Re: [dpdk-dev] [PATCH] mbuf: fix tunnel flags check

["Zhang, Helin" <helin.zhang@intel.com>]

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Wednesday, July 15, 2015 5:13 PM
> To: Zhang, Helin
> Cc: olivier.matz@6wind.com; dev@dpdk.org
> Subject: Re: [PATCH] mbuf: fix tunnel flags check
> 
> 2015-07-15 23:57, Zhang, Helin:
> > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > A packet is tunnelled if the tunnel type is identified or if it has an inner part.
> > >
> > > Fix also a typo in RTE_PTYPE_INNER_L3_MASK.
> > >
> > > Fixes: f295a00a2b44 ("mbuf: add definitions of unified packet
> > > types")
> > >
> > > Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
> |...]
> > >  /* Check if it is a tunneling packet */  -#define
> > > RTE_ETH_IS_TUNNEL_PKT(ptype) ((ptype) & RTE_PTYPE_TUNNEL_MASK)
> > > +#define RTE_ETH_IS_TUNNEL_PKT(ptype) ((ptype) &
> > > +(RTE_PTYPE_TUNNEL_MASK | \  RTE_PTYPE_INNER_L2_MASK | \
> > > +RTE_PTYPE_INNER_L3_MASK | \
> > > + RTE_PTYPE_INNER_L4_MASK))
> >
> > Could you help to explain more of why here?
> > My understanding is that if an inner one can be recognized, there must be a
> tunnel type there.
> 
> Not always.
> It was my comment in mlx4 patch:
> 	http://dpdk.org/ml/archives/dev/2015-July/021702.html
> Currently we can know that mlx4 has detected a tunnel but don't know which
> one.
I'd suggest to do more in mlx4 driver, rather than adding more checks in this macro.
If it can detect the inner l2/l3 type, the driver should tell it is a tunneled packet.
If it cannot know which tunnel it is, I'd suggest to add one more tunnel type of
RTE_PTYPE_TUNNEL_UNKNOWN.
Two reasons:
- PMD should tell enough info to high level caller or application. It should be clear enough.
- Adding more checks in those macro results in more cpu cycles for other NICs to check
the packet types.

Regards,
Helin