[PATCH 4.9 061/103] USB: serial: ti_usb_3410_5052: fix control-message error handling

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

commit 39712e8bfa8d3aa6ce1e60fc9d62c9b076c17a30 upstream.

Make sure to detect and return an error on zero-length control-message
transfers when reading from the device.

This addresses a potential failure to detect an empty transmit buffer
during close.

Also remove a redundant check for short transfer when sending a command.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/ti_usb_3410_5052.c |   12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -1556,13 +1556,10 @@ static int ti_command_out_sync(struct ti
 		(USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT),
 		value, moduleid, data, size, 1000);
 
-	if (status == size)
-		status = 0;
-
-	if (status > 0)
-		status = -ECOMM;
+	if (status < 0)
+		return status;
 
-	return status;
+	return 0;
 }
 
 
@@ -1578,8 +1575,7 @@ static int ti_command_in_sync(struct ti_
 
 	if (status == size)
 		status = 0;
-
-	if (status > 0)
+	else if (status >= 0)
 		status = -ECOMM;
 
 	return status;