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[PATCH v7 07/13] device_core: use drain_call_rcu in in qmp_device_add
From: |
Maxim Levitsky |
Subject: |
[PATCH v7 07/13] device_core: use drain_call_rcu in in qmp_device_add |
Date: |
Tue, 6 Oct 2020 15:38:58 +0300 |
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 <mlevitsk@redhat.com>
Suggested-by: Stefan Hajnoczi <stefanha@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200913160259.32145-4-mlevitsk@redhat.com>
[Don't use it in qmp_device_del. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@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
- Re: [PATCH v7 02/13] qtest: Reintroduce qtest_qmp_receive, (continued)
[PATCH v7 03/13] qtest: switch users back to qtest_qmp_receive, Maxim Levitsky, 2020/10/06
[PATCH v7 04/13] qdev: add "check if address free" callback for buses, Maxim Levitsky, 2020/10/06
[PATCH v7 05/13] scsi: switch to bus->check_address, Maxim Levitsky, 2020/10/06
[PATCH v7 06/13] scsi/scsi_bus: switch search direction in scsi_device_find, Maxim Levitsky, 2020/10/06
[PATCH v7 07/13] device_core: use drain_call_rcu in in qmp_device_add,
Maxim Levitsky <=
[PATCH v7 08/13] device-core: use RCU for list of children of a bus, Maxim Levitsky, 2020/10/06
[PATCH v7 09/13] device-core: use atomic_set on .realized property, Maxim Levitsky, 2020/10/06
[PATCH v7 10/13] scsi/scsi-bus: scsi_device_find: don't return unrealized devices, Maxim Levitsky, 2020/10/06
[PATCH v7 11/13] scsi/scsi_bus: Add scsi_device_get, Maxim Levitsky, 2020/10/06
[PATCH v7 12/13] virtio-scsi: use scsi_device_get, Maxim Levitsky, 2020/10/06
[PATCH v7 13/13] scsi/scsi_bus: fix races in REPORT LUNS, Maxim Levitsky, 2020/10/06
Re: [PATCH v7 00/13] Fix scsi devices plug/unplug races w.r.t virtio-scsi iothread, no-reply, 2020/10/06