Michael S. Tsirkin
2019-Sep-04 09:14 UTC
[PATCH] scsi: virtio_scsi: unplug LUNs when events missed
On Tue, Sep 03, 2019 at 05:04:20PM +0000, Matt Lupfer wrote:> The event handler calls scsi_scan_host() when events are missed, which > will hotplug new LUNs. However, this function won't remove any > unplugged LUNs. The result is that hotunplug doesn't work properly when > the number of unplugged LUNs exceeds the event queue size (currently 8). > > Scan existing LUNs when events are missed to check if they are still > present. If not, remove them. > > Signed-off-by: Matt Lupfer <mlupfer at ddn.com> > --- > drivers/scsi/virtio_scsi.c | 31 +++++++++++++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c > index 297e1076e571..18df77bf371b 100644 > --- a/drivers/scsi/virtio_scsi.c > +++ b/drivers/scsi/virtio_scsi.c > @@ -324,6 +324,36 @@ static void virtscsi_handle_param_change(struct virtio_scsi *vscsi, > scsi_device_put(sdev); > } > > +static void virtscsi_rescan_hotunplug(struct virtio_scsi *vscsi) > +{ > + struct scsi_device *sdev; > + struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev); > + unsigned char scsi_cmd[MAX_COMMAND_SIZE]; > + int result, inquiry_len, inq_result_len = 256; > + char *inq_result = kmalloc(inq_result_len, GFP_KERNEL); > + > + shost_for_each_device(sdev, shost) { > + inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36; > + > + memset(scsi_cmd, 0, sizeof(scsi_cmd)); > + scsi_cmd[0] = INQUIRY; > + scsi_cmd[4] = (unsigned char) inquiry_len; > + > + memset(inq_result, 0, inq_result_len); > + > + result = scsi_execute_req(sdev, scsi_cmd, DMA_FROM_DEVICE, > + inq_result, inquiry_len, NULL, > + 2, 3, NULL);Where do the weird 2 and 3 values come from? Most callers seem to use SD_TIMEOUT, SD_MAX_RETRIES...> + > + if (result == 0 && inq_result[0] >> 5) { > + /* PQ indicates the LUN is not attached */ > + scsi_remove_device(sdev); > + } > + } > + > + kfree(inq_result); > +} > + > static void virtscsi_handle_event(struct work_struct *work) > { > struct virtio_scsi_event_node *event_node > @@ -335,6 +365,7 @@ static void virtscsi_handle_event(struct work_struct *work) > cpu_to_virtio32(vscsi->vdev, VIRTIO_SCSI_T_EVENTS_MISSED)) { > event->event &= ~cpu_to_virtio32(vscsi->vdev, > VIRTIO_SCSI_T_EVENTS_MISSED); > + virtscsi_rescan_hotunplug(vscsi); > scsi_scan_host(virtio_scsi_host(vscsi->vdev)); > } > > -- > 2.23.0