- Better detect simple cycles of threads calling _lwp_wait and return
EDEADLK. Does not handle deeper cycles like t1 -> t2 -> t3 -> t1.
- If there are multiple threads in _lwp_wait, then make sure that
targeted waits take precedence over waits for any LWP to exit.
- When checking for deadlock, also count the number of zombies currently
in the process as potentially reapable. Whenever a zombie is murdered,
kick all waiters to make them check again for deadlock.
- Add more comments.
Also, while here:
- LOCK_ASSERT -> KASSERT in some places
- lwp_free: change boolean arguments to type 'bool'.
- proc_free: let lwp_free spin waiting for the last LWP to exit, there's
no reason to do it here.
fed1793605