title: How to use __sync_fetch_and_add for a Linux userspace program on beagleboard/gumstix
body: <p>I am looking to use the __sync_fetch_and_xxx functions for thread safe shared memory access on my Linux application with a beagleboard and gumstix. I can't seem to find the correct header to include. Are these functions only available for kernel development?</p>
  
  <p>Thanks</p>