Re: [PATCH net-next] ipv4/fib: send RTM_DELROUTE notify when flush fib

Stephen Hemminger
2023-07-25T16:36:22Z

On Tue, 25 Jul 2023 16:20:59 +0800
Hangbin Liu <liuhangbin@gmail.com> wrote:

> On Mon, Jul 24, 2023 at 08:48:20AM -0700, Stephen Hemminger wrote:
> > On Mon, 24 Jul 2023 16:56:37 +0800
> > Hangbin Liu <liuhangbin@gmail.com> wrote:
> >
> > > The NetworkManager keeps a cache of the routes. Missing/Wrong events mean that
> > > the cache becomes inconsistent. The IPv4 will not send src route delete info
> > > if it's bond to other device. While IPv6 only modify the src route instead of
> > > delete it, and also no notify. So NetworkManager developers complained and
> > > hope to have a consistent and clear notification about route modify/delete.
> >
> > Read FRR they get it right. The routing daemons have to track kernel,
> > and the semantics have been worked out for years.
>
> Yes, normally the routing daemon need to track kernel. On the other hand,
> the kernel also need to make a clear feedback. The userspace developers may
> not know the kernel code very well. The unclear/inconsistent notification
> would make them confused.

Right, that should be addressed by clearer documentation of the semantics
and the rational.