linux-kernel - Re: [PATCH v13 6/6] PCI/DPC: Do not do recovery for hotplug enabled system

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Date:   Mon, 16 Apr 2018 22:45:19 +0530
From:   poza@...eaurora.org
To:     Sinan Kaya <okaya@...eaurora.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Keith Busch <keith.busch@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dongdong Liu <liudongdong3@...wei.com>,
        Wei Zhang <wzhang@...com>, Timur Tabi <timur@...eaurora.org>,
        Alex Williamson <alex.williamson@...hat.com>
Subject: Re: [PATCH v13 6/6] PCI/DPC: Do not do recovery for hotplug enabled
 system

On 2018-04-16 20:16, Sinan Kaya wrote:
> On 4/15/2018 11:17 PM, Bjorn Helgaas wrote:
>> It doesn't seem right to me that we handle both ERR_NONFATAL and
>> ERR_FATAL events differently if we happen to have DPC support in a
>> switch.
>> 
>> Maybe we should consider triggering DPC only on ERR_FATAL?  That would
>> keep DPC out of the ERR_NONFATAL cases.
>> 
> From reliability perspective, it makes sense. DPC handles NONFATAL 
> errors
> by bringing down the link. If error happened behind a switch and root 
> port
> is handling DPC, we are impacting a lot of devices operation because of 
> one
> faulty device.
> 
> Keith, do you have any preference on this direction?
> 
>> For ERR_FATAL, maybe we should bite the bullet and use
>> remove/re-enumerate for AER as well as for DPC.  That would be painful
>> for higher-level software, but if we're willing to accept that pain
>> for new systems that support DPC, maybe life would be better overall
>> if it worked the same way on systems without DPC?
> 
> Sure, we can go to this route as well.


ok so finally this is what is being proposed and so far Bjorn, Sinan and 
myself agreed on following:

I need to move the stop and re-enumerate code into the AER path instead 
of patch #6 for both DPC_FATAL and AER_FATAL error types.
Also, I should turn off DPC NON_FATAL error detection.

Keith, please confirm if you are okay with above proposal.

Regards,
Oza.