On Fri, Apr 25, 2014 at 08:12:13PM +0200, Tom Gundersen wrote: > On Fri, Apr 11, 2014 at 2:45 AM, Djalal Harouni <tix...@opendz.org> wrote: > > nspawn and the container child use eventfd to wait and notify each other > > that they are ready so the container setup can be completed. > > > > However in its current form the wait/notify event ignore errors that > > may especially affect the child (container). > > > > On errors the child will jump to the "child_fail" label and terminate > > with _exit(EXIT_FAILURE) without notifying the parent. Since the eventfd > > is created without the "EFD_NONBLOCK" flag, this leaves the parent > > blocking on the eventfd_read() call. > > > > To fix this without adding extra overheads, we keep the eventfd logic > > and improve it by adding: > > > > * States of the parent and child setups: > > SETUP_INIT, SETUP_SUCCEEDED and SETUP_FAILED > > > > * In the child if the setup succeeded we notify parent by writing a > > SETUP_SUCCEEDED value, otherwise we make sure to write a SETUP_FAILED > > before the _exit(). This prevents the parent from waiting on an event > > that will never come. > > > > * In parent read the child setup state, if SETUP_SUCCEEDED continue, > > otherwise jump to "check_container_status" label, get the container > > child status and release resources. > > > > https://bugs.freedesktop.org/show_bug.cgi?id=76193 > > > > Reported-by: Tobias Hunger <tobias.hun...@gmail.com> > > Looks good to me. Thanks!
Just to inform that I've came up with an RFC patch that will make systemd nspawn robust to different signal/terminate races using eventfd. So please hold on on this one! I'll clean it and post it later this day. > Cheers, > > Tom -- Djalal Harouni http://opendz.org _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
