Re: [PATCH v4 08/11] vdpa: Use helper for safer setting of driver_override

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Stuart Yoder <stuyoder@gmail.com>,
	Laurentiu Tudor <laurentiu.tudor@nxp.com>,
	Abel Vesa <abel.vesa@nxp.com>, Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Vineeth Vijayan <vneethv@linux.ibm.com>,
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	linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
	NXP Linux Team <linux-imx@nxp.com>,
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	Linus Torvalds <torvalds@linux-foundation.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: Re: [PATCH v4 08/11] vdpa: Use helper for safer setting of driver_override
Date: Wed, 16 Mar 2022 04:56:48 -0400	[thread overview]
Message-ID: <20220316045633-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20220312132856.65163-9-krzysztof.kozlowski@canonical.com>

On Sat, Mar 12, 2022 at 02:28:53PM +0100, Krzysztof Kozlowski wrote:
> Use a helper to set driver_override to reduce amount of duplicated code.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

feel free to merge with the rest of the patchset.

> ---
>  drivers/vdpa/vdpa.c  | 29 ++++-------------------------
>  include/linux/vdpa.h |  4 +++-
>  2 files changed, 7 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 1ea525433a5c..2dabed1df35c 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -77,32 +77,11 @@ static ssize_t driver_override_store(struct device *dev,
>  				     const char *buf, size_t count)
>  {
>  	struct vdpa_device *vdev = dev_to_vdpa(dev);
> -	const char *driver_override, *old;
> -	char *cp;
> +	int ret;
>  
> -	/* 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 = vdev->driver_override;
> -	if (strlen(driver_override)) {
> -		vdev->driver_override = driver_override;
> -	} else {
> -		kfree(driver_override);
> -		vdev->driver_override = NULL;
> -	}
> -	device_unlock(dev);
> -
> -	kfree(old);
> +	ret = driver_set_override(dev, &vdev->driver_override, buf, count);
> +	if (ret)
> +		return ret;
>  
>  	return count;
>  }
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 721089bb4c84..37117404660e 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -64,7 +64,9 @@ struct vdpa_mgmt_dev;
>   * struct vdpa_device - representation of a vDPA device
>   * @dev: underlying device
>   * @dma_dev: the actual device that is performing DMA
> - * @driver_override: driver name to force a match
> + * @driver_override: driver name to force a match; do not set directly,
> + *                   because core frees it; use driver_set_override() to
> + *                   set or clear it.
>   * @config: the configuration ops for this device.
>   * @cf_mutex: Protects get and set access to configuration layout.
>   * @index: device index
> -- 
> 2.32.0

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