Re: [PATCH v3 3/3] ethdev: Reject conflicting TX offloads configuration

[fengchengwen <fengchengwen@huawei.com>]

On 8/4/2025 3:42 AM, Morten Brørup wrote:
> When an ethdev port is configured for fast mbuf release, the driver can
> use a TX burst function relying on the fast mbuf release preconditions.
> Thus, also configuring this port or a queue on the port for transmitting
> segmented packets is prohibited.
> Checks for these conflicting configurations have been added to the ethdev
> library, so the drivers don't have to implement them.

I think the new comment part of ombuf-fast-free and multi-seg in '[PATCH v3 2/3] ethdev: Improve descriptions of RX and TX offloads'
could drop or within this commit.

> 
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
> ---
> v3:
> * Shorten the added log messages. (Stephen Hemminger, Ivan Malov)
> ---
>  lib/ethdev/rte_ethdev.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
> 
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index dd7c00bc94..00afda873f 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -1531,6 +1531,18 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
>  		goto rollback;
>  	}
>  
> +	/* MBUF_FAST_FREE preconditions conflict with MULTI_SEGS support. */
> +	if ((dev_conf->txmode.offloads & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE) &&
> +	    (dev_conf->txmode.offloads & RTE_ETH_TX_OFFLOAD_MULTI_SEGS)) {
> +		RTE_ETHDEV_LOG_LINE(ERR,
> +			"id=%d offload clash, %s vs %s",

Suggest keep the same trace fmt. e.g.: Ethdev port_id=%u
The same below

> +			port_id,
> +			rte_eth_dev_tx_offload_name(RTE_ETH_TX_OFFLOAD_MULTI_SEGS),
> +			rte_eth_dev_tx_offload_name(RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE));
> +		ret = -EINVAL;
> +		goto rollback;
> +	}
> +
>  	dev->data->dev_conf.rx_adv_conf.rss_conf.rss_hf =
>  		rte_eth_rss_hf_refine(dev_conf->rx_adv_conf.rss_conf.rss_hf);
>  
> @@ -2709,6 +2721,31 @@ rte_eth_tx_queue_setup(uint16_t port_id, uint16_t tx_queue_id,
>  		return -EINVAL;
>  	}
>  
> +	/*
> +	 * If the driver uses a Tx function with MBUF_FAST_FREE preconditions,
> +	 * per-queue MULTI_SEGS support is not possible.
> +	 */
> +	if ((dev->data->dev_conf.txmode.offloads & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE) &&
> +			(local_conf.offloads & RTE_ETH_TX_OFFLOAD_MULTI_SEGS)) {
> +		RTE_ETHDEV_LOG_LINE(ERR,
> +			"id=%d txq=%d offload clash, per-queue %s vs per-port %s",
> +			port_id, tx_queue_id,
> +			rte_eth_dev_tx_offload_name(RTE_ETH_TX_OFFLOAD_MULTI_SEGS),
> +			rte_eth_dev_tx_offload_name(RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE));
> +		return -EINVAL;
> +	}
> +	/*
> +	 * If the driver uses a Tx function with MULTI_SEGS support,
> +	 * runtime support for per-queue MBUF_FAST_FREE optimization depends on the driver.
> +	 */
> +	if ((dev->data->dev_conf.txmode.offloads & RTE_ETH_TX_OFFLOAD_MULTI_SEGS) &&
> +			(local_conf.offloads & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE))
> +		RTE_ETHDEV_LOG_LINE(DEBUG,
> +			"id=%d txq=%d potential offload clash, per-queue %s vs per-port %s: PMD to decide",
> +			port_id, tx_queue_id,
> +			rte_eth_dev_tx_offload_name(RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE),
> +			rte_eth_dev_tx_offload_name(RTE_ETH_TX_OFFLOAD_MULTI_SEGS));

1\ The global port configuration will take effect on all queues.
   If it don't support both MBUF_FAST_FREE and MULTI_SEG, why don't ban it here?
2\ Debug level is easy to ignore, how about warning?

> +
>  	rte_ethdev_trace_txq_setup(port_id, tx_queue_id, nb_tx_desc, tx_conf);
>  	return eth_err(port_id, dev->dev_ops->tx_queue_setup(dev,
>  		       tx_queue_id, nb_tx_desc, socket_id, &local_conf));