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[NET_SCHED]: Eliminate qdisc_tree_lock

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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: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy
2007-04-16 17:02:10 -07:00
committed by David S. Miller
parent ffa4d7216e
commit 0463d4ae25
4 changed files with 10 additions and 45 deletions
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29
net/sched/sch_generic.c
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@@ -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))