On Sat, Aug 07, 2021 at 07:22:59AM -0700, Richard Cochran wrote:
On Fri, Aug 06, 2021 at 06:15:29PM -0700, Vinicius Costa Gomes wrote:
int ptp_clock_unregister(struct ptp_clock *ptp) {
- if (ptp_vclock_in_use(ptp)) {
pr_err("ptp: virtual clock in use\n");return -EBUSY;- }
None of the drivers (that I looked) expect ptp_clock_unregister() to return an error.
So, what should we do?
- Fix all the drivers to return an error on module unloading (that's
usually the path ptp_clock_unregister() is called)? 2. Remove all the PTP virtual clocks when the physical clock is unregistered?
This:
- 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?
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