Re: [PATCH net-next 3/5] selftests/xsk: expand XSKMAP capacity and add length-based XDP program

> diff --git a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c
> index 023d8befd4cab..543b61df3a2b1 100644
> --- a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c
> +++ b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c

[ ... ]

> @@ -75,6 +75,23 @@ SEC("xdp") int xsk_xdp_shared_umem(struct xdp_md *xdp)
>  	return bpf_redirect_map(&xsk, idx, XDP_DROP);
>  }
>
> +SEC("xdp") int xsk_xdp_shared_umem_length_based(struct xdp_md *xdp)
> +{
> +	void *data = (void *)(long)xdp->data;
> +	void *data_end = (void *)(long)xdp->data_end;
> +	__u32 pkt_len = data_end - data;
> +
> +	/*
> +	 * Route packets by total XDP-visible packet length (data_end - data):
> +	 * - Socket 0: packets <= SHARED_UMEM_LEN_SPLIT bytes
> +	 * - Socket 1: packets > SHARED_UMEM_LEN_SPLIT bytes
> +	 */
> +	if (pkt_len <= SHARED_UMEM_LEN_SPLIT)
> +		return bpf_redirect_map(&xsk, 0, XDP_DROP);
> +	else
> +		return bpf_redirect_map(&xsk, 1, XDP_DROP);
> +}

This isn't a bug, but could this comment be trimmed to a single line
like the one in xsk_xdp_shared_umem() above, and the trailing space
after the opening '/*' dropped so checkpatch stays quiet?

> diff --git a/tools/testing/selftests/bpf/xsk_xdp_common.h b/tools/testing/selftests/bpf/xsk_xdp_common.h
> index 45810ff552dae..bd9b5dcf8c8ee 100644
> --- a/tools/testing/selftests/bpf/xsk_xdp_common.h
> +++ b/tools/testing/selftests/bpf/xsk_xdp_common.h
> @@ -3,7 +3,8 @@
>  #ifndef XSK_XDP_COMMON_H_
>  #define XSK_XDP_COMMON_H_
>
> -#define MAX_SOCKETS 2
> +#define MAX_SOCKETS 4
> +#define SHARED_UMEM_LEN_SPLIT 64
>  #define PKT_HDR_ALIGN (sizeof(struct ethhdr) + 2) /* Just to align the data in the packet */

This isn't a bug, but since xsk_xdp_common.h is visible to test_xsk.c
too, would it be worth deriving the test's short/long lengths from
SHARED_UMEM_LEN_SPLIT (or noting why 64 is the right split) so the two
sides cannot drift apart?


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/31554903166