What were you trying to do that didn't work?

Creating a POSIX message queue-based systemd socket unit that starts a service.

What is the impact of this issue to you?

It results in a hang on reboot or shutdown if the POSIX message queue still has messages in it when shutting down.

Please provide the package NVR for which the bug is seen:

systemd-252-46.el9_5.3

How reproducible is this bug?:

Given the right conditions it can be reproduced at will

Steps to reproduce

1. Create a systemd socket unit that allocates a POSIX message queue
2. Write a message to the message queue
3. Reboot the system

Expected results

The system reboots

Actual results

The reboot hangs