Re: [dpdk-dev] [PATCH] eal: bus scan and probe never fail

[Thomas Monjalon <thomas@monjalon.net>]

06/10/2017 15:12, Shreyansh Jain:
> On Friday 06 October 2017 04:51 AM, Thomas Monjalon wrote:
> > 19/09/2017 20:51, Jan Blunck:
> >> On Mon, Sep 18, 2017 at 1:36 PM, Hemant Agrawal <hemant.agrawal@nxp.com> wrote:
> >>> Tested-by: Hemant Agrawal <hemant.agrawal@nxp.com>
> >>>
> >>>
> >>> On 8/12/2017 3:52 PM, Shreyansh Jain wrote:
> >>>>
> >>>> Bus scan is responsible for finding devices over *all* buses.
> >>>> Some of these buses might not be able to scan but that should
> >>>> not prevent other buses to be scanned.
> >>>>
> >>
> >> If scanning the bus fails this is signaling an error. In that case we
> >> might even want to unregister the bus.
> > 
> > A scan error seems important enough to be reported to the caller.
> > OK to continue scanning other buses, but an error code should be returned.
> 
> Isn't that counter intuitive if the scanning continues after error and 
> an error is expected to be returned from it?
> What if there are more than one error? Which one is reported.

Both are reported with the same code.
Anyway, there is no way to know which bus is failing,
except from log.

> As for cleanup, bus un-registration is not correct. Scan has failed, 
> which might mean some assumption that bus took for scanning for devices 
> doesn't exist for time being or present platform. Either way, I think 
> whatever rollback needs to be done for scan failure, would be done by 
> the bus->scan() implementation.
> 
> Let me know what you think - I will make changes to the patch and push 
> again.

We may need more opinion here.

Mine is that we should not hide a scan failure.
I would return an error code if any of the scan has failed,
but would process every scans.