tipc: convert legacy nl link stat to nl compat

Add functionality for safely appending string data to a TLV without
keeping write count in the caller.

Convert TIPC_CMD_SHOW_LINK_STATS to compat dumpit.

Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/tipc_config.h b/include/uapi/linux/tipc_config.h
index f922656..087b0ef 100644
--- a/include/uapi/linux/tipc_config.h
+++ b/include/uapi/linux/tipc_config.h
@@ -277,11 +277,21 @@
 	return ntohs(tlv->tlv_len);
 }
 
+static inline void TLV_SET_LEN(struct tlv_desc *tlv, __u16 len)
+{
+	tlv->tlv_len = htons(len);
+}
+
 static inline int TLV_CHECK_TYPE(struct tlv_desc *tlv,  __u16 type)
 {
 	return (ntohs(tlv->tlv_type) == type);
 }
 
+static inline void TLV_SET_TYPE(struct tlv_desc *tlv, __u16 type)
+{
+	tlv->tlv_type = htons(type);
+}
+
 static inline int TLV_SET(void *tlv, __u16 type, void *data, __u16 len)
 {
 	struct tlv_desc *tlv_ptr;