[libvirt] [PATCHv2 1/2] qemu: Add missing lock of virDomainObj before calling virDomainUnref

[Eric Blake]

On 03/03/2011 02:10 PM, Laine Stump wrote:
> (Eric pointed out in IRC that I should be acquiring the domainobj lock
> prior to modifying obj->privateData->mon)
> 

> The solution is to have qemuMonitorFree lock the domain object right
> before unrefing it. Since the caller to qemuMonitorFree doesn't expect
> this lock to be held, if the refcount doesn't go all the way to 0,
> qemuMonitorFree must unlock it after the unref.
> ---
>  src/qemu/qemu_process.c |    8 ++++++--
>  1 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index c419c75..9084725 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -593,10 +593,14 @@ no_memory:
>  static void qemuProcessHandleMonitorDestroy(qemuMonitorPtr mon,
>                                              virDomainObjPtr vm)
>  {
> -    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    qemuDomainObjPrivatePtr priv;
> +
> +    virDomainObjLock(vm);
> +    priv = vm->privateData;
>      if (priv->mon == mon)
>          priv->mon = NULL;
> -    virDomainObjUnref(vm);
> +    if (virDomainObjUnref(vm) > 0)
> +        virDomainObjUnlock(vm);
>  }

ACK from me for following the rules in src/qemu/THREADS.txt, although
you may want to wait for danpb to weigh in.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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