[PATCH v5 05/18] qdev: unplug blocker for devices

[Jagannathan Raman <jag.raman@oracle.com>]

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
---
 include/hw/qdev-core.h |  5 +++++
 softmmu/qdev-monitor.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index eed2983072..67df5e0081 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -193,6 +193,7 @@ struct DeviceState {
     int instance_id_alias;
     int alias_required_for_version;
     ResettableState reset;
+    GSList *unplug_blockers;
 };
 
 struct DeviceListener {
@@ -433,6 +434,10 @@ typedef bool (QDevPutBusFunc)(BusState *bus, Error **errp);
 bool qdev_set_bus_cbs(QDevGetBusFunc *get_bus, QDevPutBusFunc *put_bus,
                       Error **errp);
 
+int qdev_add_unplug_blocker(DeviceState *dev, Error *reason, Error **errp);
+void qdev_del_unplug_blocker(DeviceState *dev, Error *reason);
+bool qdev_unplug_blocked(DeviceState *dev, Error **errp);
+
 /**
  * GpioPolarity: Polarity of a GPIO line
  *
diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index 7306074019..1a169f89a2 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -978,10 +978,45 @@ void qmp_device_del(const char *id, Error **errp)
             return;
         }
 
+        if (qdev_unplug_blocked(dev, errp)) {
+            return;
+        }
+
         qdev_unplug(dev, errp);
     }
 }
 
+int qdev_add_unplug_blocker(DeviceState *dev, Error *reason, Error **errp)
+{
+    ERRP_GUARD();
+
+    if (!migration_is_idle()) {
+        error_setg(errp, "migration is in progress");
+        return -EBUSY;
+    }
+
+    dev->unplug_blockers = g_slist_prepend(dev->unplug_blockers, reason);
+
+    return 0;
+}
+
+void qdev_del_unplug_blocker(DeviceState *dev, Error *reason)
+{
+    dev->unplug_blockers = g_slist_remove(dev->unplug_blockers, reason);
+}
+
+bool qdev_unplug_blocked(DeviceState *dev, Error **errp)
+{
+    ERRP_GUARD();
+
+    if (dev->unplug_blockers) {
+        error_propagate(errp, error_copy(dev->unplug_blockers->data));
+        return true;
+    }
+
+    return false;
+}
+
 void hmp_device_add(Monitor *mon, const QDict *qdict)
 {
     Error *err = NULL;
-- 
2.20.1