Merge branch 'net_sched-skbprio-remove-overly-strict-queue-assertions'

Cong Wang says:

====================
net_sched: skbprio: Remove overly strict queue assertions
====================

Link: https://patch.msgid.link/20250329222536.696204-1-xiyou.wangcong@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/sched/sch_skbprio.c

@@ -123,8 +123,6 @@ static int skbprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 	/* Check to update highest and lowest priorities. */
 	if (skb_queue_empty(lp_qdisc)) {
 		if (q->lowest_prio == q->highest_prio) {
-			/* The incoming packet is the only packet in queue. */
-			BUG_ON(sch->q.qlen != 1);
 			q->lowest_prio = prio;
 			q->highest_prio = prio;
 		} else {
@@ -156,7 +154,6 @@ static struct sk_buff *skbprio_dequeue(struct Qdisc *sch)
 	/* Update highest priority field. */
 	if (skb_queue_empty(hpq)) {
 		if (q->lowest_prio == q->highest_prio) {
-			BUG_ON(sch->q.qlen);
 			q->highest_prio = 0;
 			q->lowest_prio = SKBPRIO_MAX_PRIORITY - 1;
 		} else {

tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json

@@ -126,5 +126,37 @@
             "$TC qdisc del dev $DUMMY root handle 1: drr",
             "$IP addr del 10.10.10.10/24 dev $DUMMY"
         ]
-   }
+    },
+    {
+        "id": "c024",
+        "name": "Test TBF with SKBPRIO - catch qlen corner cases",
+        "category": [
+            "qdisc",
+            "tbf",
+            "skbprio"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$IP link set dev $DUMMY up || true",
+            "$IP addr add 10.10.10.10/24 dev $DUMMY || true",
+            "$TC qdisc add dev $DUMMY handle 1: root tbf rate 100bit burst 2000 limit 1000",
+            "$TC qdisc add dev $DUMMY parent 1: handle 10: skbprio limit 1",
+            "ping -c 1 -W 0.1 -Q 0x00 -s 1400 -I $DUMMY 10.10.10.1 > /dev/null || true",
+            "ping -c 1 -W 0.1 -Q 0x1c -s 1400 -I $DUMMY 10.10.10.1 > /dev/null || true",
+            "ping -c 1 -W 0.1 -Q 0x00 -s 1400 -I $DUMMY 10.10.10.1 > /dev/null || true",
+            "ping -c 1 -W 0.1 -Q 0x1c -s 1400 -I $DUMMY 10.10.10.1 > /dev/null || true",
+            "sleep 0.5"
+        ],
+        "cmdUnderTest": "$TC -s qdisc show dev $DUMMY",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -s qdisc show dev $DUMMY | grep -A 5 'qdisc skbprio'",
+        "matchPattern": "dropped [1-9][0-9]*",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY handle 1: root",
+            "$IP addr del 10.10.10.10/24 dev $DUMMY || true"
+        ]
+    }
 ]