Re: [PATCH v5 2/7] scsi: libsas: Define NCQ Priority sysfs attributes for SATA devices

[John Garry <john.g.garry@oracle.com>]

On 05/03/2024 00:50, Igor Pylypiv wrote:
>   
>   static inline void sas_ata_disabled_notice(void)
> @@ -123,6 +125,10 @@ static inline int sas_ata_add_dev(struct domain_device *parent, struct ex_phy *p
>   	sas_ata_disabled_notice();
>   	return -ENODEV;
>   }
> +
> +static const struct attribute_group sas_ata_sdev_attr_group = {
> +	.attrs = NULL,
> +};

I just noticed a build issue.

With CONFIG_SCSI_SAS_ATA not set, I get this for W=1 build:

In file included from drivers/scsi/hisi_sas/hisi_sas.h:29,
                 from drivers/scsi/hisi_sas/hisi_sas_v1_hw.c:7:
./include/scsi/sas_ata.h:129:37: error: ‘sas_ata_sdev_attr_group’
defined but not used [-Werror=unused-const-variable=]
  129 | static const struct attribute_group sas_ata_sdev_attr_group = {

I suppose that marking sas_ata_sdev_attr_group as __maybe_unused is ok, 
but less than ideal. The linker should strip it out of files when unused.

I think that this is also ok:

#define sas_ata_sdev_attr_group (struct attribute_group) {}

The compiler here will create a empty structure and have 
&sas_ata_sdev_attr_group point at it.

Thanks,
John