Subject: Re: [PATCH v3] scsi: core: Fix early registration of sysfs attributes for scsi_device

From: Benjamin Block <[email-masked]>
Date: Fri, 29 Oct 2021 19:55:40 +0200

On Tue, Oct 26, 2021 at 02:48:55PM -0700, Bart Van Assche wrote:
> On 10/26/21 3:00 AM, Benjamin Block wrote:
> > Hmm, maybe this is out of scope for this fix, but couldn't we
> > essentially do the same thing for the host attributes. Have the
> > `shost_class` take the `scsi_shost_attr_group` as default attributes for
> > the shost class, and then assign the `shost_groups` from the LLDD
> > template to `shost_dev.groups` as optional attributes?
> > 
> > Then we get rid of the indirection loop in `hosts.c` as well, that was
> > introduce with he original patch by Bart.
> > 
> > Just a shot in the dark, I don't know whether the `struct class` behaves
> > the same in this case as `struct device_type`.
> 
> Is something like this what you have in mind?

Yes, exactly. That's what I meant. That make host and dev similar again.

I just wasn't really sure whether `.dev_groups` in class behaves the
same as with what Steffen did. From the documentation it does though.

> 
> Thanks,
> 
> Bart.
> 
> 
> Subject: [PATCH] scsi: core: Remove Scsi_Host.shost_dev_attr_groups
> 
> Suggested-by: Benjamin Block <[email-masked]>
> Signed-off-by: Bart Van Assche <[email-masked]>
> ---
>  drivers/scsi/hosts.c      | 15 +++------------
>  drivers/scsi/scsi_priv.h  |  2 +-
>  drivers/scsi/scsi_sysfs.c |  7 ++++++-
>  include/scsi/scsi_host.h  |  6 ------
>  4 files changed, 10 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index 17aef936bc90..f88e7ed77dbb 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -61,6 +61,7 @@ static void scsi_host_cls_release(struct device *dev)
>  static struct class shost_class = {
>  	.name		= "scsi_host",
>  	.dev_release	= scsi_host_cls_release,
> +	.dev_groups	= scsi_shost_groups,
>  };
> 
>  /**
> @@ -376,7 +377,7 @@ static struct device_type scsi_host_type = {
>  struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
>  {
>  	struct Scsi_Host *shost;
> -	int index, i, j = 0;
> +	int index;
> 
>  	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
>  	if (!shost)
> @@ -481,17 +482,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
>  	shost->shost_dev.parent = &shost->shost_gendev;
>  	shost->shost_dev.class = &shost_class;
>  	dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
> -	shost->shost_dev.groups = shost->shost_dev_attr_groups;
> -	shost->shost_dev_attr_groups[j++] = &scsi_shost_attr_group;
> -	if (sht->shost_groups) {
> -		for (i = 0; sht->shost_groups[i] &&
> -			     j < ARRAY_SIZE(shost->shost_dev_attr_groups);
> -		     i++, j++) {
> -			shost->shost_dev_attr_groups[j] =
> -				sht->shost_groups[i];
> -		}
> -	}
> -	WARN_ON_ONCE(j >= ARRAY_SIZE(shost->shost_dev_attr_groups));
> +	shost->shost_dev.groups = sht->shost_groups;
> 
>  	shost->ehandler = kthread_run(scsi_error_handler, shost,
>  			"scsi_eh_%d", shost->host_no);
> diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
> index a278fc8948f4..0f5743f4769b 100644
> --- a/drivers/scsi/scsi_priv.h
> +++ b/drivers/scsi/scsi_priv.h
> @@ -144,7 +144,7 @@ extern struct scsi_transport_template blank_transport_template;
>  extern void __scsi_remove_device(struct scsi_device *);
> 
>  extern struct bus_type scsi_bus_type;
> -extern const struct attribute_group scsi_shost_attr_group;
> +extern const struct attribute_group *scsi_shost_groups[];
> 
>  /* scsi_netlink.c */
>  #ifdef CONFIG_SCSI_NETLINK
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index c26f0e29e8cd..f360154b5241 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -424,10 +424,15 @@ static struct attribute *scsi_sysfs_shost_attrs[] = {
>  	NULL
>  };
> 
> -const struct attribute_group scsi_shost_attr_group = {
> +static const struct attribute_group scsi_shost_attr_group = {
>  	.attrs =	scsi_sysfs_shost_attrs,
>  };
> 
> +const struct attribute_group *scsi_shost_groups[] = {
> +	&scsi_shost_attr_group,
> +	NULL
> +};
> +
>  static void scsi_device_cls_release(struct device *class_dev)
>  {
>  	struct scsi_device *sdev;
> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
> index ae715959f886..97cdad14de56 100644
> --- a/include/scsi/scsi_host.h
> +++ b/include/scsi/scsi_host.h
> @@ -690,12 +690,6 @@ struct Scsi_Host {
> 
>  	/* ldm bits */
>  	struct device		shost_gendev, shost_dev;
> -	/*
> -	 * The array size 3 provides space for one attribute group defined by
> -	 * the SCSI core, one attribute group defined by the SCSI LLD and one
> -	 * terminating NULL pointer.
> -	 */
> -	const struct attribute_group *shost_dev_attr_groups[3];
> 
>  	/*
>  	 * Points to the transport data (if any) which is allocated

Reviewed-by: Benjamin Block <[email-masked]>

-- 
Best Regards, Benjamin Block  / Linux on IBM Z Kernel Development / IBM Systems
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