On Mon, Mar 24, 2014 at 11:56 AM, Jarno Rajahalme <jrajaha...@nicira.com> wrote:
> Use netlink_has_listeners() and NLM_F_ECHO flag to determine if a
> reply is needed or not for OVS_FLOW_CMD_NEW, OVS_FLOW_CMD_SET, or
> OVS_FLOW_CMD_DEL.
>
> Note: This may need compat support for older kernels.
>
> Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
> ---
> datapath/datapath.c | 57
> ++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 40 insertions(+), 17 deletions(-)
>
> diff --git a/datapath/datapath.c b/datapath/datapath.c
> index 7ce3ea6..f933831 100644
> --- a/datapath/datapath.c
> +++ b/datapath/datapath.c
> @@ -64,6 +64,15 @@
>
> int ovs_net_id __read_mostly;
>
> +/* Check if need to build a reply message.
> + * OVS userspace sets the NLM_F_ECHO flag if it needs the reply. */
> +static bool ovs_must_build_reply(struct genl_info *info,
> + const struct genl_multicast_group *grp)
> +{
> + return info->nlhdr->nlmsg_flags & NLM_F_ECHO ||
> + netlink_has_listeners(genl_info_net(info)->genl_sock,
> grp->id);
> +}
> +
> static void ovs_notify(struct sk_buff *skb, struct genl_info *info,
> struct genl_multicast_group *grp)
> {
> @@ -782,7 +791,7 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb,
> struct genl_info *info)
> struct sw_flow_key key, masked_key;
> struct sw_flow *flow = NULL;
> struct sw_flow_mask mask;
> - struct sk_buff *reply;
> + struct sk_buff *reply = NULL;
> struct datapath *dp;
> struct sw_flow_actions *acts = NULL;
> struct sw_flow_match match;
> @@ -850,7 +859,9 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb,
> struct genl_info *info)
> if (error)
> goto err_flow_free;
>
> - reply = ovs_flow_cmd_build_info(flow, dp, info,
> OVS_FLOW_CMD_NEW);
> + if (ovs_must_build_reply(info, &ovs_dp_flow_multicast_group))
> + reply = ovs_flow_cmd_build_info(flow, dp, info,
> + OVS_FLOW_CMD_NEW);
Can you move this check to ovs_flow_cmd_alloc_info()? this makes code
easy to read.
> } else {
> /* We found a matching flow. */
> /* Bail out if we're not allowed to modify an existing flow.
> @@ -876,7 +887,10 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb,
> struct genl_info *info)
> rcu_assign_pointer(flow->sf_acts, acts);
> ovs_nla_free_flow_actions(old_acts);
> }
> - reply = ovs_flow_cmd_build_info(flow, dp, info,
> OVS_FLOW_CMD_NEW);
> +
> + if (ovs_must_build_reply(info, &ovs_dp_flow_multicast_group))
> + reply = ovs_flow_cmd_build_info(flow, dp, info,
> + OVS_FLOW_CMD_NEW);
>
> /* Clear stats. */
> if (a[OVS_FLOW_ATTR_CLEAR])
> @@ -884,11 +898,14 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb,
> struct genl_info *info)
> }
> ovs_unlock();
>
> - if (!IS_ERR(reply))
> - ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
> - else
> - netlink_set_err(sock_net(skb->sk)->genl_sock, 0,
> - ovs_dp_flow_multicast_group.id,
> PTR_ERR(reply));
> + if (reply) {
> + if (!IS_ERR(reply))
> + ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
> + else
> + netlink_set_err(sock_net(skb->sk)->genl_sock, 0,
> + ovs_dp_flow_multicast_group.id,
> + PTR_ERR(reply));
> + }
> return 0;
>
> err_flow_free:
> @@ -953,7 +970,7 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct
> genl_info *info)
> struct nlattr **a = info->attrs;
> struct ovs_header *ovs_header = info->userhdr;
> struct sw_flow_key key;
> - struct sk_buff *reply;
> + struct sk_buff *reply = NULL;
> struct sw_flow *flow;
> struct datapath *dp;
> struct sw_flow_match match;
> @@ -982,22 +999,28 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct
> genl_info *info)
> goto unlock;
> }
>
> - reply = ovs_flow_cmd_alloc_info(flow, info);
> - if (!reply) {
> - err = -ENOMEM;
> - goto unlock;
> + if (ovs_must_build_reply(info, &ovs_dp_flow_multicast_group)) {
> + reply = ovs_flow_cmd_alloc_info(flow, info);
> + if (!reply) {
> + err = -ENOMEM;
> + goto unlock;
> + }
> }
>
> ovs_flow_tbl_remove(&dp->table, flow);
>
> - err = ovs_flow_cmd_fill_info(flow, dp, reply, info->snd_portid,
> - info->snd_seq, 0, OVS_FLOW_CMD_DEL);
> - BUG_ON(err < 0);
> + if (reply) {
> + err = ovs_flow_cmd_fill_info(flow, dp, reply,
> info->snd_portid,
> + info->snd_seq, 0,
> + OVS_FLOW_CMD_DEL);
> + BUG_ON(err < 0);
> + }
>
> ovs_flow_free(flow, true);
> ovs_unlock();
>
> - ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
> + if (reply)
> + ovs_notify(reply, info, &ovs_dp_flow_multicast_group);
> return 0;
> unlock:
> ovs_unlock();
> --
> 1.7.10.4
>
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