[koverstreet]

Previously, we were checking for lock ordering violations. But a lock ordering violation isn't a deadlock, just a potential deadlock.

Checking for a lock ordering violation is simpler because you only have to look at data structures for the current thread - you're just looking at what other locks the current thread is holding.

To check for a deadlock you have to do a full DFS of threads blocked on locks held by other threads, looking for cycles. Quite a bit trickier, but it was well worth it :)

[tmulcahy]

Thanks for the explanation. Very interesting! I assume you only do the DFS when you detect a lock ordering violation? So if there is the potential for a deadlock you'll do extra work to make sure that you're actually deadlocked before aborting?