System can not be rebooted due to hanged linux bridge deletion

[slava valyavskiy]

Detailed bug description:

 I have a network scheme represented below:

 eth2.555 --
            |--lnxbond0(active-backup bond iface) -- br-fake(linux bridge)
 eth2.666 --

 When I'm trying to shut down br-fake bridge(ifdown br-fake) '/etc/network/if-post-down.d/bridge' script hangs on 'brctl delbr br-fake' command.

 Meanwhile, kernel complains in log:
 <0>Jul 11 19:49:40 node-4 kernel: [ 837.904087] unregister_netdevice: waiting for br-fake to become free. Usage count = 1

Steps to reproduce:
 Create bond interface containing vlan devices and attach it into linux bridge(network template feature)
Expected results:
 Bridge can be removed.
Actual result:
  Bridge can not be removed.
Reproducibility:
 Always
Workaround:
 It's possible to remove 'br-fake' bridge if you stop lnxbond0 bond(ifdown lnxbond0) before that.
Impact:
 System can not be rebooted. It hangs on shutting down of 'br-fake' bridge.
Description of the environment:
 Operation system: Ubuntu
 Versions of components: Fuel 7.0

[slava valyavskiy (slava-val-al)]

I have found several similar issues where guys are suspecting that bugs in ipv6 & vlan protocols may be the reason of such behavior.
http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-07/msg09125.html

[slava valyavskiy (slava-val-al)]

All works fine if I'm attaching subinterfaces of different nics(eth2.555 & eth3.666) to the bond. So, network scheme looks like:

 eth2.555 --
            |--lnxbond0(active-backup bond iface) -- br-fake(linux bridge)
 eth3.666 --