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staging: comedi: restrict comedi_set_hw_dev() usage 

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@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2013-02-01 13:23:20 +00:00 committed by Greg Kroah-Hartman
parent da71751177
commit de06d7c6b8
1 changed files with 11 additions and 4 deletions
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15
drivers/staging/comedi/drivers.c
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@ -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)