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Commit bc3954b8 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
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staging: comedi: simplify comedi_set_hw_dev() 



Since `get_device()` and `put_device()` can take a NULL device
parameter, `comedi_set_hw_dev()` can be simplified to always call
`get_device()` for the new, possibly NULL hardware device, and
`put_device()` for the old, possibly NULL hardware device.  As long as
we do it in that order, there shouldn't be any problem with
`kref_release()` getting called unexpectedly when the new hardware
device is the old hardware device.

Simplify `comedi_set_hw_dev()` and update the comment because the
function is used for additional purposes since the old comment was
written.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 10464060

drivers/staging/comedi/comedidev.h

+10 −11
Original line number Diff line number Diff line
@@ -429,20 +429,19 @@ static inline unsigned int bytes_per_sample(const struct comedi_subdevice *subd) 
		return sizeof(short);

}



/* must be used in attach to set dev->hw_dev if you wish to dma directly

into comedi's buffer */

/*

 * Must set dev->hw_dev if you wish to dma directly into comedi's buffer.

 * Also useful for retrieving a previously configured hardware device of

 * known bus type.  Set automatically for auto-configured devices.

 * Automatically set to NULL when detaching hardware device.

 */

static inline void comedi_set_hw_dev(struct comedi_device *dev,

				     struct device *hw_dev)

{

	if (dev->hw_dev == hw_dev)

		return;

	if (dev->hw_dev)

		put_device(dev->hw_dev);

	dev->hw_dev = hw_dev;

	if (dev->hw_dev) {

		dev->hw_dev = get_device(dev->hw_dev);

		BUG_ON(dev->hw_dev == NULL);

	}

	struct device *old_hw_dev = dev->hw_dev;



	dev->hw_dev = get_device(hw_dev);

	put_device(old_hw_dev);

}



static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)