[acl mirror action] Mirror session ref count fix at acl rule attachment

[wendani]

Why I did it
Retry logic was introduced to ACL rule mirror action in #1486

This assumes that mirror session may not be ready when the associated ACL rule is processed.

If mirror entry exists (CONFIG_DB processed) but mirror session is not created in sai/asic, AclRuleMirror::create() is called twice, one at processing CONFIG_DB ACL rule config, and one at later mirror session activation notify (i.e., mirror session creation event in sai/asic). In this case, mirror session reference count is incremented twice for the same rule, and mirror session removal will fail due to non-zero ref count even if ACL rule is removed.

What I did
This PR fixes the above scenario.

How I verified it
Fix is validated by developing vs test, which is piggy-backed onto test_AclBindMirror

Details if related

vs test failure before the change

=========================================================================== FAILURES ===========================================================================
________________________________________________________________ TestMirror.test_AclBindMirror _________________________________________________________________

self = <test_mirror.TestMirror object at 0x7fd282c40ef0>, dvs = <conftest.DockerVirtualSwitch object at 0x7fd282c3def0>
testlog = <function testlog at 0x7fd282f8d378>

    def test_AclBindMirror(self, dvs, testlog):
        self.setup_db(dvs)
    
        self._test_AclBindMirror(dvs, testlog)
>       self._test_AclBindMirror(dvs, testlog, create_seq_test=True)

test_mirror.py:896: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_mirror.TestMirror object at 0x7fd282c40ef0>, dvs = <conftest.DockerVirtualSwitch object at 0x7fd282c3def0>
testlog = <function testlog at 0x7fd282f8d378>, create_seq_test = True

    def _test_AclBindMirror(self, dvs, testlog, create_seq_test=False):
        """
        This test tests ACL associated with mirror session with DSCP value
        The DSCP value is tested on both with mask and without mask
        """
    
        session = "MIRROR_SESSION"
        acl_table = "MIRROR_TABLE"
        acl_rule = "MIRROR_RULE"
    
        # bring up port; assign ip; create neighbor; create route
        self.set_interface_status(dvs, "Ethernet32", "up")
        self.add_ip_address("Ethernet32", "20.0.0.0/31")
        self.add_neighbor("Ethernet32", "20.0.0.1", "02:04:06:08:10:12")
        if create_seq_test == False:
            self.add_route(dvs, "4.4.4.4", "20.0.0.1")
    
        # create mirror session
        self.create_mirror_session(session, "3.3.3.3", "4.4.4.4", "0x6558", "8", "100", "0")
        assert self.get_mirror_session_state(session)["status"] == ("active" if create_seq_test == False else "inactive")
    
        # check mirror session in asic database
        tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_MIRROR_SESSION")
        assert len(tbl.getKeys()) == (1 if create_seq_test == False else 0)
        if create_seq_test == False:
            mirror_session_oid = tbl.getKeys()[0]
    
        # create acl table
        self.create_acl_table(acl_table, ["Ethernet0", "Ethernet4"])
    
        # create acl rule with dscp value 48
        self.create_mirror_acl_dscp_rule(acl_table, acl_rule, "48", session)
    
        # acl rule creation check
        tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_ACL_ENTRY")
        rule_entries = [k for k in tbl.getKeys() if k not in dvs.asicdb.default_acl_entries]
        assert len(rule_entries) == (1 if create_seq_test == False else 0)
    
        if create_seq_test == True:
            self.add_route(dvs, "4.4.4.4", "20.0.0.1")
    
            assert self.get_mirror_session_state(session)["status"] == "active"
    
            # assert mirror session in asic database
            tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_MIRROR_SESSION")
            assert len(tbl.getKeys()) == 1
            mirror_session_oid = tbl.getKeys()[0]
    
            # assert acl rule is created
            tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_ACL_ENTRY")
            rule_entries = [k for k in tbl.getKeys() if k not in dvs.asicdb.default_acl_entries]
            assert len(rule_entries) == 1
    
        (status, fvs) = tbl.get(rule_entries[0])
        assert status == True
        for fv in fvs:
            if fv[0] == "SAI_ACL_ENTRY_ATTR_FIELD_DSCP":
                assert fv[1] == "48&mask:0x3f"
            if fv[0] == "SAI_ACL_ENTRY_ATTR_ACTION_MIRROR_INGRESS":
                assert fv[1] == "1:" + mirror_session_oid
    
        # remove acl rule
        self.remove_mirror_acl_dscp_rule(acl_table, acl_rule)
    
        # create acl rule with dscp value 16/16
        self.create_mirror_acl_dscp_rule(acl_table, acl_rule, "16/16", session)
    
        # assert acl rule is created
        tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_ACL_ENTRY")
        rule_entries = [k for k in tbl.getKeys() if k not in dvs.asicdb.default_acl_entries]
        assert len(rule_entries) == 1
    
        (status, fvs) = tbl.get(rule_entries[0])
        assert status == True
        for fv in fvs:
            if fv[0] == "SAI_ACL_ENTRY_ATTR_FIELD_DSCP":
                assert fv[1] == "16&mask:0x10"
            if fv[0] == "SAI_ACL_ENTRY_ATTR_ACTION_MIRROR_INGRESS":
                assert fv[1] == "1:" + mirror_session_oid
    
        # remove acl rule
        self.remove_mirror_acl_dscp_rule(acl_table, acl_rule)
    
        # remove acl table
        self.remove_acl_table(acl_table)
    
        # remove mirror session
        self.remove_mirror_session(session)
    
        # assert no mirror session in asic database
        tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_MIRROR_SESSION")
>       assert len(tbl.getKeys()) == 0
E       assert 1 == 0
E         +1
E         -0

test_mirror.py:884: AssertionError
=================================================================== short test summary info ====================================================================
FAILED test_mirror.py::TestMirror::test_AclBindMirror - assert 1 == 0
================================================================= 1 failed in 87.26s (0:01:27) =================================================================

[prsunny]

lgtm, request @qiluo-msft to sign-off as original reviewer of #1486

[prsunny]

/azp run

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[prsunny]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[prsunny]

@wendani , can you force-push?