Hi Wolfgang,

fiddling with the CAN utils, I noticed the behaviour that rtcansend on
freshly registered but stopped devices simply blocks. And when you
meanwhile call rtcanconfig up on that device, rtcansend will continue to
block.

The reason is that during startup of CAN devices the tx-semaphore is
re-initialised while it is already set up during device registration.
Re-init on an already initialised rtdm_sem is, say, undefined.

So rtdm_sem should better only be initialised/destroyed by the drivers.
Trying to send on a shut down CAN device could be catched differently,
e.g. via the device state. This likely needs more thoughts, take it as a
note that $something should be done.

Jan