Description of problem:

During system startup we sometimes experience a situation where python-ethtool
breaks while querying IP addresses of interfaces that are (not yet) properly
configured -- see bug 1467845.

From our logs we see that calling get_ipv4_addresses() ends with an exception: 

Dummy-2::ERROR::2017-08-23 11:23:05,571::GuestAgentLinux2::217::root::Error retrieving network interfaces.                                                                    
Traceback (most recent call last):         
  File "/usr/share/ovirt-guest-agent/GuestAgentLinux2.py", line 213, in ethtool_list_nics                                                                                     
    'inet': self._get_ipv4_addresses(devinfo),                                         
  File "/usr/share/ovirt-guest-agent/GuestAgentLinux2.py", line 189, in _get_ipv4_addresses                                                                                   
    for ip in dev.get_ipv4_addresses():    
RuntimeError: Could not open a NETLINK connection for eth0      

Correlating that to the content of journal it seems like a race between time
the interface is brought UP and time when IP is assigned to it:

Aug 23 11:23:05.126492 localhost.localdomain network[695]: Bringing up loopback interface:  [  OK  ]
Aug 23 11:23:05.340381 localhost.localdomain network[695]: Bringing up interface eth0:
Aug 23 11:23:05.366656 localhost.localdomain NetworkManager[595]: <info>  [1503476585.3659] device (eth0): link connected
Aug 23 11:23:07.209084 localhost.localdomain dhclient[845]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 (xid=0x29d1da05)
Aug 23 11:23:07.588767 localhost.localdomain dhclient[845]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x29d1da05)
Aug 23 11:23:07.591290 localhost.localdomain dhclient[845]: DHCPOFFER from 10.35.83.254
Aug 23 11:23:08.097425 localhost.localdomain dhclient[845]: DHCPACK from 10.35.83.254 (xid=0x29d1da05)

It is understandable that the IP cannot be retrieved yet. The real problem is
that from now on the python-ethtool module is in an inconsistent state and
every subsequent call to get_ipv4_addresses() ends with the following
exception:

Traceback (most recent call last):         
  File "/usr/share/ovirt-guest-agent/GuestAgentLinux2.py", line 213, in ethtool_list_nics                                                                                     
    'inet': self._get_ipv4_addresses(devinfo),                                         
  File "/usr/share/ovirt-guest-agent/GuestAgentLinux2.py", line 189, in _get_ipv4_addresses                                                                                   
    for ip in dev.get_ipv4_addresses():    
SystemError: error return without exception set      


Unfortunately I wasn't able to find a workflow how to reproduce the error in
simple environment. But it is happening for us systematically. Also, we cannot
reproduce the problem anymore with version 0.13 of python-ethtool.


Version-Release number of selected component (if applicable):

0.8-5.el7