[PATCH net-next v5 0/5] selftests: Fix and migrate the XDP feature test

This series fixes the XDP feature test and moves it to drivers/net/hw.
The tester uses AF_PACKET, so the remote host does not need native XDP.
Existing remote XDP programs and offload settings are left unchanged.

Changes since v4:
- Rebase onto net-next 8df0638138d3.
- Split the helper fixes, packet probes, build rules and framework move
  into five patches.
- Move the common BPF rules, including %.skel.h, into net/bpf.mk.
- Use installed kernel headers and register the helper in TEST_GEN_FILES.
- Handle short control messages, EOF and helper timeouts. Use XDP links
  on the DUT to release the test's attachment when the process exits.
- Skip unsupported native XDP and veth XDP_TX without a peer XDP program.

Tested on x86_64 Ubuntu with Linux 6.8.0-124-generic:
- headers_install and the xdp_features build passed.
- Three veth setups: 17 PASS, 1 expected XDP_TX SKIP, no failures.
- Nine error and cleanup checks passed. Existing programs and offload
  settings were unchanged, with no helpers or namespaces left behind.
- Patch 2: two concurrent runs passed all six cases each; repeated TERM
  also left no helpers or namespaces.
- Protocol framing checks, Ruff, pylint and git diff --check passed.

These tests used veth devices. Physical-NIC testing remains unverified.

Previous version:
https://lore.kernel.org/all/20260921-xdp-features-v4-send-v4-0-a0d4ec392cb7@gmail.com/ (local)

Signed-off-by: Bochao Cao <redacted>

---
Bochao Cao (5):
      selftests/bpf: Fix XDP feature test setup and teardown
      selftests/bpf: Track XDP test processes and isolate namespaces
      selftests/bpf: Send XDP feature probes with AF_PACKET
      selftests/net: Add a shared BPF skeleton rule
      selftests/net: Move the XDP feature test to drivers/net/hw

 tools/testing/selftests/bpf/Makefile               |   11 +-
 tools/testing/selftests/bpf/test_xdp_features.sh   |  107 ---
 tools/testing/selftests/bpf/xdp_features.c         |  719 --------------
 tools/testing/selftests/drivers/net/README.rst     |   18 +
 tools/testing/selftests/drivers/net/hw/.gitignore  |    3 +
 tools/testing/selftests/drivers/net/hw/Makefile    |   15 +-
 tools/testing/selftests/drivers/net/hw/config      |    3 +
 .../net/hw/xdp_features.bpf.c}                     |   42 +-
 .../selftests/drivers/net/hw/xdp_features.c        | 1003 ++++++++++++++++++++
 .../{bpf => drivers/net/hw}/xdp_features.h         |    1 +
 .../selftests/drivers/net/hw/xdp_features.py       |  137 +++
 tools/testing/selftests/net/bpf.mk                 |   25 +
 12 files changed, 1212 insertions(+), 872 deletions(-)
---
base-commit: 8df0638138d3e0344fd1fb36cf2d1ca1cf5028f0
change-id: 20261008-xdp-v5-send-20261008-301d0e1d3165

Best regards,
--  
Bochao Cao [off-list ref]