[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: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 52eb343..1894eb7 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -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 @@
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))