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

[ Upstream commit 1e080f17750d1083e8a32f7b350584ae1cd7ff20 ]

mq / mqprio make the default child qdiscs visible. They only do
so for the qdiscs which are within real_num_tx_queues when the
device is registered. Depending on order of calls in the driver,
or if user space changes config via ethtool -L the number of
qdiscs visible under tc qdisc show will differ from the number
of queues. This is confusing to users and potentially to system
configuration scripts which try to make sure qdiscs have the
right parameters.

Add a new Qdisc_ops callback and make relevant qdiscs TTRT.

Note that this uncovers the "shortcut" created by
commit 1f27cde313d7 ("net: sched: use pfifo_fast for non real queues")
The default child qdiscs beyond initial real_num_tx are always
pfifo_fast, no matter what the sysfs setting is. Fixing this
gets a little tricky because we'd need to keep a reference
on whatever the default qdisc was at the time of creation.
In practice this is likely an non-issue the qdiscs likely have
to be configured to non-default settings, so whatever user space
is doing such configuration can replace the pfifos... now that
it will see them.

Reported-by: Matthew Massey <matthewmassey@fb.com>
Reviewed-by: Dave Taht <dave.taht@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index d737a6a2600be802672bdcd119a782aad1a5ec9d..286bc674a6e79f508dbfbdefb47d78146b0ef10c 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -216,6 +216,8 @@ 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 *);
@@ -547,6 +549,8 @@ 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);

diff --git a/net/core/dev.c b/net/core/dev.c
index 397bc2f50de08672a9bf6fe8c80db0f824f6824b..2519a90a148279426d0bd8e428d2729dff2f0f1d 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2648,6 +2648,8 @@ 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) {

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 4e15913e7519e0e2fd2150dfd3ba3edde4abfdd7..2128b77d5cb33c49db4ebee3e6ffa4001b44d61c 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1256,6 +1256,15 @@ 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;

diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index c008a316e94364a3f2e95403b2446362249b40e5..699b6bb444ceaa1e3c764190db578048478e2614 100644 (file)
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -130,6 +130,29 @@ 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);
@@ -285,6 +308,7 @@ 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,
 };

diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index fcfe41a954733cd213a902321ab766d342111748..3fd0e5dd7ae3ed39a37f42c097e348fc1dc7e49b 100644 (file)
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -308,6 +308,28 @@ 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)
 {
@@ -632,6 +654,7 @@ 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,
 };