[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>

1 files changed, 3 insertions, 19 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 2e863bdaa9a1..0ce6914f5981 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;