net: sched: make default fifo qdiscs appear in the dump

The original reason [1] for having hidden qdiscs (potential scalability
issues in qdisc_match_from_root() with single linked list in case of large
amount of qdiscs) has been invalidated by 59cc1f61f0 ("net: sched: convert
qdisc linked list to hashtable").

This allows us for bringing more clarity and determinism into the dump by
making default pfifo qdiscs visible.

We're not turning this on by default though, at it was deemed [2] too
intrusive / unnecessary change of default behavior towards userspace.
Instead, TCA_DUMP_INVISIBLE netlink attribute is introduced, which allows
applications to request complete qdisc hierarchy dump, including the
ones that have always been implicit/invisible.

Singleton noop_qdisc stays invisible, as teaching the whole infrastructure
about singletons would require quite some surgery with very little gain
(seeing no qdisc or seeing noop qdisc in the dump is probably setting
the same user expectation).

[1] http://lkml.kernel.org/r/1460732328.10638.74.camel@edumazet-glaptop3.roam.corp.google.com
[2] http://lkml.kernel.org/r/20161021.105935.1907696543877061916.davem@davemloft.net

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

15 files changed, 62 insertions, 16 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index bcf49cd22786..62567bfe52c7 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -274,7 +274,7 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
 	return NULL;
 }
 
-void qdisc_hash_add(struct Qdisc *q)
+void qdisc_hash_add(struct Qdisc *q, bool invisible)
 {
 	if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS)) {
 		struct Qdisc *root = qdisc_dev(q)->qdisc;
@@ -282,6 +282,8 @@ void qdisc_hash_add(struct Qdisc *q)
 		WARN_ON_ONCE(root == &noop_qdisc);
 		ASSERT_RTNL();
 		hash_add_rcu(qdisc_dev(q)->qdisc_hash, &q->hash, q->handle);
+		if (invisible)
+			q->flags |= TCQ_F_INVISIBLE;
 	}
 }
 EXPORT_SYMBOL(qdisc_hash_add);
@@ -1003,7 +1005,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 				goto err_out4;
 		}
 
-		qdisc_hash_add(sch);
+		qdisc_hash_add(sch, false);
 
 		return sch;
 	}
@@ -1401,9 +1403,14 @@ nla_put_failure:
 	return -1;
 }
 
-static bool tc_qdisc_dump_ignore(struct Qdisc *q)
+static bool tc_qdisc_dump_ignore(struct Qdisc *q, bool dump_invisible)
 {
-	return (q->flags & TCQ_F_BUILTIN) ? true : false;
+	if (q->flags & TCQ_F_BUILTIN)
+		return true;
+	if ((q->flags & TCQ_F_INVISIBLE) && !dump_invisible)
+		return true;
+
+	return false;
 }
 
 static int qdisc_notify(struct net *net, struct sk_buff *oskb,
@@ -1417,12 +1424,12 @@ static int qdisc_notify(struct net *net, struct sk_buff *oskb,
 	if (!skb)
 		return -ENOBUFS;
 
-	if (old && !tc_qdisc_dump_ignore(old)) {
+	if (old && !tc_qdisc_dump_ignore(old, false)) {
 		if (tc_fill_qdisc(skb, old, clid, portid, n->nlmsg_seq,
 				  0, RTM_DELQDISC) < 0)
 			goto err_out;
 	}
-	if (new && !tc_qdisc_dump_ignore(new)) {
+	if (new && !tc_qdisc_dump_ignore(new, false)) {
 		if (tc_fill_qdisc(skb, new, clid, portid, n->nlmsg_seq,
 				  old ? NLM_F_REPLACE : 0, RTM_NEWQDISC) < 0)
 			goto err_out;
@@ -1439,7 +1446,8 @@ err_out:
 
 static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
 			      struct netlink_callback *cb,
-			      int *q_idx_p, int s_q_idx, bool recur)
+			      int *q_idx_p, int s_q_idx, bool recur,
+			      bool dump_invisible)
 {
 	int ret = 0, q_idx = *q_idx_p;
 	struct Qdisc *q;
@@ -1452,7 +1460,7 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
 	if (q_idx < s_q_idx) {
 		q_idx++;
 	} else {
-		if (!tc_qdisc_dump_ignore(q) &&
+		if (!tc_qdisc_dump_ignore(q, dump_invisible) &&
 		    tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).portid,
 				  cb->nlh->nlmsg_seq, NLM_F_MULTI,
 				  RTM_NEWQDISC) <= 0)
@@ -1474,7 +1482,7 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
 			q_idx++;
 			continue;
 		}
-		if (!tc_qdisc_dump_ignore(q) &&
+		if (!tc_qdisc_dump_ignore(q, dump_invisible) &&
 		    tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).portid,
 				  cb->nlh->nlmsg_seq, NLM_F_MULTI,
 				  RTM_NEWQDISC) <= 0)
@@ -1496,12 +1504,21 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)
 	int idx, q_idx;
 	int s_idx, s_q_idx;
 	struct net_device *dev;
+	const struct nlmsghdr *nlh = cb->nlh;
+	struct tcmsg *tcm = nlmsg_data(nlh);
+	struct nlattr *tca[TCA_MAX + 1];
+	int err;
 
