[Reclaiming buffer] Support reclaiming buffer in traditional model (sonic-net#2011)

- What I did
It's to port sonic-net#1837 to master to reclaim reserved buffer.
As the way to do it differs among vendors, buffermgrd will:
1. Handle port admin down on Mellanox platform.
    - Not apply lossless buffer PG to an admin-down port
    - Remove lossless buffer PG (3-4) from a port when it is shut down.
2. Read lossless buffer PG (3-4) to a port when a port is started up.

- Why I did it
To support reclaiming reserved buffer when a port is shut down on Mellanox platform in traditional buffer model.

- How I verified it
sonic-mgmt test and vs test.

Signed-off-by: Stephen Sun <[email protected]>

Author: stephenxs

cfgmgr/buffermgr.cpp

@@ -30,6 +30,17 @@ BufferMgr::BufferMgr(DBConnector *cfgDb, DBConnector *applDb, string pg_lookup_f
         m_applBufferEgressProfileListTable(applDb, APP_BUFFER_PORT_EGRESS_PROFILE_LIST_NAME)
 {
     readPgProfileLookupFile(pg_lookup_file);
+
+    char *platform = getenv("ASIC_VENDOR");
+    if (NULL == platform)
+    {
+        SWSS_LOG_WARN("Platform environment variable is not defined");
+    }
+    else
+    {
+        m_platform = platform;
+    }
+
     dynamic_buffer_model = false;
 }
 
@@ -122,9 +133,9 @@ Create/update two tables: profile (in m_cfgBufferProfileTable) and port buffer (
         }
     }
 */
-task_process_status BufferMgr::doSpeedUpdateTask(string port)
+task_process_status BufferMgr::doSpeedUpdateTask(string port, bool admin_up)
 {
-    vector<FieldValueTuple> fvVector;
+    vector<FieldValueTuple> fvVectorPg, fvVectorProfile;
     string cable;
     string speed;
 
@@ -142,20 +153,50 @@ task_process_status BufferMgr::doSpeedUpdateTask(string port)
     }
 
     speed = m_speedLookup[port];
+
+    string buffer_pg_key = port + m_cfgBufferPgTable.getTableNameSeparator() + LOSSLESS_PGS;
+    // key format is pg_lossless_<speed>_<cable>_profile
+    string buffer_profile_key = "pg_lossless_" + speed + "_" + cable + "_profile";
+    string profile_ref = buffer_profile_key;
+
+    m_cfgBufferPgTable.get(buffer_pg_key, fvVectorPg);
+
+    if (!admin_up && m_platform == "mellanox")
+    {
+        // Remove the entry in BUFFER_PG table if any
+        if (!fvVectorPg.empty())
+        {
+            for (auto &prop : fvVectorPg)
+            {
+                if (fvField(prop) == "profile")
+                {
+                    if (fvValue(prop) == profile_ref)
+                    {
+                        SWSS_LOG_NOTICE("Removing PG %s from port %s which is administrative down", buffer_pg_key.c_str(), port.c_str());
+                        m_cfgBufferPgTable.del(buffer_pg_key);
+                    }
+                    else
+                    {
+                        SWSS_LOG_NOTICE("Not default profile %s is configured on PG %s, won't reclaim buffer", fvValue(prop).c_str(), buffer_pg_key.c_str());
+                    }
+                }
+            }
+        }
+
+        return task_process_status::task_success;
+    }
+
     if (m_pgProfileLookup.count(speed) == 0 || m_pgProfileLookup[speed].count(cable) == 0)
     {
         SWSS_LOG_ERROR("Unable to create/update PG profile for port %s. No PG profile configured for speed %s and cable length %s",
                        port.c_str(), speed.c_str(), cable.c_str());
         return task_process_status::task_invalid_entry;
     }
 
-    // Crete record in BUFFER_PROFILE table
-    // key format is pg_lossless_<speed>_<cable>_profile
-    string buffer_profile_key = "pg_lossless_" + speed + "_" + cable + "_profile";
-
     // check if profile already exists - if yes - skip creation
-    m_cfgBufferProfileTable.get(buffer_profile_key, fvVector);
-    if (fvVector.size() == 0)
+    m_cfgBufferProfileTable.get(buffer_profile_key, fvVectorProfile);
+    // Create record in BUFFER_PROFILE table
+    if (fvVectorProfile.size() == 0)
     {
         SWSS_LOG_NOTICE("Creating new profile '%s'", buffer_profile_key.c_str());
 
@@ -170,32 +211,24 @@ task_process_status BufferMgr::doSpeedUpdateTask(string port)
         // profile threshold field name
         mode += "_th";
 
