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    Subject[PATCH v3] scsi: xen-scsifront: add error handling for xenbus_printf
    Date
    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@gmail.com>
    ---
    v1->v2:
    - Fix dereferencing before checking
    v2->v3:
    - Use xenbus_dev_error to report 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..644d1ce 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->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->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->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->dev, err,
    + "%s: writing dev_state_path", __func__);
    + }
    break;
    default:
    break;
    --
    2.7.4
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