Re: [patch 13/13] s390: dasd device identifiers.

[Andrew Morton <akpm@osdl.org>]

Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
>
> @@ -45,6 +45,7 @@ struct dasd_devmap {
>          unsigned int devindex;
>          unsigned short features;
>  	struct dasd_device *device;
> +	struct dasd_uid uid;
>  };

Someone's missing a TAB key.

> +static ssize_t
> +dasd_alias_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct dasd_devmap *devmap;
> +	int alias;
> +
> +	devmap = dasd_find_busid(dev->bus_id);
> +	spin_lock(&dasd_devmap_lock);
> +	if (!IS_ERR(devmap))
> +		alias = devmap->uid.alias;
> +	else
> +		alias = 0;
> +	spin_unlock(&dasd_devmap_lock);
> +
> +	return sprintf(buf, alias ? "1\n" : "0\n");
> +}

The locking is suspicious.  We take a spinlock just for a single read?

> +/*
> + * Return copy of the device unique identifier.
> + */
> +int
> +dasd_get_uid(struct ccw_device *cdev, struct dasd_uid *uid)
> +{
> +	struct dasd_devmap *devmap;
> +
> +	devmap = dasd_find_busid(cdev->dev.bus_id);
> +	if (IS_ERR(devmap))
> +		return PTR_ERR(devmap);
> +	spin_lock(&dasd_devmap_lock);
> +	*uid = devmap->uid;
> +	spin_unlock(&dasd_devmap_lock);
> +	return 0;
> +}

And for a single write?