staging: comedi: usbdux: tidy up usbdux_ai_inttrig()

Rename the local variable used for the private data pointer to the
comedi "norm".

Remove the unnecessary sanity check of the private data pointer. This
function can only be called is the private data was allocated during
the attach.

Tidy up the exit path using goto to ensure that the semaphore is
released.

Return -EBUSY if an ai command is already running.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/usbdux.c

@@ -852,31 +852,32 @@ static int receive_dux_commands(struct comedi_device *dev, int command)
 }
 
 static int usbdux_ai_inttrig(struct comedi_device *dev,
-			     struct comedi_subdevice *s, unsigned int trignum)
+			     struct comedi_subdevice *s,
+			     unsigned int trignum)
 {
-	int ret;
-	struct usbdux_private *this_usbduxsub = dev->private;
-	if (!this_usbduxsub)
-		return -EFAULT;
+	struct usbdux_private *devpriv = dev->private;
+	int ret = -EINVAL;
 
-	down(&this_usbduxsub->sem);
+	down(&devpriv->sem);
 
-	if (trignum != 0) {
-		up(&this_usbduxsub->sem);
-		return -EINVAL;
-	}
-	if (!(this_usbduxsub->ai_cmd_running)) {
-		this_usbduxsub->ai_cmd_running = 1;
+	if (trignum != 0)
+		goto ai_trig_exit;
+
+	if (!devpriv->ai_cmd_running) {
+		devpriv->ai_cmd_running = 1;
 		ret = usbduxsub_submit_inurbs(dev);
 		if (ret < 0) {
-			this_usbduxsub->ai_cmd_running = 0;
-			up(&this_usbduxsub->sem);
-			return ret;
+			devpriv->ai_cmd_running = 0;
+			goto ai_trig_exit;
 		}
 		s->async->inttrig = NULL;
+	} else {
+		ret = -EBUSY;
 	}
-	up(&this_usbduxsub->sem);
-	return 1;
+
+ai_trig_exit:
+	up(&devpriv->sem);
+	return ret;
 }
 
 static int usbdux_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)