[B.A.T.M.A.N.] [PATCHv3 maint] batman-adv: fix TT VLAN inconsistency on VLAN re-add - B.A.T.M.A.N - lists.open-mesh.org

6 Apr 2014

From: Antonio Quartulli antonio@open-mesh.com
When a VLAN interface (on top of batX) is removed and
re-added within a short timeframe TT does not have enough
time to properly cleanup. This creates an internal TT state
mismatch as the newly created softif_vlan will be
initialized from scratch with a TT client count of zero
(even if TT entries for this VLAN still exist). The
resulting TT messages are bogus due to the counter / tt
client listing mismatch, thus creating inconsistencies on
every node in the network
To fix this issue destroy_vlan() has to not free the VLAN
object immediately but it has to be kept alive until all the
TT entries for this VLAN have been removed. destroy_vlan()
still removes the sysfs folder so that the user has the
feeling that everything went fine.
If the same VLAN is re-added before the old object is free'd,
then the latter is resurrected and re-used.
Implement such behaviour by increasing the reference counter
of a softif_vlan object every time a new local TT entry for
such VLAN is created and remove the object from the list
only when all the TT entries have been destroyed.
Signed-off-by: Antonio Quartulli antonio@open-mesh.com
---
Changes since v2:
- remove cleanup_work member that is not needed anymore in this approach
- reword commit subject
- reword commit message (Thanks Marek!)
Changes since v1:
- destroy and create vlan sysfs folder within softif_vlan_destroy/create() to
  avoid lock troubles with soft-interface destruction and delayed jobs.
soft-interface.c    | 45 ++++++++++++++++++++++++++++++++-------------
 translation-table.c | 26 ++++++++++++++++++++++++++
 types.h             |  2 ++
 3 files changed, 60 insertions(+), 13 deletions(-)

