On Fri, Apr 03, 2020 at 05:08:32PM +1100, Oliver O'Halloran wrote: > On Mon, 2020-03-30 at 15:56 +1100, Sam Bobroff wrote: > > When EEH device state was released asynchronously by the device > > release handler, it was possible for an outstanding reference to > > prevent it's release and it was necessary to work around that if a > > device was re-discovered at the same PCI location. > > I think this is a bit misleading. The main situation where you'll hit > this hack is when recovering a device with a driver that doesn't > implement the error handling callbacks. In that case the device is > removed, reset, then re-probed by the PCI core, but we assume it's the > same physical device so the eeh_device state remains active. > > If you actually changed the underlying device I suspect something bad > would happen.
I'm not sure I understand. Isn't the case you're talking about caught by
the earlier check (just above the patch)?
if (edev->pdev == dev) {
eeh_edev_dbg(edev, "Device already referenced!\n");
return;
}
>
> > Now that the state is released synchronously that is no longer
> > possible and the workaround is no longer necessary.
>
> You could probably fold this into the previous patch, but eh. You could
> probably fold this into the previous patch, but eh.
True.
> > Signed-off-by: Sam Bobroff <sbobr...@linux.ibm.com>
> > ---
> > arch/powerpc/kernel/eeh.c | 23 +----------------------
> > 1 file changed, 1 insertion(+), 22 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
> > index c36c5a7db5ca..12c248a16527 100644
> > --- a/arch/powerpc/kernel/eeh.c
> > +++ b/arch/powerpc/kernel/eeh.c
> > @@ -1206,28 +1206,7 @@ void eeh_add_device_late(struct pci_dev *dev)
> > eeh_edev_dbg(edev, "Device already referenced!\n");
> > return;
> > }
> > -
> > - /*
> > - * The EEH cache might not be removed correctly because of
> > - * unbalanced kref to the device during unplug time, which
> > - * relies on pcibios_release_device(). So we have to remove
> > - * that here explicitly.
> > - */
> > - if (edev->pdev) {
> > - eeh_rmv_from_parent_pe(edev);
> > - eeh_addr_cache_rmv_dev(edev->pdev);
> > - eeh_sysfs_remove_device(edev->pdev);
> > -
> > - /*
> > - * We definitely should have the PCI device removed
> > - * though it wasn't correctly. So we needn't call
> > - * into error handler afterwards.
> > - */
> > - edev->mode |= EEH_DEV_NO_HANDLER;
> > -
> > - edev->pdev = NULL;
> > - dev->dev.archdata.edev = NULL;
> > - }
> > + WARN_ON_ONCE(edev->pdev);
> >
> > if (eeh_has_flag(EEH_PROBE_MODE_DEV))
> > eeh_ops->probe(pdn, NULL);
>
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