batman-adv: Allow to modify slaves of soft-interfaces through rntl_link

The sysfs configuration interface of batman-adv to add/remove slaves of an
soft-iface is not deadlock free and doesn't follow the currently common way to
modify slaves of an interface.

An additional configuration interface though rtnl_link is introduced which
provides easy device adding/removing with tools like "ip":
$ ip link set dev eth0 master bat0
$ ip link set dev eth0 nomaster

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

2 files changed, 65 insertions, 3 deletions

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 6c32607a6e93..f33ced8e31f4 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -350,9 +350,13 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
         hard_iface->soft_iface = soft_iface;
         bat_priv = netdev_priv(hard_iface->soft_iface);
 
+        ret = netdev_master_upper_dev_link(hard_iface->net_dev, soft_iface);
+        if (ret)
+                goto err_dev;
+
         ret = bat_priv->bat_algo_ops->bat_iface_enable(hard_iface);
         if (ret < 0)
-                goto err_dev;
+                goto err_upper;
 
         hard_iface->if_num = bat_priv->num_ifaces;
         bat_priv->num_ifaces++;
@@ -362,7 +366,7 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
                 bat_priv->bat_algo_ops->bat_iface_disable(hard_iface);
                 bat_priv->num_ifaces--;
                 hard_iface->if_status = BATADV_IF_NOT_IN_USE;
-                goto err_dev;
+                goto err_upper;
         }
 
         hard_iface->batman_adv_ptype.type = ethertype;
@@ -401,7 +405,10 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
 out:
         return 0;
 
+err_upper:
+        netdev_upper_dev_unlink(hard_iface->net_dev, soft_iface);
 err_dev:
+        hard_iface->soft_iface = NULL;
         dev_put(soft_iface);
 err:
         batadv_hardif_free_ref(hard_iface);
@@ -450,6 +457,7 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface,
         if (!bat_priv->num_ifaces && autodel == BATADV_IF_CLEANUP_AUTO)
                 batadv_softif_destroy_sysfs(hard_iface->soft_iface);
 
+        netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->soft_iface);
         hard_iface->soft_iface = NULL;
         batadv_hardif_free_ref(hard_iface);
 
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 545c863b35fc..403b8c46085e 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -509,6 +509,58 @@ free_bat_counters:
         return ret;
 }
 
+/**
+ * batadv_softif_slave_add - Add a slave interface to a batadv_soft_interface
+ * @dev: batadv_soft_interface used as master interface
+ * @slave_dev: net_device which should become the slave interface
+ *
+ * Return 0 if successful or error otherwise.
+ */
+static int batadv_softif_slave_add(struct net_device *dev,
+                                   struct net_device *slave_dev)
+{
+        struct batadv_hard_iface *hard_iface;
+        int ret = -EINVAL;
+
+        hard_iface = batadv_hardif_get_by_netdev(slave_dev);
+        if (!hard_iface || hard_iface->soft_iface != NULL)
+                goto out;
+
+        ret = batadv_hardif_enable_interface(hard_iface, dev->name);
+
+out:
+        if (hard_iface)
+                batadv_hardif_free_ref(hard_iface);
+        return ret;
+}
+
+/**
+ * batadv_softif_slave_del - Delete a slave iface from a batadv_soft_interface
+ * @dev: batadv_soft_interface used as master interface
+ * @slave_dev: net_device which should be removed from the master interface
+ *
+ * Return 0 if successful or error otherwise.
+ */
+static int batadv_softif_slave_del(struct net_device *dev,
+                                   struct net_device *slave_dev)
+{
+        struct batadv_hard_iface *hard_iface;
+        int ret = -EINVAL;
+
+        hard_iface = batadv_hardif_get_by_netdev(slave_dev);
+
+        if (!hard_iface || hard_iface->soft_iface != dev)
+                goto out;
+
+        batadv_hardif_disable_interface(hard_iface, BATADV_IF_CLEANUP_KEEP);
+        ret = 0;
+
+out:
+        if (hard_iface)
+                batadv_hardif_free_ref(hard_iface);
+        return ret;
+}
+
 static const struct net_device_ops batadv_netdev_ops = {
         .ndo_init = batadv_softif_init_late,
         .ndo_open = batadv_interface_open,
@@ -517,7 +569,9 @@ static const struct net_device_ops batadv_netdev_ops = {
         .ndo_set_mac_address = batadv_interface_set_mac_addr,
         .ndo_change_mtu = batadv_interface_change_mtu,
         .ndo_start_xmit = batadv_interface_tx,
-        .ndo_validate_addr = eth_validate_addr
+        .ndo_validate_addr = eth_validate_addr,
+        .ndo_add_slave = batadv_softif_slave_add,
+        .ndo_del_slave = batadv_softif_slave_del,
 };
 
 /**