diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2013-01-29 16:20:17 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-29 23:11:41 -0500 |
| commit | bc3954b8147402e4495378d982cc8e708703a0f1 (patch) | |
| tree | e2624f32c9dea8b35e96586377a27d907a062931 /drivers/staging/comedi/comedidev.h | |
| parent | 104640606be0df6bcdb5ec7960a9c3c1278117ae (diff) | |
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: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/comedidev.h')
| -rw-r--r-- | drivers/staging/comedi/comedidev.h | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index e2b7d606e1c0..503dd8c4b302 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -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) |