pkt_sched: Add and use qdisc_root() and qdisc_root_lock().

When code wants to lock the qdisc tree state, the logic
operation it's doing is locking the top-level qdisc that
sits of the root of the netdev_queue.

Add qdisc_root_lock() to represent this and convert the
easiest cases.

In order for this to work out in all cases, we have to
hook up the noop_qdisc to a dummy netdev_queue.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 4 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 830ccc544a15..19c244a00839 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -633,7 +633,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
         if (!ops->init || (err = ops->init(sch, tca[TCA_OPTIONS])) == 0) {
                 if (tca[TCA_RATE]) {
                         err = gen_new_estimator(&sch->bstats, &sch->rate_est,
-                                                &sch->dev_queue->lock,
+                                                qdisc_root_lock(sch),
                                                 tca[TCA_RATE]);
                         if (err) {
                                 /*
@@ -675,7 +675,7 @@ static int qdisc_change(struct Qdisc *sch, struct nlattr **tca)
         }
         if (tca[TCA_RATE])
                 gen_replace_estimator(&sch->bstats, &sch->rate_est,
-                                      &sch->dev_queue->lock, tca[TCA_RATE]);
+                                      qdisc_root_lock(sch), tca[TCA_RATE]);
         return 0;
 }
 
@@ -967,7 +967,7 @@ static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
         q->qstats.qlen = q->q.qlen;
 
         if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS,
-                                         TCA_XSTATS, &q->dev_queue->lock, &d) < 0)
+                                         TCA_XSTATS, qdisc_root_lock(q), &d) < 0)
                 goto nla_put_failure;
 
         if (q->ops->dump_stats && q->ops->dump_stats(q, &d) < 0)
@@ -1216,7 +1216,7 @@ static int tc_fill_tclass(struct sk_buff *skb, struct Qdisc *q,
                 goto nla_put_failure;
 
         if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS,
-                                         TCA_XSTATS, &q->dev_queue->lock, &d) < 0)
+                                         TCA_XSTATS, qdisc_root_lock(q), &d) < 0)
                 goto nla_put_failure;
 
         if (cl_ops->dump_stats && cl_ops->dump_stats(q, cl, &d) < 0)