[PATCH bpf-next v4 0/2] selftests/xsk: Add tests for XDP tail adjustment in AF_XDP

[Tushar Vyavahare <tushar.vyavahare@intel.com>]

This patch series adds tests to validate the XDP tail adjustment
functionality, focusing on its use within the AF_XDP context. The tests
verify dynamic packet size manipulation using the bpf_xdp_adjust_tail()
helper function, covering both single and multi-buffer scenarios.

v1 -> v2:
1. Retain and extend stream replacement: Keep `pkt_stream_replace`
   unchanged. Add `pkt_stream_replace_ifobject` for targeted ifobject
   handling.

2. Consolidate patches: Merge patches 2 to 6 for tail adjustment tests and
   check.

v2 -> v3:
1. Introduce `adjust_value` to replace `count` for clearer communication
   with userspace.

v3 -> v4:
1. Remove `testapp_adjust_tail_common()`. [Maciej]

2. Add comments and modify code for buffer resizing logic in test cases
   (shrink/grow by specific byte sizes for testing purposes). [Maciej]

---
Patch Summary:

1. Packet stream replacement: Add `pkt_stream_replace_ifobject` to manage
   packet streams efficiently.

2. Tail adjustment tests and support check: Implement dynamic packet
   resizing in xskxceiver by adding `xsk_xdp_adjust_tail` and extend this
   functionality to userspace with `testapp_xdp_adjust_tail` for
   validation. Ensure support by adding `is_adjust_tail_supported` to
   verify the availability of `bpf_xdp_adjust_tail()`. Introduce tests for
   shrinking and growing packets using `bpf_xdp_adjust_tail()`, covering
   both single and multi-buffer scenarios when used with AF_XDP.
---

Tushar Vyavahare (2):
  selftests/xsk: Add packet stream replacement function
  selftests/xsk: Add tail adjustment tests and support check

Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>

 .../selftests/bpf/progs/xsk_xdp_progs.c       |  50 ++++++++
 tools/testing/selftests/bpf/xsk_xdp_common.h  |   1 +
 tools/testing/selftests/bpf/xskxceiver.c      | 118 ++++++++++++++++--
 tools/testing/selftests/bpf/xskxceiver.h      |   2 +
 4 files changed, 163 insertions(+), 8 deletions(-)

-- 
2.34.1