net: sch: api: add extack support in qdisc_create_dflt

This patch adds extack support for the function qdisc_create_dflt which is
a common used function in the tc subsystem. Callers which are interested
in the receiving error can assign extack to get a more detailed
information why qdisc_create_dflt failed. The function qdisc_create_dflt
will also call an init callback which can fail by any per-qdisc specific
handling.

Cc: David Ahern <dsahern@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/pkt_sched.h

@@ -89,7 +89,8 @@ extern struct Qdisc_ops pfifo_head_drop_qdisc_ops;
 
 int fifo_set_limit(struct Qdisc *q, unsigned int limit);
 struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
-			       unsigned int limit);
+			       unsigned int limit,
+			       struct netlink_ext_ack *extack);
 
 int register_qdisc(struct Qdisc_ops *qops);
 int unregister_qdisc(struct Qdisc_ops *qops);

include/net/sch_generic.h

@@ -474,7 +474,8 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 			  const struct Qdisc_ops *ops,
 			  struct netlink_ext_ack *extack);
 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
-				const struct Qdisc_ops *ops, u32 parentid);
+				const struct Qdisc_ops *ops, u32 parentid,
+				struct netlink_ext_ack *extack);
 void __qdisc_calculate_pkt_len(struct sk_buff *skb,
 			       const struct qdisc_size_table *stab);
 int skb_do_redirect(struct sk_buff *);

net/sched/sch_atm.c

@@ -290,7 +290,8 @@ static int atm_tc_change(struct Qdisc *sch, u32 classid, u32 parent,
 		goto err_out;
 	}
 
-	flow->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid);
+	flow->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid,
+				    extack);
 	if (!flow->q)
 		flow->q = &noop_qdisc;
 	pr_debug("atm_tc_change: qdisc %p\n", flow->q);
@@ -546,7 +547,7 @@ static int atm_tc_init(struct Qdisc *sch, struct nlattr *opt,
 	INIT_LIST_HEAD(&p->link.list);
 	list_add(&p->link.list, &p->flows);
 	p->link.q = qdisc_create_dflt(sch->dev_queue,
-				      &pfifo_qdisc_ops, sch->handle);
+				      &pfifo_qdisc_ops, sch->handle, extack);
 	if (!p->link.q)
 		p->link.q = &noop_qdisc;
 	pr_debug("atm_tc_init: link (%p) qdisc %p\n", &p->link, p->link.q);

net/sched/sch_cbq.c

@@ -1172,7 +1172,7 @@ static int cbq_init(struct Qdisc *sch, struct nlattr *opt,
 	q->link.common.classid = sch->handle;
 	q->link.qdisc = sch;
 	q->link.q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-				      sch->handle);
+				      sch->handle, NULL);
 	if (!q->link.q)
 		q->link.q = &noop_qdisc;
 	else
@@ -1376,8 +1376,8 @@ static int cbq_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 	struct cbq_class *cl = (struct cbq_class *)arg;
 
 	if (new == NULL) {
-		new = qdisc_create_dflt(sch->dev_queue,
+		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					&pfifo_qdisc_ops, cl->common.classid);
+					cl->common.classid, extack);
 		if (new == NULL)
 			return -ENOBUFS;
 	}
@@ -1596,7 +1596,8 @@ cbq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **t
 
 	cl->R_tab = rtab;
 	rtab = NULL;
-	cl->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid);
+	cl->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, classid,
+				  NULL);
 	if (!cl->q)
 		cl->q = &noop_qdisc;
 	else

net/sched/sch_drr.c

@@ -114,7 +114,8 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 	cl->common.classid = classid;
 	cl->quantum	   = quantum;
 	cl->qdisc	   = qdisc_create_dflt(sch->dev_queue,
-					       &pfifo_qdisc_ops, classid);
+					       &pfifo_qdisc_ops, classid,
+					       NULL);
 	if (cl->qdisc == NULL)
 		cl->qdisc = &noop_qdisc;
 	else
@@ -209,8 +210,8 @@ static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
 	struct drr_class *cl = (struct drr_class *)arg;
 
 	if (new == NULL) {
-		new = qdisc_create_dflt(sch->dev_queue,
+		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					&pfifo_qdisc_ops, cl->common.classid);
+					cl->common.classid, NULL);
 		if (new == NULL)
 			new = &noop_qdisc;
 	}

net/sched/sch_dsmark.c

@@ -71,7 +71,7 @@ static int dsmark_graft(struct Qdisc *sch, unsigned long arg,
 
 	if (new == NULL) {
 		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					sch->handle);
+					sch->handle, NULL);
 		if (new == NULL)
 			new = &noop_qdisc;
 	}
@@ -381,7 +381,8 @@ static int dsmark_init(struct Qdisc *sch, struct nlattr *opt,
 	p->default_index = default_index;
 	p->set_tc_index = nla_get_flag(tb[TCA_DSMARK_SET_TC_INDEX]);
 
-	p->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, sch->handle);
+	p->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, sch->handle,
+				 NULL);
 	if (p->q == NULL)
 		p->q = &noop_qdisc;
 	else

net/sched/sch_fifo.c

@@ -166,12 +166,14 @@ int fifo_set_limit(struct Qdisc *q, unsigned int limit)
 EXPORT_SYMBOL(fifo_set_limit);
 
 struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
-			       unsigned int limit)
+			       unsigned int limit,
+			       struct netlink_ext_ack *extack)
 {
 	struct Qdisc *q;
 	int err = -ENOMEM;
 
-	q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1));
+	q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1),
+			      extack);
 	if (q) {
 		err = fifo_set_limit(q, limit);
 		if (err < 0) {

net/sched/sch_generic.c

@@ -830,21 +830,24 @@ errout:
 
 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 				const struct Qdisc_ops *ops,
-				unsigned int parentid)
+				unsigned int parentid,
+				struct netlink_ext_ack *extack)
 {
 	struct Qdisc *sch;
 
-	if (!try_module_get(ops->owner))
+	if (!try_module_get(ops->owner)) {
+		NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 		return NULL;
+	}
 
-	sch = qdisc_alloc(dev_queue, ops, NULL);
+	sch = qdisc_alloc(dev_queue, ops, extack);
 	if (IS_ERR(sch)) {
 		module_put(ops->owner);
 		return NULL;
 	}
 	sch->parent = parentid;
 
-	if (!ops->init || ops->init(sch, NULL, NULL) == 0)
+	if (!ops->init || ops->init(sch, NULL, extack) == 0)
 		return sch;
 
 	qdisc_destroy(sch);
@@ -956,7 +959,7 @@ static void attach_one_default_qdisc(struct net_device *dev,
 	if (dev->priv_flags & IFF_NO_QUEUE)
 		ops = &noqueue_qdisc_ops;
 
-	qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT);
+	qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
 	if (!qdisc) {
 		netdev_info(dev, "activation failed\n");
 		return;
@@ -979,7 +982,7 @@ static void attach_default_qdiscs(struct net_device *dev)
 		dev->qdisc = txq->qdisc_sleeping;
 		qdisc_refcount_inc(dev->qdisc);
 	} else {
-		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
+		qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
 		if (qdisc) {
 			dev->qdisc = qdisc;
 			qdisc->ops->attach(qdisc);

net/sched/sch_hfsc.c

@@ -1062,8 +1062,8 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 	cl->cl_common.classid = classid;
 	cl->sched     = q;
 	cl->cl_parent = parent;
-	cl->qdisc = qdisc_create_dflt(sch->dev_queue,
+	cl->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-				      &pfifo_qdisc_ops, classid);
+				      classid, NULL);
 	if (cl->qdisc == NULL)
 		cl->qdisc = &noop_qdisc;
 	else
@@ -1185,7 +1185,7 @@ hfsc_graft_class(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 		return -EINVAL;
 	if (new == NULL) {
 		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					cl->cl_common.classid);
+					cl->cl_common.classid, NULL);
 		if (new == NULL)
 			new = &noop_qdisc;
 	}
@@ -1416,7 +1416,7 @@ hfsc_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
 	q->root.cl_common.classid = sch->handle;
 	q->root.sched   = q;
 	q->root.qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					  sch->handle);
+					  sch->handle, NULL);
 	if (q->root.qdisc == NULL)
 		q->root.qdisc = &noop_qdisc;
 	else

net/sched/sch_htb.c

@@ -1180,7 +1180,7 @@ static int htb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 		return -EINVAL;
 	if (new == NULL &&
 	    (new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-				     cl->common.classid)) == NULL)
+				     cl->common.classid, extack)) == NULL)
 		return -ENOBUFS;
 
