Re: [PATCH] scsi: simplify registration of scsi host sysfs attributes

[Steffen Maier <maier@linux.ibm.com>]

On 11/15/21 10:29, Damien Le Moal wrote:
> Similarly to the way attribute groups are registered for a scsi device
> using the device sdev_gendev, a scsi host attribute groups can be
> registered by specifying the generic attribute groups using the groups
> field of the scsi_host_type (struct device_type) and set the array of
> host attribute groups provided by the LLDD using the groups field of the
> host shost_dev generic device. This partially reverts the changes
> introduced by commit 92c4b58b15c5 ("scsi: core: Register sysfs
> attributes earlier"), avoiding the for loop to build a size limited
> array of attribute groups from the generic attributes and LLDD provided
> attribut groups.

See also 
https://lore.kernel.org/linux-scsi/2f5e5d18-7ba9-10f6-1855-84546172b473@linux.ibm.com/T/#md21644c177f45a0721d4fa3bdb84fbafb2bc8981 
?

E.g. your patch does not seem to remove the now unused(?) 
Scsi_Host.shost_dev_attr_groups ?

Not sure which is better: Bart using the scsi_host class or your below patch 
using scsi_host device_type.

> 
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> ---
>   drivers/scsi/hosts.c      | 15 +++------------
>   drivers/scsi/scsi_priv.h  |  2 +-
>   drivers/scsi/scsi_sysfs.c |  7 ++++++-
>   3 files changed, 10 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index 8049b00b6766..c3b6812aac5b 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -359,6 +359,7 @@ static void scsi_host_dev_release(struct device *dev)
>   static struct device_type scsi_host_type = {
>   	.name =		"scsi_host",
>   	.release =	scsi_host_dev_release,
> +	.groups =	scsi_sysfs_shost_attr_groups,
>   };
>   
>   /**
> @@ -377,7 +378,7 @@ 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)
> @@ -483,17 +484,7 @@ 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..f8ca22d495d9 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_sysfs_shost_attr_groups[];
>   
>   /* scsi_netlink.c */
>   #ifdef CONFIG_SCSI_NETLINK
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 55addd78fde4..c3b93d2de081 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_sysfs_shost_attr_groups[] = {
> +	&scsi_shost_attr_group,
> +	NULL,
> +};
> +
>   static void scsi_device_cls_release(struct device *class_dev)
>   {
>   	struct scsi_device *sdev;
> 


-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

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