selftests/tc-testing: Test case exercising potential mirred redirect deadlock

Add a test case that reproduces deadlock scenario where the user has
a drr qdisc attached to root and has a mirred action that redirects to
self on egress

Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20251210162255.1057663-2-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: vbnogueira

tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json

@@ -1052,5 +1052,51 @@
             "$TC qdisc del dev $DEV1 ingress_block 21 clsact",
             "$TC actions flush action mirred"
         ]
+    },
+    {
+        "id": "7eba",
+        "name": "Redirect multiport: dummy egress ->  dummy egress (Loop)",
+        "category": [
+            "filter",
+            "mirred"
+        ],
+        "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 $DUMMY handle 1: root drr",
+            "$TC filter add dev $DUMMY parent 1: protocol ip prio 10 matchall action mirred egress redirect dev $DUMMY index 1"
+        ],
+        "cmdUnderTest": "ping -c1 -W0.01 -I $DUMMY 10.10.10.1",
+        "expExitCode": "1",
+        "verifyCmd": "$TC -j -s actions get action mirred index 1",
+        "matchJSON": [
+            {
+                "total acts": 0
+            },
+            {
+                "actions": [
+                    {
+                        "order": 1,
+                        "kind": "mirred",
+                        "mirred_action": "redirect",
+                        "direction": "egress",
+                        "index": 1,
+                        "stats": {
+                            "packets": 1,
+                            "overlimits": 1
+                        },
+                        "not_in_hw": true
+                    }
+                ]
+            }
+        ],
+        "teardown": [
+            "$TC qdisc del dev $DUMMY root"
+        ]
     }
 ]