1 files changed, 31 insertions, 13 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index e4b6452318c0..aa6b1fe65151 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1079,17 +1079,29 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 
 	if (parent == NULL) {
 		unsigned int i, num_q, ingress;
+		struct netdev_queue *dev_queue;
 
 		ingress = 0;
 		num_q = dev->num_tx_queues;
 		if ((q && q->flags & TCQ_F_INGRESS) ||
 		    (new && new->flags & TCQ_F_INGRESS)) {
-			num_q = 1;
 			ingress = 1;
-			if (!dev_ingress_queue(dev)) {
+			dev_queue = dev_ingress_queue(dev);
+			if (!dev_queue) {
 				NL_SET_ERR_MSG(extack, "Device does not have an ingress queue");
 				return -ENOENT;
 			}
+
+			q = rtnl_dereference(dev_queue->qdisc_sleeping);
+
+			/* This is the counterpart of that qdisc_refcount_inc_nz() call in
+			 * __tcf_qdisc_find() for filter requests.
+			 */
+			if (!qdisc_refcount_dec_if_one(q)) {
+				NL_SET_ERR_MSG(extack,
+					       "Current ingress or clsact Qdisc has ongoing filter requests");
+				return -EBUSY;
+			}
 		}
 
 		if (dev->flags & IFF_UP)
@@ -1100,18 +1112,26 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 		if (new && new->ops->attach && !ingress)
 			goto skip;
 
-		for (i = 0; i < num_q; i++) {
-			struct netdev_queue *dev_queue = dev_ingress_queue(dev);
-
-			if (!ingress)
+		if (!ingress) {
+			for (i = 0; i < num_q; i++) {
 				dev_queue = netdev_get_tx_queue(dev, i);
+				old = dev_graft_qdisc(dev_queue, new);
 
-			old = dev_graft_qdisc(dev_queue, new);
-			if (new && i > 0)
-				qdisc_refcount_inc(new);
-
-			if (!ingress)
+				if (new && i > 0)
+					qdisc_refcount_inc(new);
 				qdisc_put(old);
+			}
+		} else {
+			old = dev_graft_qdisc(dev_queue, NULL);
+
+			/* {ingress,clsact}_destroy() @old before grafting @new to avoid
+			 * unprotected concurrent accesses to net_device::miniq_{in,e}gress
+			 * pointer(s) in mini_qdisc_pair_swap().
+			 */
+			qdisc_notify(net, skb, n, classid, old, new, extack);
+			qdisc_destroy(old);
+
+			dev_graft_qdisc(dev_queue, new);
 		}
 
 skip:
@@ -1125,8 +1145,6 @@ skip:
 
 			if (new && new->ops->attach)
 				new->ops->attach(new);
-		} else {
-			notify_and_destroy(net, skb, n, classid, old, new, extack);
 		}
 
 		if (dev->flags & IFF_UP)