staging: comedi: comedi_test: use comedi_handle_events()

Use comedi_handle_events() to automatically (*cancel) the async command
for an end-of-acquisition or if an error/overflow occurs.

For aesthetics, add a local variable for the comedi_subdevice pointer.
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/comedi_test.c

@@ -164,7 +164,8 @@ static void waveform_ai_interrupt(unsigned long arg)
 {
 	struct comedi_device *dev = (struct comedi_device *)arg;
 	struct waveform_private *devpriv = dev->private;
-	struct comedi_async *async = dev->read_subdev->async;
+	struct comedi_subdevice *s = dev->read_subdev;
+	struct comedi_async *async = s->async;
 	struct comedi_cmd *cmd = &async->cmd;
 	unsigned int i, j;
 	/* all times in microsec */
@@ -203,7 +204,7 @@ static void waveform_ai_interrupt(unsigned long arg)
 					       devpriv->usec_current +
 						   i * devpriv->scan_period +
 						   j * devpriv->convert_period);
-			cfc_write_to_buffer(dev->read_subdev, sample);
+			cfc_write_to_buffer(s, sample);
 		}
 	}
 
@@ -216,7 +217,7 @@ static void waveform_ai_interrupt(unsigned long arg)
 	else
 		mod_timer(&devpriv->timer, jiffies + 1);
 
-	comedi_event(dev, dev->read_subdev);
+	comedi_handle_events(dev, s);
 }
 
 static int waveform_ai_cmdtest(struct comedi_device *dev,