[201911 sonic-swss] Flushing FDB entries before removing BridgePort (#1516)

**What I did**
I added coded in sonic-swss orchagent to flush the FDB entries corresponding to the bridge port before removing the bridgeport.

**Why I did it**
I did it because if we don't flush the FDB entries before removing the bridge port and try to remove the bridge port, the bridge port removal results in a failure and the port operational status is set to down.

**How I verified it**
I created a VLAN interface, assigned IP address to it and added 2 Ethernet ports as tagged members to it. I waited for the switch to add its neighbors through these bridge ports. Then I removed VLAN membership of one of the bridge ports and see it is successful and the operational state of the port does not go down on removing the VLAN membership.

**Details if related**
flushFDBEntries() function is introduce in orchagent/fdborch.cpp and called from orchagent/portsorch.cpp

Co-authored-by: Madhan Babu <[email protected]>

Author: madhanmellanox

orchagent/fdborch.cpp

@@ -416,6 +416,46 @@ void FdbOrch::doTask(NotificationConsumer& consumer)
     }
 }
 
+void FdbOrch::flushFDBEntries(sai_object_id_t bridge_port_oid,
+                              sai_object_id_t vlan_oid)
+{
+    vector<sai_attribute_t>    attrs;
+    sai_attribute_t            attr;
+    sai_status_t               rv = SAI_STATUS_SUCCESS;
+
+    SWSS_LOG_ENTER();
+
+    if (SAI_NULL_OBJECT_ID == bridge_port_oid &&
+        SAI_NULL_OBJECT_ID == vlan_oid)
+    {
+        SWSS_LOG_WARN("Couldn't flush FDB. Bridge port OID: 0x%" PRIx64 " bvid:%" PRIx64 ",",
+                      bridge_port_oid, vlan_oid);
+        return;
+    }
+
+    if (SAI_NULL_OBJECT_ID != bridge_port_oid)
+    {
+        attr.id = SAI_FDB_FLUSH_ATTR_BRIDGE_PORT_ID;
+        attr.value.oid = bridge_port_oid;
+        attrs.push_back(attr);
+    }
+
+    if (SAI_NULL_OBJECT_ID != vlan_oid)
+    {
+        attr.id = SAI_FDB_FLUSH_ATTR_BV_ID;
+        attr.value.oid = vlan_oid;
+        attrs.push_back(attr);
+    }
+
+    SWSS_LOG_INFO("Flushing FDB bridge_port_oid: 0x%" PRIx64 ", and bvid_oid:0x%" PRIx64 ".", bridge_port_oid, vlan_oid);
+
+    rv = sai_fdb_api->flush_fdb_entries(gSwitchId, (uint32_t)attrs.size(), attrs.data());
+    if (SAI_STATUS_SUCCESS != rv)
+    {
+        SWSS_LOG_ERROR("Flushing FDB failed. rv:%d", rv);
+    }
+}
+
 void FdbOrch::updateVlanMember(const VlanMemberUpdate& update)
 {
     SWSS_LOG_ENTER();

orchagent/fdborch.h

@@ -46,6 +46,8 @@ class FdbOrch: public Orch, public Subject, public Observer
     void update(sai_fdb_event_t, const sai_fdb_entry_t *, sai_object_id_t);
     void update(SubjectType type, void *cntx);
     bool getPort(const MacAddress&, uint16_t, Port&);
+    void flushFDBEntries(sai_object_id_t bridge_port_oid,
+                         sai_object_id_t vlan_oid);
 
 private:
     PortsOrch *m_portsOrch;

orchagent/portsorch.cpp

@@ -23,6 +23,7 @@
 #include "crmorch.h"
 #include "countercheckorch.h"
 #include "notifier.h"
+#include "fdborch.h"
 
 extern sai_switch_api_t *sai_switch_api;
 extern sai_bridge_api_t *sai_bridge_api;
@@ -37,6 +38,7 @@ extern IntfsOrch *gIntfsOrch;
 extern NeighOrch *gNeighOrch;
 extern CrmOrch *gCrmOrch;
 extern BufferOrch *gBufferOrch;
+extern FdbOrch *gFdbOrch;
 
 #define VLAN_PREFIX         "Vlan"
 #define DEFAULT_VLAN_ID     1
@@ -3019,6 +3021,8 @@ bool PortsOrch::removeBridgePort(Port &port)
     /* Flush FDB entries pointing to this bridge port */
     // TODO: Remove all FDB entries associated with this bridge port before
     //       removing the bridge port itself
+    gFdbOrch->flushFDBEntries(port.m_bridge_port_id, SAI_NULL_OBJECT_ID);
+    SWSS_LOG_INFO("Flush FDB entries for port %s", port.m_alias.c_str());
 
     /* Remove bridge port */
     status = sai_bridge_api->remove_bridge_port(port.m_bridge_port_id);