Re: [RFC] PCI: enable and disable sriov support via sysfs at per device level

[Don Dutile <ddutile@redhat.com>]

On 10/02/2012 11:10 PM, Greg Kroah-Hartman wrote:
> On Tue, Oct 02, 2012 at 05:06:34PM -0400, Don Dutile wrote:
>> On 10/02/2012 04:39 PM, Greg Kroah-Hartman wrote:
>>> On Tue, Oct 02, 2012 at 04:23:40PM -0400, Don Dutile wrote:
>>>> Greg: Why not use the above functions?
>>>
>>> What "above functions"?  You make a lot of calls in the code :)
>>>
>>> You are creating an attribute group, and then manually walking through
>>> it to create/destroy the file?  That's not good, use the in-kernel
>>> functions to do that automatically for you.
>>>
>>> Also, you need to do this _before_ the device shows up to userspace,
>>> otherwise you have a race that you just lost with udev and the like.
>>>
>>> thanks,
>>>
>>> greg k-h
>>
>> So, why is it ok to create the 'reset' file after the device shows up?
>
> It's not, that should be fixed, patches are always welcome.
>
>> Like reset, SRIOV is optional.  The sysfs files are designed to only
>> be used by userspace utils to enable/disable VFs after the system is up.
>>
>> Or should the design allow a udev rule to be created that if one
>> of these new sriov files exists, then perform a set of read-max-vf&
>> enable n-vf ops ?
>
> Yes it should.  Never create sysfs files after the device is present in
> the system, otherwise userspace never knows about it.
>
> thanks,
>
> greg k-h

ok, thanks for feedback and bit of education ....
still looking for more on this 'visible' tagging though.

so, I guess Bjorn ought to add 'cleaning up pci-sysfs' to
his PCI to-do list...

maybe once i figure out the proper sriov sysfs code, I
can duplicate that effort in the reset,vga & pm-capabilities
section.

- Don