Re: [PATCH] PCI: Fix device node for virtual bus

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Tue, Nov 11, 2014 at 09:08:23PM -0700, Bjorn Helgaas wrote:
>On Tue, Nov 11, 2014 at 8:11 PM, Gavin Shan <gwshan@linux.vnet.ibm.com> wrote:
>> On Tue, Nov 11, 2014 at 07:55:19PM -0700, Bjorn Helgaas wrote:
>>>On Tue, Nov 11, 2014 at 7:42 PM, Gavin Shan <gwshan@linux.vnet.ibm.com> wrote:
>>>> pci_set_bus_of_node() sets virtual PCI bus's device node to PHB's
>>>> device node wrongly. The patch fixes the issue.
>>>
>>>This needs more detail.  How is this bug visible to users?  Is there a
>>>bug report?  Is this a regression?  Should it be marked for stable?
>>>
>>
>> I don't have opened bug for it. I just found the problem (maybe not
>> a problem) when reading the code: The original implementation binds
>> PHB device-tree node with "virtual bus", which doesn't make sense.
>
>Does this result in something being wrong in sysfs?  How is this bug
>visible to users?
>

No, I don't think it caused anything wrong in sysfs. So I'm not sure
it's a real problem and need the fix. Please judge.

Thanks,
Gavin

>> Yes, I guess it should be marked for stable if you don't object.
>>
>>>We use "virtual bus" to refer to buses created for SR-IOV VFs that are
>>>not on the same bus as the PF.  These virtual buses have no bridge
>>>device leading to them.  But I think you're talking about something
>>>totally different.  Or maybe that *is* what you're talking about,
>>>since this patch resembles 2ba29e270e97 ("PCI: Use pci_is_root_bus()
>>>to check for root bus").
>>>
>>
>> "virtual bus" here is the buses created for SR-IOV VFs. Yes, the
>> code changes resembles commit 2ba29e270e97.
>>
>> Thanks,
>> Gavin
>>
>>>Bjorn
>>>
>>>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>>>> ---
>>>>  drivers/pci/of.c | 4 ++--
>>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
>>>> index f092993..7b2256b 100644
>>>> --- a/drivers/pci/of.c
>>>> +++ b/drivers/pci/of.c
>>>> @@ -31,9 +31,9 @@ void pci_release_of_node(struct pci_dev *dev)
>>>>
>>>>  void pci_set_bus_of_node(struct pci_bus *bus)
>>>>  {
>>>> -       if (bus->self == NULL)
>>>> +       if (pci_is_root_bus(bus))
>>>>                 bus->dev.of_node = pcibios_get_phb_of_node(bus);
>>>> -       else
>>>> +       else if (bus->self)
>>>>                 bus->dev.of_node = of_node_get(bus->self->dev.of_node);
>>>>  }
>>>>
>>>> --
>>>> 1.8.3.2
>>>>
>>>
>>
>