[PATCH v2] qdev: Report an error for machine without HotplugHandler

[Akihiko Odaki <akihiko.odaki@daynix.com>]

The HotplugHandler of the machine will be used when the parent bus does
not exist, but the machine may not have one. Report an error in such a
case instead of aborting.

Fixes: 7716b8ca74 ("qdev: HotplugHandler: Add support for unplugging BUS-less devices")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
Changes in v2:
- Fixed indention.
- Link to v1: https://lore.kernel.org/r/20231202-bus-v1-1-f7540e3a8d62@daynix.com
---
 system/qdev-monitor.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index a13db763e5..5fe5d49c20 100644
--- a/system/qdev-monitor.c
+++ b/system/qdev-monitor.c
@@ -927,9 +927,16 @@ void qdev_unplug(DeviceState *dev, Error **errp)
     qdev_hot_removed = true;
 
     hotplug_ctrl = qdev_get_hotplug_handler(dev);
-    /* hotpluggable device MUST have HotplugHandler, if it doesn't
-     * then something is very wrong with it */
-    g_assert(hotplug_ctrl);
+    if (!hotplug_ctrl) {
+        /*
+         * hotpluggable bus MUST have HotplugHandler, if it doesn't
+         * then something is very wrong with it
+         */
+        assert(!dev->parent_bus);
+
+        error_setg(errp, "The machine does not support hotplugging for a device without parent bus");
+        return;
+    }
 
     /* If device supports async unplug just request it to be done,
      * otherwise just remove it synchronously */

---
base-commit: 4705fc0c8511d073bee4751c3c974aab2b10a970
change-id: 20231202-bus-75a454c5d959

Best regards,
-- 
Akihiko Odaki <akihiko.odaki@daynix.com>