Handle router HA port concurrently deleting

Router HA port may be deleted concurrently while the plugin
is trying to update. This patch catches the known exceptions.
Should not `plugin.update_port_statuses` use because:
1. plugin.update_port_statuses will hide all exception
   no matter the port exists.
2. The code just needs to catch the port not found error,
   but let all other exception raised if port still exists.

Closes-Bug: #1906375
Change-Id: Id5d9c99be3bd6854568d2b1baa86c25c0cfd4756

neutron/api/rpc/handlers/l3_rpc.py

@@ -25,6 +25,7 @@ from neutron_lib.plugins import directory
 from oslo_config import cfg
 from oslo_log import log as logging
 import oslo_messaging
+from sqlalchemy import orm
 
 
 LOG = logging.getLogger(__name__)
@@ -89,8 +90,13 @@ class L3RpcCallback(object):
                   "setting HA network ports %(ha_ports)s status to DOWN.",
                   {"host": host, "ha_ports": ha_ports})
         for p in ha_ports:
+            try:
                 self.plugin.update_port(
-                context, p, {'port': {'status': constants.PORT_STATUS_DOWN}})
+                    context, p,
+                    {'port': {'status': constants.PORT_STATUS_DOWN}})
+            except (orm.exc.StaleDataError, orm.exc.ObjectDeletedError,
+                    exceptions.PortNotFound):
+                pass
 
     def get_router_ids(self, context, host):
         """Returns IDs of routers scheduled to l3 agent on <host>