Re: [PATCH v3 4/7] scsi: add BLIST_NO_LUN_1F blacklist flag

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

On 4/27/26 4:09 AM, Phil Pemberton wrote:
> Some multi-LUN devices respond to INQUIRY on unpopulated LUNs with
> PQ=0 / PDT=0x1f instead of the standard PQ=3.  The SCSI scan layer
> normally adds such devices (PQ=0 means "connected"), producing
> spurious "No Device" entries.
> 
> The scsi_target field pdt_1f_for_no_lun already exists to suppress
> this, but was previously only set by the USB UFI driver.
> 
> Add BLIST_NO_LUN_1F so the flag can be set per-device from
> scsi_devinfo, and wire it up in scsi_add_lun() to set
> starget->pdt_1f_for_no_lun from the blacklist flags.  This runs
> during LUN 0 processing, before the sequential LUN scan probes
> higher LUNs.
> 
> Signed-off-by: Phil Pemberton <philpem@philpem.me.uk>
> ---
>  drivers/scsi/scsi_scan.c    | 3 +++
>  include/scsi/scsi_devinfo.h | 6 +++---
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 7b11bc7de0e3..d3f0540d79a2 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -1070,6 +1070,9 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
>  
>  	sdev->sdev_bflags = *bflags;
>  
> +	if (*bflags & BLIST_NO_LUN_1F)

Instead of dereferencing again bflags, maybe use sdev->sdev_bflags here ?
I would also remove the blank line before this if.

With that, looks OK to me.

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

> +		sdev->sdev_target->pdt_1f_for_no_lun = 1;
> +
>  	if (scsi_device_is_pseudo_dev(sdev))
>  		return SCSI_SCAN_LUN_PRESENT;
>  
> diff --git a/include/scsi/scsi_devinfo.h b/include/scsi/scsi_devinfo.h
> index 1d79a3b536ce..6957b0705510 100644
> --- a/include/scsi/scsi_devinfo.h
> +++ b/include/scsi/scsi_devinfo.h
> @@ -34,7 +34,8 @@
>  #define BLIST_NOSTARTONADD	((__force blist_flags_t)(1ULL << 12))
>  /* do not ask for VPD page size first on some broken targets */
>  #define BLIST_NO_VPD_SIZE	((__force blist_flags_t)(1ULL << 13))
> -#define __BLIST_UNUSED_14	((__force blist_flags_t)(1ULL << 14))
> +/* PDT 0x1f with PQ 0 means no LUN present (e.g. some ATAPI multi-LUN) */
> +#define BLIST_NO_LUN_1F		((__force blist_flags_t)(1ULL << 14))
>  #define __BLIST_UNUSED_15	((__force blist_flags_t)(1ULL << 15))
>  #define __BLIST_UNUSED_16	((__force blist_flags_t)(1ULL << 16))
>  /* try REPORT_LUNS even for SCSI-2 devs (if HBA supports more than 8 LUNs) */
> @@ -77,8 +78,7 @@
>  #define __BLIST_HIGH_UNUSED (~(__BLIST_LAST_USED | \
>  			       (__force blist_flags_t) \
>  			       ((__force __u64)__BLIST_LAST_USED - 1ULL)))
> -#define __BLIST_UNUSED_MASK (__BLIST_UNUSED_14 | \
> -			     __BLIST_UNUSED_15 | \
> +#define __BLIST_UNUSED_MASK (__BLIST_UNUSED_15 | \
>  			     __BLIST_UNUSED_16 | \
>  			     __BLIST_UNUSED_24 | \
>  			     __BLIST_UNUSED_27 | \


-- 
Damien Le Moal
Western Digital Research