Re: [PATCH 8/9] dasd: Add 'timeout' attribute

[Heiko Carstens <heiko.carstens@de.ibm.com>]

On Tue, Jan 29, 2013 at 08:12:00AM +0100, Hannes Reinecke wrote:
> This patch adds a 'timeout' attibute to the DASD driver.
> When set to non-zero, the blk_timeout function will
> be enabled with the timeout specified in the attribute.
> Setting 'timeout' to '0' will disable block timeouts.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>

[...]

> +static ssize_t
> +dasd_timeout_store(struct device *dev, struct device_attribute *attr,
> +		   const char *buf, size_t count)
> +{
> +	struct dasd_device *device;
> +	struct request_queue *q;
> +	unsigned long val, flags;
> +
> +	device = dasd_device_from_cdev(to_ccwdev(dev));
> +	if (IS_ERR(device))
> +		return -ENODEV;
> +
> +	if ((strict_strtoul(buf, 10, &val) != 0) ||
> +	    val > ULONG_MAX / HZ) {

Probably this should be UINT_MAX instead of ULONG_MAX, otherwise it
might overflow since blk_queue_rq_timeout(...) expects only an
unsigned int.


> +		dasd_put_device(device);
> +		return -EINVAL;
> +	}
> +	q = device->block->request_queue;
> +	if (!q) {
> +		dasd_put_device(device);
> +		return -ENODEV;
> +	}
> +	spin_lock_irqsave(&device->block->request_queue_lock, flags);
> +	if (!val)
> +		blk_queue_rq_timed_out(q, NULL);
> +	else
> +		blk_queue_rq_timed_out(q, dasd_times_out);
> +
> +	device->blk_timeout = val;
> +
> +	blk_queue_rq_timeout(q, device->blk_timeout * HZ);
> +	spin_unlock_irqrestore(&device->block->request_queue_lock, flags);
> +
> +	dasd_put_device(device);
> +	return count;
> +}