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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] cls_u32: use skb_copy_bits() to dereference data safely
Date: Wed, 02 Jun 2010 06:43:16 -0700 (PDT)
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From: jamal <hadi@cyberus.ca>
Date: Wed, 02 Jun 2010 09:36:37 -0400

> On Wed, 2010-06-02 at 21:14 +0800, Changli Gao wrote:
> 
> 
>> Maybe skb_header_pointer() is lighter.
> 
> A little worse than skb_copy_bits(). In any case, this change is going
> to hurt.

Umm, Jamal what are you talking about?

Using skb_header_pointer(), if the offset is in range, there is no
change from today other than a comparison.

If it is not in range, we use skb_copy_bits().  It's only for the
case where we have to fetch the value from the fragmented part
of the SKB.