Re: 4.19: udpgso_bench_tx: setsockopt zerocopy: Unknown error 524

[David Miller]

From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 18 Jun 2019 19:15:16 +0200

> On Tue, Jun 18, 2019 at 09:47:59AM -0700, David Miller wrote:
>> From: Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx>
>> Date: Tue, 18 Jun 2019 12:37:33 -0400
>> 
>> > Specific to the above test, I can add a check command testing
>> > setsockopt SO_ZEROCOPY  return value. AFAIK kselftest has no explicit
>> > way to denote "skipped", so this would just return "pass". Sounds a
>> > bit fragile, passing success when a feature is absent.
>> 
>> Especially since the feature might be absent because the 'config'
>> template forgot to include a necessary Kconfig option.
> 
> That is what the "skip" response is for, don't return "pass" if the
> feature just isn't present.  That lets people run tests on systems
> without the config option enabled as you say, or on systems without the
> needed userspace tools present.

Ok I see how skip works, thanks for explaining.

It would just be nice if it could work in a way such that we could
distinguish "too old kernel for feature" from "missing Kconfig symbol
in selftest config template". :-)