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, 15 insertions, 0 deletions

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index c561a0eda92a..423f882416d9 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -531,6 +531,21 @@ static bool comedi_is_subdevice_idle(struct comedi_subdevice *s)
 	return (runflags & (SRF_ERROR | SRF_RUNNING)) ? false : true;
 }
 
+/**
+ * comedi_set_spriv() - Set the subdevice private data pointer.
+ * @s: comedi_subdevice struct
+ * @data: pointer to the private data
+ *
+ * This also sets the subdevice runflags to allow the core to automatically
+ * free the private data during the detach.
+ */
+void comedi_set_spriv(struct comedi_subdevice *s, void *data)
+{
+	s->private = data;
+	comedi_set_subdevice_runflags(s, ~0, SRF_FREE_SPRIV);
+}
+EXPORT_SYMBOL_GPL(comedi_set_spriv);
+
 /*
    This function restores a subdevice to an idle state.
  */