Re: [PATCH v2 1/2] scsi: core: Retry passthrough commands if SCMD_RETRY_PASSTHROUGH is set

[Damien Le Moal <dlemoal@kernel.org>]

On 8/10/24 04:31, Bart Van Assche wrote:
> The SCSI core does not retry passthrough commands even if the SCSI device
> reports a retryable unit attention condition. Support retrying in this case
> by introducing the SCMD_RETRY_PASSTHROUGH flag.
> 
> Cc: Damien Le Moal <dlemoal@kernel.org>
> Cc: Mike Christie <michael.christie@oracle.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/scsi/scsi_error.c | 5 ++++-
>  include/scsi/scsi_cmnd.h  | 5 ++++-
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 612489afe8d2..9089d39c2170 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -1855,7 +1855,10 @@ 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))
> +	if (req->cmd_flags & REQ_FAILFAST_DEV)
> +		return true;
> +	if (blk_rq_is_passthrough(req) &&
> +	    !(scmd->flags & SCMD_RETRY_PASSTHROUGH))
>  		return true;
>  
>  	return false;

	return (req->cmd_flags & REQ_FAILFAST_DEV) ||
		(blk_rq_is_passthrough(req) &&
		 !(scmd->flags & SCMD_RETRY_PASSTHROUGH));

maybe ? Not necessarily more readable though.

> diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
> index 45c40d200154..19c57446ab23 100644
> --- a/include/scsi/scsi_cmnd.h
> +++ b/include/scsi/scsi_cmnd.h
> @@ -58,8 +58,11 @@ struct scsi_pointer {
>   */
>  #define SCMD_FORCE_EH_SUCCESS	(1 << 3)
>  #define SCMD_FAIL_IF_RECOVERING	(1 << 4)
> +/* If set, retry a passthrough command in case of a unit attention. */

"...in case of error". There are other sense keys than unit attention and there
is no code checking that this flag applies only to unit attention.

With this comment fixed:

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

> +#define SCMD_RETRY_PASSTHROUGH	(1 << 5)
>  /* flags preserved across unprep / reprep */
> -#define SCMD_PRESERVED_FLAGS	(SCMD_INITIALIZED | SCMD_FAIL_IF_RECOVERING)
> +#define SCMD_PRESERVED_FLAGS	\
> +	(SCMD_INITIALIZED | SCMD_FAIL_IF_RECOVERING | SCMD_RETRY_PASSTHROUGH)
>  
>  /* for scmd->state */
>  #define SCMD_STATE_COMPLETE	0

-- 
Damien Le Moal
Western Digital Research