Commit 4d8863a2 authored by David S. Miller's avatar David S. Miller
Browse files

pkt_sched: Don't hold qdisc lock over qdisc_destroy(). 



Based upon reports by Denys Fedoryshchenko, and feedback
and help from Jarek Poplawski and Herbert Xu.

We always either:

1) Never made an external reference to this qdisc.

or

2) Did a dev_deactivate() which purged all asynchronous
   references.

So do not lock the qdisc when we call qdisc_destroy(),
it's illegal anyways as when we drop the lock this is
free'd memory.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 25bfcd5a

net/sched/sch_api.c

+2 −11
Original line number Diff line number Diff line
@@ -638,11 +638,8 @@ static void notify_and_destroy(struct sk_buff *skb, struct nlmsghdr *n, u32 clid 
	if (new || old)

		qdisc_notify(skb, n, clid, old, new);



	if (old) {

		sch_tree_lock(old);

	if (old)

		qdisc_destroy(old);

		sch_tree_unlock(old);

	}

}



/* Graft qdisc "new" to class "classid" of qdisc "parent" or
@@ -1092,16 +1089,10 @@ create_n_graft: 


graft:

	if (1) {

		spinlock_t *root_lock;



		err = qdisc_graft(dev, p, skb, n, clid, q, NULL);

		if (err) {

			if (q) {

				root_lock = qdisc_root_lock(q);

				spin_lock_bh(root_lock);

			if (q)

				qdisc_destroy(q);

				spin_unlock_bh(root_lock);

			}

			return err;

		}

	}

net/sched/sch_generic.c

+0 −6
Original line number Diff line number Diff line
@@ -518,8 +518,6 @@ void qdisc_reset(struct Qdisc *qdisc) 
}

EXPORT_SYMBOL(qdisc_reset);



/* Under qdisc_lock(qdisc) and BH! */



void qdisc_destroy(struct Qdisc *qdisc)

{

	const struct Qdisc_ops  *ops = qdisc->ops;
@@ -712,14 +710,10 @@ static void shutdown_scheduler_queue(struct net_device *dev, 
	struct Qdisc *qdisc_default = _qdisc_default;



	if (qdisc) {

		spinlock_t *root_lock = qdisc_lock(qdisc);



		dev_queue->qdisc = qdisc_default;

		dev_queue->qdisc_sleeping = qdisc_default;



		spin_lock_bh(root_lock);

		qdisc_destroy(qdisc);

		spin_unlock_bh(root_lock);

	}

}

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