linux-kernel - Re: [PATCH] drivers/mfd: remove unneeded and dangerous clearing of clientdata

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Date:	Fri, 21 May 2010 00:52:10 +0200
From:	Samuel Ortiz <sameo@...ux.intel.com>
To:	Wolfram Sang <w.sang@...gutronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	Jean Delvare <khali@...ux-fr.org>, stable@...nel.org
Subject: Re: [PATCH] drivers/mfd: remove unneeded and dangerous clearing of
 clientdata

Hi Wolfgang,

On Mon, May 17, 2010 at 02:10:29PM +0200, Wolfram Sang wrote:
> Unlike real i2c-devices which get detached from the driver, dummy-devices get
> truly unregistered. So, there has never been a need to clear the clientdata
> because the device will go away anyhow. For the occasions fixed here, clearing
> clientdata was even dangerous as the structure was freed already.
Patch applied, many thanks.

Cheers,
Samuel.

> Signed-off-by: Wolfram Sang <w.sang@...gutronix.de>
> Cc: Jean Delvare <khali@...ux-fr.org>
> Cc: Samuel Ortiz <sameo@...ux.intel.com>
> Cc: stable@...nel.org
> ---
> 
> Note: While most of the other calls clearing clientdata became superfluous
> meanwhile and will be fixed later to remove redundancy, this is a seperate
> issue. It was wrong from the beginning and needs to be fixed as it can cause
> crashes. Hopefully, during this release-cycle, all other clearings of
> clientdata will be removed and we will never see the related confusion again.
> 
>  drivers/mfd/88pm860x-i2c.c |    1 -
>  drivers/mfd/max8925-i2c.c  |    2 --
>  2 files changed, 0 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mfd/88pm860x-i2c.c b/drivers/mfd/88pm860x-i2c.c
> index 4a6e718..e55f3d2 100644
> --- a/drivers/mfd/88pm860x-i2c.c
> +++ b/drivers/mfd/88pm860x-i2c.c
> @@ -200,7 +200,6 @@ static int __devexit pm860x_remove(struct i2c_client *client)
>  
>  	pm860x_device_exit(chip);
>  	i2c_unregister_device(chip->companion);
> -	i2c_set_clientdata(chip->companion, NULL);
>  	i2c_set_clientdata(chip->client, NULL);
>  	kfree(chip);
>  	return 0;
> diff --git a/drivers/mfd/max8925-i2c.c b/drivers/mfd/max8925-i2c.c
> index d9fd878..e73f3f5 100644
> --- a/drivers/mfd/max8925-i2c.c
> +++ b/drivers/mfd/max8925-i2c.c
> @@ -173,8 +173,6 @@ static int __devexit max8925_remove(struct i2c_client *client)
>  	max8925_device_exit(chip);
>  	i2c_unregister_device(chip->adc);
>  	i2c_unregister_device(chip->rtc);
> -	i2c_set_clientdata(chip->adc, NULL);
> -	i2c_set_clientdata(chip->rtc, NULL);
>  	i2c_set_clientdata(chip->i2c, NULL);
>  	kfree(chip);
>  	return 0;
> -- 
> 1.7.0
> 

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