selftests/tc-testing: add selftests for pfifo_fast qdisc

Test 900c: Create pfifo_fast with default setting
Test 7470: Dump pfifo_fast stats
Test b974: Replace pfifo_fast with different handle
Test 3240: Delete pfifo_fast with valid handle
Test 4385: Delete pfifo_fast with invalid handle
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

+[
+    {
+        "id": "900c",
+        "name": "Create pfifo_fast with default setting",
+        "category": [
+            "qdisc",
+            "pfifo_fast"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$IP link add dev $DUMMY type dummy || /bin/true"
+        ],
+        "cmdUnderTest": "$TC qdisc add dev $DUMMY handle 1: root pfifo_fast",
+        "expExitCode": "0",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc pfifo_fast 1: root refcnt [0-9]+ bands 3 priomap",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY handle 1: root",
+            "$IP link del dev $DUMMY type dummy"
+        ]
+    },
+    {
+        "id": "7470",
+        "name": "Dump pfifo_fast stats",
+        "category": [
+            "qdisc",
+            "pfifo_fast"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$IP link add dev $DUMMY type dummy || /bin/true"
+        ],
+        "cmdUnderTest": "$TC qdisc add dev $DUMMY handle 1: root pfifo_fast",
+        "expExitCode": "0",
+        "verifyCmd": "$TC -s qdisc show dev $DUMMY",
+        "matchPattern": "Sent.*bytes.*pkt \\(dropped.*overlimits.*requeues .*\\)",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY handle 1: root",
+            "$IP link del dev $DUMMY type dummy"
+        ]
+    },
+    {
+        "id": "b974",
+        "name": "Replace pfifo_fast with different handle",
+        "category": [
+            "qdisc",
+            "pfifo_fast"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$IP link add dev $DUMMY type dummy || /bin/true",
+            "$TC qdisc add dev $DUMMY handle 1: root pfifo_fast"
+        ],
+        "cmdUnderTest": "$TC qdisc replace dev $DUMMY handle 2: root pfifo_fast",
+        "expExitCode": "0",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc pfifo_fast 2: root refcnt [0-9]+ bands 3 priomap",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY handle 2: root",
+            "$IP link del dev $DUMMY type dummy"
+        ]
+    },
+    {
+        "id": "3240",
+        "name": "Delete pfifo_fast with valid handle",
+        "category": [
+            "qdisc",
+            "pfifo_fast"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$IP link add dev $DUMMY type dummy || /bin/true",
+            "$TC qdisc add dev $DUMMY handle 1: root pfifo_fast"
+        ],
+        "cmdUnderTest": "$TC qdisc del dev $DUMMY handle 1: root",
+        "expExitCode": "0",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc pfifo_fast 1: root refcnt [0-9]+ bands 3 priomap",
+        "matchCount": "0",
+        "teardown": [
+            "$IP link del dev $DUMMY type dummy"
+        ]
+    },
+    {
+        "id": "4385",
+        "name": "Delete pfifo_fast with invalid handle",
+        "category": [
+            "qdisc",
+            "pfifo_fast"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$IP link add dev $DUMMY type dummy || /bin/true",
+            "$TC qdisc add dev $DUMMY handle 1: root pfifo_fast"
+        ],
+        "cmdUnderTest": "$TC qdisc del dev $DUMMY handle 2: root",
+        "expExitCode": "2",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc pfifo_fast 1: root refcnt [0-9]+ bands 3 priomap",
+        "matchCount": "1",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY handle 1: root",
+            "$IP link del dev $DUMMY type dummy"
+        ]
+    }
+]