X25: Enable setting of cause and diagnostic fields

Adds SIOCX25SCAUSEDIAG, allowing X.25 programs to set the cause and
diagnostic fields.

Normally used to indicate status upon closing connections.

Signed-off-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c
index 511a598..352b32d 100644
--- a/net/x25/x25_subr.c
+++ b/net/x25/x25_subr.c
@@ -225,6 +225,12 @@
 			break;
 
 		case X25_CLEAR_REQUEST:
+			dptr    = skb_put(skb, 3);
+			*dptr++ = frametype;
+			*dptr++ = x25->causediag.cause;
+			*dptr++ = x25->causediag.diagnostic;
+			break;
+
 		case X25_RESET_REQUEST:
 			dptr    = skb_put(skb, 3);
 			*dptr++ = frametype;