staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers to store the pci_dev pointer in the comedi_device hw_dev variable and retrieve it easily.

Signed-off-by H Hartley Sweeten <[email protected]>

Cc Ian Abbott <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

---
  drivers/staging/comedi/comedidev.h | 5 +++++
  1 file changed, 5 insertions(+)

drivers/staging/comedi/comedidev.h +0 -0

index de8c99c..620222d 100644

Quoted 16 lines · H Hartley Sweeten

Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers to store the pci_dev pointer in the comedi_device hw_dev variable and retrieve it easily.

Signed-off-by H Hartley Sweeten <[email protected]>

Cc Ian Abbott <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

---
  drivers/staging/comedi/comedidev.h | 5 +++++
  1 file changed, 5 insertions(+)

drivers/staging/comedi/comedidev.h +0 -0

index de8c99c..620222d 100644

drivers/staging/comedi/comedidev.h static inline void comedi_set_hw_dev(struct comedi_device *dev, · line 453

Quoted 8 lines

drivers/staging/comedi/comedidev.h +5 -0

@@ -446,6 +446,11 @@ static inline void comedi_set_hw_dev(struct comedi_device *dev,
  	}
  }
 
+static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
+{
+	return to_pci_dev(dev->hw_dev);
+}
+

That needs to be something like:

	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;

Quoted 28 lines · Ian Abbott

Quoted 16 lines · H Hartley Sweeten

Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers to store the pci_dev pointer in the comedi_device hw_dev variable and retrieve it easily.

Signed-off-by H Hartley Sweeten <[email protected]>

Cc Ian Abbott <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

---
  drivers/staging/comedi/comedidev.h | 5 +++++
  1 file changed, 5 insertions(+)

drivers/staging/comedi/comedidev.h +0 -0

index de8c99c..620222d 100644

drivers/staging/comedi/comedidev.h static inline void comedi_set_hw_dev(struct comedi_device *dev, · line 453

Quoted 8 lines

drivers/staging/comedi/comedidev.h +5 -0

@@ -446,6 +446,11 @@ static inline void comedi_set_hw_dev(struct comedi_device *dev,
  	}
  }
 
+static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
+{
+	return to_pci_dev(dev->hw_dev);
+}
+

That needs to be something like:

Quoted 1 line

	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;

Hmm.. I'm not really sure.

I assumed that the container_of() macro would return NULL if the ptr passed to it was NULL. But, I'm not sure how this actually unwinds for that case.

Greg, do you know if the NULL check is needed? It's is possible that the dev->hw_dev pointer could be NULL.

Quoted 10 lines · H Hartley Sweeten

Quoted 3 lines · Ian Abbott

That needs to be something like:

	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;

Hmm.. I'm not really sure.

I assumed that the container_of() macro would return NULL if the ptr passed to it was NULL. But, I'm not sure how this actually unwinds for that case.

Quoted 3 lines

Greg, do you know if the NULL check is needed? It's is possible that the dev->hw_dev pointer could be NULL.

container_of() just does pointer math with the offset. Since ->hw_dev is not the first member of the pci_dev struct then to_pci_dev() never returns NULL. If you give it a NULL pointer it returns a bogus pointer back.