Merge branch 'qdisc-visibility'

Jakub Kicinski says:

====================
net: sched: update default qdisc visibility after Tx queue cnt changes

Matthew noticed that number of children reported by mq does not match
number of queues on reconfigured interfaces. For example if mq is
instantiated when there is 8 queues it will always show 8 children,
regardless of config being changed:

 # ethtool -L eth0 combined 8
 # tc qdisc replace dev eth0 root handle 100: mq
 # tc qdisc show dev eth0
 qdisc mq 100: root
 qdisc pfifo_fast 0: parent 100:8 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:7 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:6 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:5 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:4 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:3 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:2 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:1 bands 3 priomap 1 2 ...
 # ethtool -L eth0 combined 1
 # tc qdisc show dev eth0
 qdisc mq 100: root
 qdisc pfifo_fast 0: parent 100:8 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:7 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:6 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:5 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:4 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:3 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:2 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:1 bands 3 priomap 1 2 ...
 # ethtool -L eth0 combined 32
 # tc qdisc show dev eth0
 qdisc mq 100: root
 qdisc pfifo_fast 0: parent 100:8 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:7 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:6 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:5 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:4 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:3 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:2 bands 3 priomap 1 2 ...
 qdisc pfifo_fast 0: parent 100:1 bands 3 priomap 1 2 ...

This patchset fixes this by hashing and unhasing the default
child qdiscs as number of queues gets adjusted.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netdevsim/ethtool.c

@@ -81,6 +81,30 @@ static int nsim_set_ringparam(struct net_device *dev,
 	return 0;
 }
 
+static void
+nsim_get_channels(struct net_device *dev, struct ethtool_channels *ch)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+
+	ch->max_combined = ns->nsim_bus_dev->num_queues;
+	ch->combined_count = ns->ethtool.channels;
+}
+
+static int
+nsim_set_channels(struct net_device *dev, struct ethtool_channels *ch)
+{
+	struct netdevsim *ns = netdev_priv(dev);
+	int err;
+
+	err = netif_set_real_num_queues(dev, ch->combined_count,
+					ch->combined_count);
+	if (err)
+		return err;
+
+	ns->ethtool.channels = ch->combined_count;
+	return 0;
+}
+
 static int
 nsim_get_fecparam(struct net_device *dev, struct ethtool_fecparam *fecparam)
 {
@@ -118,6 +142,8 @@ static const struct ethtool_ops nsim_ethtool_ops = {
 	.get_coalesce			= nsim_get_coalesce,
 	.get_ringparam			= nsim_get_ringparam,
 	.set_ringparam			= nsim_set_ringparam,
+	.get_channels			= nsim_get_channels,
+	.set_channels			= nsim_set_channels,
 	.get_fecparam			= nsim_get_fecparam,
 	.set_fecparam			= nsim_set_fecparam,
 };
@@ -141,6 +167,8 @@ void nsim_ethtool_init(struct netdevsim *ns)
 	ns->ethtool.fec.fec = ETHTOOL_FEC_NONE;
 	ns->ethtool.fec.active_fec = ETHTOOL_FEC_NONE;
 
+	ns->ethtool.channels = ns->nsim_bus_dev->num_queues;
+
 	ethtool = debugfs_create_dir("ethtool", ns->nsim_dev_port->ddir);
 
 	debugfs_create_u32("get_err", 0600, ethtool, &ns->ethtool.get_err);

drivers/net/netdevsim/netdevsim.h

@@ -62,6 +62,7 @@ struct nsim_ethtool_pauseparam {
 struct nsim_ethtool {
 	u32 get_err;
 	u32 set_err;
+	u32 channels;
 	struct nsim_ethtool_pauseparam pauseparam;
 	struct ethtool_coalesce coalesce;
 	struct ethtool_ringparam ring;

include/net/sch_generic.h

@@ -308,6 +308,8 @@ struct Qdisc_ops {
 					  struct netlink_ext_ack *extack);
 	void			(*attach)(struct Qdisc *sch);
 	int			(*change_tx_queue_len)(struct Qdisc *, unsigned int);
+	void			(*change_real_num_tx)(struct Qdisc *sch,
+						      unsigned int new_real_tx);
 
 	int			(*dump)(struct Qdisc *, struct sk_buff *);
 	int			(*dump_stats)(struct Qdisc *, struct gnet_dump *);
@@ -684,6 +686,8 @@ void qdisc_class_hash_grow(struct Qdisc *, struct Qdisc_class_hash *);
 void qdisc_class_hash_destroy(struct Qdisc_class_hash *);
 
 int dev_qdisc_change_tx_queue_len(struct net_device *dev);
+void dev_qdisc_change_real_num_tx(struct net_device *dev,
+				  unsigned int new_real_tx);
 void dev_init_scheduler(struct net_device *dev);
 void dev_shutdown(struct net_device *dev);
 void dev_activate(struct net_device *dev);

net/core/dev.c

@@ -2921,6 +2921,8 @@ int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
 		if (dev->num_tc)
 			netif_setup_tc(dev, txq);
 
+		dev_qdisc_change_real_num_tx(dev, txq);
+
 		dev->real_num_tx_queues = txq;
 
 		if (disabling) {

net/sched/sch_generic.c

@@ -1330,6 +1330,15 @@ static int qdisc_change_tx_queue_len(struct net_device *dev,
 	return 0;
 }
 
+void dev_qdisc_change_real_num_tx(struct net_device *dev,
+				  unsigned int new_real_tx)
+{
+	struct Qdisc *qdisc = dev->qdisc;
+
+	if (qdisc->ops->change_real_num_tx)
+		qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
+}
+
 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
 {
 	bool up = dev->flags & IFF_UP;

net/sched/sch_mq.c

@@ -125,6 +125,29 @@ static void mq_attach(struct Qdisc *sch)
 	priv->qdiscs = NULL;
 }
 
