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Commit 7698b4fc authored by David S. Miller's avatar David S. Miller
Browse files

pkt_sched: Add and use qdisc_root() and qdisc_root_lock(). 



When code wants to lock the qdisc tree state, the logic
operation it's doing is locking the top-level qdisc that
sits of the root of the netdev_queue.

Add qdisc_root_lock() to represent this and convert the
easiest cases.

In order for this to work out in all cases, we have to
hook up the noop_qdisc to a dummy netdev_queue.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e2627c8c

include/net/sch_generic.h

+12 −0
Original line number Diff line number Diff line
@@ -161,6 +161,18 @@ struct tcf_proto 
	struct tcf_proto_ops	*ops;

};



static inline struct Qdisc *qdisc_root(struct Qdisc *qdisc)

{

	return qdisc->dev_queue->qdisc;

}



static inline spinlock_t *qdisc_root_lock(struct Qdisc *qdisc)

{

	struct Qdisc *root = qdisc_root(qdisc);



	return &root->dev_queue->lock;

}



static inline struct net_device *qdisc_dev(struct Qdisc *qdisc)

{

	return qdisc->dev_queue->dev;

net/sched/sch_api.c

+4 −4
Original line number Diff line number Diff line
@@ -633,7 +633,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue, 
	if (!ops->init || (err = ops->init(sch, tca[TCA_OPTIONS])) == 0) {

		if (tca[TCA_RATE]) {

			err = gen_new_estimator(&sch->bstats, &sch->rate_est,

						&sch->dev_queue->lock,

						qdisc_root_lock(sch),

						tca[TCA_RATE]);

			if (err) {

				/*
@@ -675,7 +675,7 @@ static int qdisc_change(struct Qdisc *sch, struct nlattr **tca) 
	}

	if (tca[TCA_RATE])

		gen_replace_estimator(&sch->bstats, &sch->rate_est,

				      &sch->dev_queue->lock, tca[TCA_RATE]);

				      qdisc_root_lock(sch), tca[TCA_RATE]);

	return 0;

}
@@ -967,7 +967,7 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid, 
	q->qstats.qlen = q->q.qlen;



	if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS,

					 TCA_XSTATS, &q->dev_queue->lock, &d) < 0)

					 TCA_XSTATS, qdisc_root_lock(q), &d) < 0)

		goto nla_put_failure;



	if (q->ops->dump_stats && q->ops->dump_stats(q, &d) < 0)
@@ -1216,7 +1216,7 @@ static int tc_fill_tclass(struct sk_buff *skb, struct Qdisc *q, 
		goto nla_put_failure;



	if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS,

					 TCA_XSTATS, &q->dev_queue->lock, &d) < 0)

					 TCA_XSTATS, qdisc_root_lock(q), &d) < 0)

		goto nla_put_failure;



	if (cl_ops->dump_stats && cl_ops->dump_stats(q, cl, &d) < 0)

net/sched/sch_cbq.c

+5 −4
Original line number Diff line number Diff line
@@ -1744,12 +1744,13 @@ static void cbq_put(struct Qdisc *sch, unsigned long arg) 


	if (--cl->refcnt == 0) {

#ifdef CONFIG_NET_CLS_ACT

		spinlock_t *root_lock = qdisc_root_lock(sch);

		struct cbq_sched_data *q = qdisc_priv(sch);



		spin_lock_bh(&sch->dev_queue->lock);

		spin_lock_bh(root_lock);

		if (q->rx_class == cl)

			q->rx_class = NULL;

		spin_unlock_bh(&sch->dev_queue->lock);

		spin_unlock_bh(root_lock);

#endif



		cbq_destroy_class(sch, cl);
@@ -1828,7 +1829,7 @@ cbq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **t 


		if (tca[TCA_RATE])

			gen_replace_estimator(&cl->bstats, &cl->rate_est,

					      &sch->dev_queue->lock,

					      qdisc_root_lock(sch),

					      tca[TCA_RATE]);

		return 0;

	}
@@ -1919,7 +1920,7 @@ cbq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, struct nlattr **t 


	if (tca[TCA_RATE])

		gen_new_estimator(&cl->bstats, &cl->rate_est,

				  &sch->dev_queue->lock, tca[TCA_RATE]);

				  qdisc_root_lock(sch), tca[TCA_RATE]);



	*arg = (unsigned long)cl;

	return 0;

net/sched/sch_generic.c

+16 −5
Original line number Diff line number Diff line
@@ -151,14 +151,17 @@ static inline int qdisc_restart(struct netdev_queue *txq, 
{

	int ret = NETDEV_TX_BUSY;

	struct net_device *dev;

	spinlock_t *root_lock;

	struct sk_buff *skb;



	/* Dequeue packet */

	if (unlikely((skb = dequeue_skb(q)) == NULL))

		return 0;



	/* And release queue */

	spin_unlock(&txq->lock);

	root_lock = qdisc_root_lock(q);



	/* And release qdisc */

	spin_unlock(root_lock);



	dev = txq->dev;
@@ -167,7 +170,7 @@ static inline int qdisc_restart(struct netdev_queue *txq, 
		ret = dev_hard_start_xmit(skb, dev, txq);

	HARD_TX_UNLOCK(dev, txq);



	spin_lock(&txq->lock);

	spin_lock(root_lock);



	switch (ret) {

	case NETDEV_TX_OK:
@@ -345,12 +348,18 @@ struct Qdisc_ops noop_qdisc_ops __read_mostly = { 
	.owner		=	THIS_MODULE,

};



static struct netdev_queue noop_netdev_queue = {

	.lock		=	__SPIN_LOCK_UNLOCKED(noop_netdev_queue.lock),

	.qdisc		=	&noop_qdisc,

};



struct Qdisc noop_qdisc = {

	.enqueue	=	noop_enqueue,

	.dequeue	=	noop_dequeue,

	.flags		=	TCQ_F_BUILTIN,

	.ops		=	&noop_qdisc_ops,

	.list		=	LIST_HEAD_INIT(noop_qdisc.list),

	.dev_queue	=	&noop_netdev_queue,

};

EXPORT_SYMBOL(noop_qdisc);
@@ -666,19 +675,21 @@ static bool some_qdisc_is_running(struct net_device *dev, int lock) 


	for (i = 0; i < dev->num_tx_queues; i++) {

		struct netdev_queue *dev_queue;

		spinlock_t *root_lock;

		struct Qdisc *q;

		int val;



		dev_queue = netdev_get_tx_queue(dev, i);

		q = dev_queue->qdisc;

		root_lock = qdisc_root_lock(q);



		if (lock)

			spin_lock_bh(&dev_queue->lock);

			spin_lock_bh(root_lock);



		val = test_bit(__QDISC_STATE_RUNNING, &q->state);



		if (lock)

			spin_unlock_bh(&dev_queue->lock);

			spin_unlock_bh(root_lock);



		if (val)

			return true;

net/sched/sch_hfsc.c

+2 −2
Original line number Diff line number Diff line
@@ -1045,7 +1045,7 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 


		if (tca[TCA_RATE])

			gen_replace_estimator(&cl->bstats, &cl->rate_est,

					      &sch->dev_queue->lock,

					      qdisc_root_lock(sch),

					      tca[TCA_RATE]);

		return 0;

	}
@@ -1104,7 +1104,7 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 


	if (tca[TCA_RATE])

		gen_new_estimator(&cl->bstats, &cl->rate_est,

				  &sch->dev_queue->lock, tca[TCA_RATE]);

				  qdisc_root_lock(sch), tca[TCA_RATE]);

	*arg = (unsigned long)cl;

	return 0;

}