[Xen-devel] [PATCH v5] scsi: xen-scsifront: add error handling for xenbus_printf

[Zhouyang Jia <jiazhouyang09@xxxxxxxxx>]

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 <jiazhouyang09@xxxxxxxxx>
v1->v2:
- Fix dereferencing before checking.
v2->v3:
- Use xenbus_dev_error to report errors.
v3->v4:
- Fix compilation errors.
v4->v5:
- Fix compilation errors.
---
 drivers/scsi/xen-scsifront.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/xen-scsifront.c b/drivers/scsi/xen-scsifront.c
index 36f59a1..61389bd 100644
--- a/drivers/scsi/xen-scsifront.c
+++ b/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;
-- 
2.7.4


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