Hi again, Sorry for being slow to reply... On Mon, 10 May 2021 at 14:28, Oliver Hartkopp <socketcan@xxxxxxxxxxxx> wrote: > > > > On 09.05.21 13:28, Erik Flodin wrote: > > On Thu, 6 May 2021 at 07:26, Oliver Hartkopp <socketcan@xxxxxxxxxxxx> 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?!? Yes, so after a frame has been sent, I want to leave the bus idle long enough to give another device on the bus that has something in its TX queue an opportunity to send. > Do you know about the Linux CAN queuing disciplines that might provide > the solution to your question? Yes, I came across that when I started my journey in CAN-land, but unfortunately the kernel I have to use doesn't have support for traffic control. That's when I started using RECV_OWN_MSGS which worked until I added filters and here we are now :) If I get the chance to update the kernel (which would have to happen before my proposed patch could be used anyway) I should perhaps try to get tc support instead. That would simplify my application at least. Thanks for your time! Best regards, // Erik
