1 files changed, 33 insertions, 6 deletions

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index f33ced8e31f4..522243aff2f3 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -307,11 +307,35 @@ batadv_hardif_deactivate_interface(struct batadv_hard_iface *hard_iface)
         batadv_update_min_mtu(hard_iface->soft_iface);
 }
 
+/**
+ * batadv_master_del_slave - remove hard_iface from the current master interface
+ * @slave: the interface enslaved in another master
+ * @master: the master from which slave has to be removed
+ *
+ * Invoke ndo_del_slave on master passing slave as argument. In this way slave
+ * is free'd and master can correctly change its internal state.
+ * Return 0 on success, a negative value representing the error otherwise
+ */
+static int batadv_master_del_slave(struct batadv_hard_iface *slave,
+                                   struct net_device *master)
+{
+        int ret;
+
+        if (!master)
+                return 0;
+
+        ret = -EBUSY;
+        if (master->netdev_ops->ndo_del_slave)
+                ret = master->netdev_ops->ndo_del_slave(master, slave->net_dev);
+
+        return ret;
+}
+
 int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
                                    const char *iface_name)
 {
         struct batadv_priv *bat_priv;
-        struct net_device *soft_iface;
+        struct net_device *soft_iface, *master;
         __be16 ethertype = __constant_htons(ETH_P_BATMAN);
         int ret;
 
@@ -321,11 +345,6 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
         if (!atomic_inc_not_zero(&hard_iface->refcount))
                 goto out;
 
-        /* hard-interface is part of a bridge */
-        if (hard_iface->net_dev->priv_flags & IFF_BRIDGE_PORT)
-                pr_err("You are about to enable batman-adv on '%s' which already is part of a bridge. Unless you know exactly what you are doing this is probably wrong and won't work the way you think it would.\n",
-                       hard_iface->net_dev->name);
-
         soft_iface = dev_get_by_name(&init_net, iface_name);
 
         if (!soft_iface) {
@@ -347,6 +366,14 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
                 goto err_dev;
         }
 
+        /* check if the interface is enslaved in another virtual one and
+         * in that case unlink it first
+         */
+        master = netdev_master_upper_dev_get(hard_iface->net_dev);
+        ret = batadv_master_del_slave(hard_iface, master);
+        if (ret)
+                goto err_dev;
+
         hard_iface->soft_iface = soft_iface;
         bat_priv = netdev_priv(hard_iface->soft_iface);