[PATCH v4 10/14] gunyah: sysfs: Add node to describe supported features

[Joe Perches]

On Wed, 2022-09-28 at 12:56 -0700, Elliot Berman wrote:
> Add a sysfs node to list the features that the Gunyah hypervisor and
> Linux supports. For now, Linux support cspace (capability IDs) and
> message queues, so only report those..
[]
> diff --git a/drivers/virt/gunyah/sysfs.c b/drivers/virt/gunyah/sysfs.c
[]
> @@ -25,9 +25,24 @@ static ssize_t variant_show(struct kobject *kobj, struct kobj_attribute *attr, c
>  }
>  static struct kobj_attribute variant_attr = __ATTR_RO(variant);
>  
> +static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr, char *buffer)
> +{
> +	int len = 0;
> +
> +	if (GH_IDENTIFY_PARTITION_CSPACE(gunyah_api.flags))
> +		len += sysfs_emit_at(buffer, len, "cspace ");
> +	if (GH_IDENTIFY_MSGQUEUE(gunyah_api.flags))
> +		len += sysfs_emit_at(buffer, len, "message-queue ");
> +
> +	len += sysfs_emit_at(buffer, len, "\n");
> +	return len;
> +}

It's generally nicer to avoid unnecessary output spaces.

Perhaps:

{
	int len = 0;

	if (GH_IDENTIFY_PARTITION_CSPACE(gunyah_api.flags))
		len += sysfs_emit_at(buffer, len, "cspace");
	if (GH_IDENTIFY_MSGQUEUE(gunyah_api.flags)) {
		if (len)
			len += sysfs_emit_at(buffer, len, " ");
		len += sysfs_emit_at(buffer, len, "message-queue");
	}

	len += sysfs_emit_at(buffer, len, "\n");

	return len;
}