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

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Message-ID: <CA+FuTSdhtGZtTnuncpYaoOROF7L=coGawCPSLv7jzos2Q+Tb=Q@mail.gmail.com>
Date:   Wed, 4 Dec 2019 15:43:00 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Valentin Vidic <vvidic@...entin-vidic.from.hr>,
        Boris Pismenny <borisp@...lanox.com>,
        Aviad Yehezkel <aviadye@...lanox.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net/tls: Fix return values for setsockopt

On Wed, Dec 4, 2019 at 2:36 PM Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
>
> (there is a v2, in case you missed)

Thanks. I meant to respond to your comment. (but should have done sooner :)

> On Wed, 4 Dec 2019 14:22:55 -0500, Willem de Bruijn wrote:
> > On Tue, Dec 3, 2019 at 6:08 PM Jakub Kicinski 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@...entin-vidic.from.hr>
> > >
> > > 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?
>
> No opinion but FWIW I'm toying with some CI for netdev, I've added a
> check for use of ENOTSUPP, apparently checkpatch already sniffs out
> uses of ENOSYS, so seems appropriate to add this one.

Good idea if not exposing this 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.
>
> For the case TLS version case?

Yes. It's a more specific signal. Quite a few error paths already return EINVAL.