cv_init(9) on FreeBSD
The text 52c5e90c37f0, as FreeBSD 15.1-RELEASE, FreeBSD 15.0-RELEASE, FreeBSD 14.5-RELEASE, FreeBSD 14.4-RELEASE, FreeBSD 14.3-RELEASE, FreeBSD 14.2-RELEASE, FreeBSD 14.1-RELEASE, FreeBSD 14.0-RELEASE shipped it.
kernel condition variable