linux-kernel - Re: [PATCH v1 2/2] mei: bus: change remove callback to return void

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Date:   Sun, 7 Feb 2021 15:48:10 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Uwe Kleine-König <uwe@...ine-koenig.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH v1 2/2] mei: bus: change remove callback to return void

On 2/7/21 2:22 PM, Uwe Kleine-König wrote:
> The driver core ignores the return value of mei_cl_device_remove() so
> passing an error value doesn't solve any problem. As most mei drivers'
> remove callbacks return 0 unconditionally and returning a different value
> doesn't have any effect, change this prototype to return void and return 0
> unconditionally in mei_cl_device_remove(). The only driver that could
> return an error value is modified to emit an explicit warning in the error
> case.
> 
> Signed-off-by: Uwe Kleine-König <uwe@...ine-koenig.org>
> ---
>  drivers/misc/mei/bus.c           | 5 ++---
>  drivers/misc/mei/hdcp/mei_hdcp.c | 7 +++++--
>  drivers/nfc/microread/mei.c      | 4 +---
>  drivers/nfc/pn544/mei.c          | 4 +---
>  drivers/watchdog/mei_wdt.c       | 4 +---

Acked-by: Guenter Roeck <linux@...ck-us.net>

>  include/linux/mei_cl_bus.h       | 2 +-
>  6 files changed, 11 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
> index 50d617e7467e..54dddae46705 100644
> --- a/drivers/misc/mei/bus.c
> +++ b/drivers/misc/mei/bus.c
> @@ -879,17 +879,16 @@ static int mei_cl_device_remove(struct device *dev)
>  {
>  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
>  	struct mei_cl_driver *cldrv = to_mei_cl_driver(dev->driver);
> -	int ret = 0;
>  
>  	if (cldrv->remove)
> -		ret = cldrv->remove(cldev);
> +		cldrv->remove(cldev);
>  
>  	mei_cldev_unregister_callbacks(cldev);
>  
>  	mei_cl_bus_module_put(cldev);
>  	module_put(THIS_MODULE);
>  
> -	return ret;
> +	return 0;
>  }
>  
>  static ssize_t name_show(struct device *dev, struct device_attribute *a,
> diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
> index 9ae9669e46ea..6a455ebe4891 100644
> --- a/drivers/misc/mei/hdcp/mei_hdcp.c
> +++ b/drivers/misc/mei/hdcp/mei_hdcp.c
> @@ -845,16 +845,19 @@ static int mei_hdcp_probe(struct mei_cl_device *cldev,
>  	return ret;
>  }
>  
> -static int mei_hdcp_remove(struct mei_cl_device *cldev)
> +static void mei_hdcp_remove(struct mei_cl_device *cldev)
>  {
>  	struct i915_hdcp_comp_master *comp_master =
>  						mei_cldev_get_drvdata(cldev);
> +	int ret;
>  
>  	component_master_del(&cldev->dev, &mei_component_master_ops);
>  	kfree(comp_master);
>  	mei_cldev_set_drvdata(cldev, NULL);
>  
> -	return mei_cldev_disable(cldev);
> +	ret = mei_cldev_disable(cldev);
> +	if (ret)
> +		dev_warn(&cldev->dev, "mei_cldev_disable() failed\n")
>  }
>  
>  #define MEI_UUID_HDCP GUID_INIT(0xB638AB7E, 0x94E2, 0x4EA2, 0xA5, \
> diff --git a/drivers/nfc/microread/mei.c b/drivers/nfc/microread/mei.c
> index 5dad8847a9b3..8fa7771085eb 100644
> --- a/drivers/nfc/microread/mei.c
> +++ b/drivers/nfc/microread/mei.c
> @@ -44,15 +44,13 @@ static int microread_mei_probe(struct mei_cl_device *cldev,
>  	return 0;
>  }
>  
> -static int microread_mei_remove(struct mei_cl_device *cldev)
> +static void microread_mei_remove(struct mei_cl_device *cldev)
>  {
>  	struct nfc_mei_phy *phy = mei_cldev_get_drvdata(cldev);
>  
>  	microread_remove(phy->hdev);
>  
>  	nfc_mei_phy_free(phy);
> -
> -	return 0;
>  }
>  
>  static struct mei_cl_device_id microread_mei_tbl[] = {
> diff --git a/drivers/nfc/pn544/mei.c b/drivers/nfc/pn544/mei.c
> index 579bc599f545..5c10aac085a4 100644
> --- a/drivers/nfc/pn544/mei.c
> +++ b/drivers/nfc/pn544/mei.c
> @@ -42,7 +42,7 @@ static int pn544_mei_probe(struct mei_cl_device *cldev,
>  	return 0;
>  }
>  
> -static int pn544_mei_remove(struct mei_cl_device *cldev)
> +static void pn544_mei_remove(struct mei_cl_device *cldev)
>  {
>  	struct nfc_mei_phy *phy = mei_cldev_get_drvdata(cldev);
>  
> @@ -51,8 +51,6 @@ static int pn544_mei_remove(struct mei_cl_device *cldev)
>  	pn544_hci_remove(phy->hdev);
>  
>  	nfc_mei_phy_free(phy);
> -
> -	return 0;
>  }
>  
>  static struct mei_cl_device_id pn544_mei_tbl[] = {
> diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
> index 5391bf3e6b11..53165e49c298 100644
> --- a/drivers/watchdog/mei_wdt.c
> +++ b/drivers/watchdog/mei_wdt.c
> @@ -619,7 +619,7 @@ static int mei_wdt_probe(struct mei_cl_device *cldev,
>  	return ret;
>  }
>  
> -static int mei_wdt_remove(struct mei_cl_device *cldev)
> +static void mei_wdt_remove(struct mei_cl_device *cldev)
>  {
>  	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
>  
> @@ -636,8 +636,6 @@ static int mei_wdt_remove(struct mei_cl_device *cldev)
>  	dbgfs_unregister(wdt);
>  
>  	kfree(wdt);
> -
> -	return 0;
>  }
>  
>  #define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
> diff --git a/include/linux/mei_cl_bus.h b/include/linux/mei_cl_bus.h
> index 959ad7d850b4..07f5ef8fc456 100644
> --- a/include/linux/mei_cl_bus.h
> +++ b/include/linux/mei_cl_bus.h
> @@ -68,7 +68,7 @@ struct mei_cl_driver {
>  
>  	int (*probe)(struct mei_cl_device *cldev,
>  		     const struct mei_cl_device_id *id);
> -	int (*remove)(struct mei_cl_device *cldev);
> +	void (*remove)(struct mei_cl_device *cldev);
>  };
>  
>  int __mei_cldev_driver_register(struct mei_cl_driver *cldrv,
>