Re: [PATCH v2 5/7] seg6: add End.M.GTP6.D.Di behavior

[Yuya Kusakabe <yuya.kusakabe@gmail.com>]

Hi Andrea,

Thank you for the review.

> The patch 4 review applies here, except for the parts where Section 6.4 is
> implemented instead of Section 6.3 (which is incorrectly implemented in
> patch 4).

Answered in the patch 4 reply: the next version of End.M.GTP6.D will
implement Section 6.3 (Args.Mob.Session stamped into SRH[0], no
preserved D), leaving the original-DA preservation exclusive to this
drop-in variant.

> input_action_end_m_gtp6_d_di() and its finish callback are largely
> identical to the patch 4 functions (input_action_end_m_gtp6_d() and its
> finish): the SRH check, GTP-U dispatch, outer strip, inner protocol
> detection, and NF_HOOK invocation are identical. The duplication should be
> reduced via shared helpers.

Will do. The plan is one decap helper (SRH check, GTP-U dispatch,
outer strip, inner protocol detection) shared between End.M.GTP6.D and
End.M.GTP6.D.Di, and one SRv6-push helper (including the GSO offload
setup) shared with H.M.GTP4.D as well, with the GTP-U parser common to
all of them. The D.Di handler then reduces to the prepended-slot
handling specific to the drop-in variant. (The NF_HOOK invocation goes
away in the initial series per the cover letter thread.)

> D.Di does not use teid or qfi, so these variables and the (void) casts are
> dead code and should be avoided. For example, seg6_mobile_parse_gtpu() could
> accept NULL for teid and qfi so callers that do not need them can pass NULL
> directly.

Will do exactly that: the GTP-U parser (and the decap helper above)
will accept NULL for teid/qfi, and the drop-in variant will pass NULL.

Thanks,
Yuya