linux-kernel - Re: [PATCH 1/2] zram: fix memory freeing in zram_meta

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Message-ID: <20151109003332.GA471@swordfish>
Date:	Mon, 9 Nov 2015 09:33:32 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Geliang Tang <geliangtang@....com>
Cc:	Minchan Kim <minchan@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] zram: fix memory freeing in zram_meta_alloc

On (11/08/15 23:32), Geliang Tang wrote:
> When meta->table is NULL, there is no need to vfree it.
> 

Hi,

So what's the benefit? It's ok to pass a NULL pointer to vfree(). Why
would we add another label? To avoid a valid call on error path?

	-ss

> Signed-off-by: Geliang Tang <geliangtang@....com>
> ---
>  drivers/block/zram/zram_drv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 81a557c..197a7ad 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -511,7 +511,7 @@ static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize)
>  	meta->table = vzalloc(num_pages * sizeof(*meta->table));
>  	if (!meta->table) {
>  		pr_err("Error allocating zram address table\n");
> -		goto out_error;
> +		goto out_free;
>  	}
>  
>  	meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM);
> @@ -524,6 +524,7 @@ static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize)
>  
>  out_error:
>  	vfree(meta->table);
> +out_free:
>  	kfree(meta);
>  	return NULL;
>  }
> -- 
> 2.5.0
> 
> 
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