Hi all, This series updates the drv-net XDP program used by the new xdp.py selftest to use the bpf_dynptr APIs for packet access. The selftest itself is unchanged. The original program accessed packet headers directly via ctx->data/data_end, implicitly assuming headers are always in the linear region. That assumption is incorrect for multi-buffer XDP and does not hold across all drivers. For example, mlx5 with striding RQ can leave the linear area empty, causing the multi-buffer cases to fail. Switching to bpf_xdp_load/store_bytes would work but always incurs copies. Instead, this series adopts bpf_dynptr, which provides safe, verifier-checked access across both linear and fragmented areas while avoiding copies. Amery Hung has also proposed a series [1] that addresses the same issues in the program, but through the use of bpf_xdp_pull_data. My series is not intended as a replacement for that work, but rather as an exploration of another viable solution, each of which may be preferable under different circumstances. In cases where the program does not return XDP_PASS, I believe dynptr has an advantage since it avoids an extra copy. Conversely, when the program returns XDP_PASS, bpf_xdp_pull_data may be preferable, as the copy will be performed in any case during skb creation. It may make sense to split the work into two separate programs, allowing us to test both solutions independently. Alternatively, we can consider a combined approach, where the more fitting solution is applied for each use case. I welcome feedback on which direction would be most useful. [1] https://lore.kernel.org/all/20250905173352.3759457-1-ameryhung@xxxxxxxxx/ Thanks! Nimrod Nimrod Oren (5): selftests: drv-net: Test XDP_TX with bpf_dynptr selftests: drv-net: Test XDP tail adjustment with bpf_dynptr selftests: drv-net: Test XDP head adjustment with bpf_dynptr selftests: drv-net: Adjust XDP header data with bpf_dynptr selftests: drv-net: Check XDP header data with bpf_dynptr .../selftests/net/lib/xdp_native.bpf.c | 219 ++++++++---------- 1 file changed, 96 insertions(+), 123 deletions(-) -- 2.45.0
