Inaky Perez-Gonzalez wrote:

+static
+int __wimax_gnl_open_reply(struct wimax_dev *wimax_dev,
+			   struct genl_info *genl_info)
+{
+	int result;
+	void *data;
+	struct sk_buff *reply_skb;
+	struct nlattr *nla_groups, *nla_group;
+	struct wimax_pipe *pipe_itr;
+
+	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);

The nla_put results must be checked unless there's a guarantee that
the attributes won't exceed the skbs size.

+		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:

This seems a bit excessive considering that its very unlikely
that you'll ever need to distinguish these cases.

+	nlmsg_free(reply_skb);
+error_new:
+	return result;
+}