Re: [PATCH 1/4] PCI: introduce helper functions for device flag operation

Alex Williamson
2014-07-29T02:31:26Z

On Tue, 2014-07-29 at 09:53 +0800, ethan zhao wrote:
> On 2014/7/29 5:00, Alex Williamson wrote:
> > On Wed, 2014-07-23 at 00:19 +0800, Ethan Zhao wrote:
> >> This patch introduced three helper functions to hide direct
> >> device flag operation.
> >>
> >> void pci_set_dev_assigned(struct pci_dev *pdev);
> >> void pci_set_dev_deassigned(struct pci_dev *pdev);
> >> bool pci_is_dev_assigned(struct pci_dev *pdev);
> >>
> >> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
> >> ---
> >> include/linux/pci.h | 13 +++++++++++++
> >> 1 files changed, 13 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/include/linux/pci.h b/include/linux/pci.h
> >> index aab57b4..5f6f8fa 100644
> >> --- a/include/linux/pci.h
> >> +++ b/include/linux/pci.h
> >> @@ -1129,6 +1129,19 @@ resource_size_t pcibios_window_alignment(struct pci_bus *bus,
> >>
> >> int pci_set_vga_state(struct pci_dev *pdev, bool decode,
> >> unsigned int command_bits, u32 flags);
> >> +/* helper functions for operation of device flag */
> >> +static inline void pci_set_dev_assigned(struct pci_dev *pdev)
> >> +{
> >> + pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
> >> +}
> >> +static inline void pci_set_dev_deassigned(struct pci_dev *pdev)
> >> +{
> >> + pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> >> +}
> > I think pci_clear_dev_assigned() would make more sense, we're not
> > setting a flag named DEASSIGNED.
> Though it is a flag operation now, may not later, we define it
> because we want to hide the internal operation.
> 'set' to 'deassigned' status is enough. So I would like keep it.

I disagree, the opposite of a 'set' is a 'clear', or at least an
'unset'. Using bit-ops-like terminology doesn't lock us into an
implementation. As written, this could just as easily be setting two
different variables.

> >
> >> +static inline bool pci_is_dev_assigned(struct pci_dev *pdev)
> >> +{
> >> + return pdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED ? true : false;
> >> +}
> > The ternary operation isn't necessary. Thanks,
> Yep,
>
> return pdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED
>
> is enough.
>
> Thanks,
> Ethan
> >
> > Alex
> >
> >> /* kmem_cache style wrapper around pci_alloc_consistent() */
> >>
> >> #include <linux/pci-dma.h>
> >
> >
>