Re: [PATCH v6 05/10] PCI/AER: Apply function level reset to RCiEP on fatal error

[Sean V Kelley]

On 25 Sep 2020, at 14:58, Bjorn Helgaas wrote:

> On Tue, Sep 22, 2020 at 02:38:54PM -0700, Sean V Kelley wrote:
> > From: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
> >
> > Attempt to do function level reset for an RCiEP associated with an
> > RCEC device on fatal error.
> >
> > Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
> > ---
> >  drivers/pci/pcie/err.c | 31 ++++++++++++++++++++++---------
> >  1 file changed, 22 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> > index e575fa6cee63..5380ecc41506 100644
> > --- a/drivers/pci/pcie/err.c
> > +++ b/drivers/pci/pcie/err.c
> > @@ -169,6 +169,17 @@ static void pci_bridge_walk(struct pci_dev 
> > *bridge, int (*cb)(struct pci_dev *,
> >  		cb(bridge, userdata);
> >  }
> >
> > +static pci_ers_result_t flr_on_rciep(struct pci_dev *dev)
> > +{
> > +	if (!pcie_has_flr(dev))
> > +		return PCI_ERS_RESULT_NONE;
> > +
> > +	if (pcie_flr(dev))
> > +		return PCI_ERS_RESULT_DISCONNECT;
> > +
> > +	return PCI_ERS_RESULT_RECOVERED;
> > +}
>
> Either we reset the device or we didn't; there is no third option.
>
> If I read it correctly, nothing in pcie_do_recovery() cares about the
> difference between PCI_ERS_RESULT_NONE and PCI_ERS_RESULT_DISCONNECT.
> The status does get returned, but only edr_handle_event() looks at it,
> and it doesn't care about the difference either.
>
> So I think this should just return PCI_ERS_RESULT_RECOVERED or
> PCI_ERS_RESULT_DISCONNECT.

You raise a good point. As currently implemented, the usage requires 
either a reset or not result. Will change.

Thanks,

Sean

> >  pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> >  			pci_channel_state_t state,
> >  			pci_ers_result_t (*reset_subordinate_devices)(struct pci_dev 
> > *pdev))
> > @@ -195,15 +206,17 @@ pci_ers_result_t pcie_do_recovery(struct 
> > pci_dev *dev,
> >  	if (state == pci_channel_io_frozen) {
> >  		pci_bridge_walk(bridge, report_frozen_detected, &status);
> >  		if (type == PCI_EXP_TYPE_RC_END) {
> > -			pci_warn(dev, "link reset not possible for RCiEP\n");
> > -			status = PCI_ERS_RESULT_NONE;
> > -			goto failed;
> > -		}
> > -
> > -		status = reset_subordinate_devices(bridge);
> > -		if (status != PCI_ERS_RESULT_RECOVERED) {
> > -			pci_warn(dev, "subordinate device reset failed\n");
> > -			goto failed;
> > +			status = flr_on_rciep(dev);
> > +			if (status != PCI_ERS_RESULT_RECOVERED) {
> > +				pci_warn(dev, "function level reset failed\n");
> > +				goto failed;
> > +			}
> > +		} else {
> > +			status = reset_subordinate_devices(bridge);
> > +			if (status != PCI_ERS_RESULT_RECOVERED) {
> > +				pci_warn(dev, "subordinate device reset failed\n");
> > +				goto failed;
> > +			}
> >  		}
> >  	} else {
> >  		pci_bridge_walk(bridge, report_normal_detected, &status);
> > --
> > 2.28.0