Re: rtcan I/O hang bug with /proc/rtcan/rtcan0/registers

On 04/24/2012 08:47 PM, Andrew Tannenbaum wrote:
> I'm running
> 
> 	Linux 2.6.38.8
> 	Xenomai 2.6.0
> 	Atom N270 CPU
> 
> I'm talking to CAN with a PEAK PCI SJA1000 CAN adapter.
> 
> I have a control loop running at 200 Hz, and I use it to drive a motor
> and read an encoder using rtcan.  My code is based on the
> rtcansend/rtcanrecv examples.
> 
> I found a bug where my control loop was hanging, and I've isolated the
> problem so that it may be reproduced with Xenomai supplied tools,
> without using my own code.
> 
> The problem is:
> 
> When I have a loop that is sending CAN packets, if I read
> /proc/rtcan/rtcan0/registers at the same time, it causes the loop to
> hang.  The hang is in rt_dev_sendto.
> 
> To reproduce:
> 
> Configure the CAN controller
> 
> 	$ rtcanconfig rtcan0 --baudrate=1000000 start
> 
> Send packets, in this case, SYNC messages at 1000 Hz