[PATCH] scsi: make "access_state" sysfs attribute always visible

[PATCH] scsi: make "access_state" sysfs attribute always visible

[mwilck]

From: Martin Wilck <mwilck@suse.com>

If a SCSI device handler module is loaded after some SCSI devices
have already been probed (e.g. via request_module() by dm-multipath),
the "access_state" and "preferred_path" sysfs attributes remain invisible for
these devices, although the handler is attached and live. The reason is
that the visibility is only checked when the sysfs attribute group is
first created. This results in an inconsistent user experience depending
on the load order of SCSI low-level drivers vs. device handler modules.

This patch changes user space API: attempting to read the "access_state"
or "preferred_path" attributes will now result in -EINVAL rather than
-ENODEV for devices that have no device handler, and tests for the existence
of these attributes will have a different result.

Signed-off-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/scsi_sysfs.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index f1e0c131b77c..226a50944c00 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1228,14 +1228,6 @@ static umode_t scsi_sdev_attr_is_visible(struct kobject *kobj,
 	    !sdev->host->hostt->change_queue_depth)
 		return 0;
 
-#ifdef CONFIG_SCSI_DH
-	if (attr == &dev_attr_access_state.attr &&
-	    !sdev->handler)
-		return 0;
-	if (attr == &dev_attr_preferred_path.attr &&
-	    !sdev->handler)
-		return 0;
-#endif
 	return attr->mode;
 }
 
-- 
2.34.1

Re: [PATCH] scsi: make "access_state" sysfs attribute always visible

[Hannes Reinecke]

On 1/27/22 15:13, mwilck@suse.com wrote:
> From: Martin Wilck <mwilck@suse.com>
> 
> If a SCSI device handler module is loaded after some SCSI devices
> have already been probed (e.g. via request_module() by dm-multipath),
> the "access_state" and "preferred_path" sysfs attributes remain invisible for
> these devices, although the handler is attached and live. The reason is
> that the visibility is only checked when the sysfs attribute group is
> first created. This results in an inconsistent user experience depending
> on the load order of SCSI low-level drivers vs. device handler modules.
> 
> This patch changes user space API: attempting to read the "access_state"
> or "preferred_path" attributes will now result in -EINVAL rather than
> -ENODEV for devices that have no device handler, and tests for the existence
> of these attributes will have a different result.
> 
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/scsi/scsi_sysfs.c | 8 --------
>   1 file changed, 8 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index f1e0c131b77c..226a50944c00 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -1228,14 +1228,6 @@ static umode_t scsi_sdev_attr_is_visible(struct kobject *kobj,
>   	    !sdev->host->hostt->change_queue_depth)
>   		return 0;
>   
> -#ifdef CONFIG_SCSI_DH
> -	if (attr == &dev_attr_access_state.attr &&
> -	    !sdev->handler)
> -		return 0;
> -	if (attr == &dev_attr_preferred_path.attr &&
> -	    !sdev->handler)
> -		return 0;
> -#endif
>   	return attr->mode;
>   }
>   
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer

Re: [PATCH] scsi: make "access_state" sysfs attribute always visible

[Martin K. Petersen]

> If a SCSI device handler module is loaded after some SCSI devices have
> already been probed (e.g. via request_module() by dm-multipath), the
> "access_state" and "preferred_path" sysfs attributes remain invisible
> for these devices, although the handler is attached and live. The
> reason is that the visibility is only checked when the sysfs attribute
> group is first created. This results in an inconsistent user
> experience depending on the load order of SCSI low-level drivers
> vs. device handler modules.
>
> This patch changes user space API: attempting to read the
> "access_state" or "preferred_path" attributes will now result in
> -EINVAL rather than -ENODEV for devices that have no device handler,
> and tests for the existence of these attributes will have a different
> result.

Applied to 5.18/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH] scsi: make "access_state" sysfs attribute always visible

[Martin K. Petersen]

On Thu, 27 Jan 2022 15:13:51 +0100, mwilck@suse.com wrote:

> From: Martin Wilck <mwilck@suse.com>
> 
> If a SCSI device handler module is loaded after some SCSI devices
> have already been probed (e.g. via request_module() by dm-multipath),
> the "access_state" and "preferred_path" sysfs attributes remain invisible for
> these devices, although the handler is attached and live. The reason is
> that the visibility is only checked when the sysfs attribute group is
> first created. This results in an inconsistent user experience depending
> on the load order of SCSI low-level drivers vs. device handler modules.
> 
> [...]

Applied to 5.18/scsi-queue, thanks!

[1/1] scsi: make "access_state" sysfs attribute always visible
      https://git.kernel.org/mkp/scsi/c/7cddf7e8d1e8

-- 
Martin K. Petersen	Oracle Linux Engineering