[PATCH v4 13/15] staging: gpib: ni_usb: Handle gpib_register_driver() errors

[Nihar Chaithanya <niharchaithanya@gmail.com>]

The usb_register() function can fail and returns an error value which
is not returned. The function gpib_register_driver() can also fail
which can result in semi-registered module.

In case gpib_register_driver() fails unregister the previous usb driver
registering function. Return the error value if gpib_register_driver()
or usb_register() functions fail.

Signed-off-by: Nihar Chaithanya <niharchaithanya@gmail.com>
---
 drivers/staging/gpib/ni_usb/ni_usb_gpib.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
index b7b6fb1be379..f20a23a023d9 100644
--- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
+++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
@@ -2619,14 +2619,21 @@ static struct usb_driver ni_usb_bus_driver = {
 static int __init ni_usb_init_module(void)
 {
 	int i;
+	int ret = 0;
 
 	pr_info("ni_usb_gpib driver loading\n");
 	for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++)
 		ni_usb_driver_interfaces[i] = NULL;
-	usb_register(&ni_usb_bus_driver);
-	gpib_register_driver(&ni_usb_gpib_interface, THIS_MODULE);
 
-	return 0;
+	ret = usb_register(&ni_usb_bus_driver);
+	if (ret)
+		return ret;
+
+	ret = gpib_register_driver(&ni_usb_gpib_interface, THIS_MODULE);
+	if (ret)
+		usb_deregister(&ni_usb_bus_driver);
+
+	return ret;
 }
 
 static void __exit ni_usb_exit_module(void)
-- 
2.34.1