Where is the code about DLM normal deadlock detection?

I found some problems when I was investigating dlm. According to the official document provided by redhat, dlm deadlock detection includes normal deadlock detection caused by loop waiting and conversion deadlock detection caused by lock conversion. I have found conversion deadlock detection from the source code of the linux kernel dlm , now I want to know where is the code for normal deadlock detection?

Finally, the dlm official document is :http://people.redhat.com/ccaulfie/docs/rhdlmbook.pdf