[PKT_SCHED]: Report qdisc parent to userspace

Report parent classid of a qdisc back to userspace. Without this there
is no way for userspace to see if the qdisc is attached to a class
other than parsing all class trees of the link and check all tcm_info
fields in the leaf classes.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/pkt_sched.h

@@ -80,6 +80,7 @@ struct Qdisc
 	int			padded;
 	struct Qdisc_ops	*ops;
 	u32			handle;
+	u32			parent;
 	atomic_t		refcnt;
 	struct sk_buff_head	q;
 	struct net_device	*dev;

net/sched/sch_api.c

@@ -371,6 +371,8 @@ int qdisc_graft(struct net_device *dev, struct Qdisc *parent, u32 classid,
 			unsigned long cl = cops->get(parent, classid);
 			if (cl) {
 				err = cops->graft(parent, cl, new, old);
+				if (new)
+					new->parent = classid;
 				cops->put(parent, cl);
 			}
 		}
@@ -821,7 +823,7 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)
 				q_idx++;
 				continue;
 			}
-			if (tc_fill_qdisc(skb, q, 0, NETLINK_CB(cb->skb).pid,
+			if (tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).pid,
 					  cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWQDISC) <= 0) {
 				read_unlock_bh(&qdisc_tree_lock);
 				goto done;