Function guard

crates/openshell-vfio/src/bind.rs:326–330

()

    static VFIO_ID_REFCOUNT_TEST_LOCK: Mutex<()> = Mutex::new(());

    pub fn guard() -> MutexGuard<'static, ()> {
        VFIO_ID_REFCOUNT_TEST_LOCK
            .lock()
            .unwrap_or_else(PoisonError::into_inner)
    }

    /// Remove a specific vendor:device key from the global refcount map.
    /// Used by tests to clean up their own entries without disturbing