Re: [PATCH] net/tls: Fix return values for setsockopt

[Willem de Bruijn]

On Tue, Dec 3, 2019 at 6:08 PM Jakub Kicinski
<jakub.kicinski@xxxxxxxxxxxxx> wrote:
>
> On Tue,  3 Dec 2019 23:44:58 +0100, Valentin Vidic wrote:
> > ENOTSUPP is not available in userspace:
> >
> >   setsockopt failed, 524, Unknown error 524
> >
> > Signed-off-by: Valentin Vidic <vvidic@xxxxxxxxxxxxxxxxxxxxxx>
>
> I'm not 100% clear on whether we can change the return codes after they
> had been exposed to user space for numerous releases..

This has also come up in the context of SO_ZEROCOPY in the past. In my
opinion the answer is no. A quick grep | wc -l in net/ shows 99
matches for this error code. Only a fraction of those probably make it
to userspace, but definitely more than this single case.

If anything, it may be time to define it in uapi?

>
>
> But if we can - please fix the tools/testing/selftests/net/tls.c test
> as well, because it expects ENOTSUPP.

Even if changing the error code, EOPNOTSUPP is arguably a better
replacement. The request itself is valid. Also considering forward
compatibility.