Merge branch 'iff_no_queue_fixups'

Phil Sutter says:

====================
fixup IFF_NO_QUEUE conversion

This series serves two purposes:

On one hand it fixes a quite embarrassing bug around the warning I added for
drivers still setting tx_queue_len = 0 to achieve noqueue operation. It turned
out to be quite useless as due to using alloc_netdev(), many in-kernel drivers
fell into the trap by accident, as well. Instead this place serves pretty well
as a sanitizing point to set IFF_NO_QUEUE for drivers not initializing
tx_queue_len, which in turn allows to drop all special treatment of the latter
being zero since that can not happen anymore without IFF_NO_QUEUE being set.

On the other hand, it provides a better solution for Eric Dumazet's concern
regarding how to assign noqueue to an interface which does not default to it
already. In order to make this possible, noqueue is being registered so users
can 'tc qd add dev eth0 root noqueue'. In addition, it resolves the ugly
situation of 'tc qd show' not showing noqueue. Finally, the former changes
allow for some code cleanup.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -340,6 +340,7 @@ extern struct Qdisc noop_qdisc;
 extern struct Qdisc_ops noop_qdisc_ops;
 extern struct Qdisc_ops pfifo_fast_ops;
 extern struct Qdisc_ops mq_qdisc_ops;
+extern struct Qdisc_ops noqueue_qdisc_ops;
 extern const struct Qdisc_ops *default_qdisc_ops;
 
 struct Qdisc_class_common {

net/core/dev.c

@@ -7010,7 +7010,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 	setup(dev);
 
 	if (!dev->tx_queue_len)
-		printk(KERN_WARNING "%s uses DEPRECATED zero tx_queue_len - convert driver to use IFF_NO_QUEUE instead.\n", name);
+		dev->priv_flags |= IFF_NO_QUEUE;
 
 	dev->num_tx_queues = txqs;
 	dev->real_num_tx_queues = txqs;

net/sched/sch_api.c

@@ -1942,6 +1942,7 @@ static int __init pktsched_init(void)
 	register_qdisc(&bfifo_qdisc_ops);
 	register_qdisc(&pfifo_head_drop_qdisc_ops);
 	register_qdisc(&mq_qdisc_ops);
+	register_qdisc(&noqueue_qdisc_ops);
 
 	rtnl_register(PF_UNSPEC, RTM_NEWQDISC, tc_modify_qdisc, NULL, NULL);
 	rtnl_register(PF_UNSPEC, RTM_DELQDISC, tc_get_qdisc, NULL, NULL);

net/sched/sch_generic.c

@@ -416,33 +416,25 @@ struct Qdisc noop_qdisc = {
 };
 EXPORT_SYMBOL(noop_qdisc);
 
-static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
+static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt)
+{
+	/* register_qdisc() assigns a default of noop_enqueue if unset,
+	 * but __dev_queue_xmit() treats noqueue only as such
+	 * if this is NULL - so clear it here. */
+	qdisc->enqueue = NULL;
+	return 0;
+}
+
+struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 	.id		=	"noqueue",
 	.priv_size	=	0,
+	.init		=	noqueue_init,
 	.enqueue	=	noop_enqueue,
 	.dequeue	=	noop_dequeue,
 	.peek		=	noop_dequeue,
 	.owner		=	THIS_MODULE,
 };
 
-static struct Qdisc noqueue_qdisc;
-static struct netdev_queue noqueue_netdev_queue = {
-	.qdisc		=	&noqueue_qdisc,
-	.qdisc_sleeping	=	&noqueue_qdisc,
-};
-
-static struct Qdisc noqueue_qdisc = {
-	.enqueue	=	NULL,
-	.dequeue	=	noop_dequeue,
-	.flags		=	TCQ_F_BUILTIN,
-	.ops		=	&noqueue_qdisc_ops,
-	.list		=	LIST_HEAD_INIT(noqueue_qdisc.list),
-	.q.lock		=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
-	.dev_queue	=	&noqueue_netdev_queue,
-	.busylock	=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.busylock),
-};
-
-
 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 	1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 };
@@ -733,18 +725,19 @@ static void attach_one_default_qdisc(struct net_device *dev,
 				     struct netdev_queue *dev_queue,
 				     void *_unused)
 {
-	struct Qdisc *qdisc = &noqueue_qdisc;
+	struct Qdisc *qdisc;
+	const struct Qdisc_ops *ops = default_qdisc_ops;
+
+	if (dev->priv_flags & IFF_NO_QUEUE)
+		ops = &noqueue_qdisc_ops;
 
-	if (dev->tx_queue_len && !(dev->priv_flags & IFF_NO_QUEUE)) {
-		qdisc = qdisc_create_dflt(dev_queue,
-					  default_qdisc_ops, TC_H_ROOT);
+	qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT);
 	if (!qdisc) {
 		netdev_info(dev, "activation failed\n");
 		return;
 	}
 	if (!netif_is_multiqueue(dev))
 		qdisc->flags |= TCQ_F_ONETXQUEUE;
-	}
 	dev_queue->qdisc_sleeping = qdisc;
 }
 
@@ -756,7 +749,6 @@ static void attach_default_qdiscs(struct net_device *dev)
 	txq = netdev_get_tx_queue(dev, 0);
 
 	if (!netif_is_multiqueue(dev) ||
-	    dev->tx_queue_len == 0 ||
 	    dev->priv_flags & IFF_NO_QUEUE) {
 		netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 		dev->qdisc = txq->qdisc_sleeping;
@@ -781,7 +773,7 @@ static void transition_one_qdisc(struct net_device *dev,
 		clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
 
 	rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
-	if (need_watchdog_p && new_qdisc != &noqueue_qdisc) {
+	if (need_watchdog_p) {
 		dev_queue->trans_start = 0;
 		*need_watchdog_p = 1;
 	}