Resending because the first mail got rejected by vger.
On Fri, Sep 6, 2013 at 4:09 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>
> [+cc Kenji, Alex]
>
> On Fri, Sep 06, 2013 at 09:45:56AM +0800, Wei Yang wrote:
> > In __pci_bus_size_bridges() we check whether a pci bus is a root
> > bus by testing bus->self. As indicated by commit 79af72d7
> > ("PCI: pci_is_root_bus helper"), bus->self == NULL is not a proper
> > way to check the pci root bus.
> >
> > This patch changes it to pci_is_root_bus() to check whether it is
> > a root bus.
>
> I think this is a good change, even if only on the grounds of
> consistency.
>
> Did you trip over a case where a root bus has bus->self != NULL?
> I'd like to know more details about the case where:
>
> (bus->parent == NULL) && (bus->self != NULL)
>
> I'm sure that situation exists, or Kenji and Alex would not have
> made the change in 79af72d7, but I don't know the details.
>
> I'd like to know the details so I can recognize similar problems
> elsewhere.
It has been quite a long time, and so I had to google around in the
archives to try and remind myself why we made this change.
Unfortunately, I couldn't find anything public...
Reaching back into my unreliable human memory though, I truly seem to
recall that this interface was created out of paranoia/future-proofing
and not because we had tripped over any actual issues we had found in
the wild at that time.
Sorry for not being more helpful.
/ac
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