[PATCH v3 06/11] s390: cio: Use driver_set_override() instead of open-coding

[Vineeth Vijayan]

On 2/27/22 14:52, Krzysztof Kozlowski wrote:
> Use a helper for seting driver_override to reduce amount of duplicated
> code. Make the driver_override field const char, because it is not
> modified by the core and it matches other subsystems.
s/seting/setting/

Also could you please change the title to start with "s390/cio:"
instead of "s390 : cio"

Otherwise,

Acked-by: Vineeth Vijayan <vneethv at linux.ibm.com>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at canonical.com>
> ---
>   drivers/s390/cio/cio.h |  7 ++++++-
>   drivers/s390/cio/css.c | 28 ++++------------------------
>   2 files changed, 10 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
> index 1cb9daf9c645..e110c10613e8 100644
> --- a/drivers/s390/cio/cio.h
> +++ b/drivers/s390/cio/cio.h
> @@ -103,7 +103,12 @@ struct subchannel {
>   	struct work_struct todo_work;
>   	struct schib_config config;
>   	u64 dma_mask;
> -	char *driver_override; /* Driver name to force a match */
> +	/*
> +	 * Driver name to force a match.
> +	 * Do not set directly, because core frees it.
> +	 * Use driver_set_override() to set or clear it.
> +	 */
As Bjorn Helgaas mentioned, please wrap this comment.
> +	const char *driver_override;
>   } __attribute__ ((aligned(8)));
>   
>   DECLARE_PER_CPU_ALIGNED(struct irb, cio_irb);
> diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
> index fa8293335077..913b6ddd040b 100644
> --- a/drivers/s390/cio/css.c
> +++ b/drivers/s390/cio/css.c
> @@ -338,31 +338,11 @@ static ssize_t driver_override_store(struct device *dev,
>   				     const char *buf, size_t count)
>   {
>   	struct subchannel *sch = to_subchannel(dev);
> -	char *driver_override, *old, *cp;
> -
> -	/* We need to keep extra room for a newline */
> -	if (count >= (PAGE_SIZE - 1))
> -		return -EINVAL;
> -
> -	driver_override = kstrndup(buf, count, GFP_KERNEL);
> -	if (!driver_override)
> -		return -ENOMEM;
> -
> -	cp = strchr(driver_override, '\n');
> -	if (cp)
> -		*cp = '\0';
> -
> -	device_lock(dev);
> -	old = sch->driver_override;
> -	if (strlen(driver_override)) {
> -		sch->driver_override = driver_override;
> -	} else {
> -		kfree(driver_override);
> -		sch->driver_override = NULL;
> -	}
> -	device_unlock(dev);
> +	int ret;
>   
> -	kfree(old);
> +	ret = driver_set_override(dev, &sch->driver_override, buf, count);
> +	if (ret)
> +		return ret;
>   
>   	return count;
>   }