RDS: don't update ip address tables if the address hasn't changed

If the ip address tables hasn't changed, there is no need to remove
them only to be added back again.

Lets fix it.
Reviewed-by: NAjaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Signed-off-by: NSantosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/rds/ib_rdma.c

@@ -151,12 +151,17 @@ int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
 	struct rds_ib_device *rds_ibdev_old;
 
 	rds_ibdev_old = rds_ib_get_device(ipaddr);
-	if (rds_ibdev_old) {
+	if (!rds_ibdev_old)
+		return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
+
+	if (rds_ibdev_old != rds_ibdev) {
 		rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr);
 		rds_ib_dev_put(rds_ibdev_old);
+		return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
 	}
+	rds_ib_dev_put(rds_ibdev_old);
 
-	return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
+	return 0;
 }
 
 void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)