[ovs-dev] [PATCH 2/3] datapath: Avoid using wrong metadata for recic action.

[Andy Zhou]

Looks good in general. Some minor comments inline.

Acked-by: Andy Zhou <azhou at nicira.com>

On Tue, Aug 5, 2014 at 4:46 PM, Pravin B Shelar <pshelar at nicira.com> wrote:
> Recirc action needs to extract flow key from packet, it uses tun_info
> from OVS_CB for setting tunnel meta data in flow key. But tun_info
> can be overwritten by tunnel send action. This would result in wrong
> flow key for the recirculation.
> Following patch copies flow-key meta data from OVS_CB packet key
> itself thus avoids this bug.
>
> Signed-off-by: Pravin B Shelar <pshelar at nicira.com>
> ---
>  datapath/actions.c      |    6 ++----
>  datapath/flow.c         |   10 ++++++++++
>  datapath/flow.h         |    9 +++++++++
>  datapath/flow_netlink.c |    7 +------
>  4 files changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/datapath/actions.c b/datapath/actions.c
> index 5a0bfa9..6de65d3 100644
> --- a/datapath/actions.c
> +++ b/datapath/actions.c
> @@ -649,17 +649,15 @@ static int execute_recirc(struct datapath *dp, struct sk_buff *skb,
>                                  const struct nlattr *a)
>  {
>         struct sw_flow_key recirc_key;
> -       uint32_t hash = OVS_CB(skb)->pkt_key->ovs_flow_hash;
>         int err;
>
> -       err = ovs_flow_key_extract(skb, &recirc_key);
> +       err = ovs_flow_key_extract_recirc(nla_get_u32(a), OVS_CB(skb)->pkt_key,
> +                                         skb, &recirc_key);
>         if (err) {
>                 kfree_skb(skb);
>                 return err;
>         }
>
> -       recirc_key.ovs_flow_hash = hash;
> -       recirc_key.recirc_id = nla_get_u32(a);
>
>         ovs_dp_process_packet_with_key(skb, &recirc_key, true);
>
> diff --git a/datapath/flow.c b/datapath/flow.c
> index 7fdce6a..1feca85 100644
> --- a/datapath/flow.c
> +++ b/datapath/flow.c
> @@ -718,3 +718,13 @@ int ovs_flow_key_extract_userspace(const struct nlattr *attr,
>
>         return key_extract(skb, key);
>  }
> +
> +int ovs_flow_key_extract_recirc(u32 recirc_id,

Could we make the recirc_id argument as const?

> +                               const struct sw_flow_key *key,
> +                               struct sk_buff *skb,
> +                               struct sw_flow_key *new_key)
> +{
> +       memcpy(new_key, key, OVS_SW_FLOW_KEY_METADATA_SIZE);
It is a bit odd to make recirc_id 0 then overwrite it just one line
below. May be we can memcpy sizeof (recirc_id) less bytes?
> +       new_key->recirc_id = recirc_id;
> +       return key_extract(skb, new_key);
> +}
> diff --git a/datapath/flow.h b/datapath/flow.h
> index 69664cd..ee63b8b 100644
> --- a/datapath/flow.h
> +++ b/datapath/flow.h
> @@ -87,6 +87,11 @@ static inline void ovs_flow_tun_info_init(struct ovs_tunnel_info *tun_info,
>         tun_info->options_len = opts_len;
>  }
>
> +#define OVS_SW_FLOW_KEY_METADATA_SIZE                  \
> +       (offsetof(struct sw_flow_key, recirc_id) +      \
> +       FIELD_SIZEOF(struct sw_flow_key, recirc_id))
> +
> +
>  struct sw_flow_key {
>         u8 tun_opts[255];
>         u8 tun_opts_len;
> @@ -222,5 +227,9 @@ int ovs_flow_key_extract(struct sk_buff *skb, struct sw_flow_key *key);
>  int ovs_flow_key_extract_userspace(const struct nlattr *attr,
>                                    struct sk_buff *skb,
>                                    struct sw_flow_key *key);
> +int ovs_flow_key_extract_recirc(u32 recirc_id,

same as above comment.
> +                               const struct sw_flow_key *key,
> +                               struct sk_buff *skb,
> +                               struct sw_flow_key *new_key);
>
>  #endif /* flow.h */
> diff --git a/datapath/flow_netlink.c b/datapath/flow_netlink.c
> index ada21ae..75172de 100644
> --- a/datapath/flow_netlink.c
> +++ b/datapath/flow_netlink.c
> @@ -1016,13 +1016,8 @@ int ovs_nla_get_flow_metadata(const struct nlattr *attr,
>         memset(&match, 0, sizeof(match));
>         match.key = key;
>
> -       key->tun_opts_len = 0;
> -       memset(&key->tun_key, 0, sizeof(key->tun_key));
> -       key->phy.priority = 0;
> -       key->phy.skb_mark = 0;
> +       memset(key, 0, OVS_SW_FLOW_KEY_METADATA_SIZE);
>         key->phy.in_port = DP_MAX_PORTS;
> -       key->ovs_flow_hash = 0;
> -       key->recirc_id = 0;
>
>         return metadata_from_nlattrs(&match, &attrs, a, false);
>  }
> --
> 1.7.1
>
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