[libvirt] [PATCH] qemu: Call qemuSetupHostdevCGroup later during hotplug

[Daniel P. Berrange]

On Thu, Nov 14, 2013 at 03:04:13PM +0100, Jiri Denemark wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1025108
> 
> So far qemuSetupHostdevCGroup was called very early during hotplug, even
> before we knew the device we were about to hotplug was actually
> available. By calling the function later, we make sure QEMU won't be
> allowed to access devices used by other domains.
> 
> Another important effect of this change is that hopluging USB devices
> specified by vendor and product (but not by their USB address) works
> again. This was broken since v1.0.5-171-g7d763ac, when the call to
> qemuFindHostdevUSBDevice was moved after the call to
> qemuSetupHostdevCGroup, which then used an uninitialized USB address.
> 
> Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
> ---
>  src/qemu/qemu_hotplug.c | 36 +++++++++++++++++++++++++++---------
>  1 file changed, 27 insertions(+), 9 deletions(-)

I won't nack the patch for this, but wanted to point out that we should
expand the qemuhotplugtest.c file to use an LD_PRELOAD to mock out the
cgroups filesystem. Then we can validate that the cgroups setup is being
done correctly for each hotplug operation we test.

Daniel
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