linux-kernel - Re: [PATCH v3 06/11] s390: cio: Use driver_set

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Date:   Tue, 1 Mar 2022 17:01:24 +0100
From:   Vineeth Vijayan <vneethv@...ux.ibm.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Abel Vesa <abel.vesa@....com>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Andy Gross <agross@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-hyperv@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        alsa-devel@...a-project.org, linux-spi@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH v3 06/11] s390: cio: Use driver_set_override() instead of
 open-coding


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@...ux.ibm.com>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.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;
>   }