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: <168130333143.150247.11159481574477358816.stgit@firesoul>
 <168130336725.150247.12193228778654006957.stgit@firesoul> <ZDbiofWhQhFEfIsr@google.com>
 <34152b76-88c8-0848-9f30-bd9755b1ee25@redhat.com>
In-Reply-To: <34152b76-88c8-0848-9f30-bd9755b1ee25@redhat.com>
From:   Stanislav Fomichev <sdf@google.com>
Date:   Wed, 12 Apr 2023 10:56:14 -0700
Message-ID: <CAKH8qBub-b0R42k-J=3gyvKeWVDBy7DoxQCn7GAynEDB8z9rbw@mail.gmail.com>
Subject: Re: [PATCH bpf V8 2/7] selftests/bpf: Add counters to xdp_hw_metadata
To:     Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc:     brouer@redhat.com, bpf@vger.kernel.org,
        =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        martin.lau@kernel.org, ast@kernel.org, daniel@iogearbox.net,
        alexandr.lobakin@intel.com, larysa.zaremba@intel.com,
        xdp-hints@xdp-project.net, anthony.l.nguyen@intel.com,
        yoong.siang.song@intel.com, boon.leong.ong@intel.com,
        intel-wired-lan@lists.osuosl.org, pabeni@redhat.com,
        jesse.brandeburg@intel.com, kuba@kernel.org, edumazet@google.com,
        john.fastabend@gmail.com, hawk@kernel.org, davem@davemloft.net,
        tariqt@nvidia.com, saeedm@nvidia.com, leon@kernel.org,
        linux-rdma@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, Apr 12, 2023 at 10:52=E2=80=AFAM Jesper Dangaard Brouer
<jbrouer@redhat.com> wrote:
>
>
> On 12/04/2023 18.56, Stanislav Fomichev wrote:
> > On 04/12, Jesper Dangaard Brouer wrote:
> >> Add counters for skipped, failed and redirected packets.
> >> The xdp_hw_metadata program only redirects UDP port 9091.
> >> This helps users to quickly identify then packets are
> >> skipped and identify failures of bpf_xdp_adjust_meta.
> >>
> >> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> >> ---
> >>   .../testing/selftests/bpf/progs/xdp_hw_metadata.c  |   15 ++++++++++=
+++--
> >>   tools/testing/selftests/bpf/xdp_hw_metadata.c      |    4 +++-
> >>   2 files changed, 16 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/too=
ls/testing/selftests/bpf/progs/xdp_hw_metadata.c
> >> index b0104763405a..a07ef7534013 100644
> >> --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> >> +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> >> @@ -25,6 +25,10 @@ struct {
> >>      __type(value, __u32);
> >>   } xsk SEC(".maps");
> >>
> >> +volatile __u64 pkts_skip =3D 0;
> >> +volatile __u64 pkts_fail =3D 0;
> >> +volatile __u64 pkts_redir =3D 0;
> >> +
> >>   extern int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx,
> >>                                       __u64 *timestamp) __ksym;
> >>   extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx,
> >> @@ -59,16 +63,21 @@ int rx(struct xdp_md *ctx)
> >>                      udp =3D NULL;
> >>      }
> >>
> >> -    if (!udp)
> >> +    if (!udp) {
> >> +            pkts_skip++;
> >>              return XDP_PASS;
> >> +    }
> >>
> >>      /* Forwarding UDP:9091 to AF_XDP */
> >> -    if (udp->dest !=3D bpf_htons(9091))
> >> +    if (udp->dest !=3D bpf_htons(9091)) {
> >> +            pkts_skip++;
> >>              return XDP_PASS;
> >> +    }
> >>
> >>      ret =3D bpf_xdp_adjust_meta(ctx, -(int)sizeof(struct xdp_meta));
> >>      if (ret !=3D 0) {
> >
> > [..]
> >
> >>              bpf_printk("bpf_xdp_adjust_meta returned %d", ret);
> >
> > Maybe let's remove these completely? Merge patch 1 and 2, remove printk=
,
> > add counters. We can add more counters in the future if the existing
> > ones are not enough.. WDYT?
> >
>
> Sure, lets just remove all of the bpf_printk, and add these counter inste=
ad.
> Rolling V9.
>
> >> +            pkts_fail++;
>
> This fail counter should be enough for driver devel to realize that they
> also need to implement/setup XDP metadata pointers correctly (for
> bpf_xdp_adjust_meta to work).

Agreed. As long as we have a clear signal "something's not working"
(instead of failing silently), that should be enough to get to the
bottom of it..

> >>              return XDP_PASS;
> >>      }
>