linux-kernel - Re: [PATCH 2/2] udf: reduce stack usage of udf_get

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Date:	Wed, 19 Nov 2008 16:54:18 +0100
From:	Jan Kara <jack@...e.cz>
To:	Marcin Slusarz <marcin.slusarz@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] udf: reduce stack usage of udf_get_filename

On Sun 16-11-08 19:02:45, Marcin Slusarz wrote:
> Allocate strings with kmalloc.
> 
> Checkstack output:
> Before: udf_get_filename:          600
> After:  udf_get_filename:          136
> 
> Signed-off-by: Marcin Slusarz <marcin.slusarz@...il.com>
> Cc: Jan Kara <jack@...e.cz>
  Both patches look fine. Thanks Martin. I've merged them to my UDF tree.

										Honza

> ---
>  fs/udf/unicode.c |   41 +++++++++++++++++++++++++----------------
>  1 files changed, 25 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
> index 9fdf8c9..a3bbdbd 100644
> --- a/fs/udf/unicode.c
> +++ b/fs/udf/unicode.c
> @@ -324,34 +324,43 @@ try_again:
>  int udf_get_filename(struct super_block *sb, uint8_t *sname, uint8_t *dname,
>  		     int flen)
>  {
> -	struct ustr filename, unifilename;
> -	int len;
> +	struct ustr *filename, *unifilename;
> +	int len = 0;
>  
> -	if (udf_build_ustr_exact(&unifilename, sname, flen))
> +	filename = kmalloc(sizeof(struct ustr), GFP_NOFS);
> +	if (!filename)
>  		return 0;
>  
> +	unifilename = kmalloc(sizeof(struct ustr), GFP_NOFS);
> +	if (!unifilename)
> +		goto out1;
> +
> +	if (udf_build_ustr_exact(unifilename, sname, flen))
> +		goto out2;
> +
>  	if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
> -		if (!udf_CS0toUTF8(&filename, &unifilename)) {
> +		if (!udf_CS0toUTF8(filename, unifilename)) {
>  			udf_debug("Failed in udf_get_filename: sname = %s\n",
>  				  sname);
> -			return 0;
> +			goto out2;
>  		}
>  	} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
> -		if (!udf_CS0toNLS(UDF_SB(sb)->s_nls_map, &filename,
> -				  &unifilename)) {
> +		if (!udf_CS0toNLS(UDF_SB(sb)->s_nls_map, filename,
> +				  unifilename)) {
>  			udf_debug("Failed in udf_get_filename: sname = %s\n",
>  				  sname);
> -			return 0;
> +			goto out2;
>  		}
>  	} else
> -		return 0;
> -
> -	len = udf_translate_to_linux(dname, filename.u_name, filename.u_len,
> -				     unifilename.u_name, unifilename.u_len);
> -	if (len)
> -		return len;
> -
> -	return 0;
> +		goto out2;
> +
> +	len = udf_translate_to_linux(dname, filename->u_name, filename->u_len,
> +				     unifilename->u_name, unifilename->u_len);
> +out2:
> +	kfree(unifilename);
> +out1:
> +	kfree(filename);
> +	return len;
>  }
>  
>  int udf_put_filename(struct super_block *sb, const uint8_t *sname,
> -- 
> 1.5.6.4
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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