On Fri, Dec 13 2019, Michal Sojka wrote:
> Hi Oliver,
>
> On Fri, Dec 13 2019, Oliver Hartkopp wrote:
>> Did you do anything weird (e.g. pulling the USB plug on the run) to get
>> this problem?
>
> No, I just connected it to an ECU and started sending messages on the
> bus. The behaviour was like if the messages were not acknowledged, i.e.,
> initially, candump on my laptop showed the messages sent, but after some
> time (perhaps after TX buffers were full), candump stopped. I was also
> not able to see any messages sent by the ECU (both before and after I
> sent my messages).
>
> When I used the same ECU and all the wiring with peak_usb, communication
> with the ECU was without any problems.
I did more investigation - I was able to fix the problem by adding a
terminator resistor to the bus.
However, the problem can be easily reproduced by the following sequence
of commands, when the USB2CAN is not connected to any bus:
ip link set can0 up txqueuelen 1000 type can bitrate 500000
candump can0
cangen -v -g 50 can0
when candump stops printing the messages, run:
ip link set down dev can0
and the warnings appear in dmesg. I was also trying this with latest
mainline kernel, which includes the fix for use-after-free, and the
warnings are still there.
-Michal
