netdev - Re: [PATCH net-next 1/8] flow_keys: Record IP layer protocol in skb_flow

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Date:	Thu, 19 Jun 2014 11:06:52 -0700
From:	Chema Gonzalez <chema@...keley.edu>
To:	Govindarajulu Varadarajan <_govind@....com>
Cc:	davem@...emloft.net, netdev <netdev@...r.kernel.org>,
	ssujith@...co.com, gvaradar@...co.com, benve@...co.com
Subject: Re: [PATCH net-next 1/8] flow_keys: Record IP layer protocol in skb_flow_dissect()

On Mon, Jun 9, 2014 at 11:32 AM, Govindarajulu Varadarajan
<_govind@....com> wrote:
> skb_flow_dissect() dissects only transport header type in ip_proto. It dose not
> give any information about IPv4 or IPv6.
>
> This patch adds new member, n_proto, to struct flow_keys. Which records the
> IP layer type. i.e IPv4 or IPv6.
>
> This can be used in netdev->ndo_rx_flow_steer driver function to dissect flow.
>
> Adding new member to flow_keys increases the struct size by around 4 bytes.
> This causes BUILD_BUG_ON(sizeof(qcb->data) < sz); to fail in
> qdisc_cb_private_validate()
>
> So increase data size by 4
>
> Signed-off-by: Govindarajulu Varadarajan <_govind@....com>
> ---
>  include/net/flow_keys.h   | 14 ++++++++++++++
>  include/net/sch_generic.h |  2 +-
>  net/core/flow_dissector.c |  1 +
>  3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h
> index 7e64bd8..fbefdca 100644
> --- a/include/net/flow_keys.h
> +++ b/include/net/flow_keys.h
> @@ -1,6 +1,19 @@
>  #ifndef _NET_FLOW_KEYS_H
>  #define _NET_FLOW_KEYS_H
>
> +/* struct flow_keys:
> + *     @src: source ip address in case of IPv4
> + *           For IPv6 it contains 32bit hash of src address
> + *     @dst: destination ip address in case of IPv4
> + *           For IPv6 it contains 32bit hash of dst address
> + *     @ports: port numbers of Transport header
> + *             port16[0]: src port number
> + *             port16[1]: dst port number
> + *     @thoff: Transport header offset
> + *     @n_proto: Network header protocol (eg. IPv4/IPv6)
> + *     @ip_proto: Transport header protocol (eg. TCP/UDP)
> + * All the members, except thoff, are in network byte order.
> + */
>  struct flow_keys {
>         /* (src,dst) must be grouped, in the same way than in IP header */
>         __be32 src;
> @@ -10,6 +23,7 @@ struct flow_keys {
>                 __be16 port16[2];
>         };
>         u16 thoff;
> +       u16 n_proto;
>         u8 ip_proto;
If you add n_proto, have you considered adding nhoff too? That way the
L3 and L4 headers will be completely pinned by the flow dissector.

-Chema


>  };
>
> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
> index 624f985..a3cfb8e 100644
> --- a/include/net/sch_generic.h
> +++ b/include/net/sch_generic.h
> @@ -231,7 +231,7 @@ struct qdisc_skb_cb {
>         unsigned int            pkt_len;
>         u16                     slave_dev_queue_mapping;
>         u16                     _pad;
> -       unsigned char           data[20];
> +       unsigned char           data[24];
>  };
>
>  static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index 107ed12..c2b53c1 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -175,6 +175,7 @@ ipv6:
>                 break;
>         }
>
> +       flow->n_proto = proto;
>         flow->ip_proto = ip_proto;
>         flow->ports = skb_flow_get_ports(skb, nhoff, ip_proto);
>         flow->thoff = (u16) nhoff;
> --
> 2.0.0
>
> --
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