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Date: Thu, 13 Oct 2016 23:04:04 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Olivier MATZ <olivier.matz@6wind.com>
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On Thu, Oct 13, 2016 at 04:52:25PM +0200, Olivier MATZ wrote:
> >In the "else" clause, the ip header is still in the mbuf, right?
> >Why do you have to access it the way like:
> >
> >	ip_version = *rte_pktmbuf_mtod_offset(m, uint8_t *,
> >		m->l2_len) >> 4;
> >
> >Why can't you just use
> >
> >	iph = rte_pktmbuf_mtod_offset(m, struct ipv4_hdr *, m->l2_len);
> >	iph->version_ihl ....;
> 
> AFAIK, there is no requirement that each network header has to be contiguous
> in a mbuf segment.
> 
> Of course, a split in the middle of a network header probably never
> happens... but we never knows, as it is not forbidden. I think the code
> should be robust enough to avoid accesses to wrong addresses.

One more question is do you have any case to trigger the "else" clause?

	--yliu