[PATCH 07/10] qemu: exit thread synchronously in qemuDomainObjStopWorker

[Daniel P. Berrangé]

On Tue, Jul 14, 2020 at 12:32:58PM +0300, Nikolay Shirokovskiy wrote:
> The change won't hurt much current callers performance I guess and now we can
> use the function when we need to be sure of synchronous thread exit as well.

I can't remember the exact scenario, but I'm reasonably sure i tried
this approach when adding the event thread support and hit scenario
where this would deadlock.

> 
> Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
> ---
>  src/qemu/qemu_domain.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 2d9d822..18651d0 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -1571,6 +1571,7 @@ qemuDomainObjStopWorker(virDomainObjPtr dom)
>      qemuDomainObjPrivatePtr priv = dom->privateData;
>  
>      if (priv->eventThread) {
> +        virEventThreadClose(priv->eventThread);
>          g_object_unref(priv->eventThread);

IIRC, it was something like this unref does not always release the
last reference. 

>          priv->eventThread = NULL;

IOW, despite setting evnetThread to NULL, the thread may linger for
a short while longer in the background until any operations have
completed.


Regards,
Daniel
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