Re: [PATCH net-next] bond: pass get_ts_info and SIOC[SG]HWTSTAMP ioctl to active device

[Hangbin Liu <liuhangbin@gmail.com>]

On Tue, Nov 30, 2021 at 07:19:56AM -0800, Jakub Kicinski wrote:
> On Tue, 30 Nov 2021 15:09:32 +0800 Hangbin Liu wrote:
> > We have VLAN PTP support(via get_ts_info) on kernel, and bond support(by
> > getting active interface via netlink message) on userspace tool linuxptp.
> > But there are always some users who want to use PTP with VLAN over bond,
> > which is not able to do with the current implementation.
> > 
> > This patch passed get_ts_info and SIOC[SG]HWTSTAMP ioctl to active device
> > with bond mode active-backup/tlb/alb. With this users could get kernel native
> > bond or VLAN over bond PTP support.
> > 
> > Test with ptp4l and it works with VLAN over bond after this patch:
> > ]# ptp4l -m -i bond0.23
> > ptp4l[53377.141]: selected /dev/ptp4 as PTP clock
> > ptp4l[53377.142]: port 1: INITIALIZING to LISTENING on INIT_COMPLETE
> > ptp4l[53377.143]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
> > ptp4l[53377.143]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
> > ptp4l[53384.127]: port 1: LISTENING to MASTER on ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES
> > ptp4l[53384.127]: selected local clock e41d2d.fffe.123db0 as best master
> > ptp4l[53384.127]: port 1: assuming the grand master role
> 
> Does the Ethernet spec say something about PTP over bond/LACP?

bond_option_active_slave_get_rcu() only supports bond mode active-backup/tlb/alb.
With LACP mode _no_ active interface returns and we will use software
timestamping.

But you remind me that we should return -EOPNOTSUPP when there is no real_dev
for bond_eth_ioctl(). I will send a fixup later.

> 
> What happens during failover? Presumably the user space daemon will
> start getting HW stamps based on a different PHC than it's disciplining?

linuxptp will switch to new active interface's PHC device when there is a
bonding failover by filtering netlink message on pure bond.

But for VLAN over bond I need to figure out how to get the bond failover
message on VLAN interface and update the new PHC device.

Thanks
Hangbin