Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230808134049.1407498-1-leitao@debian.org> <ZNJ8zGcYClv/VCwG@google.com>
 <ZNNfK5e+lc0tsjj/@gmail.com>
In-Reply-To: <ZNNfK5e+lc0tsjj/@gmail.com>
From:   Stanislav Fomichev <sdf@google.com>
Date:   Wed, 9 Aug 2023 09:26:52 -0700
Message-ID: <CAKH8qBvw86nb50h2ha77La9WVpBE3Ln7a00YTnQST0KyROmvqQ@mail.gmail.com>
Subject: Re: [PATCH v2 0/8] io_uring: Initial support for {s,g}etsockopt commands
To:     Breno Leitao <leitao@debian.org>
Cc:     axboe@kernel.dk, asml.silence@gmail.com,
        willemdebruijn.kernel@gmail.com, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        io-uring@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, Aug 9, 2023 at 2:41=E2=80=AFAM Breno Leitao <leitao@debian.org> wro=
te:
>
> On Tue, Aug 08, 2023 at 10:35:08AM -0700, Stanislav Fomichev wrote:
> > On 08/08, Breno Leitao wrote:
> > > This patchset adds support for getsockopt (SOCKET_URING_OP_GETSOCKOPT=
)
> > > and setsockopt (SOCKET_URING_OP_SETSOCKOPT) in io_uring commands.
> > > SOCKET_URING_OP_SETSOCKOPT implements generic case, covering all leve=
ls
> > > nad optnames. On the other hand, SOCKET_URING_OP_GETSOCKOPT just
> > > implements level SOL_SOCKET case, which seems to be the
> > > most common level parameter for get/setsockopt(2).
> > >
> > > struct proto_ops->setsockopt() uses sockptr instead of userspace
> > > pointers, which makes it easy to bind to io_uring. Unfortunately
> > > proto_ops->getsockopt() callback uses userspace pointers, except for
> > > SOL_SOCKET, which is handled by sk_getsockopt(). Thus, this patchset
> > > leverages sk_getsockopt() to imlpement the SOCKET_URING_OP_GETSOCKOPT
> > > case.
> > >
> > > In order to support BPF hooks, I modified the hooks to use  sockptr, =
so,
> > > it is flexible enough to accept user or kernel pointers for
> > > optval/optlen.
> > >
> > > PS1: For getsockopt command, the optlen field is not a userspace
> > > pointers, but an absolute value, so this is slightly different from
> > > getsockopt(2) behaviour. The new optlen value is returned in cqe->res=
.
> > >
> > > PS2: The userspace pointers need to be alive until the operation is
> > > completed.
> > >
> > > These changes were tested with a new test[1] in liburing. On the BPF
> > > side, I tested that no regression was introduced by running "test_pro=
gs"
> > > self test using "sockopt" test case.
> > >
> > > [1] Link: https://github.com/leitao/liburing/blob/getsock/test/socket=
-getsetsock-cmd.c
> > >
> > > RFC -> V1:
> > >     * Copy user memory at io_uring subsystem, and call proto_ops
> > >       callbacks using kernel memory
> > >     * Implement all the cases for SOCKET_URING_OP_SETSOCKOPT
> >
> > I did a quick pass, will take a close look later today. So far everythi=
ng makes
> > sense to me.
> >
> > Should we properly test it as well?
> > We have tools/testing/selftests/bpf/prog_tests/sockopt.c which does
> > most of the sanity checks, but it uses regular socket/{g,s}etsockopt
> > syscalls.
>
> Right, that is what I've been using to test the changes.
>
> > Seems like it should be pretty easy to extend this with
> > io_uring path? tools/testing/selftests/net/io_uring_zerocopy_tx.c
> > already implements minimal wrappers which we can most likely borrow.
>
> Sure, I can definitely do it. Do you want to see the new tests in this
> patchset, or, in a following patches?

Let's keep it in the same series if possible?