+static void mq_change_real_num_tx(struct Qdisc *sch, unsigned int new_real_tx)
+{
+#ifdef CONFIG_NET_SCHED
+	struct net_device *dev = qdisc_dev(sch);
+	struct Qdisc *qdisc;
+	unsigned int i;
+
+	for (i = new_real_tx; i < dev->real_num_tx_queues; i++) {
+		qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
+		/* Only update the default qdiscs we created,
+		 * qdiscs with handles are always hashed.
+		 */
+		if (qdisc != &noop_qdisc && !qdisc->handle)
+			qdisc_hash_del(qdisc);
+	}
+	for (i = dev->real_num_tx_queues; i < new_real_tx; i++) {
+		qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
+		if (qdisc != &noop_qdisc && !qdisc->handle)
+			qdisc_hash_add(qdisc, false);
+	}
+#endif
+}
+
 static int mq_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
 	struct net_device *dev = qdisc_dev(sch);
@@ -288,6 +311,7 @@ struct Qdisc_ops mq_qdisc_ops __read_mostly = {
 	.init		= mq_init,
 	.destroy	= mq_destroy,
 	.attach		= mq_attach,
+	.change_real_num_tx = mq_change_real_num_tx,
 	.dump		= mq_dump,
 	.owner		= THIS_MODULE,
 };

net/sched/sch_mqprio.c

@@ -306,6 +306,28 @@ static void mqprio_attach(struct Qdisc *sch)
 	priv->qdiscs = NULL;
 }
 
+static void mqprio_change_real_num_tx(struct Qdisc *sch,
+				      unsigned int new_real_tx)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	struct Qdisc *qdisc;
+	unsigned int i;
+
+	for (i = new_real_tx; i < dev->real_num_tx_queues; i++) {
+		qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
+		/* Only update the default qdiscs we created,
+		 * qdiscs with handles are always hashed.
+		 */
+		if (qdisc != &noop_qdisc && !qdisc->handle)
+			qdisc_hash_del(qdisc);
+	}
+	for (i = dev->real_num_tx_queues; i < new_real_tx; i++) {
+		qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
+		if (qdisc != &noop_qdisc && !qdisc->handle)
+			qdisc_hash_add(qdisc, false);
+	}
+}
+
 static struct netdev_queue *mqprio_queue_get(struct Qdisc *sch,
 					     unsigned long cl)
 {
@@ -623,6 +645,7 @@ static struct Qdisc_ops mqprio_qdisc_ops __read_mostly = {
 	.init		= mqprio_init,
 	.destroy	= mqprio_destroy,
 	.attach		= mqprio_attach,
+	.change_real_num_tx = mqprio_change_real_num_tx,
 	.dump		= mqprio_dump,
 	.owner		= THIS_MODULE,
 };

tools/testing/selftests/drivers/net/netdevsim/ethtool-common.sh

@@ -50,7 +50,7 @@ function make_netdev {
 	modprobe netdevsim
     fi
 
-    echo $NSIM_ID > /sys/bus/netdevsim/new_device
+    echo $NSIM_ID $@ > /sys/bus/netdevsim/new_device
     # get new device name
     ls /sys/bus/netdevsim/devices/netdevsim${NSIM_ID}/net/
 }

tools/testing/selftests/drivers/net/netdevsim/tc-mq-visibility.sh

@@ -0,0 +1,77 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+
+source ethtool-common.sh
+
+set -o pipefail
+
+n_children() {
+    n=$(tc qdisc show dev $NDEV | grep '^qdisc' | wc -l)
+    echo $((n - 1))
+}
+
+tcq() {
+    tc qdisc $1 dev $NDEV ${@:2}
+}
+
+n_child_assert() {
+    n=$(n_children)
+    if [ $n -ne $1 ]; then
+	echo "ERROR ($root): ${@:2}, expected $1 have $n"
+	((num_errors++))
+    else
+	((num_passes++))
+    fi
+}
+
+
+for root in mq mqprio; do
+    NDEV=$(make_netdev 1 4)
+
+    opts=
+    [ $root == "mqprio" ] && opts='hw 0 num_tc 1 map 0 0 0 0  queues 1@0'
+
+    tcq add root handle 100: $root $opts
+    n_child_assert 4 'Init'
+
+    # All defaults
+
+    for n in 3 2 1 2 3 4 1 4; do
+	ethtool -L $NDEV combined $n
+	n_child_assert $n "Change queues to $n while down"
+    done
+
+    ip link set dev $NDEV up
+
+    for n in 3 2 1 2 3 4 1 4; do
+	ethtool -L $NDEV combined $n
+	n_child_assert $n "Change queues to $n while up"
+    done
+
+    # One real one
+    tcq replace parent 100:4 handle 204: pfifo_fast
+    n_child_assert 4 "One real queue"
+
+    ethtool -L $NDEV combined 1
+    n_child_assert 2 "One real queue, one default"
+
+    ethtool -L $NDEV combined 4
+    n_child_assert 4 "One real queue, rest default"
+
+    # Graft some
+    tcq replace parent 100:1 handle 204:
+    n_child_assert 3 "Grafted"
+
+    ethtool -L $NDEV combined 1
+    n_child_assert 1 "Grafted, one"
+
+    cleanup_nsim
+done
+
+if [ $num_errors -eq 0 ]; then
+    echo "PASSED all $((num_passes)) checks"
+    exit 0
+else
+    echo "FAILED $num_errors/$((num_errors+num_passes)) checks"
+    exit 1
+fi