USB: usbip: convert to use dev_groups

USB drivers now support the ability for the driver core to handle the
creation and removal of device-specific sysfs files in a race-free
manner.  Take advantage of that by converting the driver to use this by
moving the sysfs attributes into a group and assigning the dev_groups
pointer to it.

Cc: Valentina Manea <valentina.manea.m@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Link: https://lore.kernel.org/r/20190806144502.17792-13-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/stub_dev.c

@@ -106,38 +106,13 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a
 }
 static DEVICE_ATTR_WO(usbip_sockfd);
 
-static int stub_add_files(struct device *dev)
-{
-	int err = 0;
-
-	err = device_create_file(dev, &dev_attr_usbip_status);
-	if (err)
-		goto err_status;
-
-	err = device_create_file(dev, &dev_attr_usbip_sockfd);
-	if (err)
-		goto err_sockfd;
-
-	err = device_create_file(dev, &dev_attr_usbip_debug);
-	if (err)
-		goto err_debug;
-
-	return 0;
-
-err_debug:
-	device_remove_file(dev, &dev_attr_usbip_sockfd);
-err_sockfd:
-	device_remove_file(dev, &dev_attr_usbip_status);
-err_status:
-	return err;
-}
-
-static void stub_remove_files(struct device *dev)
-{
-	device_remove_file(dev, &dev_attr_usbip_status);
-	device_remove_file(dev, &dev_attr_usbip_sockfd);
-	device_remove_file(dev, &dev_attr_usbip_debug);
-}
+static struct attribute *usbip_attrs[] = {
+	&dev_attr_usbip_status.attr,
+	&dev_attr_usbip_sockfd.attr,
+	&dev_attr_usbip_debug.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(usbip);
 
 static void stub_shutdown_connection(struct usbip_device *ud)
 {
@@ -379,17 +354,8 @@ static int stub_probe(struct usb_device *udev)
 		goto err_port;
 	}
 
-	rc = stub_add_files(&udev->dev);
-	if (rc) {
-		dev_err(&udev->dev, "stub_add_files for %s\n", udev_busid);
-		goto err_files;
-	}
-
 	return 0;
 
-err_files:
-	usb_hub_release_port(udev->parent, udev->portnum,
-			     (struct usb_dev_state *) udev);
 err_port:
 	dev_set_drvdata(&udev->dev, NULL);
 	usb_put_dev(udev);
@@ -457,7 +423,6 @@ static void stub_disconnect(struct usb_device *udev)
 	/*
 	 * NOTE: rx/tx threads are invoked for each usb_device.
 	 */
-	stub_remove_files(&udev->dev);
 
 	/* release port */
 	rc = usb_hub_release_port(udev->parent, udev->portnum,
@@ -526,4 +491,5 @@ struct usb_device_driver stub_driver = {
 	.resume		= stub_resume,
 #endif
 	.supports_autosuspend	=	0,
+	.dev_groups	= usbip_groups,
 };