3 files changed, 28 insertions, 16 deletions

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 9c69585a1be8..88eb9de095de 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -46,6 +46,7 @@ struct Qdisc
 #define TCQ_F_THROTTLED         2
 #define TCQ_F_INGRESS           4
 #define TCQ_F_CAN_BYPASS        8
+#define TCQ_F_MQROOT            16
 #define TCQ_F_WARN_NONWC        (1 << 16)
         int                     padded;
         struct Qdisc_ops        *ops;
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 2a78d5410154..3af106140f35 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -733,7 +733,8 @@ static struct lock_class_key qdisc_rx_lock;
 
 static struct Qdisc *
 qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
-             u32 parent, u32 handle, struct nlattr **tca, int *errp)
+             struct Qdisc *p, u32 parent, u32 handle,
+             struct nlattr **tca, int *errp)
 {
         int err;
         struct nlattr *kind = tca[TCA_KIND];
@@ -810,24 +811,21 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
                 if (tca[TCA_RATE]) {
                         spinlock_t *root_lock;
 
+                        err = -EOPNOTSUPP;
+                        if (sch->flags & TCQ_F_MQROOT)
+                                goto err_out4;
+
                         if ((sch->parent != TC_H_ROOT) &&
-                            !(sch->flags & TCQ_F_INGRESS))
+                            !(sch->flags & TCQ_F_INGRESS) &&
+                            (!p || !(p->flags & TCQ_F_MQROOT)))
                                 root_lock = qdisc_root_sleeping_lock(sch);
                         else
                                 root_lock = qdisc_lock(sch);
 
                         err = gen_new_estimator(&sch->bstats, &sch->rate_est,
                                                 root_lock, tca[TCA_RATE]);
-                        if (err) {
-                                /*
-                                 * Any broken qdiscs that would require
-                                 * a ops->reset() here? The qdisc was never
-                                 * in action so it shouldn't be necessary.
-                                 */
-                                if (ops->destroy)
-                                        ops->destroy(sch);
-                                goto err_out3;
-                        }
+                        if (err)
+                                goto err_out4;
                 }
 
                 qdisc_list_add(sch);
@@ -843,6 +841,15 @@ err_out2:
 err_out:
         *errp = err;
         return NULL;
+
+err_out4:
+        /*
+         * Any broken qdiscs that would require a ops->reset() here?
+         * The qdisc was never in action so it shouldn't be necessary.
+         */
+        if (ops->destroy)
+                ops->destroy(sch);
+        goto err_out3;
 }
 
 static int qdisc_change(struct Qdisc *sch, struct nlattr **tca)
@@ -867,13 +874,16 @@ static int qdisc_change(struct Qdisc *sch, struct nlattr **tca)
         qdisc_put_stab(sch->stab);
         sch->stab = stab;
 
-        if (tca[TCA_RATE])
+        if (tca[TCA_RATE]) {
                 /* NB: ignores errors from replace_estimator
                    because change can't be undone. */
+                if (sch->flags & TCQ_F_MQROOT)
+                        goto out;
                 gen_replace_estimator(&sch->bstats, &sch->rate_est,
                                             qdisc_root_sleeping_lock(sch),
                                             tca[TCA_RATE]);
-
+        }
+out:
         return 0;
 }
 
@@ -1097,7 +1107,7 @@ create_n_graft:
         if (!(n->nlmsg_flags&NLM_F_CREATE))
                 return -ENOENT;
         if (clid == TC_H_INGRESS)
-                q = qdisc_create(dev, &dev->rx_queue,
+                q = qdisc_create(dev, &dev->rx_queue, p,
                                  tcm->tcm_parent, tcm->tcm_parent,
                                  tca, &err);
         else {
@@ -1106,7 +1116,7 @@ create_n_graft:
                 if (p && p->ops->cl_ops && p->ops->cl_ops->select_queue)
                         ntx = p->ops->cl_ops->select_queue(p, tcm);
 
-                q = qdisc_create(dev, netdev_get_tx_queue(dev, ntx),
+                q = qdisc_create(dev, netdev_get_tx_queue(dev, ntx), p,
                                  tcm->tcm_parent, tcm->tcm_handle,
                                  tca, &err);
         }
diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index c84dec9c8c7d..dd5ee022f1f7 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -64,6 +64,7 @@ static int mq_init(struct Qdisc *sch, struct nlattr *opt)
                 priv->qdiscs[ntx] = qdisc;
         }
 
+        sch->flags |= TCQ_F_MQROOT;
         return 0;
 
 err: