Merge tag 'for-linus-4.18-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:
 "This contains the following fixes/cleanups:

   - the removal of a BUG_ON() which wasn't necessary and which could
     trigger now due to a recent change

   - a correction of a long standing bug happening very rarely in Xen
     dom0 when a hypercall buffer from user land was not accessible by
     the hypervisor for very short periods of time due to e.g. page
     migration or compaction

   - usage of EXPORT_SYMBOL_GPL() instead of EXPORT_SYMBOL() in a
     Xen-related driver (no breakage possible as using those symbols
     without others already exported via EXPORT-SYMBOL_GPL() wouldn't
     make any sense)

   - a simplification for Xen PVH or Xen ARM guests

   - some additional error handling for callers of xenbus_printf()"

* tag 'for-linus-4.18-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Remove unnecessary BUG_ON from __unbind_from_irq()
  xen: add new hypercall buffer mapping device
  xen/scsiback: add error handling for xenbus_printf
  scsi: xen-scsifront: add error handling for xenbus_printf
  xen/grant-table: Export gnttab_{alloc|free}_pages as GPL
  xen: add error handling for xenbus_printf
  xen: share start flags between PV and PVH

drivers/scsi/xen-scsifront.c

@@ -654,10 +654,17 @@ static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
 static int scsifront_sdev_configure(struct scsi_device *sdev)
 {
 	struct vscsifrnt_info *info = shost_priv(sdev->host);
+	int err;
 
-	if (info && current == info->curr)
-		xenbus_printf(XBT_NIL, info->dev->nodename,
+	if (info && current == info->curr) {
+		err = xenbus_printf(XBT_NIL, info->dev->nodename,
 			      info->dev_state_path, "%d", XenbusStateConnected);
+		if (err) {
+			xenbus_dev_error(info->dev, err,
+				"%s: writing dev_state_path", __func__);
+			return err;
+		}
+	}
 
 	return 0;
 }
@@ -665,10 +672,15 @@ static int scsifront_sdev_configure(struct scsi_device *sdev)
 static void scsifront_sdev_destroy(struct scsi_device *sdev)
 {
 	struct vscsifrnt_info *info = shost_priv(sdev->host);
+	int err;
 
-	if (info && current == info->curr)
-		xenbus_printf(XBT_NIL, info->dev->nodename,
+	if (info && current == info->curr) {
+		err = xenbus_printf(XBT_NIL, info->dev->nodename,
 			      info->dev_state_path, "%d", XenbusStateClosed);
+		if (err)
+			xenbus_dev_error(info->dev, err,
+				"%s: writing dev_state_path", __func__);
+	}
 }
 
 static struct scsi_host_template scsifront_sht = {
@@ -1003,9 +1015,12 @@ static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 
 			if (scsi_add_device(info->host, chn, tgt, lun)) {
 				dev_err(&dev->dev, "scsi_add_device\n");
-				xenbus_printf(XBT_NIL, dev->nodename,
+				err = xenbus_printf(XBT_NIL, dev->nodename,
 					      info->dev_state_path,
 					      "%d", XenbusStateClosed);
+				if (err)
+					xenbus_dev_error(dev, err,
+						"%s: writing dev_state_path", __func__);
 			}
 			break;
 		case VSCSIFRONT_OP_DEL_LUN:
@@ -1019,10 +1034,14 @@ static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
 			}
 			break;
 		case VSCSIFRONT_OP_READD_LUN:
-			if (device_state == XenbusStateConnected)
-				xenbus_printf(XBT_NIL, dev->nodename,
+			if (device_state == XenbusStateConnected) {
+				err = xenbus_printf(XBT_NIL, dev->nodename,
 					      info->dev_state_path,
 					      "%d", XenbusStateConnected);
+				if (err)
+					xenbus_dev_error(dev, err,
+						"%s: writing dev_state_path", __func__);
+			}
 			break;
 		default:
 			break;