On Wed, 3 Jul 2024 14:27:58 +0200 Sebastian Andrzej Siewior wrote: > During the introduction of struct bpf_net_context handling for > XDP-redirect, the tun driver has been missed. > > Set the bpf_net_context before invoking BPF XDP program within the TUN > driver. Sorry if I'm missing the point but I think this is insufficient. You've covered the NAPI-like entry point to the Rx stack in your initial work, but there's also netif_receive_skb() which drivers may call outside of NAPI, simply disabling BH before the call. The only concern in that case is that we end up in do_xdp_generic(), and there's no bpf_net_set_ctx() anywhere on the way. So my intuition would be to add the bpf_net_set_ctx() inside the if(xdp_prog) in do_xdp_generic(). "XDP generic" has less stringent (more TC-like) perf requirements, so setting context once per packet should be fine. And it will also cover drivers like TUN which use both netif_receive_skb() and call do_xdp_generic(), in a single place.
