Allow XS_INTRODUCE to be used for rebinding the xenstore evtchn.

Signed-off-by: Andrei Petrov <andrei.petrov@xensource.com>

tools/xenstore/xenstored_domain.c

@@ -343,13 +343,14 @@ void do_introduce(struct connection *conn, struct buffered_data *in)
 		fire_watches(conn, "@introduceDomain", false);
 	}
 	else {
-		/* Check that the given details match the ones we have
-		   previously recorded. */
-		if (port != domain->remote_port ||
-		    mfn != domain->mfn) {
-			send_error(conn, EINVAL);
-			return;
-		}
+		int rc;
+
+		/* Use XS_INTRODUCE for recreating the xenbus event-channel. */
+		if (domain->port)
+			xc_evtchn_unbind(xce_handle, domain->port);
+		rc = xc_evtchn_bind_interdomain(xce_handle, domid, port);
+		domain->port = (rc == -1) ? 0 : rc;
+		domain->remote_port = port;
 	}
 
 	send_ack(conn, XS_INTRODUCE);