USB: sierra: error handling in runtime PM

resumption of devices can fail. Errors must be handled.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/sierra.c

@@ -373,7 +373,10 @@ static int sierra_send_setup(struct usb_serial_port *port)
 	if (!do_send)
 		return 0;
 
-	usb_autopm_get_interface(serial->interface);
+	retval = usb_autopm_get_interface(serial->interface);
+	if (retval < 0)
+		return retval;
+
 	retval = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
 		0x22, 0x21, val, interface, NULL, 0, USB_CTRL_SET_TIMEOUT);
 	usb_autopm_put_interface(serial->interface);
@@ -808,8 +811,12 @@ static void sierra_close(struct usb_serial_port *port)
 		mutex_lock(&serial->disc_mutex);
 		if (!serial->disconnected) {
 			serial->interface->needs_remote_wakeup = 0;
-			usb_autopm_get_interface(serial->interface);
+			/* odd error handling due to pm counters */
+			if (!usb_autopm_get_interface(serial->interface))
 				sierra_send_setup(port);
+			else
+				usb_autopm_get_interface_no_resume(serial->interface);
+				
 		}
 		mutex_unlock(&serial->disc_mutex);
 		spin_lock_irq(&intfdata->susp_lock);
@@ -862,6 +869,7 @@ static int sierra_open(struct tty_struct *tty, struct usb_serial_port *port)
 		/* get rid of everything as in close */
 		sierra_close(port);
 		/* restore balance for autopm */
+		if (!serial->disconnected)
 			usb_autopm_put_interface(serial->interface);
 		return err;
 	}