[systemd-devel] udev event vs kernel uevent ordering guarantees

[Ilya Dryomov]

Hello,

(resending - one has to subscribe to post)

What are udev event ordering guarantees?  Specifically, if I get three
kernel uevents with seqnums i, i+1 and i+2, is it guaranteed that udev
will deliver them to the udev monitor socket in the same (i.e., seqnum)
order?  I don't have any logs and the problem occurs very infrequently,
but what I'm seeing could be explained by udev delivering those three
events in i+1, i+2, i order.  Is that possible?

There doesn't seem to be much out there on this topic, other than
"udev: remove seqnum API and all assumptions about seqnums", but that's
about "udevadm settle" blocking forever.

Thanks,

                Ilya