Re: [PATCH] Fix wrong checksum calculation on 64-bit MIPS

[David Miller <davem@davemloft.net>]

From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Wed, 24 Jan 2007 15:43:34 +0900 (JST)

> The commit 8e3d8433d8c22ca6c42cba4a67d300c39aae7822 ([NET]: MIPS
> checksum annotations and cleanups) broke 64-bit MIPS.
> 
> The problem is the commit replaces some unsigned long with __be32.  On
> 64bit MIPS, a __be32 (i.e. unsigned int) value is represented as a
> sign-extented 32-bit value in a 64-bit argument register.  So the
> address 192.168.0.1 (0xc0a80001) is passed as 0xffffffffc0a80001 to
> csum_tcpudp_nofold() but the asm code in the function expects
> 0x00000000c0a80001, therefore it returns a wrong checksum.  Explicit
> cast to unsigned long is needed to drop high 32bit.
> 
> Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

Al, let me know if you want this fixed differently.
Thanks.