rand() is racy in multi-threaded programs?

[Andriy Gapon]

Specifically, concurrent "first" calls to rand().
There can be a moment when rand3_state is allocated but not completely set up
with initstate_r().
Is this a known / documented issue?
Should we try to do better?

P.S.
I am seeing this issue from time to time when running ztest program (from ZFS).
I guess that it uses rand() just because that's what OpenZFS did / does on
illumos and Linux.

P.P.S.
Just realized that the problem can be relatively recent.
https://svnweb.freebsd.org/base?view=revision&revision=357382

-- 
Andriy Gapon