xen: close evtchn port if binding to irq fails

commit e7e44e44 upstream.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/xen/evtchn.c

@@ -269,6 +269,14 @@ static int evtchn_bind_to_user(struct per_user_data *u, int port)
 				       u->name, (void *)(unsigned long)port);
 	if (rc >= 0)
 		rc = 0;
+	else {
+		/* bind failed, should close the port now */
+		struct evtchn_close close;
+		close.port = port;
+		if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
+			BUG();
+		set_port_user(port, NULL);
+	}
 
 	return rc;
 }
@@ -277,6 +285,8 @@ static void evtchn_unbind_from_user(struct per_user_data *u, int port)
 {
 	int irq = irq_from_evtchn(port);
 
+	BUG_ON(irq < 0);
+
 	unbind_from_irqhandler(irq, (void *)(unsigned long)port);
 
 	set_port_user(port, NULL);