From: Maxim Levitsky <mlevi...@redhat.com>
Soon, a device removal might only happen on RCU callback execution.
This is okay for device-del which provides a DEVICE_DELETED event,
but not for the failure case of device-add. To avoid changing
monitor semantics, just drain all pending RCU callbacks on error.
Signed-off-by: Maxim Levitsky <mlevi...@redhat.com>
Suggested-by: Stefan Hajnoczi <stefa...@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
Message-Id: <20200913160259.32145-4-mlevi...@redhat.com>
[Don't use it in qmp_device_del. - Paolo]
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
qdev-monitor.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/qdev-monitor.c b/qdev-monitor.c
index e9b7228480..bcfb90a08f 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -803,6 +803,18 @@ void qmp_device_add(QDict *qdict, QObject **ret_data,
Error **errp)
return;
}
dev = qdev_device_add(opts, errp);
+
+ /*
+ * Drain all pending RCU callbacks. This is done because
+ * some bus related operations can delay a device removal
+ * (in this case this can happen if device is added and then
+ * removed due to a configuration error)
+ * to a RCU callback, but user might expect that this interface
+ * will finish its job completely once qmp command returns result
+ * to the user
+ */
+ drain_call_rcu();
+
if (!dev) {
qemu_opts_del(opts);
return;
--
2.26.2
