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

ethan zhao
2014-07-29T02:43:33Z

On 2014/7/29 10:31, Alex Williamson wrote:
> 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.
So there are two pairs of opposite:

set assigned ---> unset assigned
set assigned ---> set deassigned

Here you prefer the 'verb' set /unset, and I prefer the 'adj.'
assigned / deassigned.

Do they really have different meaning or make confusion ? I don't
think so.

Thanks,
Ethan

>
>>>> +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>
>>>
>
>