linux-kernel - Re: [PATCH v2 3/3] backlight: lp855x: remove goto err_sysfs and goto err

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Message-Id: <20120816113119.85222ba7.akpm@linux-foundation.org>
Date:	Thu, 16 Aug 2012 11:31:19 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Jingoo Han <jg1.han@...sung.com>
Cc:	"'LKML'" <linux-kernel@...r.kernel.org>,
	"'Richard Purdie'" <rpurdie@...ys.net>,
	"'Milo(Woogyom) Kim'" <milo.kim@...com>
Subject: Re: [PATCH v2 3/3] backlight: lp855x: remove goto err_sysfs and
 goto err_dev

On Tue, 07 Aug 2012 18:25:44 +0900
Jingoo Han <jg1.han@...sung.com> wrote:

> This patch removes goto err_sysfs and goto err_dev, which makes code
> a bit smaller.
> 
> ...
>
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -272,29 +272,25 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>  	if (ret) {
>  		dev_err(lp->dev, "i2c communication err: %d", ret);
>  		if (mode == REGISTER_BASED)
> -			goto err_dev;
> +			return ret;
>  	}
>  
>  	ret = lp855x_backlight_register(lp);
>  	if (ret) {
>  		dev_err(lp->dev,
>  			"failed to register backlight. err: %d\n", ret);
> -		goto err_dev;
> +		return ret;
>  	}
>  
>  	ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
>  	if (ret) {
>  		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
> -		goto err_sysfs;
> +		lp855x_backlight_unregister(lp);
> +		return ret;
>  	}
>  
>  	backlight_update_status(lp->bl);
>  	return 0;
> -
> -err_sysfs:
> -	lp855x_backlight_unregister(lp);
> -err_dev:
> -	return ret;
>  }
>  
>  static int __devexit lp855x_remove(struct i2c_client *cl)

err, no.  We've learned from hard experience that having multiple return
points from a non-trivial function easily leads to resource leaks and
missed unlocks.  For this reason, kernel code frequently uses the "goto
out" technique, providing a single site where deallocation and
unlocking occurs.


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