Index: sys/x86/xen/xen_intr.c
===================================================================
--- sys/x86/xen/xen_intr.c
+++ sys/x86/xen/xen_intr.c
@@ -45,6 +45,7 @@
 #include <sys/interrupt.h>
 #include <sys/pcpu.h>
 #include <sys/smp.h>
+#include <sys/refcount.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
@@ -128,6 +129,7 @@
 	u_int		xi_activehi:1;
 	u_int		xi_edgetrigger:1;
 	u_int		xi_masked:1;
+	volatile u_int	xi_refcount;
 };
 
 static void	xen_intr_suspend(struct pic *);
@@ -325,6 +327,7 @@
 	    (type == EVTCHN_TYPE_PIRQ) ? &xen_intr_pirq_pic : &xen_intr_pic;
 	isrc->xi_vector = vector;
 	isrc->xi_type = type;
+	refcount_init(&isrc->xi_refcount, 1);
 	intr_register_source(&isrc->xi_intsrc);
 	mtx_lock(&xen_intr_isrc_lock);
 
@@ -343,7 +346,12 @@
 {
 
 	mtx_lock(&xen_intr_isrc_lock);
+	if (refcount_release(&isrc->xi_refcount) == 0) {
+		mtx_unlock(&xen_intr_isrc_lock);
+		return (0);
+	}
 	if (isrc->xi_intsrc.is_handlers != 0) {
+		refcount_acquire(&isrc->xi_refcount);
 		mtx_unlock(&xen_intr_isrc_lock);
 		return (EBUSY);
 	}
@@ -1563,6 +1571,33 @@
 	return (error);
 }
 
+int
+xen_intr_get_reference(evtchn_port_t port)
+{
+
+	if (!is_valid_evtchn(port) || port >= NR_EVENT_CHANNELS)
+		return (EINVAL);
+
+	mtx_lock(&xen_intr_isrc_lock);
+	if (xen_intr_port_to_isrc[port] == NULL) {
+		mtx_unlock(&xen_intr_isrc_lock);
+		return (EINVAL);
+	}
+	refcount_acquire(&xen_intr_port_to_isrc[port]->xi_refcount);
+	mtx_unlock(&xen_intr_isrc_lock);
+	return (0);
+}
+
+int
+xen_intr_put_reference(evtchn_port_t port)
+{
+
+	if (!is_valid_evtchn(port) || port >= NR_EVENT_CHANNELS ||
+	    xen_intr_port_to_isrc[port] == NULL)
+		return (EINVAL);
+	return (xen_intr_release_isrc(xen_intr_port_to_isrc[port]));
+}
+
 #ifdef DDB
 static const char *
 xen_intr_print_type(enum evtchn_type type)
Index: sys/xen/xen_intr.h
===================================================================
--- sys/xen/xen_intr.h
+++ sys/xen/xen_intr.h
@@ -263,4 +263,15 @@
 	driver_intr_t handler, void *arg, enum intr_type flags,
 	xen_intr_handle_t handle);
 
+/**
+ * Get and put references to an event channel port
+ *
+ * \param port	    Event channel port to which we get or put
+ *		    a reference
+ *
+ * \returns  0 on success, otherwise an errno.
+ */
+int xen_intr_get_reference(evtchn_port_t port);
+int xen_intr_put_reference(evtchn_port_t port);
+
 #endif /* _XEN_INTR_H_ */