Upstream glibc has test coverage for POSIX condition variables but the testing has never observed the failure reported by customers in upstream bug #25847 (https://sourceware.org/bugzilla/show_bug.cgi?id=25847) where a wakeup signal is missed.

The test coverage for POSIX condition variables should be extended to show that the failure mode can be detected. This is a pre-requisite first step to resolving the issue and ensuring the issue stays fixed.

Resolution of the actual missed wakup is here: https://issues.redhat.com/browse/RHEL-2419

This issue is considered resolved if we develop a test case that we can submit upstream for inclusion, and use downstream in our testing for validation purposes. This issue applies equally to RHEL8 and RHEL10 which have the same POSIX condition variable implementation.