linux-kernel - Re: [PATCH] crc32: Don't reference unnecessary crc32 tables in single-bit mode

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Message-ID: <4F1A1927.7020206@xenotime.net>
Date:	Fri, 20 Jan 2012 17:47:19 -0800
From:	Randy Dunlap <rdunlap@...otime.net>
To:	djwong@...ibm.com
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] crc32: Don't reference unnecessary crc32 tables in	single-bit
 mode

On 01/20/2012 04:36 PM, Darrick J. Wong wrote:
> When compiling with single bit mode (CRC32_BIT=y) we shouldn't reference the
> crc32 tables, since they aren't built in single-bit mode.  Many thanks to Randy
> Dunlap for finding this bug:
> http://marc.info/?l=linux-kernel&m=132709702422141&w=2
> 
> This patch is against next-20120120.
> 
> Signed-off-by: Darrick J. Wong <djwong@...ibm.com>

Reported-by: Randy Dunlap <rdunlap@...otime.net>

Acked-by: Randy Dunlap <rdunlap@...otime.net>

Thanks.

> ---
> 
>  lib/crc32.c |   21 +++++++++++++++++++--
>  1 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/crc32.c b/lib/crc32.c
> index ebc5911..b0d278f 100644
> --- a/lib/crc32.c
> +++ b/lib/crc32.c
> @@ -174,16 +174,26 @@ static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
>  	return crc;
>  }
>  
> +#if CRC_LE_BITS == 1
> +u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
> +{
> +	return crc32_le_generic(crc, p, len, NULL, CRCPOLY_LE);
> +}
> +u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
> +{
> +	return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
> +}
> +#else
>  u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
>  {
>  	return crc32_le_generic(crc, p, len, crc32table_le, CRCPOLY_LE);
>  }
> -EXPORT_SYMBOL(crc32_le);
> -
>  u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
>  {
>  	return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE);
>  }
> +#endif
> +EXPORT_SYMBOL(crc32_le);
>  EXPORT_SYMBOL(__crc32c_le);
>  
>  /**
> @@ -233,10 +243,17 @@ static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
>  	return crc;
>  }
>  
> +#if CRC_LE_BITS == 1
> +u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
> +{
> +	return crc32_be_generic(crc, p, len, NULL, CRCPOLY_BE);
> +}
> +#else
>  u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
>  {
>  	return crc32_be_generic(crc, p, len, crc32table_be, CRCPOLY_BE);
>  }
> +#endif
>  EXPORT_SYMBOL(crc32_be);
>  
>  #ifdef CONFIG_CRC32_SELFTEST
> 
> --


-- 
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
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