Re: [PATCH net-next] net, sched: add clsact qdisc

On 07.01.2016 12:58, Daniel Borkmann wrote:

On 01/07/2016 11:09 AM, Hannes Frederic Sowa wrote:

quoted

Hi Daniel and Alexei,

On 07.01.2016 04:53, Alexei Starovoitov wrote:

quoted

On Wed, Jan 06, 2016 at 02:00:56AM +0100, Daniel Borkmann wrote:

quoted

I decided to extend the sch_ingress module with clsact functionality so
that commonly used code can be reused, the module is being aliased with
sch_clsact so that it can be auto-loaded properly. Alternative would
have been
to add a flag when initializing ingress to alter its behaviour plus
aliasing
to a different name (as it's more than just ingress). However, the
first would
end up, based on the flag, choosing the new/old behaviour by calling
different
function implementations to handle each anyway, the latter would
require to
register ingress qdisc once again under different alias. So, this
really begs
to provide a minimal, cleaner approach to have Qdisc_ops and
Qdisc_class_ops
by its own that share callbacks used by both.

...

quoted

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

we've been going back and forth on the design and this final approach
presented seems to be the best, since pros outweigh the cons.

Acked-by: Alexei Starovoitov <ast@kernel.org>

One question:

With the advance in lockless qdiscs by John Fastabend, is it possible
to push the handle_egress hook further down into sched layer?

Idea was that this is done before we pick txq as stated. F.e., could also
be that we end up not having enqueue handler, thus moving this further down
(not sure if there's a good place?), might make it all more scattered resp.
complex to cover all parts.

My understanding is that using redirects and something like 
ifb/imq-alike could already solve some of those problems while not 
adding yet another handler to the stack?

Bye,
Hannes