> -----Original Message-----
> From: Miroslav Lichvar <mlich...@redhat.com>
> Sent: Tuesday, May 9, 2023 5:31 AM
> To: Zaborowski, Andrew <andrew.zaborow...@intel.com>
> Cc: linuxptp-devel@lists.sourceforge.net
> Subject: Re: [Linuxptp-devel] [PATCH] sk: Reset timestamping mode on exit, use
> locks
>
> On Tue, May 09, 2023 at 02:02:05PM +0200, Andrew Zaborowski wrote:
> > Per https://www.kernel.org/doc/Documentation/networking/timestamping.txt
> > section 3:
> > "User space is responsible to ensure that multiple processes don't interfere
> > with each other and that the settings are reset."
> >
> > Add locking for the interface's HW timestamping mode to ensure that in a
> > setup with multiple ptp4l sessions sharing interfaces the sessions don't
> > overwrite each other's timestamping mode and that there is one session
> > responsible for resetting the mode on exit.
>
> Is this intended to catch misconfigurations where different ptp4l
> instances are setting incompatible RX filters?
>
> If I understand the solution correctly, stopping ptp4l would break
> another ptp4l instance if they don't share the same filesystem (e.g.
> containers), or a different program is using HW timestamping (e.g.
> chronyd).
>
Yea this only prevents ptp4l instances on the same file system from
interfering. I think we'd have to extend the "locking" to kernel if we wanted
to protect anything more complex, but I'm not sure how useful that would be in
practice.
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