Re: [PATCH] lib/checksum.c: optimize do_csum a bit

From: David Miller <davem@davemloft.net>
Date: Thu, 07 Jul 2011 04:36:25 -0700 (PDT)

From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 7 Jul 2011 12:32:45 +0100

quoted

On 07/07/11 12:29, David Miller wrote:

quoted

From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 7 Jul 2011 12:18:49 +0100

quoted

Reduce the number of variables modified by the loop in do_csum() by 1,
which seems like a good idea.  On Nios II (a RISC CPU with 3-operand
instruction set) it reduces the loop from 7 to 6 instructions, including
the conditional branch.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>

I think you'll overshoot past the end of the buffer when there are
trailing bytes to handle.

The whole reason we need the count variable is to handle those
kinds of cases.

I don't think it does.  That's what the & ~3 was for.

Aha, yes that indeed makes it work.

I've applied this to net-next-2.6, thanks.