Subject: [PATCH] scsi: core: Fix early registration of sysfs attributes for scsi_device

From: Steffen Maier <[email-masked]>
Date: Sun, 24 Oct 2021 13:18:15 +0200

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.

Fix it by assigning the pointer of that new field to the groups
field of sdev_gendev so the driver core gets our LLDD groups.
Just like scsi_host_alloc() was changed by the same commit,
although scsi_host_alloc() already had assigned something to
shost_dev.groups so the necessary change was more obvious there.

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.

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 <[email-masked]>
Fixes: 92c4b58b15c5 ("scsi: core: Register sysfs attributes earlier")
---
 drivers/scsi/scsi_sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index c26f0e29e8cd..a3e37d3728df 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1583,7 +1583,7 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev)
 	scsi_enable_async_suspend(&sdev->sdev_gendev);
 	dev_set_name(&sdev->sdev_gendev, "%d:%d:%d:%llu",
 		     sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
-	sdev->gendev_attr_groups[j++] = &scsi_sdev_attr_group;
+	sdev->sdev_gendev.groups = sdev->gendev_attr_groups;
 	if (hostt->sdev_groups) {
 		for (i = 0; hostt->sdev_groups[i] &&
 			     j < ARRAY_SIZE(sdev->gendev_attr_groups);
-- 
2.25.1