Re: [PATCH v2 10/13] qemu: avoid deadlock in qemuDomainObjStopWorker

[Daniel Henrique Barboza]

On 7/23/20 7:14 AM, Nikolay Shirokovskiy wrote:

We are dropping the only reference here so that the event loop thread
is going to be exited synchronously. In order to avoid deadlocks we
need to unlock the VM so that any handler being called can finish
execution and thus even loop thread be finished too.

Signed-off-by: Nikolay Shirokovskiy <nshirokovs...@virtuozzo.com>
---

Reviewed-by: Daniel Henrique Barboza <danielhb...@gmail.com>

  src/qemu/qemu_domain.c | 18 ++++++++++++++----
  1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 5b22eb2..82b3d11 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1637,11 +1637,21 @@ void
  qemuDomainObjStopWorker(virDomainObjPtr dom)
  {
      qemuDomainObjPrivatePtr priv = dom->privateData;
+    virEventThread *eventThread;

- if (priv->eventThread) {

-        g_object_unref(priv->eventThread);
-        priv->eventThread = NULL;
-    }
+    if (!priv->eventThread)
+        return;
+
+    /*
+     * We are dropping the only reference here so that the event loop thread
+     * is going to be exited synchronously. In order to avoid deadlocks we
+     * need to unlock the VM so that any handler being called can finish
+     * execution and thus even loop thread be finished too.
+     */
+    eventThread = g_steal_pointer(&priv->eventThread);
+    virObjectUnlock(dom);
+    g_object_unref(eventThread);
+    virObjectLock(dom);
  }