BTPROTO_RFCOMM
err = bt_sock_register(BTPROTO_RFCOMM, &rfcomm_sock_family_ops);
bt_sock_unregister(BTPROTO_RFCOMM);
bt_sock_unregister(BTPROTO_RFCOMM);
sk = rfcomm_sock_alloc(sock_net(parent), NULL, BTPROTO_RFCOMM, GFP_ATOMIC, 0);
bt_sock_reclassify_lock(sk, BTPROTO_RFCOMM);