[PATCH net-next v5 0/2] seg6: skip route refcounts in seg6local lookups

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

seg6local looks up the nexthop of its IPv6 and IPv4 behaviors from the
RCU read-side section of the receive path, yet takes and drops a route
reference for every packet.  Skip the reference, as ip6_route_input()
and ip_rcv_finish() do.

An LLM coding assistant helped write and test this series.

---
Changes in v5:
- Rebase onto net-next after the merge window; no other changes.
- Link to v4: https://patch.msgid.link/20261023-seg6-lookup-noref-v4-0-0ad0a83960ef@gmail.com

Changes in v4:
- Take no reference on ip6_blk_hole_entry after a noref lookup,
  including for a missing table.  An End whose next segment is a local
  address took one for every packet (Andrea Mayer).
- Comment that the noref helpers need RCU held until dst_input()
  (Andrea Mayer, Sashiko).
- Link to v3: https://patch.msgid.link/20261015-seg6-lookup-noref-v3-0-6d51a60a67d3@gmail.com

Changes in v3:
- Keep the refcounted lookup in seg6_lookup_nexthop() and give
  seg6_lookup_any_nexthop() a noref argument instead, so the BPF LWT
  helpers see no change while a route is released (Andrea Mayer,
  Gabriel Goller, Sashiko).
- Mention NFQUEUE reinjection and the release race in the commit
  messages (Andrea Mayer).
- Link to v2: https://patch.msgid.link/20261010-seg6-lookup-noref-v2-0-51c09dd98197@gmail.com

Changes in v2:
- Split the lookup into a noref primitive for the seg6local input
  actions and a refcounted seg6_lookup_nexthop() wrapper, which the BPF
  LWT helpers also call (Andrea Mayer, Sashiko).
- Rebase onto net-next and re-measure.
- Link to v1: https://patch.msgid.link/20261005-seg6-lookup-noref-v1-0-092e84774e80@gmail.com

---
Yuya Kusakabe (2):
      seg6: skip the route refcount in seg6local IPv6 lookups
      seg6: skip the route refcount in seg6local IPv4 lookups

 net/ipv6/seg6_local.c | 59 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 41 insertions(+), 18 deletions(-)
---
base-commit: 7b6ab4dbc156e2f96419715130b3d5738a306c93
change-id: 20261004-seg6-lookup-noref-e016495b60ed

Best regards,
--  
Yuya Kusakabe <yuya.kusakabe@gmail.com>