4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Zhouyang Jia <jiazhouyan...@gmail.com>

[ Upstream commit 93efbd39870474cc536b9caf4a6efeb03b0bc56f ]

When xenbus_printf fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling xenbus_printf.

Signed-off-by: Zhouyang Jia <jiazhouyan...@gmail.com>
Reviewed-by: Juergen Gross <jgr...@suse.com>
Signed-off-by: Juergen Gross <jgr...@suse.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/scsi/xen-scsifront.c |   33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

--- a/drivers/scsi/xen-scsifront.c
+++ b/drivers/scsi/xen-scsifront.c
@@ -676,10 +676,17 @@ static int scsifront_dev_reset_handler(s
 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;
 }
@@ -687,10 +694,15 @@ static int scsifront_sdev_configure(stru
 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 = {
@@ -1025,9 +1037,12 @@ static void scsifront_do_lun_hotplug(str
 
                        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:
@@ -1041,10 +1056,14 @@ static void scsifront_do_lun_hotplug(str
                        }
                        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;


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