On 07/03/2024 19:39, Ilya Maximets wrote:
> It's hard to debug situations where driver rejects packets for some
> reason.  Dumping out the mbuf should help with that.
> 
> Sample output looks like this:
> 
>   |netdev_dpdk(pmd-c03/id:8)|DBG|ovs-p1: First invalid packet:
>   dump mbuf at 0x1180bce140, iova=0x2cb7ce400, buf_len=2176
>     pkt_len=64, ol_flags=0x2, nb_segs=1, port=65535, ptype=0
>     segment at 0x1180bce140, data=0x1180bce580, len=90, off=384, refcnt=1
>     Dump data at [0x1180bce580], len=64
>   00000000: 33 33 00 00 00 16 AA 27 91 F9 4D 96 86 DD 60 00 | 33.....'..M...`.
>   00000010: 00 00 00 24 00 01 00 00 00 00 00 00 00 00 00 00 | ...$............
>   00000020: 00 00 00 00 00 00 FF 02 00 00 00 00 00 00 00 00 | ................
>   00000030: 00 00 00 00 00 16 3A 00 05 02 00 00 01 00 8F 00 | ......:.........
> 
> Signed-off-by: Ilya Maximets <[email protected]>

Acked-by: Kevin Traynor <[email protected]>

> ---
> 
> Version 2:
>   * Only dumping the first invalid packet as we don't actually
>     know if the other ones correct or not.  [Kevin]
> 
> Also, we may want to have this backported to 3.3 and maybe 3.2,
> as I suspect those will be branches where will will actually have
> to debug offloading rejection issues.  We already have a few.
> For example: https://github.com/openvswitch/ovs-issues/issues/321
> for which I actually prepared this patch in the first place.
> 
> This is a debug-only change that should not have any impact
> on end users.
> 
> Thoughts?
> 

I think it's reasonable to backport it. It is non-intrusive for the
normal case and will be helpful for debug.

>  lib/netdev-dpdk.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index 45f61930d..9444c53b1 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -2664,6 +2664,35 @@ netdev_dpdk_prep_hwol_batch(struct netdev_dpdk *dev, 
> struct rte_mbuf **pkts,
>      return cnt;
>  }
>  
> +static void
> +netdev_dpdk_mbuf_dump(const char *prefix, const char *message,
> +                      const struct rte_mbuf *mbuf)
> +{
> +    static struct vlog_rate_limit dump_rl = VLOG_RATE_LIMIT_INIT(5, 5);
> +    char *response = NULL;
> +    FILE *stream;
> +    size_t size;
> +
> +    if (VLOG_DROP_DBG(&dump_rl)) {
> +        return;
> +    }
> +
> +    stream = open_memstream(&response, &size);
> +    if (!stream) {
> +        VLOG_ERR("Unable to open memstream for mbuf dump: %s.",
> +                 ovs_strerror(errno));
> +        return;
> +    }
> +
> +    rte_pktmbuf_dump(stream, mbuf, rte_pktmbuf_pkt_len(mbuf));
> +
> +    fclose(stream);
> +
> +    VLOG_DBG(prefix ? "%s: %s:\n%s" : "%s%s:\n%s",
> +             prefix ? prefix : "", message, response);
> +    free(response);
> +}
> +
>  /* Tries to transmit 'pkts' to txq 'qid' of device 'dev'.  Takes ownership of
>   * 'pkts', even in case of failure.
>   *
> @@ -2680,6 +2709,8 @@ netdev_dpdk_eth_tx_burst(struct netdev_dpdk *dev, int 
> qid,
>          VLOG_WARN_RL(&rl, "%s: Output batch contains invalid packets. "
>                       "Only %u/%u are valid: %s", netdev_get_name(&dev->up),
>                       nb_tx_prep, cnt, rte_strerror(rte_errno));
> +        netdev_dpdk_mbuf_dump(netdev_get_name(&dev->up),
> +                              "First invalid packet", pkts[nb_tx_prep]);
>      }
>  
>      while (nb_tx != nb_tx_prep) {

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