-        fvVector.push_back(make_pair("pool", INGRESS_LOSSLESS_PG_POOL_NAME));
-        fvVector.push_back(make_pair("xon", m_pgProfileLookup[speed][cable].xon));
+        fvVectorProfile.push_back(make_pair("pool", INGRESS_LOSSLESS_PG_POOL_NAME));
+        fvVectorProfile.push_back(make_pair("xon", m_pgProfileLookup[speed][cable].xon));
         if (m_pgProfileLookup[speed][cable].xon_offset.length() > 0) {
-            fvVector.push_back(make_pair("xon_offset",
+            fvVectorProfile.push_back(make_pair("xon_offset",
                                          m_pgProfileLookup[speed][cable].xon_offset));
         }
-        fvVector.push_back(make_pair("xoff", m_pgProfileLookup[speed][cable].xoff));
-        fvVector.push_back(make_pair("size", m_pgProfileLookup[speed][cable].size));
-        fvVector.push_back(make_pair(mode, m_pgProfileLookup[speed][cable].threshold));
-        m_cfgBufferProfileTable.set(buffer_profile_key, fvVector);
+        fvVectorProfile.push_back(make_pair("xoff", m_pgProfileLookup[speed][cable].xoff));
+        fvVectorProfile.push_back(make_pair("size", m_pgProfileLookup[speed][cable].size));
+        fvVectorProfile.push_back(make_pair(mode, m_pgProfileLookup[speed][cable].threshold));
+        m_cfgBufferProfileTable.set(buffer_profile_key, fvVectorProfile);
     }
     else
     {
         SWSS_LOG_NOTICE("Reusing existing profile '%s'", buffer_profile_key.c_str());
     }
 
-    fvVector.clear();
-
-    string buffer_pg_key = port + m_cfgBufferPgTable.getTableNameSeparator() + LOSSLESS_PGS;
-
-    string profile_ref = buffer_profile_key;
-
     /* Check if PG Mapping is already then log message and return. */
-    m_cfgBufferPgTable.get(buffer_pg_key, fvVector);
-
-    for (auto& prop : fvVector)
+    for (auto& prop : fvVectorPg)
     {
         if ((fvField(prop) == "profile") && (profile_ref == fvValue(prop)))
         {
@@ -204,10 +237,10 @@ task_process_status BufferMgr::doSpeedUpdateTask(string port)
         }
     }
 
-    fvVector.clear();
+    fvVectorPg.clear();
 
-    fvVector.push_back(make_pair("profile", profile_ref));
-    m_cfgBufferPgTable.set(buffer_pg_key, fvVector);
+    fvVectorPg.push_back(make_pair("profile", profile_ref));
+    m_cfgBufferPgTable.set(buffer_pg_key, fvVectorPg);
     return task_process_status::task_success;
 }
 
@@ -379,26 +412,35 @@ void BufferMgr::doTask(Consumer &consumer)
         task_process_status task_status = task_process_status::task_success;
         if (op == SET_COMMAND)
         {
-            for (auto i : kfvFieldsValues(t))
+            if (table_name == CFG_PORT_CABLE_LEN_TABLE_NAME)
             {
-                if (table_name == CFG_PORT_CABLE_LEN_TABLE_NAME)
+                // receive and cache cable length table
+                for (auto i : kfvFieldsValues(t))
                 {
-                    // receive and cache cable length table
                     task_status = doCableTask(fvField(i), fvValue(i));
                 }
-                if (m_pgfile_processed && table_name == CFG_PORT_TABLE_NAME && (fvField(i) == "speed" || fvField(i) == "admin_status"))
+            }
+            else if (m_pgfile_processed && table_name == CFG_PORT_TABLE_NAME)
+            {
+                bool admin_up = false;
+                for (auto i : kfvFieldsValues(t))
                 {
                     if (fvField(i) == "speed")
                     {
                         m_speedLookup[port] = fvValue(i);
                     }
-                    
-                    if (m_speedLookup.count(port) != 0)
+                    if (fvField(i) == "admin_status")
                     {
-                        // create/update profile for port
-                        task_status = doSpeedUpdateTask(port);
+                        admin_up = ("up" == fvValue(i));
                     }
                 }
+
+                if (m_speedLookup.count(port) != 0)
+                {
+                    // create/update profile for port
+                    task_status = doSpeedUpdateTask(port, admin_up);
+                }
+
                 if (task_status != task_process_status::task_success)
                 {
                     break;

cfgmgr/buffermgr.h

@@ -36,6 +36,8 @@ class BufferMgr : public Orch
     using Orch::doTask;
 
 private:
+    std::string m_platform;
+
     Table m_cfgPortTable;
     Table m_cfgCableLenTable;
     Table m_cfgBufferProfileTable;
@@ -58,7 +60,7 @@ class BufferMgr : public Orch
     std::string getPgPoolMode();
     void readPgProfileLookupFile(std::string);
     task_process_status doCableTask(std::string port, std::string cable_length);
-    task_process_status doSpeedUpdateTask(std::string port);
+    task_process_status doSpeedUpdateTask(std::string port, bool admin_up);
     void doBufferTableTask(Consumer &consumer, ProducerStateTable &applTable);
 
     void transformSeperator(std::string &name);