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

[Lennart Poettering]

On Wed, 10.02.16 19:40, Ilya Dryomov (idryomov at gmail.com) wrote:

> 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?

udev only maintains order between child and parent nodes, but not
otherwise.

Nobody should subscribe to kernel uevents directly, except for udev
itself.

Lennart

-- 
Lennart Poettering, Red Hat