On Tue, Oct 26, 2021 at 03:42:40AM +0200, Steffen Maier wrote:
> v4.17 commit 86b87cde0b55 ("scsi: core: host template attribute groups")
> introduced explicit sysfs_create_groups() in scsi_sysfs_add_sdev()
> and sysfs_remove_groups() in __scsi_remove_device(), both for sdev_gendev,
> based on a new field const struct attribute_group **sdev_groups
> of struct scsi_host_template.
>
> Commit 92c4b58b15c5 ("scsi: core: Register sysfs attributes earlier")
> removed above explicit (de)registration of scsi_device attribute groups.
> It also converted all scsi_device attributes and attribute_groups to
> end up in a new field const struct attribute_group *gendev_attr_groups[6]
> of struct scsi_device. However, that new field was not used anywhere.
>
> Surprisingly, this only caused missing LLDD specific scsi_device sysfs
> attributes. Whereas, scsi core attributes from scsi_sdev_attr_groups
> did continue to exist because of scsi_dev_type.groups.
>
> We separate scsi core attibutes from LLDD specific attributes.
> Hence, we keep the initializing assignment scsi_dev_type =
> { .groups = scsi_sdev_attr_groups, } as this takes care of core
> attributes. Without the separation, it would cause attribute double
> registration due to scsi_dev_type.groups and sdev_gendev.groups.
>
> Julian suggested to assign the sdev_groups pointer of the
> scsi_host_template directly to the groups pointer of sdev_gendev.
> This way we can delete the container scsi_device.gendev_attr_groups
> and the loop copying each entry from hostt->sdev_groups to
> sdev->gendev_attr_groups.
>
> Alternative approaches ruled out:
> Assigning gendev_attr_groups to sdev_dev has no visible effect.
> Assigning sdev->gendev_attr_groups to scsi_dev_type.groups
> caused scsi_device of all scsi host types to get LLDD specific
> attributes of the LLDD for which the last sdev alloc happened to occur,
> as that overwrote scsi_dev_type.groups,
> e.g. scsi_debug had zfcp-specific scsi_device attributes.
>
> Signed-off-by: Steffen Maier <maier@xxxxxxxxxxxxx>
> Fixes: 92c4b58b15c5 ("scsi: core: Register sysfs attributes earlier")
> Suggested-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
> ---
>
> Notes:
> Changes in v3:
> * integrated Julian's feedback of dropping detour through
> gendev_attr_groups
>
> Changes in v2:
> * integrated Bart's feedback of updating the comment for
> the gendev_attr_groups declaration to match the code change
> * in that spirit also adapted the vector size of that field
> * eliminated the now unnecessary second loop counter 'j'
>
> drivers/scsi/scsi_sysfs.c | 11 +----------
> include/scsi/scsi_device.h | 6 ------
> 2 files changed, 1 insertion(+), 16 deletions(-)
>
Looks good to me.
Reviewed-by: Benjamin Block <bblock@xxxxxxxxxxxxx>
--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development / IBM Systems
IBM Deutschland Research & Development GmbH / https://www.ibm.com/privacy
Vorsitz. AufsR.: Gregor Pillen / Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294
