[PATCH] mbuf: dump Tx offload metadata

[David Marchand]

On Fri, 31 Oct 2025 at 15:29, Morten Brørup <mb at smartsharesystems.com> wrote:
>
> > From: David Marchand [mailto:david.marchand at redhat.com]
> > Sent: Friday, 31 October 2025 15.08
> >
> > On Fri, 31 Oct 2025 at 14:28, Morten Brørup <mb at smartsharesystems.com>
> > wrote:
> > > Printing of outer_l2_len and outer_l3_len could be omitted if not
> > present, like the VLAN IDs, e.g.:
> > >
> > > fprintf(f, "  ");
> > > if (m->outer_l2_len != 0)
> > >         fprintf(f, "outer_l2_len=%u, ", m->outer_l2_len);
> > > if (m->outer_l3_len != 0)
> > >         fprintf(f, "outer_l3_len=%u, ", m->outer_l3_len);
> > > fprintf(f, "l2_len=%u, l3_len=%u, l4_len=%u, tso_segsz=%u\n",
> > >         m->l2_len, m->l3_len, m->l4_len, m->tso_segsz);
> >
> > Mm, why specifically those two only?
> > If the intention is to make this debug output shorter, I would apply
> > the same to all those fields, and omit the whole (new) line if no
> > field is set.
>
> The intention is not do make the output shorter, but to reduce the amount of "noise" (useless data) in the output.
> My suggestion omits noise for non-tunneled packets.
>
> Maybe tso_segsz could be conditional on non-zero too.
>
> It depends on what the user/developer is debugging, whether l2/l3/l4_len are considered noise. I don't object to making them conditional too, if you prefer.
>
> Anyway, I just realized that the tx_offload field is not cleared on RX, so the discussed zero-check is useless (checking uninitialized data) when dumping an mbuf at an early stage in the application's packet processing pipeline.
> I have an idea to get around this... The TX flags in ol_flags are cleared at RX, so we can consider tx_offload uninitialized until one of the TX flags in ol_flags has been set.

LGTM, it is stated that those fields are for Tx offloads.
I'll post a v2.


-- 
David Marchand