We use ifwait to monitor a bridged interface so we can add or remove it
to the bridge by bringing the associated service up or down. However,
bridge related netlink events can cause ifwait to incorrectly consider
the interface to have gone down. For example, nlmsg_type=RTM_DELLINK
with ifi_family=AF_BRIDGE, which is triggered by removing an interface
from a bridge, and does not indicate that the interface itself was
removed. Because a later RTM_NEWLINK will indicate that the link is still
up, ifwait will bring the service down and then up again, triggering
more netlink messages that keep ifwait in an infinite loop.
Fix it by checking specifically for RTM_NEWLINK and RTM_DELLINK messages
with ifi_family=AF_UNSPEC, which indicates an event related to the
interface itself.
15a886cf9a