linux-kernel - Re: [PATCH v2 1/2] mei: bus: simplify mei_cl_device

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Message-ID: <YCD0qdaOG1pb+gPM@kroah.com>
Date:   Mon, 8 Feb 2021 09:22:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Uwe Kleine-König <uwe@...ine-koenig.org>
Cc:     Tomas Winkler <tomas.winkler@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mei: bus: simplify mei_cl_device_remove()

On Mon, Feb 08, 2021 at 08:37:04AM +0100, Uwe Kleine-König wrote:
> The driver core only calls a bus' remove function when there is actually
> a driver and a device. So drop the needless check and assign cldrv earlier.
> 
> (Side note: The check for cldev being non-NULL is broken anyhow, because
> to_mei_cl_device() is a wrapper around container_of() for a member that is
> not the first one. So cldev only can become NULL if dev is (void *)0xc
> (for archs with 32 bit pointers) or (void *)0x18 (for archs with 64 bit
> pointers).)
> 
> Signed-off-by: Uwe Kleine-König <uwe@...ine-koenig.org>
> ---
>  drivers/misc/mei/bus.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
> index 2907db260fba..50d617e7467e 100644
> --- a/drivers/misc/mei/bus.c
> +++ b/drivers/misc/mei/bus.c
> @@ -878,13 +878,9 @@ static int mei_cl_device_probe(struct device *dev)
>  static int mei_cl_device_remove(struct device *dev)
>  {
>  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
> -	struct mei_cl_driver *cldrv;
> +	struct mei_cl_driver *cldrv = to_mei_cl_driver(dev->driver);
>  	int ret = 0;
>  
> -	if (!cldev || !dev->driver)

Yes, anyone checking that the results of a container_of() wrapper can be
NULL is not checking anything at all :)

thanks for the cleanups, I'll go queue them up.

greg k-h