Here is a list of all related documentation pages:

Caveats
Contexts	It is possible that libusbx may be used simultaneously from two independent libraries linked into the same executable
Synchronous and asynchronous device I/O
Packets and overflows
Multi-threaded applications and asynchronous I/O	Libusbx is a thread-safe library, but extra considerations must be applied to applications which interact with libusbx from multiple threads