On Sat, Aug 07, 2021 at 05:43:32PM +0300, Vladimir Oltean wrote:

quoted

 3. Let the vclocks hold a reference to the underlying posix dynamic clock.

So even if the vclock holds a reference to the underlying POSIX clock,
that won't prevent the hardware driver from unbinding, and further
gettime() calls on the vclock from faulting, will it?

Oh, your are right.  The vclocks call the real PHC clock's methods
directly, not through the posix dynamic clock layer.

What about:

4. Create a device link with the vclock being a consumer and the parent
   clock being a supplier? This way, ptp_vclock_unregister() is
   automatically called whenever (and before) ptp_clock_unregister() is.

https://www.kernel.org/doc/html/latest/driver-api/device_link.html

Sounds promising.

Thanks,
Richard