diff -r c783f340bef8 -r f4e09625f1dd linux-2.6-xen-sparse/drivers/xen/pciback/pciback_ops.c
--- a/linux-2.6-xen-sparse/drivers/xen/pciback/pciback_ops.c	Tue Apr 11 08:58:04 2006
+++ b/linux-2.6-xen-sparse/drivers/xen/pciback/pciback_ops.c	Tue Apr 11 17:40:03 2006
@@ -36,21 +36,13 @@
 			dev->is_busmaster = 0;
 		}
 	}
-
-	pciback_config_reset(dev);
 }
 
-irqreturn_t pciback_handle_event(int irq, void *dev_id, struct pt_regs *regs)
+void pciback_do_op(void *data)
 {
-	struct pciback_device *pdev = dev_id;
+	struct pciback_device *pdev = data;
 	struct pci_dev *dev;
 	struct xen_pci_op *op = &pdev->sh_info->op;
-
-	if (unlikely(!test_bit(_XEN_PCIF_active,
-			       (unsigned long *)&pdev->sh_info->flags))) {
-		pr_debug("pciback: interrupt, but no active operation\n");
-		goto out;
-	}
 
 	dev = pciback_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
 
@@ -65,9 +57,31 @@
 	else
 		op->err = XEN_PCI_ERR_not_implemented;
 
+	/* Mark that we're done */
+	atomic_inc(&pdev->in_use);
+
+	/* Tell the driver domain that we're done */
 	wmb();
 	clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 	notify_remote_via_irq(pdev->evtchn_irq);
+}
+
+irqreturn_t pciback_handle_event(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct pciback_device *pdev = dev_id;
+
+	if (unlikely(!test_bit(_XEN_PCIF_active,
+			       (unsigned long *)&pdev->sh_info->flags))) {
+		pr_debug("pciback: interrupt, but no active operation\n");
+		goto out;
+	}
+
+	/* Make sure driver domain doesn't trigger another interrupt while
+	 * we're still processing the last one */
+	if (atomic_dec_and_test(&pdev->in_use))
+		schedule_work(&pdev->op_work);
+	else
+		atomic_inc(&pdev->in_use);
 
       out:
 	return IRQ_HANDLED;
diff -r c783f340bef8 -r f4e09625f1dd linux-2.6-xen-sparse/drivers/xen/pciback/xenbus.c
--- a/linux-2.6-xen-sparse/drivers/xen/pciback/xenbus.c	Tue Apr 11 08:58:04 2006
+++ b/linux-2.6-xen-sparse/drivers/xen/pciback/xenbus.c	Tue Apr 11 17:40:03 2006
@@ -30,6 +30,9 @@
 	pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
 	pdev->be_watching = 0;
 
+	atomic_set(&pdev->in_use, 1);
+	INIT_WORK(&pdev->op_work, pciback_do_op, pdev);
+
 	if (pciback_init_devices(pdev)) {
 		kfree(pdev);
 		pdev = NULL;
@@ -46,6 +49,11 @@
 	/* Ensure the guest can't trigger our handler before removing devices */
 	if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ)
 		unbind_from_irqhandler(pdev->evtchn_irq, pdev);
+
+	/* If the driver domain started an op, make sure we complete it or
+	 * delete it before releasing the shared memory */
+	cancel_delayed_work(&pdev->op_work);
+	flush_scheduled_work();
 
 	if (pdev->sh_info)
 		xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);