Re: [PATCH 0/4, v14] PCI, ACPI: Physical PCI slot objects

[Kenji Kaneshige]

Alex-san,

Alex Chiang wrote:
> Hi Kenji-san,
>
> * Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>:
> > Alex-san, Jesse-san,
> >
> > > Note how we're checking get_slot_from_name. That should prevent
> > > your scenario (b) that you describe above.
> > >
> > > Maybe the diff was confusing, but I am definitely not removing
> > > your code. I'm simply adding on top of a86161b3134465f, and not
> > > removing it.
> > I have to apologize. I was using v14 unintentionally on my test
> > environment yesterday, while I thought I was using v15.
> >
> > I think v15 will prevent senario (b), though I have not tried it
> > yet. I'll check it again.
>
> You can check either v15, which applies to Stephen Rothwell's
> linux-next, or you can check v16, which applies to Jesse's
> linux-next.
>
> The only difference is in patch 1/3, where we are touching
> fakephp, which is not the patch that is confusing us here. :)
>
> > And I agree that Alex-san's patch go to Jesse-san's linux-next.
> > If I found something after that, I'll report it or send a
> > incremental patch. To tell the truth, I have several patches
> > that are waiting for Alex-san's patch to be merged to linux-next:)
>
> Yeah, I think incremental patches from here out are good.
>
> > > > I made a below patch to prevent (b), please take a look. And could you
> > > > please consider merging it to "[PATCH 2/3] Introduce pci_slot" in your
> > > > latest series.
> > > Ok, now this is very confusing to me. Why is this patch so
> > > different from a86161b3134465f?
> > >
> > > Are you saying the call to get_slot_from_name() is no longer
> > > sufficient?
> > Though I might misunderstand something about your patch, I thought
> > get_slot_from_name() approach would break what your patch is trying
> > to do.
> >
> > My understanding about your patch is as follows:
> >
> > (x) If multiple hotplug drivers try to register the same slot (try
> >    to handle the same slot, in other words), pci_hp_register()
> >    returns -EBUSY.
> >
> > (y) If one or more drivers try to assign the same name to multiple
> >    slots, pci_hp_register() returns -EEXIST.
>
> That was the original intent, but I think that returning -EEXIST
> for (x) should be sufficient. If it turns out we really do want
> -EBUSY for (x), we can add your latest fixup patch later.

Ok, I understood. Thank you for clarification. I also think your
latest patch is sufficient.

Just in case, I would like to tell you the fact that (x) has following
two cases, though I think you already recognized about it.

 (x-1) If multiple hotplug drivers try to handle the same slot with
       different names, pci_hp_register() returns -EBUSY.

 (x-2) If multiple hotplug drivers try to handle the same slot with
       the same name, pci_hp_register() returns -EEXIST.

Thanks,
Kenji Kaneshige

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