Re: [1/1] connector/CBUS: new messaging subsystem. Revision number next.

Evgeniy Polyakov
2005-04-26T18:14:14Z

On Tue, 26 Apr 2005 22:10:26 +0400
Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:

> > > > There may not be the same work with different data.
> > > >
> > >
> > > Ugh, that really blows. Now every user of a particular message type
> > > has to coordinate efforts with other users of the same message type...
> > >
> > > Imability to "fire and forget" undermines usefulness of whole
> > > connector. How will you for example implement hotplug notification
> > > over connector? Have kobject_hotplug wait and block other instances?
> > > But wait on what?
> >
> > This is a simple load balancing schema.
> > Netlink messages may be dropped in socket queue when
> > they are bing delivered to userspace - this is the same -
> > if work queue can not be scheduled, message will be dropped,
> > but in this case userspace also can not be scheduled
> > and message will be dropped.
>
> Btw, I belive we see that it is reverse direction...
> So we have reverse load balancing schema here -
> exactly like userspace socket queueing.
> We basically can not sleep here - it will be DOS.

And yet another btw - netlink is unreliable protocol,
that is why there are seq and ack fields in connector's header -
connector's users must implement some check on top of
raw connector messages - it could be returned message with
timeout resending and so on.
I wrote it several times and it is in connector's documentation.

Evgeniy Polyakov

Only failure makes us experts. -- Theo de Raadt