linux-kernel - Re: [PATCH] acerhdf: fix resource reclaim in error path

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Date:	Wed, 7 Jul 2010 10:19:00 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Axel Lin <axel.lin@...il.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Peter Feuerer <peter@...e.net>,
	Matthew Garrett <mjg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Len Brown <len.brown@...el.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH] acerhdf: fix resource reclaim in error path

From: Axel Lin <axel.lin@...il.com>
Date: Wed, Jul 07, 2010 at 10:22:19AM +0800

Good, I like it. Go down for comments :)

> This patch fix resource reclaim in below cases:
> 1. acerhdf_register_platform() does not properly handle
>    platform_device_alloc() failure and platform_device_add() failure.
>    This patch adds error handling for acerhdf_register_platform().
> 2. acerhdf_register_platform() return err with acerhdf_dev == NULL.
>    as a result, acerhdf_unregister_platform() does not do resource
>    reclaim in acerhdf_init() error path.
>    This patch adds error handing for acerhdf_register_platform(),
>    thus correct the error handing path in acerhdf_init().
>    goto out_err instead of err_unreg if acerhdf_register_platform() fail.
> 3. platform_device_del() should be only used in error handling.
>    Current implementation missed a platform_device_put() in acerhdf_exit.
>    This patch fixes it by using platform_device_unregister() instead of
>    platform_device_del() in acerhdf_unregister_platform().
> 
> Signed-off-by: Axel Lin <axel.lin@...il.com>
> ---
>  drivers/platform/x86/acerhdf.c |   20 ++++++++++++++++----
>  1 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
> index 7b2384d..e938a86 100644
> --- a/drivers/platform/x86/acerhdf.c
> +++ b/drivers/platform/x86/acerhdf.c
> @@ -579,9 +579,21 @@ static int acerhdf_register_platform(void)
>  		return err;
>  
>  	acerhdf_dev = platform_device_alloc("acerhdf", -1);
> -	platform_device_add(acerhdf_dev);
> +	if (!acerhdf_dev) {
> +		err = -ENOMEM;
> +		goto err_device_alloc;
> +	}
> +	err = platform_device_add(acerhdf_dev);
> +	if (err)
> +		goto err_device_add;
>  
>  	return 0;
> +
> +err_device_add:
> +	platform_device_put(acerhdf_dev);
> +err_device_alloc:
> +	platform_driver_unregister(&acerhdf_driver);
> +	return err;
>  }
>  
>  static void acerhdf_unregister_platform(void)
> @@ -589,7 +601,7 @@ static void acerhdf_unregister_platform(void)
>  	if (!acerhdf_dev)
>  		return;

while you're at it, you can remove the above check since
platform_device_del() does that anyway and with your error checking,
acerhdf_dev won't be unitialized in this path.

>  
> -	platform_device_del(acerhdf_dev);
> +	platform_device_unregister(acerhdf_dev);
>  	platform_driver_unregister(&acerhdf_driver);
>  }
>  
> @@ -633,7 +645,7 @@ static int __init acerhdf_init(void)
>  
>  	err = acerhdf_register_platform();
>  	if (err)
> -		goto err_unreg;
> +		goto out_err;
>  
>  	err = acerhdf_register_thermal();
>  	if (err)
> @@ -646,7 +658,7 @@ err_unreg:
>  	acerhdf_unregister_platform();
>  
>  out_err:
> -	return -ENODEV;
> +	return err;
>  }
>  
>  static void __exit acerhdf_exit(void)
> -- 
> 1.5.4.3
> 
> 
> 

-- 
Regards/Gruss,
    Boris.
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