On Tue, Mar 21, 2023 at 6:47 AM Jesper Dangaard Brouer
<brouer@xxxxxxxxxx> wrote:
>
> When driver developers add XDP-hints kfuncs for RX hash it is
> practical to print the return code in bpf_printk trace pipe log.
>
> Print hash value as a hex value, both AF_XDP userspace and bpf_prog,
> as this makes it easier to spot poor quality hashes.
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> ---
> .../testing/selftests/bpf/progs/xdp_hw_metadata.c | 9 ++++++---
> tools/testing/selftests/bpf/xdp_hw_metadata.c | 5 ++++-
> 2 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> index 40c17adbf483..ce07010e4d48 100644
> --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> @@ -77,10 +77,13 @@ int rx(struct xdp_md *ctx)
> meta->rx_timestamp = 0; /* Used by AF_XDP as not avail signal */
> }
>
> - if (!bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash))
> - bpf_printk("populated rx_hash with %u", meta->rx_hash);
> - else
> + ret = bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash);
> + if (ret >= 0) {
> + bpf_printk("populated rx_hash with 0x%08X", meta->rx_hash);
> + } else {
> + bpf_printk("rx_hash not-avail errno:%d", ret);
> meta->rx_hash = 0; /* Used by AF_XDP as not avail signal */
> + }
>
> 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 400bfe19abfe..f3ec07ccdc95 100644
> --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> @@ -3,6 +3,9 @@
> /* Reference program for verifying XDP metadata on real HW. Functional test
> * only, doesn't test the performance.
> *
> + * BPF-prog bpf_printk info outout can be access via
> + * /sys/kernel/debug/tracing/trace_pipe
s/outout/output/
But let's maybe drop it? If you want to make it more usable, let's
have a separate patch to enable tracing and periodically dump it to
the console instead (as previously discussed).
With this addressed:
Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> + *
> * RX:
> * - UDP 9091 packets are diverted into AF_XDP
> * - Metadata verified:
> @@ -156,7 +159,7 @@ static void verify_xdp_metadata(void *data, clockid_t clock_id)
>
> meta = data - sizeof(*meta);
>
> - printf("rx_hash: %u\n", meta->rx_hash);
> + printf("rx_hash: 0x%08X\n", meta->rx_hash);
> printf("rx_timestamp: %llu (sec:%0.4f)\n", meta->rx_timestamp,
> (double)meta->rx_timestamp / NANOSEC_PER_SEC);
> if (meta->rx_timestamp) {
>
>
