Merging upstream version 4.19.304.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 43 insertions, 15 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 5a0e71873..ab57c0ee9 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1004,12 +1004,13 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 
 skip:
 		if (!ingress) {
-			notify_and_destroy(net, skb, n, classid,
-					   dev->qdisc, new);
+			old = dev->qdisc;
 			if (new && !new->ops->attach)
 				qdisc_refcount_inc(new);
 			dev->qdisc = new ? : &noop_qdisc;
 
+			notify_and_destroy(net, skb, n, classid, old, new);
+
 			if (new && new->ops->attach)
 				new->ops->attach(new);
 		} else {
@@ -1438,10 +1439,28 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 	return 0;
 }
 
+static bool req_create_or_replace(struct nlmsghdr *n)
+{
+	return (n->nlmsg_flags & NLM_F_CREATE &&
+		n->nlmsg_flags & NLM_F_REPLACE);
+}
+
+static bool req_create_exclusive(struct nlmsghdr *n)
+{
+	return (n->nlmsg_flags & NLM_F_CREATE &&
+		n->nlmsg_flags & NLM_F_EXCL);
+}
+
+static bool req_change(struct nlmsghdr *n)
+{
+	return (!(n->nlmsg_flags & NLM_F_CREATE) &&
+		!(n->nlmsg_flags & NLM_F_REPLACE) &&
+		!(n->nlmsg_flags & NLM_F_EXCL));
+}
+
 /*
  * Create/change qdisc.
  */
-
 static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 			   struct netlink_ext_ack *extack)
 {
@@ -1538,27 +1557,35 @@ replay:
 				 *
 				 *   We know, that some child q is already
 				 *   attached to this parent and have choice:
-				 *   either to change it or to create/graft new one.
+				 *   1) change it or 2) create/graft new one.
+				 *   If the requested qdisc kind is different
+				 *   than the existing one, then we choose graft.
+				 *   If they are the same then this is "change"
+				 *   operation - just let it fallthrough..
 				 *
 				 *   1. We are allowed to create/graft only
-				 *   if CREATE and REPLACE flags are set.
+				 *   if the request is explicitly stating
+				 *   "please create if it doesn't exist".
 				 *
-				 *   2. If EXCL is set, requestor wanted to say,
-				 *   that qdisc tcm_handle is not expected
+				 *   2. If the request is to exclusive create
+				 *   then the qdisc tcm_handle is not expected
 				 *   to exist, so that we choose create/graft too.
 				 *
 				 *   3. The last case is when no flags are set.
+				 *   This will happen when for example tc
+				 *   utility issues a "change" command.
 				 *   Alas, it is sort of hole in API, we
 				 *   cannot decide what to do unambiguously.
-				 *   For now we select create/graft, if
-				 *   user gave KIND, which does not match existing.
+				 *   For now we select create/graft.
 				 */
-				if ((n->nlmsg_flags & NLM_F_CREATE) &&
-				    (n->nlmsg_flags & NLM_F_REPLACE) &&
-				    ((n->nlmsg_flags & NLM_F_EXCL) ||
-				     (tca[TCA_KIND] &&
-				      nla_strcmp(tca[TCA_KIND], q->ops->id))))
-					goto create_n_graft;
+				if (tca[TCA_KIND] &&
+				    nla_strcmp(tca[TCA_KIND], q->ops->id)) {
+					if (req_create_or_replace(n) ||
+					    req_create_exclusive(n))
+						goto create_n_graft;
+					else if (req_change(n))
+						goto create_n_graft2;
+				}
 			}
 		}
 	} else {
@@ -1592,6 +1619,7 @@ create_n_graft:
 		NL_SET_ERR_MSG(extack, "Qdisc not found. To create specify NLM_F_CREATE flag");
 		return -ENOENT;
 	}
+create_n_graft2:
 	if (clid == TC_H_INGRESS) {
 		if (dev_ingress_queue(dev)) {
 			q = qdisc_create(dev, dev_ingress_queue(dev), p,