Re: [PATCH v7 2/6] ata: libata-scsi: convert dev->sdev to per-LUN array

[Hannes Reinecke]

On 6/11/26 04:43, Phil Pemberton wrote:
> Multi-LUN ATAPI devices (PD/CD combos, CD changers) share a single
> ata_device but expose multiple scsi_devices.  The previous single
> dev->sdev pointer could only track one LUN, making all other LUNs
> invisible to code that operates on sdevs: port detach, suspend/resume,
> ACPI uevent, ZPODD, media change notification, and EH teardown.
>
> Replace the scalar struct scsi_device *sdev with a fixed-size array
> dev->sdev[ATAPI_MAX_LUN] indexed by LUN number, where ATAPI_MAX_LUN
> is 8 (the SCSI-2 ceiling, LUN values 0..7).  All callers are updated
> to iterate the full array and skip NULL slots; only populated LUN slots
> are ever non-NULL so single-LUN devices (the vast majority) see no
> change in behaviour.
>
> Add an inline helper ata_dev_scsi_device(dev, lun) that returns
> dev->sdev[lun] guarded by a WARN_ON_ONCE(lun >= ATAPI_MAX_LUN) bounds
> check.  Use it for the hardcoded LUN-0 references in libata-acpi
> (uevent kobj), libata-zpodd (disk events, wake notify for all LUNs),
> and the door-lock and OF-node paths in libata-scsi.
>
> Key changes per call site:
>    - ata_scsi_dev_config:    bounds-check lun, assign sdev to dev->sdev[sdev->lun]
>    - ata_scsi_sdev_destroy:  clear per-LUN slot; trigger ATA detach only
>                              when the last populated LUN is destroyed
>    - ata_port_detach:        iterate all ATAPI_MAX_LUN slots descending;
>                              clear dev->sdev[lun] before unlock to close
>                              the UAF window (Hannes Reinecke)
>    - ata_scsi_offline_dev:   iterate all slots
>    - ata_scsi_remove_dev:    snapshot all LUN slots then remove outside lock
>    - ata_scsi_media_change_notify: send event to all populated LUNs
>    - ata_scsi_dev_rescan:    snapshot all LUNs under lock, then resume and
>                              rescan each; release remaining refs on early exit
>    - ACPI, ZPODD, door-lock: use ata_dev_scsi_device(dev, 0)
>    - ZPODD disk-events:      iterate all LUNs for enable/disable and wake
>
> Signed-off-by: Phil Pemberton <philpem@xxxxxxxxxxxxx>
> ---
>   drivers/ata/libata-acpi.c  |   9 +-
>   drivers/ata/libata-core.c  |  11 ++-
>   drivers/ata/libata-scsi.c  | 164 +++++++++++++++++++++----------------
>   drivers/ata/libata-zpodd.c |  27 ++++--
>   include/linux/libata.h     |  10 ++-
>   5 files changed, 138 insertions(+), 83 deletions(-)

Reviewed-by: Hannes Reinecke <hare@xxxxxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@xxxxxxx                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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