[PATCH net v4 0/4] net: hsr: fix GRO/GSO super-packet handling

[Xin Xie <xiexinet@gmail.com>]

HSR/PRP requires per-wire-frame tags/RCTs and sequence numbers, and
duplicate discard is per frame. RX GRO and TX GSO can present
multiple frames as one skb and violate that assumption: a super-skb
is either rejected by a constrained lower device, or forwarded
without valid per-frame trailers and sequence numbers.

Patch 1 adds netif_disable_gro()/dev_disable_gro() and disables
GRO and GRO_HW on lower devices at HSR/PRP enslavement time,
mirroring the existing LRO treatment.

Patch 2 shrinks hsr->seqnr_lock from whole hsr_forward_skb() calls
to the sequence counter updates, so the segmentation work of
patch 3 never runs under the global sequence lock. The outer lock
also incidentally serialized the tx statistics updates in
hsr_forward_skb(); those now use the atomic DEV_STATS_* helpers.

Patch 3 unfolds the remaining GSO super-packets at the forward
entry with the top-level GSO dispatch (__skb_gso_segment()), so
each wire frame gets its own tag and sequence number. The HSR
master also drops NETIF_F_GSO_MASK from its advertised features so
locally generated traffic is segmented as early as possible.

Patch 1 provides the normal setup-time default. Patch 3 is the
fail-safe when a privileged override or another source still
presents a GSO/GRO super-packet: plain-Ethernet super-packets from
the master or the untagged SAN side are segmented, while
super-packets from tagged LAN ingress are rejected by ingress-port
policy.

Patch 4 adds a kselftest covering the series.

Patch 1 is independent. Patch 3 depends on patch 2, and patches 2
and 3 are selected for stable only on 7.0 and newer, where
sparse-bitmap duplicate discard accepts out-of-order arrival.
Older branches need adapted backports.

Validation:
* the v4 kernel builds cleanly, and W=1 allmodconfig/allyesconfig
  base-vs-patched shows no new warnings;
* hsr_gro_superpacket passes on the v4 kernel and fails on the
  base kernel with the expected mechanism;
* hsr_ping, hsr_redbox, link_faults and prp_ping all pass;
* no kernel WARN/BUG/Oops, no leftover namespaces.

Note on the contest report: the contest conflict is with the
already merged PRP RedBox work.

- In send_prp_supervision_frame(), preserve the Type-30 RedBox-MAC
  TLV and EOT construction, release seqnr_lock immediately after
  the sequence-number update, and remove the later stale unlocks.
- Insert hsr_gro_superpacket.sh at the sorted Makefile position.

This composition builds and both the GRO/GSO and PRP RedBox
selftests pass on the tested net-next tree (69963a0678a3).

---

Changes in v4:
- Patches 2/3: the four tx statistics updates affected by the
  seqnr_lock shrink now use DEV_STATS_*, so they cannot lose
  increments on the concurrently callable forwarding paths.
- Patch 4: three namespace variables are explicitly initialized
  (empty), clearing the ShellCheck SC2154 findings.
- Patch 1 is payload-identical to v3 and carries Ali Ahmet
  Memis's Reviewed-by and Tested-by from the v3 thread; his
  Reviewed-by is not carried on the modified patches 2-4.

Previous postings (newest first):
v3: https://lore.kernel.org/netdev/20260731090224.18-1-xiexinet@gmail.com/
v2: https://lore.kernel.org/netdev/20260724161253.79-1-xiexinet@gmail.com/
v1: https://lore.kernel.org/netdev/20260722171836.196-1-xiexinet@gmail.com/

Xin Xie (4):
  net: hsr: fix packet drops caused by GRO superpackets
  net: hsr: shrink seqnr_lock to sequence counter updates
  net: hsr: unfold GSO super-packets at the forward entry
  selftests: net: hsr: add GRO super-packet forwarding test

 include/linux/netdevice.h                     |   2 +
 net/core/dev.c                                |  18 +
 net/core/dev_api.c                            |  16 +
 net/hsr/hsr_device.c                          |  17 +-
 net/hsr/hsr_forward.c                         |  59 ++-
 net/hsr/hsr_slave.c                           |  12 +-
 tools/testing/selftests/net/hsr/Makefile      |   1 +
 .../selftests/net/hsr/hsr_gro_superpacket.sh  | 465 ++++++++++++++++++
 8 files changed, 563 insertions(+), 27 deletions(-)
 create mode 100755 tools/testing/selftests/net/hsr/hsr_gro_superpacket.sh

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2.43.0