Re: [PATCH 1/1] Introduce notification events for routing changes

[David Miller <davem@davemloft.net>]

From: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Date: Tue, 27 Nov 2012 21:27:25 +0100

> The netfilter MASQUERADE target does not handle the case when the routing
> changes and the source address of existing connections become invalid.
> The problem can be solved if routing modifications create events to which
> the MASQUERADE target can subscribe and then delete the affected
> connections.
> 
> The patch adds the required event support for IPv4/IPv6.
> 
> Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

What part of the information are you actually interested in?

Because just saying that a route is added or removed using fib_info X
doesn't tell you a whole lot.

fib_info only encapsulates the information that can be shared heaving
with many ipv4 routes.  It doesn't include the TOS or other aspects
stored in the fib_alias part.  I can only guess that you did not
use fib_alias in order to avoid having to export that structure to
the callers, as it is currently private to net/ipv4/

The notifier doesn't seem to distinguish between adds or removes
either, making it less useful in another way.

I would suggest passing a super-structure that gives the event type:

	struct route_changed_info {
		enum {
			add,
			remove,
		} event_type;
		void *data;
	};

or something like that.

Can you also show us exactly how this will be used?  Otherwise we
have to guess.