selftests/tc-testing: Add tests that force multiq and taprio to enqueue to child's gso_skb

Add test cases to reproduce scenarios fixed recently [1] where
multiqueue and taprio forced their children into enqueueing an skb to
gso_skb (during peek), but failed to dequeue from gso_skb because they
called the child's dequeue callback directly. This causes a desync in the
child's qlen/backlog and results in an eventual null-ptr-deref (with a
qfq or dualpi2 child).

Test cases are the following:

- Force multiq to dequeue from its child's gso_skb with qfq leaf (fb6c)
- Force multiq to dequeue from its child's gso_skb with dualpi2 leaf (1922)
- Force taprio to dequeue from its child's gso_skb with qfq leaf (476f)
- Force taprio to dequeue from its child's gso_skb with dualpi2 leaf (0235)

[1] https://lore.kernel.org/netdev/20260625-b4-disp-31bcb279-v1-0-85c40b83c529@proton.me/

Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Link: https://patch.msgid.link/20260630153651.249752-1-victor@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 164 insertions, 0 deletions

diff --git a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
index a1f97a4b606e..0cf12c50fb74 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
@@ -1540,5 +1540,169 @@
             "$TC qdisc del dev $DUMMY root",
             "$IP addr del 10.10.10.10/24 dev $DUMMY || true"
         ]
+    },
+    {
+        "id": "fb6c",
+        "name": "Force multiq to dequeue from its child's gso_skb with qfq leaf",
+        "category": [
+            "qdisc",
+            "tbf",
+            "multiq",
+            "qfq"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "echo \"1 1 4\" > /sys/bus/netdevsim/new_device",
+            "$IP link set dev $ETH up || true",
+            "$IP l set addr 01:02:03:04:05:06 dev $ETH || true",
+            "$IP n add dev $ETH 10.10.11.1 lladdr 01:02:03:04:05:06 dev $ETH || true",
+            "$IP addr add 10.10.11.10/24 dev $ETH || true",
+            "$TC qdisc add dev $ETH root handle 1: tbf rate 88bit burst 1661b peakrate 2257333 minburst 1024 limit 7b",
+            "$TC qdisc add dev $ETH parent 1: handle 2: multiq",
+            "$TC qdisc add dev $ETH parent 2:1 handle 3: qfq",
+            "$TC class add dev $ETH classid 3:1 parent 3: qfq maxpkt 512 weight 1",
+            "$TC filter add dev $ETH parent 2: protocol all prio 1 matchall action skbedit queue_mapping 0",
+            "$TC filter add dev $ETH parent 3: protocol all prio 1 matchall classid 3:1 action ok"
+        ],
+        "cmdUnderTest": "ping -c 1 10.10.11.1 -W0.01 -I$ETH || true",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -s -j qdisc ls dev $ETH parent 1:",
+        "matchJSON": [
+            {
+                "kind": "multiq",
+                "handle": "2:",
+                "bytes": 98,
+                "packets": 1,
+                "backlog": 0,
+                "qlen": 0
+            }
+        ],
+        "teardown": [
+            "$TC qdisc del dev $ETH handle 1: root",
+            "echo \"1\" > /sys/bus/netdevsim/del_device"
+        ]
+    },
+    {
+        "id": "1922",
+        "name": "Force multiq to dequeue from its child's gso_skb with dualpi2 leaf",
+        "category": [
+            "qdisc",
+            "tbf",
+            "multiq",
+            "dualpi2"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "echo \"1 1 4\" > /sys/bus/netdevsim/new_device",
+            "$IP link set dev $ETH up || true",
+            "$IP l set addr 01:02:03:04:05:06 dev $ETH || true",
+            "$IP n add dev $ETH 10.10.11.1 lladdr 01:02:03:04:05:06 dev $ETH || true",
+            "$IP addr add 10.10.11.10/24 dev $ETH || true",
+            "$TC qdisc add dev $ETH root handle 1: tbf rate 88bit burst 1661b peakrate 2257333 minburst 1024 limit 7b",
+            "$TC qdisc add dev $ETH parent 1: handle 2: multiq",
+            "$TC qdisc add dev $ETH parent 2:1 handle 3: dualpi2",
