[ovs-dev] [PATCH 01/16] User-Space MPLS actions and matches

Ben Pfaff blp at nicira.com
Tue Jan 22 23:49:42 UTC 2013

On Thu, Jan 17, 2013 at 02:26:06PM +0900, Simon Horman wrote:
> > On Tue, Jan 15, 2013 at 11:05:45PM -0800, Ben Pfaff wrote:
> > > parse_l3_onward() could use flow_innermost_dl_type() since that's what
> > > it's effectively calculating as 'dl_type' (maybe it should be
> > > 'inner_dl_type' or 'innermost_dl_type').
> I'm not so sure about this.
> flow_innermost_dl_type(), in its current incantation, is used to
> obtain the innermost dl_type of a struct flow. In other words,
> it reads flow->encap_dl_type.
> On the other hand, parse_l3_onward() may write flow->encap_dl_type
> and never reads it.

Before parse_l3_onward() gets called, flow->dl_type is set and
flow->encap_dl_type is 0, so 'dl_type' is initialized with the
innermost ethertype at that point.

After the first block in parse_l3_onward() runs, flow->encap_dl_type
may now be initialized to the inner ethertype and, if so, 'dl_type' is
updated to the same value.  So 'dl_type' is also initialized with the
innermost ethertype at that point too.

I think it's the same behavior, either way, so I'm not going to press
the point, but if you see a difference in behavior then please let me

(It now occurs to me that we should probably rename this function

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