[Joker_vD]

> the unwinder has to take (or used to, things got better recently) a global lock to prevent races with dlclose

If someone from another thread decided to unload a library whose code is still being executed in this thread then this thread would normally crash anyhow, and do so irrecoverably, right?

[gpderetta]

well yes, but I think the mutex also protects some other global datastructures.

I think the mutex was mostly removed recently, by observing exactly what you mention: any race would be UB anyway.