+static int names_ccw(struct udev_device *dev, struct netnames *names) {
+ struct udev_device *cdev;
+ const char *bus_id;
+ size_t bus_id_len;
+ int rc;
+
+ /* Retrieve the associated CCW device */
+ cdev = udev_device_get_parent(dev);
+ if (!cdev)
+ return -ENOENT;
+
+ /* Network devices are always grouped CCW devices */
+ if (!streq_ptr("ccwgroup", udev_device_get_subsystem(cdev)))
+ return -ENOENT;
+
+ /* Retrieve bus-ID of the grouped CCW device. The bus-ID uniquely
+ * identifies the network device on the Linux on System z channel
+ * subsystem. Note that the bus-ID contains lowercase characters.
+ */
+ bus_id = udev_device_get_sysname(cdev);
+ if (!bus_id)
+ return -ENOENT;
+
+ /* Check the length of the bus-ID. Rely on that the kernel provides
+ * a correct bus-ID; alternatively, improve this check and parse and
+ * verify each bus-ID part...
+ */
+ bus_id_len = strlen(bus_id);
+ if (!bus_id_len || bus_id_len < 8 || bus_id_len > 9)
+ return -EINVAL;
+
+ /* Store the CCW bus-ID for use as network device name */
+ rc = snprintf(names->ccw_group, sizeof(names->ccw_group), "ccw%s", bus_id);
+ if (rc >= 0 && rc < (int)sizeof(names->ccw_group))
+ names->type = NET_CCWGROUP;
+ return 0;
+}
+