Commit 30723673 authored by David S. Miller's avatar David S. Miller
Browse files

pkt_sched: Manage qdisc list inside of root qdisc. 



Idea is from Patrick McHardy.

Instead of managing the list of qdiscs on the device level, manage it
in the root qdisc of a netdev_queue.  This solves all kinds of
visibility issues during qdisc destruction.

The way to iterate over all qdiscs of a netdev_queue is to visit
the netdev_queue->qdisc, and then traverse it's list.

The only special case is to ignore builting qdiscs at the root when
dumping or doing a qdisc_lookup().  That was not needed previously
because builtin qdiscs were not added to the device's qdisc_list.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 72b25a91

include/linux/netdevice.h

+0 −2
Original line number Diff line number Diff line
@@ -636,8 +636,6 @@ struct net_device 
	unsigned int		real_num_tx_queues;



	unsigned long		tx_queue_len;	/* Max frames per queue allowed */

	spinlock_t		qdisc_list_lock;

	struct list_head	qdisc_list;



/*

 * One part is mostly used on xmit path (device)

net/core/dev.c

+0 −2
Original line number Diff line number Diff line
@@ -3888,8 +3888,6 @@ int register_netdevice(struct net_device *dev) 
	net = dev_net(dev);



	spin_lock_init(&dev->addr_list_lock);

	spin_lock_init(&dev->qdisc_list_lock);

	INIT_LIST_HEAD(&dev->qdisc_list);

	netdev_init_queue_locks(dev);



	dev->iflink = -1;

net/sched/sch_api.c

+131 −44
Original line number Diff line number Diff line
@@ -185,12 +185,21 @@ EXPORT_SYMBOL(unregister_qdisc); 


struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle)

{

	struct Qdisc *q;

	unsigned int i;



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

		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);

		struct Qdisc *q, *txq_root = txq->qdisc;



	list_for_each_entry(q, &dev->qdisc_list, list) {

		if (!(txq_root->flags & TCQ_F_BUILTIN) &&

		    txq_root->handle == handle)

			return txq_root;



		list_for_each_entry(q, &txq_root->list, list) {

			if (q->handle == handle)

				return q;

		}

	}

	return NULL;

}
@@ -676,9 +685,8 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue, 
				goto err_out3;

			}

		}

		spin_lock_bh(&dev->qdisc_list_lock);

		list_add_tail(&sch->list, &dev->qdisc_list);

		spin_unlock_bh(&dev->qdisc_list_lock);

		if (parent)

			list_add_tail(&sch->list, &dev_queue->qdisc->list);



		return sch;

	}
@@ -1037,13 +1045,57 @@ err_out: 
	return -EINVAL;

}



static bool tc_qdisc_dump_ignore(struct Qdisc *q)

{

	return (q->flags & TCQ_F_BUILTIN) ? true : false;

}



static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,

			      struct netlink_callback *cb,

			      int *q_idx_p, int s_q_idx)

{

	int ret = 0, q_idx = *q_idx_p;

	struct Qdisc *q;



	if (!root)

		return 0;



	q = root;

	if (q_idx < s_q_idx) {

		q_idx++;

	} else {

		if (!tc_qdisc_dump_ignore(q) &&

		    tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).pid,

				  cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWQDISC) <= 0)

			goto done;

		q_idx++;

	}

	list_for_each_entry(q, &root->list, list) {

		if (q_idx < s_q_idx) {

			q_idx++;

			continue;

		}

		if (!tc_qdisc_dump_ignore(q) && 

		    tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).pid,

				  cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWQDISC) <= 0)

			goto done;

		q_idx++;

	}



out:

	*q_idx_p = q_idx;

	return ret;

done:

	ret = -1;

	goto out;

}



static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)

{

	struct net *net = sock_net(skb->sk);

	int idx, q_idx;

	int s_idx, s_q_idx;

	struct net_device *dev;

	struct Qdisc *q;



	if (net != &init_net)

		return 0;
@@ -1053,21 +1105,22 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb) 
	read_lock(&dev_base_lock);

	idx = 0;

	for_each_netdev(&init_net, dev) {

		struct netdev_queue *dev_queue;



		if (idx < s_idx)

			goto cont;

		if (idx > s_idx)

			s_q_idx = 0;

		q_idx = 0;

		list_for_each_entry(q, &dev->qdisc_list, list) {

			if (q_idx < s_q_idx) {

				q_idx++;

				continue;

			}

			if (tc_fill_qdisc(skb, q, q->parent, NETLINK_CB(cb->skb).pid,

					  cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWQDISC) <= 0)



		dev_queue = netdev_get_tx_queue(dev, 0);

		if (tc_dump_qdisc_root(dev_queue->qdisc, skb, cb, &q_idx, s_q_idx) < 0)

			goto done;

			q_idx++;

