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Date: Mon, 16 Apr 2007 09:51:57 +0200 (MEST)
From: Patrick McHardy <kaber@...sh.net>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, Patrick McHardy <kaber@...sh.net>
Subject: [NET_SCHED 04/04]: Eliminate qdisc_tree_lock
[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@...sh.net>
---
commit cc965189583f5a980e1fc6acaf708c47d3661a22
tree faede9cc5c6b86b39517c56c71caa6942e748f20
parent 49310148887f3d7a6b78809b0a771628be4ef0a8
author Patrick McHardy <kaber@...sh.net> Mon, 16 Apr 2007 09:05:39 +0200
committer Patrick McHardy <kaber@...sh.net> Mon, 16 Apr 2007 09:05:39 +0200
include/net/pkt_sched.h | 2 --
net/sched/cls_api.c | 2 --
net/sched/sch_api.c | 22 +++-------------------
net/sched/sch_generic.c | 29 +++++++----------------------
4 files changed, 10 insertions(+), 45 deletions(-)
diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index b2cc9a8..5754d53 100644
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -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))
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index ca3da50..ebf94ed 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 2e863bd..0ce6914 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 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 @@ 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))
-
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