Re: [dpdk-dev] [PATCH v6 1/2] app/testpmd: fix max rx packet length for VLAN packets

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 10/22/2020 9:48 AM, SteveX Yang wrote:
> When the max rx packet length is smaller than the sum of mtu size and
> ether overhead size, it should be enlarged, otherwise the VLAN packets
> will be dropped.
> 
> Fixes: 35b2d13fd6fd ("net: add rte prefix to ether defines")
> 
> Signed-off-by: SteveX Yang <stevex.yang@intel.com>
> ---
>   app/test-pmd/testpmd.c | 52 ++++++++++++++++++++++++++++++------------
>   1 file changed, 38 insertions(+), 14 deletions(-)
> 
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
> index 33fc0fddf..9031c6145 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -1418,9 +1418,13 @@ init_config(void)
>   	unsigned int nb_mbuf_per_pool;
>   	lcoreid_t  lc_id;
>   	uint8_t port_per_socket[RTE_MAX_NUMA_NODES];
> +	struct rte_eth_dev_info *dev_info;
> +	struct rte_eth_conf *dev_conf;
>   	struct rte_gro_param gro_param;
>   	uint32_t gso_types;
>   	uint16_t data_size;
> +	uint16_t overhead_len;
> +	uint16_t frame_size;
>   	bool warning = 0;
>   	int k;
>   	int ret;
> @@ -1448,18 +1452,40 @@ init_config(void)
>   
>   	RTE_ETH_FOREACH_DEV(pid) {
>   		port = &ports[pid];
> +
> +		dev_info = &port->dev_info;
> +		dev_conf = &port->dev_conf;
> +
>   		/* Apply default TxRx configuration for all ports */
> -		port->dev_conf.txmode = tx_mode;
> -		port->dev_conf.rxmode = rx_mode;
> +		dev_conf->txmode = tx_mode;
> +		dev_conf->rxmode = rx_mode;

Hi Steve,

This patch does a small refactoring ('dev_info' & 'dev_conf') and a small 
update, but the refactoring shows the patch more complex than it actually is, if 
you think that is required can you please seperate these two?

>   
> -		ret = eth_dev_info_get_print_err(pid, &port->dev_info);
> +		ret = eth_dev_info_get_print_err(pid, dev_info);
>   		if (ret != 0)
>   			rte_exit(EXIT_FAILURE,
>   				 "rte_eth_dev_info_get() failed\n");
>   
> -		if (!(port->dev_info.tx_offload_capa &
> +		/*
> +		 * Update the max_rx_pkt_len to ensure that its size equals the
> +		 * sum of default mtu size and ether overhead length at least.
> +		 */

What about simplifying the above comment like:
" Update the max_rx_pkt_len to have MTU as RTE_ETHER_MTU "

> +		if (dev_info->max_rx_pktlen && dev_info->max_mtu)
> +			overhead_len =
> +				dev_info->max_rx_pktlen - dev_info->max_mtu;
> +		else
> +			overhead_len =
> +				RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
> +
> +		frame_size = RTE_ETHER_MTU + overhead_len;
> +		if (frame_size > RTE_ETHER_MAX_LEN) {
> +			dev_conf->rxmode.max_rx_pkt_len = frame_size;
> +			dev_conf->rxmode.offloads |=
> +				DEV_RX_OFFLOAD_JUMBO_FRAME;

I am not sure the jumbo frame asignment is always true.
'frame_size' can be bigger than 'RTE_ETHER_MAX_LEN', but mtu still can be <= 
1500. What about dropping this?

> +		}
> +
> +		if (!(dev_info->tx_offload_capa &
>   		      DEV_TX_OFFLOAD_MBUF_FAST_FREE))
> -			port->dev_conf.txmode.offloads &=
> +			dev_conf->txmode.offloads &=
>   				~DEV_TX_OFFLOAD_MBUF_FAST_FREE;
>   		if (numa_support) {
>   			if (port_numa[pid] != NUMA_NO_CONFIG)
> @@ -1478,13 +1504,11 @@ init_config(void)
>   		}
>   
>   		/* Apply Rx offloads configuration */
> -		for (k = 0; k < port->dev_info.max_rx_queues; k++)
> -			port->rx_conf[k].offloads =
> -				port->dev_conf.rxmode.offloads;
> +		for (k = 0; k < dev_info->max_rx_queues; k++)
> +			port->rx_conf[k].offloads = dev_conf->rxmode.offloads;
>   		/* Apply Tx offloads configuration */
> -		for (k = 0; k < port->dev_info.max_tx_queues; k++)
> -			port->tx_conf[k].offloads =
> -				port->dev_conf.txmode.offloads;
> +		for (k = 0; k < dev_info->max_tx_queues; k++)
> +			port->tx_conf[k].offloads = dev_conf->txmode.offloads;
>   
>   		/* set flag to initialize port/queue */
>   		port->need_reconfig = 1;
> @@ -1494,10 +1518,10 @@ init_config(void)
>   		/* Check for maximum number of segments per MTU. Accordingly
>   		 * update the mbuf data size.
>   		 */
> -		if (port->dev_info.rx_desc_lim.nb_mtu_seg_max != UINT16_MAX &&
> -				port->dev_info.rx_desc_lim.nb_mtu_seg_max != 0) {
> +		if (dev_info->rx_desc_lim.nb_mtu_seg_max != UINT16_MAX &&
> +				dev_info->rx_desc_lim.nb_mtu_seg_max != 0) {
>   			data_size = rx_mode.max_rx_pkt_len /
> -				port->dev_info.rx_desc_lim.nb_mtu_seg_max;
> +				dev_info->rx_desc_lim.nb_mtu_seg_max;
>   
>   			if ((data_size + RTE_PKTMBUF_HEADROOM) >
>   							mbuf_data_size[0]) {
>