net: switchdev: do not propagate bridge updates across bridges

When configuring a tree of independent bridges, propagating changes
from the upper bridge across a bridge master to the lower bridge
ports brings surprises.

For example, a lower bridge may have vlan filtering enabled. It
may have a vlan interface attached to the bridge master, which may
then be incorporated into another bridge. As soon as the lower
bridge vlan interface is attached to the upper bridge, the lower
bridge has vlan filtering disabled.

This occurs because switchdev recursively applies its changes to
all lower devices no matter what.

Reviewed-by: Ido Schimmel <[e-mail]>
Tested-by: Ido Schimmel <[e-mail]>
Signed-off-by: Russell King <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/switchdev/switchdev.c

···
 	 * necessary to go through this helper.
 	 */
 	netdev_for_each_lower_dev(dev, lower_dev, iter) {
+		if (netif_is_bridge_master(lower_dev))
+			continue;
+
 		err = __switchdev_handle_port_obj_add(lower_dev, port_obj_info,
 						      check_cb, add_cb);
 		if (err && err != -EOPNOTSUPP)
···
 	 * necessary to go through this helper.
 	 */
 	netdev_for_each_lower_dev(dev, lower_dev, iter) {
+		if (netif_is_bridge_master(lower_dev))
+			continue;
+
 		err = __switchdev_handle_port_obj_del(lower_dev, port_obj_info,
 						      check_cb, del_cb);
 		if (err && err != -EOPNOTSUPP)
···
 	 * necessary to go through this helper.
 	 */
 	netdev_for_each_lower_dev(dev, lower_dev, iter) {
+		if (netif_is_bridge_master(lower_dev))
+			continue;
+
 		err = __switchdev_handle_port_attr_set(lower_dev, port_attr_info,
 						       check_cb, set_cb);
 		if (err && err != -EOPNOTSUPP)