Don't allow comedi drivers to change `dev->hw_dev` using
`comedi_set_hw_dev()` if it's already been set. Return `-EEXIST` in
that case.
`dev->hw_dev` needs to be set to NULL by the core during clean-up of the
comedi device, so add a local function `comedi_clear_hw_dev()` to do
that.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index 8dfaa56..17d3498 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -45,14 +45,21 @@ struct comedi_driver *comedi_drivers;
int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
{
- struct device *old_hw_dev = dev->hw_dev;
-
+ if (hw_dev == dev->hw_dev)
+ return 0;
+ if (dev->hw_dev != NULL)
+ return -EEXIST;
dev->hw_dev = get_device(hw_dev);
- put_device(old_hw_dev);
return 0;
}
EXPORT_SYMBOL_GPL(comedi_set_hw_dev);
+static void comedi_clear_hw_dev(struct comedi_device *dev)
+{
+ put_device(dev->hw_dev);
+ dev->hw_dev = NULL;
+}
+
int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
{
struct comedi_subdevice *s;
@@ -108,7 +115,7 @@ static void cleanup_device(struct comedi_device *dev)
dev->write_subdev = NULL;
dev->open = NULL;
dev->close = NULL;
- comedi_set_hw_dev(dev, NULL);
+ comedi_clear_hw_dev(dev);
}
static void __comedi_device_detach(struct comedi_device *dev)
--
1.8.1.1
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