+            "$TC filter add dev $ETH parent 2: protocol ip prio 1 u32 match ip dst 10.10.11.1 action skbedit queue_mapping 0",
+            "$TC filter add dev $ETH parent 3: protocol ip prio 1 u32 match ip dst 10.10.11.1 classid 3:1 action ok"
+        ],
+        "cmdUnderTest": "ping -c 1 10.10.11.1 -W0.01 -I$ETH || true",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -j -s qdisc ls dev $ETH handle 3:",
+        "matchJSON": [
+            {
+                "kind": "dualpi2",
+                "handle": "3:",
+                "bytes": 98,
+                "packets": 1,
+                "backlog": 0,
+                "qlen": 0
+            }
+        ],
+        "teardown": [
+            "$TC qdisc del dev $ETH handle 1: root",
+            "echo \"1\" > /sys/bus/netdevsim/del_device"
+        ]
+    },
+    {
+        "id": "476f",
+        "name": "Force taprio to dequeue from its child's gso_skb with qfq leaf",
+        "category": [
+            "qdisc",
+            "tbf",
+            "multiq",
+            "qfq"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "echo \"1 1 4\" > /sys/bus/netdevsim/new_device",
+            "$IP link set dev $ETH up || true",
+            "$IP l set addr 01:02:03:04:05:06 dev $ETH || true",
+            "$IP n add dev $ETH 10.10.11.1 lladdr 01:02:03:04:05:06 dev $ETH || true",
+            "$TC qdisc add dev $ETH root handle 1: taprio num_tc 2 map 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 1@1 base-time 9000000000000000000 sched-entry S 03 200000 flags 0x0 clockid CLOCK_TAI",
+            "$TC qdisc add dev $ETH parent 1:1 handle 3: qfq",
+            "$TC class add dev $ETH classid 3:1 parent 3: qfq maxpkt 512 weight 1",
+            "$TC filter add dev $ETH parent 3: protocol all prio 1 matchall classid 3:1 action ok"
+        ],
+        "cmdUnderTest": "ping -c 1 10.10.11.1 -W0.01 -I$ETH || true",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -s -j qdisc ls dev $ETH",
+        "matchJSON": [
+            {
+                "kind": "taprio",
+                "handle": "1:",
+                "bytes": 98,
+                "packets": 1,
+                "backlog": 0,
+                "qlen": 0
+            }
+        ],
+        "teardown": [
+            "$TC qdisc del dev $ETH handle 1: root",
+            "echo \"1\" > /sys/bus/netdevsim/del_device"
+        ]
+    },
+    {
+        "id": "0235",
+        "name": "Force taprio to dequeue from its child's gso_skb with dualpi2 leaf",
+        "category": [
+            "qdisc",
+            "tbf",
+            "taprio",
+            "dualpi2"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "echo \"1 1 4\" > /sys/bus/netdevsim/new_device",
+            "$IP link set dev $ETH up || true",
+            "$IP l set addr 01:02:03:04:05:06 dev $ETH || true",
+            "$IP n add dev $ETH 10.10.11.1 lladdr 01:02:03:04:05:06 dev $ETH || true",
+            "$TC qdisc add dev $ETH root handle 1: taprio num_tc 2 map 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 1@1 base-time 9000000000000000000 sched-entry S 03 200000 flags 0x0 clockid CLOCK_TAI",
+            "$TC qdisc replace dev $ETH parent 1:1 handle 3: dualpi2",
+            "$TC filter add dev $ETH parent 3: protocol ip prio 1 u32 match ip dst 10.10.11.1 classid 3:1 action ok"
+        ],
+        "cmdUnderTest": "ping -c 1 10.10.11.1 -W0.01 -I$ETH || true",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -j -s qdisc ls dev $ETH handle 3:",
+        "matchJSON": [
+            {
+                "kind": "dualpi2",
+                "handle": "3:",
+                "bytes": 98,
+                "packets": 1,
+                "backlog": 0,
+                "qlen": 0
+            }
+        ],
+        "teardown": [
+            "$TC qdisc del dev $ETH handle 1: root",
+            "echo \"1\" > /sys/bus/netdevsim/del_device"
+        ]
     }
 ]