[libvirt] [PATCH] Fix deadlock in QEMU close callback APIs
Daniel P. Berrange
berrange at redhat.com
Thu Feb 28 13:38:17 UTC 2013
On Thu, Feb 28, 2013 at 01:33:31PM +0000, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange at redhat.com>
>
> There is a lock ordering problem in the QEMU close callback
> APIs.
>
> When starting a guest we have a lock on the VM. We then
> set a autodestroy callback, which acquires a lock on the
> close callbacks.
>
> When running auto-destroy, we obtain a lock on the close
> callbacks, then run each callbacks - which obtains a lock
> on the VM.
>
> This causes deadlock if anyone tries to start a VM, while
> autodestroy is taking place.
>
> The fix is to do autodestroy in 2 phases. First obtain
> all the callbacks and remove them from the list under
> the close callback lock. Then invoke each callback
> from outside the close callback lock.
>
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
> src/qemu/qemu_conf.c | 106 ++++++++++++++++++++++++++++++++++++++++++--------
> src/util/virnetlink.c | 5 ++-
> 2 files changed, 92 insertions(+), 19 deletions(-)
>
> diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c
> index 0b36fdc..8b47ede 100644
> --- a/src/util/virnetlink.c
> +++ b/src/util/virnetlink.c
> @@ -335,8 +335,9 @@ virNetlinkEventCallback(int watch,
> if (length == 0)
> return;
> if (length < 0) {
> - virReportSystemError(errno,
> - "%s", _("nl_recv returned with error"));
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("nl_recv returned with error: %s"),
> + nl_geterror(length));
> return;
> }
This chunk wasn't supposed to be here. I've sent it as a separate fix
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
More information about the libvir-list
mailing list