On Thu, 2008-11-27 at 10:54 +0100, Johannes Berg wrote:

quoted

+	result = -ENOMEM;
+	reply_skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (reply_skb == NULL)
+		goto error_new;
+	data = genlmsg_put_reply(reply_skb, genl_info,
+				 &wimax_dev->gnl_family,
+				 0, WIMAX_GNL_RP_IFINFO);
+	if (data == NULL)
+		goto error_put_reply;
+
+	nla_groups = nla_nest_start(reply_skb, WIMAX_GNL_IFINFO_MC_GROUPS);
+	if (nla_groups == NULL)
+		goto error_groups_start;
+
+	list_for_each_entry(pipe_itr, &wimax_dev->pipe_list,
+			    list_node) {
+		nla_group = nla_nest_start(reply_skb,
+					   WIMAX_GNL_IFINFO_MC_GROUP);
+		if (nla_group == NULL)
+			goto error_group_start;
+
+		nla_put_u16(reply_skb, WIMAX_GNL_IFINFO_MC_ID,
+			    pipe_itr->mcg.id);
+		nla_put_string(reply_skb, WIMAX_GNL_IFINFO_MC_NAME,
+			       pipe_itr->mcg.name);

All this is discoverable via the genl controller and a pipe naming
scheme, so I don't think you need this "open" command at all.

In fact, it's entirely trivial since you use a genl family for each
interface, thus you just have to ask the genl controller for the groups
associated with that family. If you need sample code, check out iw.

johannes