[TIPC]: Unrecognized configuration command now returns error message

This patch causes TIPC to return an error message when it receives
an unrecognized configuration command.  (Previously, the sender
received no feedback.)
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Per Liden <per.liden@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/config.c

@@ -2,7 +2,7 @@
  * net/tipc/config.c: TIPC configuration management code
  * 
  * Copyright (c) 2002-2006, Ericsson AB
- * Copyright (c) 2004-2005, Wind River Systems
+ * Copyright (c) 2004-2006, Wind River Systems
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -613,7 +613,8 @@ struct sk_buff *tipc_cfg_do_cmd(u32 orig_node, u16 cmd, const void *request_area
 		rep_tlv_buf = tipc_cfg_reply_unsigned(tipc_net_id);
 		break;
 	default:
-		rep_tlv_buf = NULL;
+		rep_tlv_buf = tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
+							  " (unknown command)");
 		break;
 	}