The icmpv6 socket ist neither made nonblocking via O_NONBLOCK nor is recvfrom(2) passed MSG_DONTWAIT.
One cloud of course make the the fd nonblocking after retrieving it via ndp_get_eventfd() and
check -EAGAIN on ndp_callall_eventfd_handler(). Is that how it's supposed to work?
I saw the NetworkManager code ignore the return of ndp_callall_eventfd_handler() altogether.