Re: [PATCHv2 1/4] pci: Add is_removed state

[Keith Busch <keith.busch@intel.com>]

On Sat, Sep 17, 2016 at 10:35:06AM +0200, Lukas Wunner wrote:
> On Tue, Sep 06, 2016 at 04:00:16PM -0600, Keith Busch wrote:
> > -	return pci_bus_read_dev_vendor_id(pdev->bus, pdev->devfn, &v, 0);
> > +	if (pdev->is_removed)
> > +		return false;
> > +
> > +	if (!pci_bus_read_dev_vendor_id(pdev->bus, pdev->devfn, &v, 0)) {
> > +		pdev->is_removed = 1;
> > +		return false;
> > +	}
> > +	return true;
> >  }
> >  EXPORT_SYMBOL_GPL(pci_device_is_present);
> 
> I've kept this series on my development branch and found a bug now:
> 
> In the above hunk, it's okay to return false if pdev->is_removed is set,
> but it's not okay to set pdev->is_removed if pci_bus_read_dev_vendor_id()
> returns false.  That's because pci_bus_read_dev_vendor_id() can fail for
> other reasons, such as the device being powered down to D3cold, or
> currently unreachable because a PCIe port above it was suspended to D3hot
> so that the link is down.  Those are transient issues, the device isn't
> removed in those cases.

Thanks for the info. I wasn't sure about making the removed return sticky
on a failed vendor id check, so I will remove that from this path and
resend the entire series.