linux-kernel - Re: [PATCH 3/4] parisc: checksum: Remove folding from csum

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Date: Thu, 22 Feb 2024 08:04:35 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Charlie Jenkins <charlie@...osinc.com>
Cc: "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
	Helge Deller <deller@....de>, Arnd Bergmann <arnd@...db.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH 3/4] parisc: checksum: Remove folding from csum_partial

On Wed, Feb 21, 2024 at 06:37:13PM -0800, Charlie Jenkins wrote:
> The parisc implementation of csum_partial previously folded the result
> into 16 bits instead of returning all 32 bits and letting consumers like
> ip_compute_csum do the folding. Since ip_compute_csum no longer depends
> on this requirement, remove the folding so that the parisc
> implementation operates the same as other architectures.
> 
> Signed-off-by: Charlie Jenkins <charlie@...osinc.com>

Tested-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  arch/parisc/lib/checksum.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/parisc/lib/checksum.c b/arch/parisc/lib/checksum.c
> index 05f5ca4b2f96..eaa660491e24 100644
> --- a/arch/parisc/lib/checksum.c
> +++ b/arch/parisc/lib/checksum.c
> @@ -95,14 +95,11 @@ unsigned int do_csum(const unsigned char *buff, int len)
>  /*
>   * computes a partial checksum, e.g. for TCP/UDP fragments
>   */
> -/*
> - * why bother folding?
> - */
>  __wsum csum_partial(const void *buff, int len, __wsum sum)
>  {
>  	unsigned int result = do_csum(buff, len);
>  	addc(result, sum);
> -	return (__force __wsum)from32to16(result);
> +	return (__force __wsum)result;
>  }
>  
>  EXPORT_SYMBOL(csum_partial);
> 
> -- 
> 2.34.1
>