Re: RFC: Retrying SCSI pass-through commands

[Mike Christie <michael.christie@oracle.com>]

On 7/31/24 3:22 PM, Bart Van Assche wrote:
> 
> 
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index da7dac77f8cd..e21becc5bcf9 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -1816,6 +1816,12 @@ bool scsi_noretry_cmd(struct scsi_cmnd *scmd)
>          * assume caller has checked sense and determined
>          * the check condition was retryable.
>          */
> -       if (req->cmd_flags & REQ_FAILFAST_DEV || blk_rq_is_passthrough(req))
> -               return true;
> +       if (req->cmd_flags & REQ_FAILFAST_DEV)
> +               return true;
> +       if (/* submitted by the SCSI core */)
> +               return false;
> +       if (blk_rq_is_passthrough(req))
> +               return true;

Do you just want to retry UAs or all internal passthrough command
errors that go through here?

For just the specific UA or NOT_READY/0x04/0x01 case for an example.
Does every scsi core passthrough caller want that retried? If so, then
I can see where you are coming from where you feel it's a bug. I would
agree we would normally want to retry that in general. Maybe others know
about some specific old case though.

However, I'm not sure for MEDIUM_ERROR or ABORTED_COMMAND.
I think MEDIUM_ERROR probably would not come up for the cases we are
talking about though.

I don't think we want to always retry DID_TIME_OUT though. The funny
thing is that I think Martin just wanted to retry one specific case
for that error. We had to do the scsi_check_passthrough patches so
we could retry just for scsi_probe_lun.