On Wed, 2008-11-26 at 15:07 -0800, Inaky Perez-Gonzalez wrote:

When user space wants to open a handle to a WiMAX device, it needs
information that is provided as a response to an "open" generic
netlink message.

Why is this called "open" when it's not actually any opening that would
be bracketed with "close"? It seems more like "get info" to me?

+	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.

+		nla_nest_end(reply_skb, nla_group);
+	}
+	nla_nest_end(reply_skb, nla_groups);
+	genlmsg_end(reply_skb, data);
+
+	result = genlmsg_reply(reply_skb, genl_info);
+	if (result < 0)
+		goto error_reply;
+	return 0;
+
+error_group_start:
+error_groups_start:
+error_reply:
+error_put_reply:
+	nlmsg_free(reply_skb);
+error_new:
+	return result;
+}
+
+
+static
+int wimax_gnl_doit_open(struct sk_buff *skb, struct genl_info *info)
+{
+	int result;
+	struct wimax_dev *wimax_dev;
+
+	d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
+	result = -EPERM;
+	if (security_netlink_recv(skb, CAP_NET_ADMIN))
+		goto error_perm;

Ehm, you can do that check by adding the flag below...

+	result = -ENODEV;
+	wimax_dev = wimax_dev_get_by_genl_info(info);
+	if (wimax_dev == NULL)
+		goto error_no_wimax_dev;
+	mutex_lock(&wimax_dev->mutex);
+	result = wimax_dev_is_ready(wimax_dev);
+	if (result < 0)
+		goto error_not_ready;
+	result = __wimax_gnl_open_reply(wimax_dev, info);
+error_not_ready:
+	mutex_unlock(&wimax_dev->mutex);
+	dev_put(wimax_dev->net_dev);
+error_no_wimax_dev:
+error_perm:
+	d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
+	return result;
+}
+
+
+struct genl_ops wimax_gnl_open = {
+	.cmd = WIMAX_GNL_OP_OPEN,
+	.flags = 0,

GENL_ADMIN_PERM and remove the checks above?