Re: [PATCH v12 10/15] PCI/ERR: Limit AER resets in pcie_do_recovery()

[Kelley, Sean V]

Hi Bjorn,


> On Dec 2, 2020, at 1:27 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> 
> On Wed, Dec 02, 2020 at 08:53:54PM +0000, Kelley, Sean V wrote:
>>> On Nov 30, 2020, at 4:25 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>>> On Mon, Nov 30, 2020 at 07:54:37PM +0000, Kelley, Sean V wrote:
> 
>>>> -	if (pcie_aer_is_native(bridge))
>>>> -		pcie_clear_device_status(bridge);
>>>> -	pci_aer_clear_nonfatal_status(bridge);
>>>> 
>>>> +	if (type == PCI_EXP_TYPE_ROOT_PORT ||
>>>> +	    type == PCI_EXP_TYPE_DOWNSTREAM ||
>>>> +	    type == PCI_EXP_TYPE_RC_EC) {
>>>> +		if (pcie_aer_is_native(bridge))
>>>> +			pcie_clear_device_status(bridge);
>>>> +		pci_aer_clear_nonfatal_status(bridge);
>>>> +	}
> 
> Back to this specific hunk, what if we made it this?
> 
>  struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
> 
>  if (host->native_aer || pcie_ports_native) {
>    pcie_clear_device_status(bridge);
>    pci_aer_clear_nonfatal_status(bridge);
>  }
> 
> Previously, if "bridge" didn't have an AER Capability, we didn't
> pcie_clear_device_status().  In the case of a DPC bridge without AER,
> I think we *should* call pcie_clear_device_status().

Agree, I was overlooking DPC here with the AER check.

> 
> Otherwise, I think this should work the same and would be a little
> simpler.

Looks fine to me.  It simplifies it a bit.

> 
>>> It seems like there are basically two devices of interest in
>>> pcie_do_recovery(): the endpoint where we have to call the driver
>>> error recovery, and the port that generated the interrupt.  I wonder
>>> if this would make more sense if the caller passed both of them in
>>> explicitly instead of having pcie_do_recovery() check the type of
>>> "dev" and try to figure things out after the fact.
>> 
>> On this last point I wanted to add that this is a possibility that
>> could provide a clearer distinction, especially where actions need
>> to be taken or not taken as a part of pcie_do_recovery(), i.e.,
>> bridge versus dev.  In this patch series we have taken steps to
>> minimize the need for the distinction by pushing the awareness into
>> the driver’s error recovery routine, i.e., dev->rcec.  A future
>> evolution after this series could lead to both devices of interest
>> being passed explicitly for the larger scope EDR/DPC/AER/etc.
> 
> Yeah, not worth doing in *this* series.
> 
> Bjorn

Thanks,

Sean