Re: [PATCH v2 1/2] can: add support for filtering own messages only

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 09.05.21 13:28, Erik Flodin wrote:
> On Thu, 6 May 2021 at 07:26, Oliver Hartkopp <socketcan@hartkopp.net> wrote:

>>>>    From what I understood your main requirement is to double check the
>>>> outgoing traffic whether is has been sent.
>>>
>>> What I would like to have is:
>>> 1. Be notified when a frame has been sent. I send (from user space) a
>>> single frame and wait until I get confirmation before sending the next
>>> to give other nodes on the bus a slot to start sending, even if their
>>> frames have ID with lower priority.
>>
>> o_O
>>
>> Sorry, but I have problems to get behind your use-case.
>>
>> 1. You are sending a frame
>> 2. You get a confirmation
>> 3. You are waiting some time (which is not written above), to give other
>> nodes a slot??
> 
> No explicit sleep is needed. The machine is sufficient slow so that
> just waiting for the confirmation before sending the next frame is
> enough. But if the frames are queued in the socket/device then the
> frames are sent back-to-back.

Ok, I feel I'm getting behind your requirement ...

You mainly want to throttle the outgoing traffic, to make sure that e.g. 
a specific CAN ID is not sent 'back-to'back' and might lead to a DoS 
situation on the wire?!?

Do you know about the Linux CAN queuing disciplines that might provide 
the solution to your question?

See:

http://rtime.felk.cvut.cz/can/

http://rtime.felk.cvut.cz/can/socketcan-qdisc-final.pdf


A four-slides-intro to the concept can be found here (slides 41ff):

https://wiki.automotivelinux.org/_media/agl-distro/agl2017-socketcan-print.pdf

Best,
Oliver

> 
>> 4. goto 1??
> 
> Yes.
> 
> // Erik
>