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

Ethan Zhao
2014-07-29T03:47:42Z

Both of you and Alex W prefer the 'Verb' , Ok, I accept the suggestion.

Thanks,
Ethan

On Tue, Jul 29, 2014 at 11:37 AM, Alexander Duyck
<alexander.duyck@gmail.com> wrote:
> On 07/28/2014 07:43 PM, ethan zhao wrote:
>>
>> 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
>>
>
> I agree with Alex W. If you are going to use the "set" name you should
> probably use "clear" for the operation that undoes it. Using the term
> set implies that it is setting a bit and we currently don't have a
> deassigned/unassigned bit.
>
> If that doesn't work perhaps you could use something like
> get/put_assigned_device or acquire/release_assigned_device. You just
> need to describe what it is you are doing. You could even consider
> adding some tests to return an error if you attempt to assign a device
> that is already assigned.
>
> Thanks,
>
> Alex D
>