		}



		dev_queue = &dev->rx_queue;

		if (tc_dump_qdisc_root(dev_queue->qdisc, skb, cb, &q_idx, s_q_idx) < 0)

			goto done;



cont:

		idx++;

	}
@@ -1285,35 +1338,20 @@ static int qdisc_class_dump(struct Qdisc *q, unsigned long cl, struct qdisc_walk 
			      a->cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWTCLASS);

}



static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb)

static int tc_dump_tclass_qdisc(struct Qdisc *q, struct sk_buff *skb,

				struct tcmsg *tcm, struct netlink_callback *cb,

				int *t_p, int s_t)

{

	struct net *net = sock_net(skb->sk);

	int t;

	int s_t;

	struct net_device *dev;

	struct Qdisc *q;

	struct tcmsg *tcm = (struct tcmsg*)NLMSG_DATA(cb->nlh);

	struct qdisc_dump_args arg;



	if (net != &init_net)

		return 0;



	if (cb->nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*tcm)))

		return 0;

	if ((dev = dev_get_by_index(&init_net, tcm->tcm_ifindex)) == NULL)

		return 0;



	s_t = cb->args[0];

	t = 0;



	list_for_each_entry(q, &dev->qdisc_list, list) {

		if (t < s_t || !q->ops->cl_ops ||

	if (tc_qdisc_dump_ignore(q) ||

	    *t_p < s_t || !q->ops->cl_ops ||

	    (tcm->tcm_parent &&

	     TC_H_MAJ(tcm->tcm_parent) != q->handle)) {

			t++;

			continue;

		(*t_p)++;

		return 0;

	}

		if (t > s_t)

	if (*t_p > s_t)

		memset(&cb->args[1], 0, sizeof(cb->args)-sizeof(cb->args[0]));

	arg.w.fn = qdisc_class_dump;

	arg.skb = skb;
@@ -1324,10 +1362,59 @@ static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb) 
	q->ops->cl_ops->walk(q, &arg.w);

	cb->args[1] = arg.w.count;

	if (arg.w.stop)

			break;

		t++;

		return -1;

	(*t_p)++;

	return 0;

}



static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,

			       struct tcmsg *tcm, struct netlink_callback *cb,

			       int *t_p, int s_t)

{

	struct Qdisc *q;



	if (!root)

		return 0;



	if (tc_dump_tclass_qdisc(root, skb, tcm, cb, t_p, s_t) < 0)

		return -1;



	list_for_each_entry(q, &root->list, list) {

		if (tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0)

			return -1;

	}



	return 0;

}



static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb)

{

	struct tcmsg *tcm = (struct tcmsg*)NLMSG_DATA(cb->nlh);

	struct net *net = sock_net(skb->sk);

	struct netdev_queue *dev_queue;

	struct net_device *dev;

	int t, s_t;



	if (net != &init_net)

		return 0;



	if (cb->nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*tcm)))

		return 0;

	if ((dev = dev_get_by_index(&init_net, tcm->tcm_ifindex)) == NULL)

		return 0;



	s_t = cb->args[0];

	t = 0;



	dev_queue = netdev_get_tx_queue(dev, 0);

	if (tc_dump_tclass_root(dev_queue->qdisc, skb, tcm, cb, &t, s_t) < 0)

		goto done;



	dev_queue = &dev->rx_queue;

	if (tc_dump_tclass_root(dev_queue->qdisc, skb, tcm, cb, &t, s_t) < 0)

		goto done;



done:

	cb->args[0] = t;



	dev_put(dev);

net/sched/sch_generic.c

+2 −8
Original line number Diff line number Diff line
@@ -480,15 +480,12 @@ static void __qdisc_destroy(struct rcu_head *head) 


void qdisc_destroy(struct Qdisc *qdisc)

{

	struct net_device *dev = qdisc_dev(qdisc);



	if (qdisc->flags & TCQ_F_BUILTIN ||

	    !atomic_dec_and_test(&qdisc->refcnt))

		return;



	spin_lock_bh(&dev->qdisc_list_lock);

	if (qdisc->parent)

		list_del(&qdisc->list);

	spin_unlock_bh(&dev->qdisc_list_lock);



	call_rcu(&qdisc->q_rcu, __qdisc_destroy);

}
@@ -520,9 +517,6 @@ static void attach_one_default_qdisc(struct net_device *dev, 
			printk(KERN_INFO "%s: activation failed\n", dev->name);

			return;

		}

		spin_lock_bh(&dev->qdisc_list_lock);

		list_add_tail(&qdisc->list, &dev->qdisc_list);

		spin_unlock_bh(&dev->qdisc_list_lock);

	} else {

		qdisc =  &noqueue_qdisc;

	}

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