 	*old = qdisc_replace(sch, new, &cl->un.leaf.q);
@@ -1290,7 +1290,8 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg)
 
 	if (!cl->level && htb_parent_last_child(cl)) {
 		new_q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					  cl->parent->common.classid);
+					  cl->parent->common.classid,
+					  NULL);
 		last_child = 1;
 	}
 
@@ -1426,8 +1427,8 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
 		 * so that can't be used inside of sch_tree_lock
 		 * -- thanks to Karlis Peisenieks
 		 */
-		new_q = qdisc_create_dflt(sch->dev_queue,
+		new_q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					  &pfifo_qdisc_ops, classid);
+					  classid, NULL);
 		sch_tree_lock(sch);
 		if (parent && !parent->level) {
 			unsigned int qlen = parent->un.leaf.q->q.qlen;

net/sched/sch_mq.c

@@ -61,7 +61,8 @@ static int mq_init(struct Qdisc *sch, struct nlattr *opt,
 		dev_queue = netdev_get_tx_queue(dev, ntx);
 		qdisc = qdisc_create_dflt(dev_queue, get_default_qdisc_ops(dev, ntx),
 					  TC_H_MAKE(TC_H_MAJ(sch->handle),
-						    TC_H_MIN(ntx + 1)));
+						    TC_H_MIN(ntx + 1)),
+					  extack);
 		if (!qdisc)
 			return -ENOMEM;
 		priv->qdiscs[ntx] = qdisc;

net/sched/sch_mqprio.c

@@ -230,7 +230,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt,
 		qdisc = qdisc_create_dflt(dev_queue,
 					  get_default_qdisc_ops(dev, i),
 					  TC_H_MAKE(TC_H_MAJ(sch->handle),
-						    TC_H_MIN(i + 1)));
+						    TC_H_MIN(i + 1)), extack);
 		if (!qdisc)
 			return -ENOMEM;
 

net/sched/sch_multiq.c

@@ -216,7 +216,7 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt,
 			child = qdisc_create_dflt(sch->dev_queue,
 						  &pfifo_qdisc_ops,
 						  TC_H_MAKE(sch->handle,
-							    i + 1));
+							    i + 1), extack);
 			if (child) {
 				sch_tree_lock(sch);
 				old = q->queues[i];

net/sched/sch_prio.c

@@ -176,7 +176,8 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt,
 	/* Before commit, make sure we can allocate all new qdiscs */
 	for (i = oldbands; i < qopt->bands; i++) {
 		queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					      TC_H_MAKE(sch->handle, i + 1));
+					      TC_H_MAKE(sch->handle, i + 1),
+					      extack);
 		if (!queues[i]) {
 			while (i > oldbands)
 				qdisc_destroy(queues[--i]);

net/sched/sch_qfq.c

@@ -480,8 +480,8 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 	cl->common.classid = classid;
 	cl->deficit = lmax;
 
-	cl->qdisc = qdisc_create_dflt(sch->dev_queue,
+	cl->qdisc = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-				      &pfifo_qdisc_ops, classid);
+				      classid, NULL);
 	if (cl->qdisc == NULL)
 		cl->qdisc = &noop_qdisc;
 
@@ -601,8 +601,8 @@ static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
 	struct qfq_class *cl = (struct qfq_class *)arg;
 
 	if (new == NULL) {
-		new = qdisc_create_dflt(sch->dev_queue,
+		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
-					&pfifo_qdisc_ops, cl->common.classid);
+					cl->common.classid, NULL);
 		if (new == NULL)
 			new = &noop_qdisc;
 	}

net/sched/sch_red.c

@@ -225,7 +225,8 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt,
 		return -EINVAL;
 
 	if (ctl->limit > 0) {
-		child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit);
+		child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit,
+					 extack);
 		if (IS_ERR(child))
 			return PTR_ERR(child);
 	}

net/sched/sch_sfb.c

@@ -513,7 +513,7 @@ static int sfb_change(struct Qdisc *sch, struct nlattr *opt,
 	if (limit == 0)
 		limit = qdisc_dev(sch)->tx_queue_len;
 
-	child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
+	child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit, extack);
 	if (IS_ERR(child))
 		return PTR_ERR(child);
 

net/sched/sch_tbf.c

@@ -386,7 +386,8 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
 		if (err)
 			goto done;
 	} else if (qopt->limit > 0) {
-		child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit);
+		child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit,
+					 extack);
 		if (IS_ERR(child)) {
 			err = PTR_ERR(child);
 			goto done;