Re: [RFC Patch 01/12] PCI: Add virtfn_index for struct pci_device

["Lan, Tianyu" <tianyu.lan@intel.com>]

On 10/22/2015 2:07 AM, Alexander Duyck wrote:
> On 10/21/2015 09:37 AM, Lan Tianyu wrote:
>> Add "virtfn_index" member in the struct pci_device to record VF sequence
>> of PF. This will be used in the VF sysfs node handle.
>>
>> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
>> ---
>>   drivers/pci/iov.c   | 1 +
>>   include/linux/pci.h | 1 +
>>   2 files changed, 2 insertions(+)
>>
>> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>> index ee0ebff..065b6bb 100644
>> --- a/drivers/pci/iov.c
>> +++ b/drivers/pci/iov.c
>> @@ -136,6 +136,7 @@ static int virtfn_add(struct pci_dev *dev, int id,
>> int reset)
>>       virtfn->physfn = pci_dev_get(dev);
>>       virtfn->is_virtfn = 1;
>>       virtfn->multifunction = 0;
>> +    virtfn->virtfn_index = id;
>>       for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
>>           res = &dev->resource[i + PCI_IOV_RESOURCES];
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 353db8d..85c5531 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -356,6 +356,7 @@ struct pci_dev {
>>       unsigned int    io_window_1k:1;    /* Intel P2P bridge 1K I/O
>> windows */
>>       unsigned int    irq_managed:1;
>>       pci_dev_flags_t dev_flags;
>> +    unsigned int    virtfn_index;
>>       atomic_t    enable_cnt;    /* pci_enable_device has been called */
>>       u32        saved_config_space[16]; /* config space saved at
>> suspend time */
>>
>
> Can't you just calculate the VF index based on the VF BDF number
> combined with the information in the PF BDF number and VF
> offset/stride?  Seems kind of pointless to add a variable that is only
> used by one driver and is in a slowpath when you can just calculate it
> pretty quickly.

Good suggestion. Will try it.

>
> - Alex