Re: Upgraded multiple systems to systemd 249.3 and all had eth1 not started / configured

[Lennart Poettering <lennart@xxxxxxxxxxxxxx>]

On Mo, 16.08.21 17:31, Amish (anon.amish@xxxxxxxxx) wrote:

>
> On 16/08/21 5:25 pm, Lennart Poettering wrote:
> > On Mo, 16.08.21 16:09, Amish (anon.amish@xxxxxxxxx) wrote:
> >
> > > Some old scripts that we have expect interface names starting with eth. But
> > > those names are not predictable.
> > >
> > > So to get predictable names starting with eth*, first I temporarily rename
> > > all interface with tmpeth*. This is done via udev rules.
> > >
> > > SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="XX:XX:XX:XX:XX:XX",
> > > NAME="tmpeth0"
> > > SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="XX:XX:XX:XX:XX:YY",
> > > NAME="tmpeth1"
> > > SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="XX:XX:XX:XX:XX:ZZ",
> > > NAME="tmpeth2"
> > >
> > > Then I have a small service (script) which runs before network-pre.target to
> > > convert these names back to eth*
> > >
> > > #search for network interface with name starting from "tmpeth" and rename
> > > them to "eth"
> > > /usr/bin/find /sys/class/net -maxdepth 1 -name "tmpeth[0-9]" -type l -printf
> > > "%f\n" | while read tmpiface; do /usr/bin/ip link set dev "$tmpiface" name
> > > "$(echo $tmpiface | sed s/tmpeth/eth/)"; done
> > >
> > > This ensures that I have predictable names starting with eth*. And it is
> > > working fine from 2-3 years. Even with current issue, name assignment is
> > > working fine.
> > This cannot work and is necesarily race. Stay out of the ethXYZ
> > namespace, that's the kernel's namespace. Pick any other names,
> > i.e. "foobar0", "foobar1", but otherwise you just have a racy racy
> > mess, because the kernel might take the name whenever it pleases.
>
> No I dont think this is race. Because my script runs after Udev has finished
> assigning the interfaces names.

device probing can take any time it wants. there isn't a point in time
where everything is probed.

Lennart

--
Lennart Poettering, Berlin