 	s_idx = cb->args[0];
 	s_q_idx = q_idx = cb->args[1];
 
 	idx = 0;
 	ASSERT_RTNL();
+
+	err = nlmsg_parse(nlh, sizeof(*tcm), tca, TCA_MAX, NULL);
+	if (err < 0)
+		return err;
+
 	for_each_netdev(net, dev) {
 		struct netdev_queue *dev_queue;
 
@@ -1512,13 +1529,14 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)
 		q_idx = 0;
 
 		if (tc_dump_qdisc_root(dev->qdisc, skb, cb, &q_idx, s_q_idx,
-				       true) < 0)
+				       true, tca[TCA_DUMP_INVISIBLE]) < 0)
 			goto done;
 
 		dev_queue = dev_ingress_queue(dev);
 		if (dev_queue &&
 		    tc_dump_qdisc_root(dev_queue->qdisc_sleeping, skb, cb,
-				       &q_idx, s_q_idx, false) < 0)
+				       &q_idx, s_q_idx, false,
+				       tca[TCA_DUMP_INVISIBLE]) < 0)
 			goto done;
 
 cont:
@@ -1762,7 +1780,7 @@ static int tc_dump_tclass_qdisc(struct Qdisc *q, struct sk_buff *skb,
 {
 	struct qdisc_dump_args arg;
 
-	if (tc_qdisc_dump_ignore(q) ||
+	if (tc_qdisc_dump_ignore(q, false) ||
 	    *t_p < s_t || !q->ops->cl_ops ||
 	    (tcm->tcm_parent &&
 	     TC_H_MAJ(tcm->tcm_parent) != q->handle)) {
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index d6ca18dc04c3..cf93e5ff3d63 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1161,6 +1161,8 @@ static int cbq_init(struct Qdisc *sch, struct nlattr *opt)
 				      sch->handle);
 	if (!q->link.q)
 		q->link.q = &noop_qdisc;
+	else
+		qdisc_hash_add(q->link.q, true);
 
 	q->link.priority = TC_CBQ_MAXPRIO - 1;
 	q->link.priority2 = TC_CBQ_MAXPRIO - 1;
@@ -1600,6 +1602,9 @@ cbq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **t
 	cl->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid);
 	if (!cl->q)
 		cl->q = &noop_qdisc;
+	else
+		qdisc_hash_add(cl->q, true);
+
 	cl->common.classid = classid;
 	cl->tparent = parent;
 	cl->qdisc = sch;
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index bb4cbdf75004..9fe67e257dfa 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -117,6 +117,8 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 					       &pfifo_qdisc_ops, classid);
 	if (cl->qdisc == NULL)
 		cl->qdisc = &noop_qdisc;
+	else
+		qdisc_hash_add(cl->qdisc, true);
 
 	if (tca[TCA_RATE]) {
 		err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c
index 802ac7c2e5e8..1b98cb2160ff 100644
--- a/net/sched/sch_dsmark.c
+++ b/net/sched/sch_dsmark.c
@@ -368,6 +368,8 @@ static int dsmark_init(struct Qdisc *sch, struct nlattr *opt)
 	p->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, sch->handle);
 	if (p->q == NULL)
 		p->q = &noop_qdisc;
+	else
+		qdisc_hash_add(p->q, true);
 
 	pr_debug("%s: qdisc %p\n", __func__, p->q);
 
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index b052b27a984e..3e64d23e098c 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -795,7 +795,7 @@ static void attach_default_qdiscs(struct net_device *dev)
 	}
 #ifdef CONFIG_NET_SCHED
 	if (dev->qdisc)
-		qdisc_hash_add(dev->qdisc);
+		qdisc_hash_add(dev->qdisc, false);
 #endif
 }
 
