netdev - Re: [PATCH net-next v3 5/7] net: devmem: add ring parameter filtering

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Message-ID: <70c16ec6-c1e8-4de2-8da7-a9cc83df816a@amd.com>
Date: Thu, 3 Oct 2024 11:35:43 -0700
From: Brett Creeley <bcreeley@....com>
To: Taehee Yoo <ap420073@...il.com>, davem@...emloft.net, kuba@...nel.org,
 pabeni@...hat.com, edumazet@...gle.com, almasrymina@...gle.com,
 netdev@...r.kernel.org, linux-doc@...r.kernel.org, donald.hunter@...il.com,
 corbet@....net, michael.chan@...adcom.com
Cc: kory.maincent@...tlin.com, andrew@...n.ch, maxime.chevallier@...tlin.com,
 danieller@...dia.com, hengqi@...ux.alibaba.com, ecree.xilinx@...il.com,
 przemyslaw.kitszel@...el.com, hkallweit1@...il.com, ahmed.zaki@...el.com,
 paul.greenwalt@...el.com, rrameshbabu@...dia.com, idosch@...dia.com,
 asml.silence@...il.com, kaiyuanz@...gle.com, willemb@...gle.com,
 aleksander.lobakin@...el.com, dw@...idwei.uk, sridhar.samudrala@...el.com
Subject: Re: [PATCH net-next v3 5/7] net: devmem: add ring parameter filtering



On 10/3/2024 9:06 AM, Taehee Yoo wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
> 
> 
> If driver doesn't support ring parameter or tcp-data-split configuration
> is not sufficient, the devmem should not be set up.
> Before setup the devmem, tcp-data-split should be ON and
> tcp-data-split-thresh value should be 0.
> 
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
> 
> v3:
>   - Patch added.
> 
>   net/core/devmem.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 
> diff --git a/net/core/devmem.c b/net/core/devmem.c
> index 11b91c12ee11..a9e9b15028e0 100644
> --- a/net/core/devmem.c
> +++ b/net/core/devmem.c
> @@ -8,6 +8,8 @@
>    */
> 
>   #include <linux/dma-buf.h>
> +#include <linux/ethtool.h>
> +#include <linux/ethtool_netlink.h>
>   #include <linux/genalloc.h>
>   #include <linux/mm.h>
>   #include <linux/netdevice.h>
> @@ -131,6 +133,8 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
>                                      struct net_devmem_dmabuf_binding *binding,
>                                      struct netlink_ext_ack *extack)
>   {
> +       struct kernel_ethtool_ringparam kernel_ringparam = {};
> +       struct ethtool_ringparam ringparam = {};
>          struct netdev_rx_queue *rxq;
>          u32 xa_idx;
>          int err;
> @@ -146,6 +150,20 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
>                  return -EEXIST;
>          }
> 
> +       if (!dev->ethtool_ops->get_ringparam) {
> +               NL_SET_ERR_MSG(extack, "can't get ringparam");
> +               return -EINVAL;
> +       }

Is EINVAL the correct return value here? I think it makes more sense as 
EOPNOTSUPP.

> +
> +       dev->ethtool_ops->get_ringparam(dev, &ringparam,
> +                                       &kernel_ringparam, extack);
> +       if (kernel_ringparam.tcp_data_split != ETHTOOL_TCP_DATA_SPLIT_ENABLED ||
> +           kernel_ringparam.tcp_data_split_thresh) {
> +               NL_SET_ERR_MSG(extack,
> +                              "tcp-header-data-split is disabled or threshold is not zero");
> +               return -EINVAL;
> +       }
> +
Maybe just my personal opinion, but IMHO these checks should be separate 
so the error message can be more concise/clear.

Also, a small nit, but I think both of these checks should be before 
getting the rxq via __netif_get_rx_queue().


Thanks,

Brett
>   #ifdef CONFIG_XDP_SOCKETS
>          if (rxq->pool) {
>                  NL_SET_ERR_MSG(extack, "designated queue already in use by AF_XDP");
> --
> 2.34.1
>