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Commit 53049978 authored by David S. Miller's avatar David S. Miller
Browse files

pkt_sched: Make qdisc grafting locking more specific. 



Lock the root of the qdisc being operated upon.

All explicit references to qdisc_tree_lock() are now gone.
The only remaining uses are via the sch_tree_{lock,unlock}()
and tcf_tree_{lock,unlock}() macros.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ead81cc5

net/sched/sch_api.c

+29 −12
Original line number Diff line number Diff line
@@ -441,15 +441,29 @@ static struct Qdisc * 
dev_graft_qdisc(struct net_device *dev, struct Qdisc *qdisc)

{

	struct netdev_queue *dev_queue;

	spinlock_t *root_lock;

	struct Qdisc *oqdisc;

	int ingress;



	if (dev->flags & IFF_UP)

		dev_deactivate(dev);



	qdisc_lock_tree(dev);

	if (qdisc && qdisc->flags&TCQ_F_INGRESS) {

	ingress = 0;

	if (qdisc && qdisc->flags&TCQ_F_INGRESS)

		ingress = 1;



	if (ingress) {

		dev_queue = &dev->rx_queue;

		oqdisc = dev_queue->qdisc;

	} else {

		dev_queue = netdev_get_tx_queue(dev, 0);

		oqdisc = dev_queue->qdisc_sleeping;

	}



	root_lock = qdisc_root_lock(oqdisc);

	spin_lock_bh(root_lock);



	if (ingress) {

		/* Prune old scheduler */

		if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1) {

			/* delete */
@@ -460,9 +474,6 @@ dev_graft_qdisc(struct net_device *dev, struct Qdisc *qdisc) 
		}



	} else {

		dev_queue = netdev_get_tx_queue(dev, 0);

		oqdisc = dev_queue->qdisc_sleeping;



		/* Prune old scheduler */

		if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)

			qdisc_reset(oqdisc);
@@ -474,7 +485,7 @@ dev_graft_qdisc(struct net_device *dev, struct Qdisc *qdisc) 
		dev_queue->qdisc = &noop_qdisc;

	}



	qdisc_unlock_tree(dev);

	spin_unlock_bh(root_lock);



	if (dev->flags & IFF_UP)

		dev_activate(dev);
@@ -765,10 +776,12 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n, void *arg) 
		if ((err = qdisc_graft(dev, p, clid, NULL, &q)) != 0)

			return err;

		if (q) {

			spinlock_t *root_lock = qdisc_root_lock(q);



			qdisc_notify(skb, n, clid, q, NULL);

			qdisc_lock_tree(dev);

			spin_unlock_bh(root_lock);

			qdisc_destroy(q);

			qdisc_unlock_tree(dev);

			spin_unlock_bh(root_lock);

		}

	} else {

		qdisc_notify(skb, n, clid, NULL, q);
@@ -911,20 +924,24 @@ create_n_graft: 
graft:

	if (1) {

		struct Qdisc *old_q = NULL;

		spinlock_t *root_lock;



		err = qdisc_graft(dev, p, clid, q, &old_q);

		if (err) {

			if (q) {

				qdisc_lock_tree(dev);

				root_lock = qdisc_root_lock(q);

				spin_lock_bh(root_lock);

				qdisc_destroy(q);

				qdisc_unlock_tree(dev);

				spin_unlock_bh(root_lock);

			}

			return err;

		}

		qdisc_notify(skb, n, clid, old_q, q);

		if (old_q) {

			qdisc_lock_tree(dev);

			root_lock = qdisc_root_lock(old_q);

			spin_lock_bh(root_lock);

			qdisc_destroy(old_q);

			qdisc_unlock_tree(dev);

			spin_unlock_bh(root_lock);

		}

	}

	return 0;