diff --git a/soft-interface.c b/soft-interface.c
index d962363..87e2371 100644
--- a/soft-interface.c
+++ b/soft-interface.c
@@ -437,10 +437,15 @@ out:
  *  possibly free it
  * @softif_vlan: the vlan object to release
  */
-void batadv_softif_vlan_free_ref(struct batadv_softif_vlan *softif_vlan)
+void batadv_softif_vlan_free_ref(struct batadv_softif_vlan *vlan)
 {
-	if (atomic_dec_and_test(&softif_vlan->refcount))
-		kfree_rcu(softif_vlan, rcu);
+	if (atomic_dec_and_test(&vlan->refcount)) {
+		spin_lock_bh(&vlan->bat_priv->softif_vlan_list_lock);
+		hlist_del_rcu(&vlan->list);
+		spin_unlock_bh(&vlan->bat_priv->softif_vlan_list_lock);
+
+		kfree_rcu(vlan, rcu);
+	}
 }
/**
@@ -494,6 +499,7 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
    if (!vlan)
    	return -ENOMEM;
+	vlan->bat_priv = bat_priv;
    vlan->vid = vid;
    atomic_set(&vlan->refcount, 1);
@@ -505,6 +511,10 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
    	return err;
    }
+	spin_lock_bh(&bat_priv->softif_vlan_list_lock);
+	hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list);
+	spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
+
    /* add a new TT local entry. This one will be marked with the NOPURGE
     * flag
     */
@@ -512,10 +522,6 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
    		    bat_priv->soft_iface->dev_addr, vid,
    		    BATADV_NULL_IFINDEX, BATADV_NO_MARK);
-	spin_lock_bh(&bat_priv->softif_vlan_list_lock);
-	hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list);
-	spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
-
    return 0;
 }
@@ -527,18 +533,13 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
 static void batadv_softif_destroy_vlan(struct batadv_priv *bat_priv,
    			       struct batadv_softif_vlan *vlan)
 {
-	spin_lock_bh(&bat_priv->softif_vlan_list_lock);
-	hlist_del_rcu(&vlan->list);
-	spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
-
-	batadv_sysfs_del_vlan(bat_priv, vlan);
-
    /* explicitly remove the associated TT local entry because it is marked
     * with the NOPURGE flag
     */
    batadv_tt_local_remove(bat_priv, bat_priv->soft_iface->dev_addr,
    		       vlan->vid, "vlan interface destroyed", false);
+	batadv_sysfs_del_vlan(bat_priv, vlan);
    batadv_softif_vlan_free_ref(vlan);
 }
@@ -556,6 +557,8 @@ static int batadv_interface_add_vid(struct net_device *dev, __be16 proto,
    			    unsigned short vid)
 {
    struct batadv_priv *bat_priv = netdev_priv(dev);
+	struct batadv_softif_vlan *vlan;
+	int ret;
/* only 802.1Q vlans are supported.
     * batman-adv does not know how to handle other types
@@ -565,6 +568,22 @@ static int batadv_interface_add_vid(struct net_device *dev, __be16 proto,
vid |= BATADV_VLAN_HAS_TAG;
+	/* if a new vlan is getting created, but it is found in the list, it
+	 * means that it was not deleted yet. Make batadv_softif_vlan_get()
+	 * increase the refcounter by one and return
+	 */
+	vlan = batadv_softif_vlan_get(bat_priv, vid);
+	if (vlan) {
+		ret = 0;
+		if (!vlan->kobj) {
+			ret = batadv_sysfs_add_vlan(bat_priv->soft_iface, vlan);
+			if (ret)
+				batadv_softif_vlan_free_ref(vlan);
+		}
+
+		return ret;
+	}
+
    return batadv_softif_create_vlan(bat_priv, vid);
 }
diff --git a/translation-table.c b/translation-table.c
index 959dde7..b689981 100644
--- a/translation-table.c
+++ b/translation-table.c
@@ -485,6 +485,7 @@ bool batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
    struct batadv_priv *bat_priv = netdev_priv(soft_iface);
    struct batadv_tt_local_entry *tt_local;
    struct batadv_tt_global_entry *tt_global;
+	struct batadv_softif_vlan *vlan;
    struct net_device *in_dev = NULL;
    struct hlist_head *head;
    struct batadv_tt_orig_list_entry *orig_entry;
@@ -544,6 +545,9 @@ bool batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
    if (!tt_local)
    	goto out;
+	/* increase the refcounter of the related vlan */
+	vlan = batadv_softif_vlan_get(bat_priv, vid);
+
    batadv_dbg(BATADV_DBG_TT, bat_priv,
    	   "Creating new local tt entry: %pM (vid: %d, ttvn: %d)\n",
    	   addr, BATADV_PRINT_VID(vid),
@@ -573,6 +577,7 @@ bool batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
    if (unlikely(hash_added != 0)) {
    	/* remove the reference for the hash */
    	batadv_tt_local_entry_free_ref(tt_local);
+		batadv_softif_vlan_free_ref(vlan);
    	goto out;
    }
@@ -978,6 +983,7 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
 {
    struct batadv_tt_local_entry *tt_local_entry;
    uint16_t flags, curr_flags = BATADV_NO_FLAGS;
+	struct batadv_softif_vlan *vlan;
tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr, vid);
    if (!tt_local_entry)
@@ -1008,6 +1014,11 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
    hlist_del_rcu(&tt_local_entry->common.hash_entry);
    batadv_tt_local_entry_free_ref(tt_local_entry);
+	/* decrease the reference held for this vlan */
+	vlan = batadv_softif_vlan_get(bat_priv, vid);
+	batadv_softif_vlan_free_ref(vlan);
+	batadv_softif_vlan_free_ref(vlan);
+
 out:
    if (tt_local_entry)
    	batadv_tt_local_entry_free_ref(tt_local_entry);
@@ -1080,6 +1091,7 @@ static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
    spinlock_t *list_lock; /* protects write access to the hash lists */
    struct batadv_tt_common_entry *tt_common_entry;
    struct batadv_tt_local_entry *tt_local;
+	struct batadv_softif_vlan *vlan;
    struct hlist_node *node_tmp;
    struct hlist_head *head;
    uint32_t i;
@@ -1100,6 +1112,13 @@ static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
    		tt_local = container_of(tt_common_entry,
    					struct batadv_tt_local_entry,
    					common);
+
+			/* decrease the reference held for this vlan */
+			vlan = batadv_softif_vlan_get(bat_priv,
+						      tt_common_entry->vid);
+			batadv_softif_vlan_free_ref(vlan);
+			batadv_softif_vlan_free_ref(vlan);
+
    		batadv_tt_local_entry_free_ref(tt_local);
    	}
    	spin_unlock_bh(list_lock);
@@ -3078,6 +3097,7 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
    struct batadv_hashtable *hash = bat_priv->tt.local_hash;
    struct batadv_tt_common_entry *tt_common;
    struct batadv_tt_local_entry *tt_local;
+	struct batadv_softif_vlan *vlan;
    struct hlist_node *node_tmp;
    struct hlist_head *head;
    spinlock_t *list_lock; /* protects write access to the hash lists */
@@ -3106,6 +3126,12 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
    		tt_local = container_of(tt_common,
    					struct batadv_tt_local_entry,
    					common);
+
+			/* decrease the reference held for this vlan */
+			vlan = batadv_softif_vlan_get(bat_priv, tt_common->vid);
+			batadv_softif_vlan_free_ref(vlan);
+			batadv_softif_vlan_free_ref(vlan);
+
    		batadv_tt_local_entry_free_ref(tt_local);
    	}
    	spin_unlock_bh(list_lock);
diff --git a/types.h b/types.h
index 78370ab..c4aba2f 100644
--- a/types.h
+++ b/types.h
@@ -638,6 +638,7 @@ struct batadv_priv_nc {
/**
  * struct batadv_softif_vlan - per VLAN attributes set
+ * @bat_priv: pointer to the mesh object
  * @vid: VLAN identifier
  * @kobj: kobject for sysfs vlan subdirectory
  * @ap_isolation: AP isolation state
@@ -647,6 +648,7 @@ struct batadv_priv_nc {
  * @rcu: struct used for freeing in a RCU-safe manner
  */
 struct batadv_softif_vlan {
+	struct batadv_priv *bat_priv;
    unsigned short vid;
    struct kobject *kobj;
    atomic_t ap_isolation;		/* boolean */
-- 
1.8.3.2


    