On Mon, 25 Aug 2025 12:39:11 -0700 Amery Hung wrote: > Hi all, > > This patchset introduces a new kfunc bpf_xdp_pull_data() to allow > pulling nonlinear xdp data. This may be useful when a driver places > headers in fragments. When an xdp program would like to keep parsing > packet headers using direct packet access, it can call > bpf_xdp_pull_data() to make the header available in the linear data > area. The kfunc can also be used to decapsulate the header in the > nonlinear data, as currently there is no easy way to do this. > > This patchset also tries to fix an issue in the mlx5e driver. The driver > curretly assumes the packet layout to be unchanged after xdp program > runs and may generate packet with corrupted data or trigger kernel warning > if xdp programs calls layout-changing kfunc such as bpf_xdp_adjust_tail(), > bpf_xdp_adjust_head() or bpf_xdp_pull_data() introduced in this set. > > Tested with the added bpf selftest using bpf test_run and also on > mlx5e with the tools/testing/selftests/drivers/net/xdp.py. mlx5e with > striding RQ will produce xdp_buff with empty linear data. > xdp.test_xdp_native_pass_mb would fail to parse the header before this > patchset. > > Grateful for any feedback (especially the driver part). CC: Gal, this is the correct way to resolve the XDP not having headers in the first frag for mlx5.
