Package: ifupdown
Version: 0.8.8
Severity: important
Hello
I have been having a problem where my network devices are not being configured
properly on boot. I suspect that my problems are caused in a fundamental
oversight
in the /etc/init.d/networking init script, though I'm not sure.
/etc/init.d/networking calls "udevadm settle" to determine when device drivers
are
loaded and network devices exist. However, that's not what "udevadm settle"
does.
"udevadm settle" returns before drivers have finished loading and before
devices
exist. As a result, it is possible for ifup to try and start network interfaces
on devices which don't exist yet.
I don't know if ifup itself may have some internal checking to make sure that
devices actually exist. If it does, than this checking is insufficient. If it
does not, then the situation is even worse than I suspected.
In my particular case, I have a bridge interface with eth0 and wlan0 members. I
find it common that the wlan0 interface has not finished loading the driver
when the bridge attempts to start. I have several "pre-up" commands required
for
my setup, and they fail because the devices onto which the commands rely don't
yet exist (iw or ethtool as examples).
The solution to this problem is that the init script must wait for these
network
devices to exist. Before they exist, it does not seem appropriate for ifup to
be
called.
It is notable that in my particular case, ifquery simply returns the name of my
bridge interface, br0, and not the member interfaces (eth0 and wlan0, since
they
have no normal config stanzas). Thus, ifquery will probably need to know about
these interfaces for the init script to wait for them.
One possibility is that I should add a config like this, but this might not be
a great idea for all types of special interface configs (LACP bundles come to
mind):
auto eth0
iface eth0 inet manual
Alternatively, a new configuration parameter indicating a device dependency,
such
as "waitdev wlan0" might be appropriate.
I don't know what the right solution is here. Feedback would be apreciated.
For now, as a workaround, I can do something horrible like this in my bridge
interface config:
pre-up while ! [ -e /sys/class/net/wlan0 ] ; do echo "dev wlan0 not
ready!" ; sleep 0.25 ; done
Please advise
-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 4.3.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages ifupdown depends on:
ii adduser 3.113+nmu3
ii init-system-helpers 1.25
ii iproute2 4.3.0-1
ii libc6 2.21-6
ii lsb-base 9.20160110
Versions of packages ifupdown recommends:
ii isc-dhcp-client [dhcp-client] 4.3.3-5
Versions of packages ifupdown suggests:
pn ppp <none>
pn rdnssd <none>
-- debconf-show failed
