linux-kernel - Re: [PATCH 3/4] backlight: lcd: call put_device if device

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Message-id: <006f01cefa1a$97ea4710$c7bed530$%han@samsung.com>
Date:	Mon, 16 Dec 2013 13:52:16 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	'Levente Kurusa' <levex@...ux.com>,
	'Andrew Morton' <akpm@...ux-foundation.org>
Cc:	'LKML' <linux-kernel@...r.kernel.org>,
	'Jean-Christophe Plagniol-Villard' <plagnioj@...osoft.com>,
	'Tomi Valkeinen' <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org, 'Jingoo Han' <jg1.han@...sung.com>
Subject: Re: [PATCH 3/4] backlight: lcd: call put_device if device_register
 fails

On Saturday, December 14, 2013 3:40 AM, Levente Kurusa wrote:
> 
> Currently we kfree the container of the device which failed to register.
> This is wrong as the last reference is not given up with a put_device
> call. Also, now that we have put_device() callen, we no longer need
> the kfree as the new_ld->dev.release function will take care of kfreeing
> the associated memory.
> 
> Signed-off-by: Levente Kurusa <levex@...ux.com>

(+cc Andrew Morton)

Acked-by: Jingoo Han <jg1.han@...sung.com>

It looks good.
According to the comment of device_register, put_device()
should be used, instead of directly freeing.

./drivers/base/core.c

 * NOTE: _Never_ directly free @dev after calling this function, even
 * if it returned an error! Always use put_device() to give up the
 * reference initialized in this function instead.
 */
int device_register(struct device *dev)
{
        device_initialize(dev);
        return device_add(dev);
}
EXPORT_SYMBOL_GPL(device_register);

Levente Kurusa,
By the way, don't send the same mails three times, without any
reason. It is the waste of traffic. :-(

Best regards,
Jingoo Han

> ---
>  drivers/video/backlight/lcd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
> index 93cf15e..7de847d 100644
> --- a/drivers/video/backlight/lcd.c
> +++ b/drivers/video/backlight/lcd.c
> @@ -228,7 +228,7 @@ struct lcd_device *lcd_device_register(const char *name, struct device *parent,
> 
>  	rc = device_register(&new_ld->dev);
>  	if (rc) {
> -		kfree(new_ld);
> +		put_device(&new_ld->dev);
>  		return ERR_PTR(rc);
>  	}
> 
> --
> 1.8.3.1

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