Re: [PATCH bpf V8 2/7] selftests/bpf: Add counters to xdp_hw_metadata

From: Stanislav Fomichev
Date: Wed Apr 12 2023 - 12:56:40 EST


On 04/12, Jesper Dangaard Brouer wrote:
> Add counters for skipped, failed and redirected packets.
> The xdp_hw_metadata program only redirects UDP port 9091.
> This helps users to quickly identify then packets are
> skipped and identify failures of bpf_xdp_adjust_meta.
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> ---
> .../testing/selftests/bpf/progs/xdp_hw_metadata.c | 15 +++++++++++++--
> tools/testing/selftests/bpf/xdp_hw_metadata.c | 4 +++-
> 2 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> index b0104763405a..a07ef7534013 100644
> --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> @@ -25,6 +25,10 @@ struct {
> __type(value, __u32);
> } xsk SEC(".maps");
>
> +volatile __u64 pkts_skip = 0;
> +volatile __u64 pkts_fail = 0;
> +volatile __u64 pkts_redir = 0;
> +
> extern int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx,
> __u64 *timestamp) __ksym;
> extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx,
> @@ -59,16 +63,21 @@ int rx(struct xdp_md *ctx)
> udp = NULL;
> }
>
> - if (!udp)
> + if (!udp) {
> + pkts_skip++;
> return XDP_PASS;
> + }
>
> /* Forwarding UDP:9091 to AF_XDP */
> - if (udp->dest != bpf_htons(9091))
> + if (udp->dest != bpf_htons(9091)) {
> + pkts_skip++;
> return XDP_PASS;
> + }
>
> ret = bpf_xdp_adjust_meta(ctx, -(int)sizeof(struct xdp_meta));
> if (ret != 0) {

[..]

> bpf_printk("bpf_xdp_adjust_meta returned %d", ret);

Maybe let's remove these completely? Merge patch 1 and 2, remove printk,
add counters. We can add more counters in the future if the existing
ones are not enough.. WDYT?

> + pkts_fail++;
> return XDP_PASS;
> }
>
> @@ -78,6 +87,7 @@ int rx(struct xdp_md *ctx)
>
> if (meta + 1 > data) {
> bpf_printk("bpf_xdp_adjust_meta doesn't appear to work");
> + pkts_fail++;
> return XDP_PASS;
> }
>
> @@ -91,6 +101,7 @@ int rx(struct xdp_md *ctx)
> else
> meta->rx_hash = 0; /* Used by AF_XDP as not avail signal */
>
> + pkts_redir++;
> return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
> }
>
> diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> index 1c8acb68b977..3b942ef7297b 100644
> --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> @@ -212,7 +212,9 @@ static int verify_metadata(struct xsk *rx_xsk, int rxq, int server_fd)
> while (true) {
> errno = 0;
> ret = poll(fds, rxq + 1, 1000);
> - printf("poll: %d (%d)\n", ret, errno);
> + printf("poll: %d (%d) skip=%llu fail=%llu redir=%llu\n",
> + ret, errno, bpf_obj->bss->pkts_skip,
> + bpf_obj->bss->pkts_fail, bpf_obj->bss->pkts_redir);
> if (ret < 0)
> break;
> if (ret == 0)
>
>