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

Jan Blunck jblunck at infradead.org
Fri Oct 6 19:34:46 CEST 2017

On Fri, Oct 6, 2017 at 3:37 PM, Thomas Monjalon <thomas at monjalon.net> wrote:
> 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 at nxp.com> wrote:
>> >>> Tested-by: Hemant Agrawal <hemant.agrawal at 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.

Correct. Also there is no way to handle that failure except for
reporting it to the log in all detail.

>> 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.

Hide scan failures? Do you mean hiding it from the log? I wouldn't do that.

> I would return an error code if any of the scan has failed,
> but would process every scans.

FWIW I agree.

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