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, 1 insertions, 2 deletions

diff --git a/drivers/staging/comedi/drivers/addi_watchdog.c b/drivers/staging/comedi/drivers/addi_watchdog.c
index 2c21a1625547..decc97d0e415 100644
--- a/drivers/staging/comedi/drivers/addi_watchdog.c
+++ b/drivers/staging/comedi/drivers/addi_watchdog.c
@@ -129,11 +129,10 @@ int addi_watchdog_init(struct comedi_subdevice *s, unsigned long iobase)
 	spriv = kzalloc(sizeof(*spriv), GFP_KERNEL);
 	if (!spriv)
 		return -ENOMEM;
+	comedi_set_spriv(s, spriv);
 
 	spriv->iobase = iobase;
 
-	s->private	= spriv;
-
 	s->type		= COMEDI_SUBD_TIMER;
 	s->subdev_flags	= SDF_WRITEABLE;
 	s->n_chan	= 1;