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 3ffaa6fb0990..0198c6cdda49 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1066,6 +1066,8 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 				      &pfifo_qdisc_ops, classid);
 	if (cl->qdisc == NULL)
 		cl->qdisc = &noop_qdisc;
+	else
+		qdisc_hash_add(cl->qdisc, true);
 	INIT_LIST_HEAD(&cl->children);
 	cl->vt_tree = RB_ROOT;
 	cl->cf_tree = RB_ROOT;
@@ -1425,6 +1427,8 @@ hfsc_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 					  sch->handle);
 	if (q->root.qdisc == NULL)
 		q->root.qdisc = &noop_qdisc;
+	else
+		qdisc_hash_add(q->root.qdisc, true);
 	INIT_LIST_HEAD(&q->root.children);
 	q->root.vt_tree = RB_ROOT;
 	q->root.cf_tree = RB_ROOT;
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 4cd5fb134bc9..95867033542e 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1460,6 +1460,8 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
 		qdisc_class_hash_insert(&q->clhash, &cl->common);
 		if (parent)
 			parent->children++;
+		if (cl->un.leaf.q != &noop_qdisc)
+			qdisc_hash_add(cl->un.leaf.q, true);
 	} else {
 		if (tca[TCA_RATE]) {
 			err = gen_replace_estimator(&cl->bstats, NULL,
diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index 20b7f1646f69..cadfdd4f1e52 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -84,7 +84,7 @@ static void mq_attach(struct Qdisc *sch)
 			qdisc_destroy(old);
 #ifdef CONFIG_NET_SCHED
 		if (ntx < dev->real_num_tx_queues)
-			qdisc_hash_add(qdisc);
+			qdisc_hash_add(qdisc, false);
 #endif
 
 	}
diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index 922683418e53..b851e209da4d 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -175,7 +175,7 @@ static void mqprio_attach(struct Qdisc *sch)
 		if (old)
 			qdisc_destroy(old);
 		if (ntx < dev->real_num_tx_queues)
-			qdisc_hash_add(qdisc);
+			qdisc_hash_add(qdisc, false);
 	}
 	kfree(priv->qdiscs);
 	priv->qdiscs = NULL;
diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c
index e7839a0d0eaa..43a3a10b3c81 100644
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -217,6 +217,8 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt)
 				sch_tree_lock(sch);
 				old = q->queues[i];
 				q->queues[i] = child;
+				if (child != &noop_qdisc)
+					qdisc_hash_add(child, true);
 
 				if (old != &noop_qdisc) {
 					qdisc_tree_reduce_backlog(old,
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index d4d7db267b6e..92c2e6d448d7 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -192,8 +192,11 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
 		qdisc_destroy(child);
 	}
 
-	for (i = oldbands; i < q->bands; i++)
+	for (i = oldbands; i < q->bands; i++) {
 		q->queues[i] = queues[i];
+		if (q->queues[i] != &noop_qdisc)
+			qdisc_hash_add(q->queues[i], true);
+	}
 
 	sch_tree_unlock(sch);
 	return 0;
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index f9e712ce2d15..6c85f3e9239b 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -494,6 +494,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 			goto destroy_class;
 	}
 
+	if (cl->qdisc != &noop_qdisc)
+		qdisc_hash_add(cl->qdisc, true);
 	sch_tree_lock(sch);
 	qdisc_class_hash_insert(&q->clhash, &cl->common);
 	sch_tree_unlock(sch);
diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index 249b2a18acbd..799ea6dd69b2 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -191,6 +191,8 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt)
 			return PTR_ERR(child);
 	}
 
+	if (child != &noop_qdisc)
+		qdisc_hash_add(child, true);
 	sch_tree_lock(sch);
 	q->flags = ctl->flags;
 	q->limit = ctl->limit;
diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c
index fe6963d21519..ae862f172c94 100644
--- a/net/sched/sch_sfb.c
+++ b/net/sched/sch_sfb.c
@@ -513,6 +513,8 @@ static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
 	if (IS_ERR(child))
 		return PTR_ERR(child);
 
+	if (child != &noop_qdisc)
+		qdisc_hash_add(child, true);
 	sch_tree_lock(sch);
 
 	qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 303355c449ab..40c29a801391 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -396,6 +396,8 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
 					  q->qdisc->qstats.backlog);
 		qdisc_destroy(q->qdisc);
 		q->qdisc = child;
+		if (child != &noop_qdisc);
+			qdisc_hash_add(child, true);
 	}
 	q->limit = qopt->limit;
 	if (tb[TCA_TBF_PBURST])