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[PATCH v5 3/9] device_core: use drain_call_rcu in in hmp_device_del/qmp_
From: |
Maxim Levitsky |
Subject: |
[PATCH v5 3/9] device_core: use drain_call_rcu in in hmp_device_del/qmp_device_add |
Date: |
Sun, 13 Sep 2020 19:02:53 +0300 |
Soon, a device removal might only happen on RCU callback execution,
but to avoid chanding HMP semantics, just drain all pending RCU
callbacks
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Suggested-by: Stefan Hajnoczi <stefanha@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
qdev-monitor.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/qdev-monitor.c b/qdev-monitor.c
index e9b7228480..c66ba13780 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;
@@ -894,6 +906,16 @@ void qmp_device_del(const char *id, Error **errp)
}
qdev_unplug(dev, errp);
+
+ /*
+ * Drain all pending RCU callbacks. This is done because
+ * some bus related operations can delay a device removal
+ * 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();
}
}
--
2.26.2
- [PATCH v5 0/9] Fix scsi devices plug/unplug races w.r.t virtio-scsi iothread, Maxim Levitsky, 2020/09/13
- [PATCH v5 1/9] scsi/scsi_bus: switch search direction in scsi_device_find, Maxim Levitsky, 2020/09/13
- [PATCH v5 2/9] rcu: Implement drain_call_rcu, Maxim Levitsky, 2020/09/13
- [PATCH v5 3/9] device_core: use drain_call_rcu in in hmp_device_del/qmp_device_add,
Maxim Levitsky <=
- [PATCH v5 4/9] device-core: use RCU for list of childs of a bus, Maxim Levitsky, 2020/09/13
- [PATCH v5 5/9] device-core: use atomic_set on .realized property, Maxim Levitsky, 2020/09/13
- [PATCH v5 6/9] scsi/scsi-bus: scsi_device_find: don't return unrealized devices, Maxim Levitsky, 2020/09/13
- [PATCH v5 7/9] scsi/scsi_bus: Add scsi_device_get, Maxim Levitsky, 2020/09/13
- [PATCH v5 8/9] virtio-scsi: use scsi_device_get, Maxim Levitsky, 2020/09/13
- [PATCH v5 9/9] scsi/scsi_bus: fix races in REPORT LUNS, Maxim Levitsky, 2020/09/13