Re: netlink - notify when the socket gets closed

[Patrick McHardy]

m m wrote:
> On Sat, Dec 6, 2008 at 3:58 PM, Patrick McHardy <kaber@xxxxxxxxx> wrote:
> > That doesn't make sense. When you use multicast, multiple applications
> > can be listening to the messages. If you really need state for a single
> > listener and exchange messages in both directions, it sounds like you
> > should use unicast.
> My user app register in kernel for a data. When there is a first
> application request,
> kernel module creates an internal record and ask DATA subsystem for a data,
> which are then passed to the user application.
>
> The data are then delivered to the application as they are comming from
> the DATA subsystem.
>
> When there's another application requesting the same data type, kernel module
> just increase reference count in the internal record, and multicast delivers
> data to the other app.
>
> Now when one of those applications end, kernel module just decrease
> the reference count in the internal record.
>
> When the other application ends, kernel module needs to release the internal
> record and ask the DATA subsystem to stop delivering data.
>
> Hope this make sense... I could do some ascii art next time if needed :)

Thats an unusual way to use netlink, but it sounds reasonable.

Adding a notifier for multicast unsubscriptions should be easy.
Nothing in the kernel needs it though, so you need to carry the
patch to do this yourself until you submit your module.
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