Re: [PATCH v13 0/6] Address error and recovery for AER and DPC

[poza]

On 2018-04-16 18:57, Bjorn Helgaas wrote:
> On Mon, Apr 16, 2018 at 11:33:13AM +0530, poza@xxxxxxxxxxxxxx wrote:
> > On 2018-04-16 09:23, Sinan Kaya wrote:
> > > On 4/15/2018 11:16 PM, Bjorn Helgaas wrote:
> > > > On Mon, Apr 09, 2018 at 10:41:48AM -0400, Oza Pawandeep wrote:
> > > > > This patch set brings in error handling support for DPC
> > > > >
> > > > > The current implementation of AER and error message broadcasting
> > > > > to the
> > > > > EP driver is tightly coupled and limited to AER service driver.
> > > > > It is important to factor out broadcasting and other link handling
> > > > > callbacks. So that not only when AER gets triggered, but also
> > > > > when DPC get
> > > > > triggered (for e.g. ERR_FATAL), callbacks are handled appropriately.
> > > > >
> > > > > DPC should behave identical to AER as far as error handling is
> > > > > concerned.
> > > > > DPC should remove the devices and not to do recovery for hotplug
> > > > > enabled system.
> > > >
> > > > Is there a specific bug that's fixed by these patches?  I didn't see
> > > > one mentioned in the changelogs.
> > > >
> > >
> > > There is no actual bug.
> > >
> > > We realized that DPC and hotplug is heavily integrated today. We
> > > have use cases for systems without hotplug support but still
> > > support DPC. That's the problem we are trying to solve with this
> > > patchset.
>
> Apparently there's a problem with systems that have DPC but not
> hotplug.  It will be extremely helpful if you can articulate what that
> problem is and include it in the appropriate changelog.
>
> > Adding to what Sinan said;
> >
> > DPC should handle the error handling and recovery similar to AER,
> > because finally both are attempting recovery in some or the other
> > way, and for that error handling and recovery framework has to be
> > loosely coupled.  It achieves uniformity and transparency to the
> > error handling agents such as AER, DPC, with respect to recovery and
> > error handling.
> >
> > So, this patch-set tries to unify lot of things between error agents
> > and make them behave in a well defined way. (be it error (FATAL,
> > NON_FATAL) handling or recovery).
>
> I totally support this objective.

Thanks Bjorn, I will include this objective in Changelog along with 
Sinan's text.
I am not clear on one last thing Bjorn; which is;
do we need last patch ? patch-6 which handles hotplug case.
Also I think we could take this patch-set as basic changes/attempt to 
unify the code which it does.

And, in the next follow-up patches we can improve upon the things such 
as,
whether to do different actions for FATAL cases and NON_FATAL cases. And 
then I can make needed changes to AER and DPC
Please let me know how this sounds.

> Bjorn