Re: [PATCH 2/2] app/testpmd: fix incorrect MTU verification

["Singh, Aman Deep" <aman.deep.singh@intel.com>]

On 4/6/2022 2:15 PM, Min Hu (Connor) wrote:
> From: Huisong Li <lihuisong@huawei.com>
>
> The macro RTE_ETHER_MIN_LEN isn't the minimum value of MTU. But testpmd
> used it when execute 'port config mtu 0 xx' cmd. This patch fix it.
>
> Fixes: 1bb4a528c41f ("ethdev: fix max Rx packet length")
> Cc: stable@dpdk.org
>
> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> ---
>   app/test-pmd/cmdline.c |  4 ---
>   app/test-pmd/config.c  | 55 ++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 55 insertions(+), 4 deletions(-)
>
> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
> index 6ffea8e21a..91e4090582 100644
> --- a/app/test-pmd/cmdline.c
> +++ b/app/test-pmd/cmdline.c
> @@ -2050,10 +2050,6 @@ cmd_config_mtu_parsed(void *parsed_result,
>   {
>   	struct cmd_config_mtu_result *res = parsed_result;
>   
> -	if (res->value < RTE_ETHER_MIN_LEN) {
> -		fprintf(stderr, "mtu cannot be less than %d\n", RTE_ETHER_MIN_LEN);
> -		return;
> -	}
>   	port_mtu_set(res->port_id, res->value);
>   }
>   
> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
> index bd689f9f86..1b1e738f83 100644
> --- a/app/test-pmd/config.c
> +++ b/app/test-pmd/config.c
> @@ -1254,6 +1254,57 @@ port_reg_set(portid_t port_id, uint32_t reg_off, uint32_t reg_v)
>   	display_port_reg_value(port_id, reg_off, reg_v);
>   }
>   
> +static uint32_t
> +eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu)
> +{
> +	uint32_t overhead_len;
> +
> +	if (max_mtu != UINT16_MAX && max_rx_pktlen > max_mtu)
> +		overhead_len = max_rx_pktlen - max_mtu;
> +	else
> +		overhead_len = RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
> +
> +	return overhead_len;
> +}
> +
> +static int
> +eth_dev_validate_mtu(uint16_t port_id, uint16_t mtu)
> +{
> +	struct rte_eth_dev_info dev_info;
> +	uint32_t overhead_len;
> +	uint32_t frame_size;
> +	int ret;
> +
> +	ret = rte_eth_dev_info_get(port_id, &dev_info);
> +	if (ret != 0)
> +		return ret;
> +
> +	if (mtu < dev_info.min_mtu) {
> +		fprintf(stderr,
> +			"MTU (%u) < device min MTU (%u) for port_id %u\n",
> +			mtu, dev_info.min_mtu, port_id);
> +		return -EINVAL;
> +	}
> +	if (mtu > dev_info.max_mtu) {
> +		fprintf(stderr,
> +			"MTU (%u) > device max MTU (%u) for port_id %u\n",
> +			mtu, dev_info.max_mtu, port_id);
> +		return -EINVAL;
> +	}
> +
> +	overhead_len = eth_dev_get_overhead_len(dev_info.max_rx_pktlen,
> +			dev_info.max_mtu);
> +	frame_size = mtu + overhead_len;
> +	if (frame_size > dev_info.max_rx_pktlen) {
> +		fprintf(stderr,
> +			"Frame size (%u) > device max frame size (%u) for port_id %u\n",
> +			frame_size, dev_info.max_rx_pktlen, port_id);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>   void
>   port_mtu_set(portid_t port_id, uint16_t mtu)
>   {
> @@ -1263,6 +1314,10 @@ port_mtu_set(portid_t port_id, uint16_t mtu)
>   	if (port_id_is_invalid(port_id, ENABLED_WARN))
>   		return;
>   
> +	diag = eth_dev_validate_mtu(port_id, mtu);
> +	if (diag != 0)
> +		return;
> +
>   	if (port->need_reconfig == 0) {
>   		diag = rte_eth_dev_set_mtu(port_id, mtu);
>   		if (diag != 0) {
I just wanted to know if these added functions eth_dev_validate_mtu() &  
eth_dev_get_overhead_len()
are copy of ethdev library API's in file "rte_ethdev.c", which get 
called by rte_eth_dev_set_mtu.
Is our intent, is to call these twice ?