I use diplay driver 195.62 at gtx260.
The program was hang with exception error, when clEnqueueWriteImage was accessed from multi threads with the same sommand_queue at the same time.(of course, different cl_mem object)
OpenCL specification says
“OpenCL API calls that are thread-safe allow an application to call these functions in multiple host threads without having to implement mutual exclusion across these host threads.”