diff -r de57c3f218fb drivers/xen/evtchn/evtchn.c
--- a/drivers/xen/evtchn/evtchn.c	Thu Mar 20 11:35:25 2008 +0000
+++ b/drivers/xen/evtchn/evtchn.c	Wed Apr 02 21:59:29 2008 +0200
@@ -346,9 +346,12 @@ static long evtchn_ioctl(struct file *fi
 			spin_unlock_irq(&port_user_lock);
 			break;
 		}
+		
 
 		port_user[unbind.port] = NULL;
+
 		mask_evtchn(unbind.port);
+		rebind_evtchn_to_cpu(unbind.port, 0);
 
 		spin_unlock_irq(&port_user_lock);
 
@@ -457,7 +460,9 @@ static int evtchn_release(struct inode *
 			continue;
 
 		port_user[i] = NULL;
+
 		mask_evtchn(i);
+		rebind_evtchn_to_cpu(i, 0);
 
 		close.port = i;
 		ret = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);