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authorPatrick McHardy <kaber@trash.net>2007-04-16 17:02:10 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-04-25 22:29:07 -0700
commit0463d4ae25771aaf3379bb6b2392f6edf23c2828 (patch)
tree5c820b718abfe086a7b1d91814cb99d721439a46 /net/sched
parentffa4d7216e848fbfdcb8e6f0bb66abeaa1888964 (diff)
[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>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/cls_api.c2
-rw-r--r--net/sched/sch_api.c22
-rw-r--r--net/sched/sch_generic.c29
3 files changed, 10 insertions, 43 deletions
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index ca3da5013b7..ebf94edf047 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -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 @@ errout:
if (cl)
cops->put(q, cl);
out:
- read_unlock(&qdisc_tree_lock);
dev_put(dev);
return skb->len;
}
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 2e863bdaa9a..0ce6914f598 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -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;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 52eb3439d7c..1894eb72f6c 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 @@ 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))