... otherwise two successive calls to qdev_unplug() (e.g. by an impatient
user) will effectively overwrite pbdev->release_timer, resulting in a
memory leak. We are effectively already processing the unplug.

If there is already a release_timer, the unplug will be performed after
the timeout.

Can be easily triggered by
(hmp) device_add virtio-mouse-pci,id=test
(hmp) stop
(hmp) device_del test
(hmp) device_del test

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/s390x/s390-pci-bus.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index 1349050838..f27c5852db 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -972,6 +972,9 @@ static void s390_pcihost_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     case ZPCI_FS_STANDBY:
         break;
     default:
+        if (pbdev->release_timer) {
+            return;
+        }
         s390_pci_generate_plug_event(HP_EVENT_DECONFIGURE_REQUEST,
                                      pbdev->fh, pbdev->fid);
         pbdev->release_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
-- 
2.17.2