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, 2 insertions, 2 deletions

diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 997d520ca580..5090708ba384 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1045,7 +1045,7 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 
                 if (tca[TCA_RATE])
                         gen_replace_estimator(&cl->bstats, &cl->rate_est,
-                                              &sch->dev_queue->lock,
+                                              qdisc_root_lock(sch),
                                               tca[TCA_RATE]);
                 return 0;
         }
@@ -1104,7 +1104,7 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
 
         if (tca[TCA_RATE])
                 gen_new_estimator(&cl->bstats, &cl->rate_est,
-                                  &sch->dev_queue->lock, tca[TCA_RATE]);
+                                  qdisc_root_lock(sch), tca[TCA_RATE]);
         *arg = (unsigned long)cl;
         return 0;
 }