Re: [PATCH v3 01/11] scsi: scsi_debug: Fix check for sdev queue full

Douglas Gilbert
2023-03-28T23:35:40Z

On 2023-03-27 03:43, John Garry wrote:
> There is a report that the blktests scsi/004 test for "TASK SET FULL" (TSF)
> now fails.
>
> The condition upon we should issue this TSF is when the sdev queue is
> full. The check for a full queue has an off-by-1 error. Previously we
> would increment the number of requests in the queue after testing if the
> queue would be full, i.e. test if one less than full. Since we now use
> scsi_device_busy() to count the number of requests in the queue, this
> would already account for the current request, so fix the test for queue
> full accordingly.
>
> Fixes: 151f0ec9ddb5 ("scsi: scsi_debug: Drop sdebug_dev_info.num_in_q")
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Link: https://lore.kernel.org/oe-lkp/202303201334.18b30edc-oliver.sang@intel.com
> Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com

Thanks.

> ---
> drivers/scsi/scsi_debug.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index 7ed117e78bd4..782515abca2c 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -5580,7 +5580,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
> int num_in_q = scsi_device_busy(sdp);
> int qdepth = cmnd->device->queue_depth;
>
> - if ((num_in_q == (qdepth - 1)) &&
> + if ((num_in_q == qdepth) &&
> (atomic_inc_return(&sdebug_a_tsf) >=
> abs(sdebug_every_nth))) {
> atomic_set(&sdebug_a_tsf, 0);