A reentrant mutex will allow you to unlock it multiple times so long as you're on the same thread. That means if Thread A takes the lock then later some code on

A reentrant mutex will allow you to unlock it multiple times so long as you're on the same thread. That means if Thread A takes the lock then later some code on Thread A tries to take the lock again to get a connection to pass to Thread B you'll have the connection the mutex was protecting on two threads at the same time. The rust version of the mutex prevents this by making the data the mutex is protecting unable to be sent to other threads. That means you can only share the mutex which will block on Thread B when you try to take the lock, as expected.