Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0463d4ae authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NET_SCHED]: Eliminate qdisc_tree_lock 



Since we're now holding the rtnl during the entire dump operation, we
can remove qdisc_tree_lock, whose only purpose is to protect dump
callbacks from concurrent changes to the qdisc tree.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ffa4d721

include/net/pkt_sched.h

+0 −2
Original line number Diff line number Diff line
@@ -13,8 +13,6 @@ struct qdisc_walker 
	int	(*fn)(struct Qdisc *, unsigned long cl, struct qdisc_walker *);

};



extern rwlock_t qdisc_tree_lock;



#define QDISC_ALIGNTO		32

#define QDISC_ALIGN(len)	(((len) + QDISC_ALIGNTO-1) & ~(QDISC_ALIGNTO-1))

net/sched/cls_api.c

+0 −2
Original line number Diff line number Diff line
@@ -400,7 +400,6 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) 
	if ((dev = dev_get_by_index(tcm->tcm_ifindex)) == NULL)

		return skb->len;



	read_lock(&qdisc_tree_lock);

	if (!tcm->tcm_parent)

		q = dev->qdisc_sleeping;

	else
@@ -457,7 +456,6 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb) 
	if (cl)

		cops->put(q, cl);

out:

	read_unlock(&qdisc_tree_lock);

	dev_put(dev);

	return skb->len;

}

net/sched/sch_api.c

+3 −19
Original line number Diff line number Diff line
@@ -191,7 +191,7 @@ int unregister_qdisc(struct Qdisc_ops *qops) 
   (root qdisc, all its children, children of children etc.)

 */



static struct Qdisc *__qdisc_lookup(struct net_device *dev, u32 handle)

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

{

	struct Qdisc *q;
@@ -202,16 +202,6 @@ static struct Qdisc *__qdisc_lookup(struct net_device *dev, u32 handle) 
	return NULL;

}



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

{

	struct Qdisc *q;



	read_lock(&qdisc_tree_lock);

	q = __qdisc_lookup(dev, handle);

	read_unlock(&qdisc_tree_lock);

	return q;

}



static struct Qdisc *qdisc_leaf(struct Qdisc *p, u32 classid)

{

	unsigned long cl;
@@ -405,7 +395,7 @@ void qdisc_tree_decrease_qlen(struct Qdisc *sch, unsigned int n) 
	if (n == 0)

		return;

	while ((parentid = sch->parent)) {

		sch = __qdisc_lookup(sch->dev, TC_H_MAJ(parentid));

		sch = qdisc_lookup(sch->dev, TC_H_MAJ(parentid));

		cops = sch->ops->cl_ops;

		if (cops->qlen_notify) {

			cl = cops->get(sch, parentid);
@@ -905,7 +895,6 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb) 
			continue;

		if (idx > s_idx)

			s_q_idx = 0;

		read_lock(&qdisc_tree_lock);

		q_idx = 0;

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

			if (q_idx < s_q_idx) {
@@ -913,13 +902,10 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb) 
				continue;

			}

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

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

				read_unlock(&qdisc_tree_lock);

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

				goto done;

			}

			q_idx++;

		}

		read_unlock(&qdisc_tree_lock);

	}



done:
@@ -1142,7 +1128,6 @@ static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb) 
	s_t = cb->args[0];

	t = 0;



	read_lock(&qdisc_tree_lock);

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

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

		    (tcm->tcm_parent &&
@@ -1164,7 +1149,6 @@ static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb) 
			break;

		t++;

	}

	read_unlock(&qdisc_tree_lock);



	cb->args[0] = t;

net/sched/sch_generic.c

+7 −22
Original line number Diff line number Diff line
@@ -36,34 +36,23 @@ 


/* Main transmission queue. */



/* Main qdisc structure lock.



   However, modifications

   to data, participating in scheduling must be additionally

   protected with dev->queue_lock spinlock.



   The idea is the following:

   - enqueue, dequeue are serialized via top level device

     spinlock dev->queue_lock.

   - tree walking is protected by read_lock(qdisc_tree_lock)

     and this lock is used only in process context.

   - updates to tree are made only under rtnl semaphore,

     hence this lock may be made without local bh disabling.



   qdisc_tree_lock must be grabbed BEFORE dev->queue_lock!

/* Modifications to data participating in scheduling must be protected with

 * dev->queue_lock spinlock.

 *

 * The idea is the following:

 * - enqueue, dequeue are serialized via top level device

 *   spinlock dev->queue_lock.

 * - updates to tree and tree walking are only done under the rtnl mutex.

 */

DEFINE_RWLOCK(qdisc_tree_lock);



void qdisc_lock_tree(struct net_device *dev)

{

	write_lock(&qdisc_tree_lock);

	spin_lock_bh(&dev->queue_lock);

}



void qdisc_unlock_tree(struct net_device *dev)

{

	spin_unlock_bh(&dev->queue_lock);

	write_unlock(&qdisc_tree_lock);

}



/*
@@ -528,15 +517,11 @@ void dev_activate(struct net_device *dev) 
				printk(KERN_INFO "%s: activation failed\n", dev->name);

				return;

			}

			write_lock(&qdisc_tree_lock);

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

			write_unlock(&qdisc_tree_lock);

		} else {

			qdisc =  &noqueue_qdisc;

		}

		write_lock(&qdisc_tree_lock);

		dev->qdisc_sleeping = qdisc;

		write_unlock(&qdisc_tree_lock);

	}



	if (!netif_carrier_ok(dev))