Re: [dpdk-dev] [PATCH v3 2/4] net/af_xdp: specify minimal and maximal MTU

[David Marchand <david.marchand@redhat.com>]

On Wed, Apr 17, 2019 at 11:02 AM Xiaolong Ye <xiaolong.ye@intel.com> wrote:

> Since AF_XDP pmd doesn't support multi segment, we need to add a valid
> check in eth_dev_mtu_set.
>

How about:
Properly report mtu capability in port device info.


Reported-by: David Marchand <david.marchand@redhat.com>

Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
> ---
>  drivers/net/af_xdp/rte_eth_af_xdp.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c
> b/drivers/net/af_xdp/rte_eth_af_xdp.c
> index 5cc643ce2..8430921af 100644
> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -351,6 +351,9 @@ eth_dev_info(struct rte_eth_dev *dev, struct
> rte_eth_dev_info *dev_info)
>         dev_info->max_rx_queues = 1;
>         dev_info->max_tx_queues = 1;
>
> +       dev_info->min_mtu = ETHER_MIN_MTU;
> +       dev_info->max_mtu = ETH_AF_XDP_FRAME_SIZE -
> ETH_AF_XDP_DATA_HEADROOM;
> +
>
        dev_info->default_rxportconf.nb_queues = 1;
>         dev_info->default_txportconf.nb_queues = 1;
>         dev_info->default_rxportconf.ring_size = ETH_AF_XDP_DFLT_NUM_DESCS;
> @@ -654,6 +657,15 @@ eth_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
>         int ret;
>         int s;
>
> +       if (mtu > ETH_AF_XDP_FRAME_SIZE - ETH_AF_XDP_DATA_HEADROOM ||
> +                       mtu < ETHER_MIN_MTU) {
> +               AF_XDP_LOG(ERR, "Unsupported MTU of %d. "
> +                       "max mtu: %d, min mtu: %d", mtu,
> +                       ETH_AF_XDP_FRAME_SIZE - ETH_AF_XDP_DATA_HEADROOM,
> +                       ETHER_MIN_MTU);
> +               return -EINVAL;
> +       }
> +
>

Sorry, I suppose my previous mail was confusing.
If you provide min/max_mtu, ethdev will enforce those checks for you and
you don't need to care about it.

See:
https://git.dpdk.org/dpdk/tree/lib/librte_ethdev/rte_ethdev.c?h=v19.05-rc1#n2630

With this block removed, you can add my review tag.

Thanks.

-- 
David Marchand