netdev - Re: [PATCH net-next] net: dsa: Implement flow dissection for tag

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Date:   Mon, 23 Mar 2020 01:57:57 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Alexander Lobakin <alobakin@...nk.ru>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] net: dsa: Implement flow dissection for tag_brcm.c

On Sun, 22 Mar 2020 at 23:10, Florian Fainelli <f.fainelli@...il.com> wrote:
>
> Provide a flow_dissect callback which returns the network offset and
> where to find the skb protocol, given the tags structure a common
> function works for both tagging formats that are supported.
>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---

Looks good to me.

>  net/dsa/tag_brcm.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
> index 9c3114179690..0d3f796d14a3 100644
> --- a/net/dsa/tag_brcm.c
> +++ b/net/dsa/tag_brcm.c
> @@ -142,6 +142,27 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
>
>         return skb;
>  }
> +
> +static int brcm_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
> +                                int *offset)
> +{
> +       /* We have been called on the DSA master network device after
> +        * eth_type_trans() which pulled the Ethernet header already.
> +        * Frames have one of these two layouts:
> +        * -----------------------------------
> +        * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
> +        * -----------------------------------
> +        * -----------------------------------
> +        * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
> +        * -----------------------------------
> +        * skb->data points 2 bytes before the actual Ethernet type field and
> +        * we have an offset of 4bytes between where skb->data and where the
> +        * payload starts.
> +        */
> +       *offset = BRCM_TAG_LEN;
> +       *proto = ((__be16 *)skb->data)[1];
> +       return 0;
> +}
>  #endif
>
>  #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
> @@ -177,6 +198,7 @@ static const struct dsa_device_ops brcm_netdev_ops = {
>         .xmit   = brcm_tag_xmit,
>         .rcv    = brcm_tag_rcv,
>         .overhead = BRCM_TAG_LEN,
> +       .flow_dissect = brcm_tag_flow_dissect,
>  };
>
>  DSA_TAG_DRIVER(brcm_netdev_ops);
> @@ -205,6 +227,7 @@ static const struct dsa_device_ops brcm_prepend_netdev_ops = {
>         .xmit   = brcm_tag_xmit_prepend,
>         .rcv    = brcm_tag_rcv_prepend,
>         .overhead = BRCM_TAG_LEN,
> +       .flow_dissect = brcm_tag_flow_dissect,
>  };
>
>  DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
> --
> 2.19.1
>

Regards,
-Vladimir