_IF_NOT_IN_USE) &&
+                    (if_outgoing->if_status != BATADV_IF_TO_BE_REMOVED))
+                        continue;
+
+                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+                           "neighbor/ifinfo purge: neighbor %pM, iface: %s\n",
+                           neigh->addr, if_outgoing->net_dev->name);
+
+                hlist_del_rcu(&neigh_ifinfo->list);
+                batadv_neigh_ifinfo_free_ref(neigh_ifinfo);
+        }
+
+        spin_unlock_bh(&neigh->ifinfo_lock);
+}
+
+/**
  * batadv_purge_orig_ifinfo - purge obsolete ifinfo entries from originator
  * @bat_priv: the bat priv with all the soft interface information
  * @orig_node: orig node which is to be checked
@@ -800,6 +846,11 @@ batadv_purge_orig_neighbors(struct batadv_priv *bat_priv,
 
                         hlist_del_rcu(&neigh_node->list);
                         batadv_neigh_node_free_ref(neigh_node);
+                } else {
+                        /* only necessary if not the whole neighbor is to be
+                         * deleted, but some interface has been removed.
+                         */
+                        batadv_purge_neigh_ifinfo(bat_priv, neigh_node);
                 }
         }
 
@@ -857,7 +908,7 @@ static bool batadv_purge_orig_node(struct batadv_priv *bat_priv,
 {
         struct batadv_neigh_node *best_neigh_node;
         struct batadv_hard_iface *hard_iface;
-        bool changed;
+        bool changed_ifinfo, changed_neigh;
 
         if (batadv_has_timed_out(orig_node->last_seen,
                                  2 * BATADV_PURGE_TIMEOUT)) {
@@ -867,10 +918,10 @@ static bool batadv_purge_orig_node(struct batadv_priv *bat_priv,
                            jiffies_to_msecs(orig_node->last_seen));
                 return true;
         }
-        changed = batadv_purge_orig_ifinfo(bat_priv, orig_node);
-        changed = changed || batadv_purge_orig_neighbors(bat_priv, orig_node);
+        changed_ifinfo = batadv_purge_orig_ifinfo(bat_priv, orig_node);
+        changed_neigh = batadv_purge_orig_neighbors(bat_priv, orig_node);
 
-        if (!changed)
+        if (!changed_ifinfo && !changed_neigh)
                 return false;
 
         /* first for NULL ... */