[PATCH net v2 2/2] selftests/tc-testing: add qdisc hierarchy depth tests

From: Zijie Huang <[email protected]>

Add tdc coverage for the qdisc hierarchy depth limit.

The tests verify that the deepest allowed hierarchy can still be created
and that adding another child qdisc below it is rejected.

Signed-off-by: Zijie Huang <[email protected]>
Assisted-by: Codex:gpt-5.4
Signed-off-by: Ren Wei <[email protected]>
---
 .../tc-testing/tc-tests/qdiscs/depth.json     | 74 +++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 tools/testing/selftests/tc-testing/tc-tests/qdiscs/depth.json

diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/depth.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/depth.json
new file mode 100644
index 000000000000..48f8683f0d1a
--- /dev/null
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/depth.json
@@ -0,0 +1,74 @@
+[
+    {
+        "id": "ad43",
+        "name": "Create qdisc hierarchy at maximum depth",
+        "category": [
+            "qdisc",
+            "depth"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$TC qdisc add dev $DUMMY root handle 1: htb default 1",
+            "$TC class add dev $DUMMY parent 1: classid 1:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 1:1 handle 2: htb default 1",
+            "$TC class add dev $DUMMY parent 2: classid 2:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 2:1 handle 3: htb default 1",
+            "$TC class add dev $DUMMY parent 3: classid 3:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 3:1 handle 4: htb default 1",
+            "$TC class add dev $DUMMY parent 4: classid 4:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 4:1 handle 5: htb default 1",
+            "$TC class add dev $DUMMY parent 5: classid 5:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 5:1 handle 6: htb default 1",
+            "$TC class add dev $DUMMY parent 6: classid 6:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 6:1 handle 7: htb default 1",
+            "$TC class add dev $DUMMY parent 7: classid 7:1 htb rate 10mbit"
+        ],
+        "cmdUnderTest": "$TC qdisc add dev $DUMMY parent 7:1 handle 8: htb default 1",
+        "expExitCode": "0",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc htb 8: parent 7:1",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY root"
+        ]
+    },
+    {
+        "id": "c519",
+        "name": "Reject qdisc hierarchy above maximum depth",
+        "category": [
+            "qdisc",
+            "depth"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$TC qdisc add dev $DUMMY root handle 1: htb default 1",
+            "$TC class add dev $DUMMY parent 1: classid 1:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 1:1 handle 2: htb default 1",
+            "$TC class add dev $DUMMY parent 2: classid 2:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 2:1 handle 3: htb default 1",
+            "$TC class add dev $DUMMY parent 3: classid 3:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 3:1 handle 4: htb default 1",
+            "$TC class add dev $DUMMY parent 4: classid 4:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 4:1 handle 5: htb default 1",
+            "$TC class add dev $DUMMY parent 5: classid 5:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 5:1 handle 6: htb default 1",
+            "$TC class add dev $DUMMY parent 6: classid 6:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 6:1 handle 7: htb default 1",
+            "$TC class add dev $DUMMY parent 7: classid 7:1 htb rate 10mbit",
+            "$TC qdisc add dev $DUMMY parent 7:1 handle 8: htb default 1",
+            "$TC class add dev $DUMMY parent 8: classid 8:1 htb rate 10mbit"
+        ],
+        "cmdUnderTest": "$TC qdisc add dev $DUMMY parent 8:1 handle 9: htb default 1",
+        "expExitCode": "2",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc htb 9:",
+        "matchCount": "0",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY root"
+        ]
+    }
+]
-- 
2.47.2