Re: [PATCH v11 1/8] PCI/ERR: Update error status after reset_link()

[Kuppuswamy Sathyanarayanan]

On 1/3/20 4:34 PM, Bjorn Helgaas wrote:
> On Thu, Dec 26, 2019 at 04:39:07PM -0800, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
> > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> >
> > Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") uses
> > reset_link() to recover from fatal errors. But, if the reset is
> > successful there is no need to continue the rest of the error recovery
> > checks. Also, during fatal error recovery, if the initial value of error
> > status is PCI_ERS_RESULT_DISCONNECT or PCI_ERS_RESULT_NO_AER_DRIVER then
> > even after successful recovery (using reset_link()) pcie_do_recovery()
> > will report the recovery result as failure. So update the status of
> > error after reset_link().
> I like the part about updating "status" with the result of
> reset_link(), and I split that into its own patch because it
> seems like a fix that *can* be separated.
>
> But I'm not convinced that we should skip the ->slot_reset()
> callbacks if the reset_link() was successful.
If reset_link() call is successful then the result value will be
"PCI_ERS_RESULT_RECOVERED". So even if you proceed with
rest of the code, slot_reset() will never get called right ?
>    According to
> Documentation/PCI/pci-error-recovery.rst, we should call
> ->slot_reset() after completion of the reset.
>
> For example, rsxx_err_handler implements ->slot_reset(), but
> not ->resume().  If we reset the device, we'll claim success and
> return, but we won't call rsxx_slot_reset(), which does a bunch
> of important-looking recovery stuff.
>
> If pci-error-recovery.rst is wrong, we should fix that (after
> auditing all the drivers to make sure they match).
>
> > Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery")
> > Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> > Cc: Keith Busch <keith.busch@xxxxxxxxx>
> > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> > Acked-by: Keith Busch <keith.busch@xxxxxxxxx>
> > ---
> >   drivers/pci/pcie/err.c | 10 +++++++---
> >   1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> > index b0e6048a9208..53cd9200ec2c 100644
> > --- a/drivers/pci/pcie/err.c
> > +++ b/drivers/pci/pcie/err.c
> > @@ -204,9 +204,12 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state,
> >   	else
> >   		pci_walk_bus(bus, report_normal_detected, &status);
> >   
> > -	if (state == pci_channel_io_frozen &&
> > -	    reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED)
> > -		goto failed;
> > +	if (state == pci_channel_io_frozen) {
> > +		status = reset_link(dev, service);
> > +		if (status != PCI_ERS_RESULT_RECOVERED)
> > +			goto failed;
> > +		goto done;
> > +	}
> >   
> >   	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
> >   		status = PCI_ERS_RESULT_RECOVERED;
> > @@ -228,6 +231,7 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state,
> >   	if (status != PCI_ERS_RESULT_RECOVERED)
> >   		goto failed;
> >   
> > +done:
> >   	pci_dbg(dev, "broadcast resume message\n");
> >   	pci_walk_bus(bus, report_resume, &status);
> >   
> > --
> > 2.21.0
--
Sathyanarayanan Kuppuswamy
Linux kernel developer