[libvirt] [PATCH v2 0/4] Fix deadlock in nwfilter code

Daniel P. Berrange berrange at redhat.com
Tue Jan 28 10:02:13 UTC 2014


On Mon, Jan 27, 2014 at 03:23:29PM -0500, Stefan Berger wrote:
> On 01/27/2014 12:18 PM, Daniel P. Berrange wrote:
> >Since we introduced fine grained locking into the QEMU driver so
> >that VM start can run in parallel, we appear to have caused a
> >race with the nwfilter code. In particular since we no longer
> >hold the global QEMU driver lock for the duration of VM startup
> >we have a lock ordering flaw. This results in deadlock when
> >nwfilter operations happen in parallel with VM startup. This
> >also affects the LXC driver.
> >
> >This patch series attempts to address the problem
> >
> >   https://bugzilla.redhat.com/show_bug.cgi?id=929412
> >
> >the removal of the windows thread impl isn't strictly required,
> >I just didn't want to waste time creating a read/write lock impl
> >for Windows threads.
> >
> >See also this callgraph
> >
> >   http://berrange.fedorapeople.org/nwfilter.ps
> 
> What tool do you use to render this? Ghostview only shows me part of
> the content.

evince renders the whole thing nicely.

Daniel
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