XDP REDIRECT(9)

✨ xdp redirect ✨

Okay bestie, welcome to xdp redirect(9) from the Kernel API Manual — we're doing kernel networking today, and honestly? It's giving main-character energy 💅.

So XDP_REDIRECT works by a three-step process, implemented in the functions below:

1. The bpf_redirect and bpf_redirect_map helpers will lookup the target of the redirect and store it (along with some other metadata) in a per-CPU struct bpf_redirect_info 🎀.
2. When the program returns the XDP_REDIRECT return code, the driver will call xdp_do_redirect, which will use the information in struct bpf_redirect_info to actually enqueue the frame into a map type-specific bulk queue structure 💖.
3. Before exiting its NAPI poll loop, the driver will call xdp_do_flush, which will flush all the different bulk queues, thus completing the redirect ✨.

⚠️ Important note, bestie: xdp_do_flush must be called before napi_complete_done in the driver, as the XDP_REDIRECT logic relies on being inside a single NAPI instance through to the xdp_do_flush call for RCU protection of all in-kernel data structures 😭. Like, do not mess with that ordering, fr fr.

🔍 SEE ALSO 🔍

• Kernel file ./net/core/filter.c
• sk_filter_trim_cap(9)
• bpf_convert_filter(9)
• bpf_check_classic(9)
• sk_filter_release_rcu(9)
• sk_filter_release(9)
• bpf_prog_create(9)
• bpf_prog_create_from_user(9)
• sk_attach_filter(9)
• bpf_skb_meta_pointer(9)
• bpf_dynptr_from_skb_meta(9)
• bpf_xdp_pull_data(9)
• bpf_icmp_send(9)

💖 Cute little sign-off: this icon came from source ./net/core, dated October 2026, and it's filed under xdp redirect(9) — slay, go read those see-alsos 🫶🎀