From bc3954b8147402e4495378d982cc8e708703a0f1 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Tue, 29 Jan 2013 16:20:17 +0000 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/comedidev.h | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index e2b7d60..503dd8c 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) -- 2.7.4