Re: [Qemu-devel] [PATCH 1/3] Unified Datagram Socket Transport

[Anton Ivanov]

[snip]

> > +    NetUnifiedState *s = (NetUnifiedState *) us;
> > +    L2TPV3TunnelParams *p = (L2TPV3TunnelParams *) s->params;
>
> How about embedding NetUnifiedState into this structure and keep using 
> NetL2TPV3State? Then:
>
> -  's' could be kept and lots of lines of changes could be saved here 
> and l2tpv3_verify_header()
> -  each transport could have their own type instead of using 
> NET_CLIENT_DRIVER_L2TPV3

That means each of them having their own read/write functions in each 
transport, destroy functions, etc.

I am trying to achieve exactly the opposite which across all transports 
should save more code. There should be nothing in a transport which 
leverages the common datagram processing backend except:

1. Init and parse arguments
2. Form Header
3. Verify Header

All the rest can be common for a large family of datagram based 
transports - L2TPv3, GRE, RAW (both full interface and just pulling a 
specific vlan out of it), etc.

It is trivial to do that for fixed size headers (as in the current 
patchset family). It is a bit more difficult to that for variable 
headers, but still datagram (GUE, Geneve, etc).

These may also add 4 - I/O to control plane, but it remains to be seen 
if that is needed.

This also makes any improvements to the backend - f.e. switching from 
send() to sendmmsg() automatically available for all transports.

What cannot be done is to shoehorn into this stream based. I believe we 
have only one of those - the original socket.c in tcp mode and we can 
leave it to stay that way and switch only the datagram mode to a better 
backend.

I am going through the other comments in the meantime to see if I missed 
something else and fixing the omissions.

A.

[snip]

--
Anton R. Ivanov

Cambridge Greys Limited, England and Wales company No 10273661
http://www.cambridgegreys.com/