staging: comedi: introduce, and use, comedi_spriv_free()

The comedi_subdevice 'private' variable is a void * that is available
for the subdevice to use in manner. It's common in comedi drivers for
the driver to allocate memory for a subdevice and store the pointer
to that memory in the 'private' variable. It's then the responsibility
of the driver to free that memory when the device is detached.

Due to how the attach/detach works in comedi, the drivers need to do
some sanity checking before they can free the allocated memory during
the detach.

Introduce a helper function, comedi_spriv_free(), to handle freeing
the private data allocated for a subdevice. This allows moving all the
sanity checks into the helper function and makes it safe to call
with any context. It also allows removing some of the boilerplate
code in the (*detach) functions.

Remove the subdev_8255_cleanup() export in the 8255 subdevice driver
as well as the addi_watchdog_cleanup() export in the addi_watchdog
driver and use the new helper instead.

The amplc_dio200_common driver uses a number of local helper functions
to free the private data for it's subdevices. Remove those as well and
use the new helper.

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>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/staging/comedi/drivers/pcl724.c b/drivers/staging/comedi/drivers/pcl724.c
index 2821ead2772c..0f5a4821cf5f 100644
--- a/drivers/staging/comedi/drivers/pcl724.c
+++ b/drivers/staging/comedi/drivers/pcl724.c
@@ -170,13 +170,10 @@ static int pcl724_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 static void pcl724_detach(struct comedi_device *dev)
 {
 	const struct pcl724_board *board = comedi_board(dev);
-	struct comedi_subdevice *s;
 	int i;
 
-	for (i = 0; i < dev->n_subdevices; i++) {
-		s = &dev->subdevices[i];
-		subdev_8255_cleanup(dev, s);
-	}
+	for (i = 0; i < dev->n_subdevices; i++)
+		comedi_spriv_free(dev, i);
 #ifdef PCL724_IRQ
 	if (dev->irq)
 		free_irq(dev->irq, dev);