Prevent profile creation for invalid cable length

Added a check to skip profile creation when the cable length is 0m.
This change ensures that profiles are not created for invalid cable
lengths, preventing potential configuration errors.
Logged a notice message when skipping profile creation due to 0m
cable length.

Signed-off-by: Jianyue Wu <jianyuew@nvidia.com>

Author: jianyuewu

cfgmgr/buffermgrdyn.cpp

@@ -1474,6 +1474,13 @@ task_process_status BufferMgrDynamic::refreshPgsForPort(const string &port, cons
             {
                 threshold = m_defaultThreshold;
             }
+
+            // Skip new profile if cable length is 0m.
+            if (cable_length == "0m")
+            {
+                SWSS_LOG_NOTICE("Skipping profile creation for cable length '0m'");
+                return task_process_status::task_success;
+            }
             newProfile = getDynamicProfileName(speed, cable_length, mtu, threshold, gearbox_model, laneCount);
             auto rc = allocateProfile(speed, cable_length, mtu, threshold, gearbox_model, laneCount, newProfile);
             if (task_process_status::task_success != rc)

tests/mock_tests/buffermgrdyn_ut.cpp

@@ -1471,4 +1471,76 @@ namespace buffermgrdyn_test
         HandleTable(cableLengthTable);
         ASSERT_EQ(m_dynamicBuffer->m_portInfoLookup["Ethernet12"].state, PORT_READY);
     }
+
+    TEST_F(BufferMgrDynTest, SkipProfileCreationForZeroCableLength)
+    {
+        vector<FieldValueTuple> fieldValues;
+        vector<string> keys;
+
+        // Prepare information that will be read at the beginning
+        InitDefaultLosslessParameter();
+        InitMmuSize();
+
+        StartBufferManager();
+
+        InitPort();
+        ASSERT_EQ(m_dynamicBuffer->m_portInfoLookup["Ethernet0"].state, PORT_INITIALIZING);
+
+        SetPortInitDone();
+        // Timer will be called
+        m_dynamicBuffer->doTask(m_selectableTable);
+
+        ASSERT_EQ(m_dynamicBuffer->m_bufferPoolLookup.size(), 0);
+        InitBufferPool();
+        ASSERT_EQ(m_dynamicBuffer->m_bufferPoolLookup.size(), 3);
+        appBufferPoolTable.getKeys(keys);
+        ASSERT_EQ(keys.size(), 3);
+
+        // Initialize buffer profiles
+        InitBufferPg("Ethernet0|3-4");
+        InitDefaultBufferProfile();
+        appBufferProfileTable.getKeys(keys);
+        ASSERT_EQ(keys.size(), 3);
+        ASSERT_EQ(m_dynamicBuffer->m_bufferProfileLookup.size(), 3);
+
+        // 1. Set cable length to "0m"
+        InitCableLength("Ethernet0", "0m");
+        ASSERT_EQ(m_dynamicBuffer->m_portInfoLookup["Ethernet0"].state, PORT_READY);
+        // Expect profile not created
+        auto zeroMProfile = "pg_lossless_100000_0m_profile";
+        ASSERT_EQ(m_dynamicBuffer->m_bufferProfileLookup.find(zeroMProfile), m_dynamicBuffer->m_bufferProfileLookup.end());
+
+        // 2. Check if the reference for 5m profile of this port had been deleted in buffer PG table
+        // Since the cable length is set to 0m, previous profile for 5m should not exist.
+        ASSERT_TRUE(m_dynamicBuffer->m_bufferProfileLookup.find("pg_lossless_100000_5m_profile") == m_dynamicBuffer->m_bufferProfileLookup.end());
+
+        // 3. Add a PG, Ethernet0:6, it should not be created with 0m profile
+        // The expectation is that no new PGs should be created with a cable length of 0m.
+        InitBufferPg("Ethernet0|6");
+        ASSERT_TRUE(m_dynamicBuffer->m_portPgLookup.find("Ethernet0:6") == m_dynamicBuffer->m_portPgLookup.end());
+
+        // 4. Update cable length to 5m, then Ethernet0:6 and Ethernet0:3-4 should be created with 5m profile
+        InitCableLength("Ethernet0", "5m");
+        // Simulate the task to apply changes
+        m_dynamicBuffer->doTask(m_selectableTable);
+        // Check if the profiles are created correctly
+        CheckPg("Ethernet0", "Ethernet0:3-4", "pg_lossless_100000_5m_profile");
+        CheckPg("Ethernet0", "Ethernet0:6", "pg_lossless_100000_5m_profile");
+
+        // 5. Update cable length to 0m, then Ethernet0:6 should be deleted, Ethernet0:3-4 should be deleted and 0m profile also not exist, and 5m profile should be deleted, PG also deleted, as profiles not exist
+        InitCableLength("Ethernet0", "0m");
+        m_dynamicBuffer->doTask(m_selectableTable);
+        // Check that the profiles for 0m do not exist
+        ASSERT_TRUE(m_dynamicBuffer->m_bufferProfileLookup.find("pg_lossless_100000_0m_profile") == m_dynamicBuffer->m_bufferProfileLookup.end());
+        // Check that the PGs for Ethernet0:3-4 and Ethernet0:6 have been deleted
+        ASSERT_TRUE(m_dynamicBuffer->m_portPgLookup.find("Ethernet0:3-4") == m_dynamicBuffer->m_portPgLookup.end());
+        ASSERT_TRUE(m_dynamicBuffer->m_portPgLookup.find("Ethernet0:6") == m_dynamicBuffer->m_portPgLookup.end());
+
+        // 6. Check if port MTU update, PG and profile still there
+        string mtu = "4096";
+        m_dynamicBuffer->m_portInfoLookup["Ethernet0"].mtu = mtu;
+        // Check if the profile is created correctly
+        auto expectedProfile = "pg_lossless_100000_5m_profile";
+        CheckPg("Ethernet0", "Ethernet0:3-4", expectedProfile);
+    }
 }