Avoid adding loopback interface (ip link add) when setting nat zone on loopback interface (sonic-net#1411)

* Avoid adding loopback interface (ip link add) when nat zone is set on loopback interface

Signed-off-by: Akhilesh Samineni <[email protected]>

Author: AkhileshSamineni

cfgmgr/intfmgr.cpp

@@ -426,7 +426,12 @@ bool IntfMgr::doIntfGeneralTask(const vector<string>& keys,
 
         if (is_lo)
         {
-            addLoopbackIntf(alias);
+            if (m_loopbackIntfList.find(alias) == m_loopbackIntfList.end())
+            {
+                addLoopbackIntf(alias);
+                m_loopbackIntfList.insert(alias);
+                SWSS_LOG_INFO("Added %s loopback interface", alias.c_str());
+            }
         }
         else
         {
@@ -540,6 +545,7 @@ bool IntfMgr::doIntfGeneralTask(const vector<string>& keys,
         if (is_lo)
         {
             delLoopbackIntf(alias);
+            m_loopbackIntfList.erase(alias);
         }
 
         if (!subIntfAlias.empty())

cfgmgr/intfmgr.h

@@ -22,20 +22,21 @@ class IntfMgr : public Orch
     Table m_statePortTable, m_stateLagTable, m_stateVlanTable, m_stateVrfTable, m_stateIntfTable;
 
     std::set<std::string> m_subIntfList;
+    std::set<std::string> m_loopbackIntfList;
 
     void setIntfIp(const std::string &alias, const std::string &opCmd, const IpPrefix &ipPrefix);
     void setIntfVrf(const std::string &alias, const std::string &vrfName);
     void setIntfMac(const std::string &alias, const std::string &macAddr);
-    
+
     bool doIntfGeneralTask(const std::vector<std::string>& keys, std::vector<FieldValueTuple> data, const std::string& op);
     bool doIntfAddrTask(const std::vector<std::string>& keys, const std::vector<FieldValueTuple>& data, const std::string& op);
     void doTask(Consumer &consumer);
-    
+
     bool isIntfStateOk(const std::string &alias);
     bool isIntfCreated(const std::string &alias);
     bool isIntfChangeVrf(const std::string &alias, const std::string &vrfName);
     int getIntfIpCount(const std::string &alias);
-    
+
     void addLoopbackIntf(const std::string &alias);
     void delLoopbackIntf(const std::string &alias);
     void flushLoopbackIntfs(void);