Re: [dpdk-dev] [PATCH v2] net/failsafe: fix source port ID in Rx packets

[Thomas Monjalon <thomas@monjalon.net>]

18/04/2019 17:32, Adrien Mazarguil:
> When passed to the application, Rx packets retain the port ID value
> originally set by slave devices. Unfortunately these IDs have no meaning to
> applications, which are typically unaware of their existence.
> 
> This confuses those caring about the source port field in mbufs (m->port)
> which experience issues ranging from traffic drop to crashes.
> 
> Fixes: a46f8d584eb8 ("net/failsafe: add fail-safe PMD")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
> Reviewed-by: David Marchand <david.marchand@redhat.com>
> Acked-by: Gaetan Rivet <gaetan.rivet@6wind.com>
> --
> v2 changes:
> 
> Modified "rxq->priv->dev->data->port_id" (v18.11-style) to
> "rxq->priv->data->port_id" (since v19.05) and checked compilation against
> master this time.
> 
> Given the limited scope of that change, reviewed-by/acked-by lines were
> kept.
> ---
> +/*
> + * Override source port in Rx packets.
> + *
> + * Make Rx packets originate from this PMD instance instead of one of its
> + * slaves. This is mandatory to avoid breaking applications.

"slave" is a wording from bonding.
In failsafe, it is sub-device, isn't it?

> + */
> +static void
> +failsafe_rx_set_port(struct rte_mbuf **rx_pkts, uint16_t nb_pkts, uint16_t port)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i != nb_pkts; ++i)
> +		rx_pkts[i]->port = port;
> +}
> +
>  uint16_t
>  failsafe_rx_burst(void *queue,
>  		  struct rte_mbuf **rx_pkts,
> @@ -87,6 +102,9 @@ failsafe_rx_burst(void *queue,
>  		sdev = sdev->next;
>  	} while (nb_rx == 0 && sdev != rxq->sdev);
>  	rxq->sdev = sdev;
> +	if (nb_rx)
> +		failsafe_rx_set_port(rx_pkts, nb_rx,
> +				     rxq->priv->data->port_id);
>  	return nb_rx;
>  }

I'm afraid the performance drop to be hard.
How the port id in mbuf is used exactly? What crash are you seeing?