On Mon, Feb 17 2025 at 21:24, Thomas Gleixner wrote:

quoted

One limitation
remains: querying the adjusted frequency of a PTP device (using
adjtime() with an empty modes field) is not supported for chardevs
opened without WRITE permissions, as the POSIX layer mandates WRITE
access for any adjtime operation.

That's a fixable problem, no?

Absolutely, but to be honest I wasn't sure about how to properly change
the access check in adjtime given it's a "generic" API. I ended up with
something along the lines of:

   if (tx->modes & ~(ADJ_NANO | ADJ_MICRO))
     /* require WRITE */

being that ADJ_NANO and ADJ_MICRO by themselves don't mean the clock will
be modified. So the modes field is not really "empty" per se and the check
becomes less self-explanatory.

But then maybe I'm overthinking it. If you think the above modes check is
the right way to go, I'll send a v4 (using the opportunity to add the
Reviewed-By and Acked-By tags from v2 I missed in v3 - I'm new to kernel
development, sorry).

Thanks,
W