staging: comedi: drivers: let core handle freeing s->private

Introduce a new subdevice runflags, SRF_FREE_SPRIV, and a new helper
function, comedi_set_spriv(), that the drivers can use to set the
comedi_subdevice private data pointer. The helper function will also
set SRF_FREE_SPRIV to allow the comedi core to automatically free the
subdevice private data during the cleanup_device() stage of the detach.

Currently s->private is only allocated by the 8255, addi_watchdog,
amplc_dio200_common, and ni_65xx drivers. All users of those drivers
can then have the comedi_spriv_free() calls removed and in many cases
the (*detach) can then simply be the appropriate comedi core provided
function.

The ni_65xx driver uses a helper function, ni_65xx_alloc_subdevice_private(),
to allocate the private data. Refactor the function to return an errno
or call comedi_set_spriv() instead of returning a pointer to the private
data and requiring the caller to handle it.

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, 12 deletions

diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index f3e57fd..e25eba5 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -83,18 +83,6 @@ int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
 }
 EXPORT_SYMBOL_GPL(comedi_alloc_subdevices);
 
-void comedi_spriv_free(struct comedi_device *dev, int subdev_num)
-{
-	struct comedi_subdevice *s;
-
-	if (dev->subdevices && subdev_num < dev->n_subdevices) {
-		s = &dev->subdevices[subdev_num];
-		kfree(s->private);
-		s->private = NULL;
-	}
-}
-EXPORT_SYMBOL_GPL(comedi_spriv_free);
-
 static void cleanup_device(struct comedi_device *dev)
 {
 	int i;
@@ -103,6 +91,8 @@ static void cleanup_device(struct comedi_device *dev)
 	if (dev->subdevices) {
 		for (i = 0; i < dev->n_subdevices; i++) {
 			s = &dev->subdevices[i];
+			if (s->runflags & SRF_FREE_SPRIV)
+				kfree(s->private);
 			comedi_free_subdevice_minor(s);
 			if (s->async) {
 				comedi_buf_alloc(dev, s, 0);