Re: [PATCH net-next RFC v2 2/3] ipv4: add support for light weight tunnel encap attributes

[Thomas Graf <tgraf@suug.ch>]

On 06/18/15 at 09:49pm, Roopa Prabhu wrote:
> From: Roopa Prabhu <roopa@cumulusnetworks.com>
> 
> Introduces two netlink attributes RTA_ENCAP_TYPE and
> RTA_ENCAP to support attaching encap information to ipv4 routes.
> 
> RTA_ENCAP is a nested attribute as suggested by Thomas
> (and also as Robert had it in his series). RTA_ENCAP
> netlink policy is declared by the light weight tunnel
> drivers that support this encap type.
> 
> fib code calls the following for each nexthop:
> 	- new route handler:
> 		lwt build state (that parses RTA_ENCAP and returns
> 	  	lwt state that lives in every fib_nh)
> 	- del dump hanlder:
> 		lwt release handler to release lwt state data
> 	- route dump hanlder:
> 		lwt dump encap to fill RTA_ENCAP data
> 	- during input route lookup
> 		sets dst->output to lwtunnel_output which
> 		in turn calls the corresponding lwt tunnel
> 		output function which applies the required
> 		encap and xmits the packet

Thanks for putting in the flag! I think introducing helpers for the
lwt work would help as it can centralize the required ifdef magic
and be defined as a static inline nop or macros so the core routing
code doesn't need to have ifdefs spread around.