[PATCH v4] net/bonding: call Tx prepare before Tx burst

[Chas Williams]

On 10/8/22 23:36, Chengwen Feng wrote:
>   	uint16_t slaves[RTE_MAX_ETHPORTS];
>   	uint8_t tx_failed_flag = 0;
>   	uint16_t num_of_slaves;
> +	uint16_t num_tx_prep;
>   
>   	uint16_t max_nb_of_tx_pkts = 0;
>   
> @@ -1320,12 +1339,18 @@ bond_ethdev_tx_burst_broadcast(void *queue, struct rte_mbuf **bufs,
>   	for (i = 0; i < nb_pkts; i++)
>   		rte_pktmbuf_refcnt_update(bufs[i], num_of_slaves - 1);
>   
> +	/* It is rare that bond different PMDs together, so just call tx-prepare once */
> +	num_tx_prep = rte_eth_tx_prepare(slaves[0], bd_tx_q->queue_id,
> +					bufs, nb_pkts);

You probably want to do this before you update the refcnt on the mbufs.
Otherwise, the common rte_eth_tx_prepare operation, rte_vlan_insert, will
fail since the refcnt will not be 1.

> +	if (unlikely(num_tx_prep < nb_pkts))
> +		tx_failed_flag = 1;
> +
>   	/* Transmit burst on each active slave */
>   	for (i = 0; i < num_of_slaves; i++) {
>   		slave_tx_total[i] = rte_eth_tx_burst(slaves[i], bd_tx_q->queue_id,
> -					bufs, nb_pkts);
> +					bufs, num_tx_prep);
>   
> -		if (unlikely(slave_tx_total[i] < nb_pkts))
> +		if (unlikely(slave_tx_total[i] < num_tx_prep))
>   			tx_failed_flag = 1;
>   
>   		/* record the value and slave index for the slave which transmits the
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index e8d1e1c658..b0396bb86e 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -6031,6 +6031,10 @@ uint16_t rte_eth_call_tx_callbacks(uint16_t port_id, uint16_t queue_id,
>    * @see rte_eth_tx_prepare to perform some prior checks or adjustments
>    * for offloads.
>    *
> + * @note This function must not modify mbufs (including packets data) unless
> + * the refcnt is 1. The exception is the bonding PMD, which does not have
> + * tx-prepare function, in this case, mbufs maybe modified.

Exactly. See my comment about calling prepare before you modify the refcnt.

> + *
>    * @param port_id
>    *   The port identifier of the Ethernet device.
>    * @param queue_id