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[Stable-8.2.3 09/87] system/qdev-monitor: move drain_call_rcu call under
From: |
Michael Tokarev |
Subject: |
[Stable-8.2.3 09/87] system/qdev-monitor: move drain_call_rcu call under if (!dev) in qmp_device_add() |
Date: |
Wed, 10 Apr 2024 10:21:42 +0300 |
From: Dmitrii Gavrilov <ds-gavr@yandex-team.ru>
Original goal of addition of drain_call_rcu to qmp_device_add was to cover
the failure case of qdev_device_add. It seems call of drain_call_rcu was
misplaced in 7bed89958bfbf40df what led to waiting for pending RCU callbacks
under happy path too. What led to overall performance degradation of
qmp_device_add.
In this patch call of drain_call_rcu moved under handling of failure of
qdev_device_add.
Signed-off-by: Dmitrii Gavrilov <ds-gavr@yandex-team.ru>
Message-ID: <20231103105602.90475-1-ds-gavr@yandex-team.ru>
Fixes: 7bed89958bf ("device_core: use drain_call_rcu in in qmp_device_add",
2020-10-12)
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 012b170173bcaa14b9bc26209e0813311ac78489)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index a13db763e5..874d65191c 100644
--- a/system/qdev-monitor.c
+++ b/system/qdev-monitor.c
@@ -858,19 +858,18 @@ 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) {
+ /*
+ * 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();
+
qemu_opts_del(opts);
return;
}
--
2.39.2
- [Stable-8.2.3 00/87] Patch Round-up for stable 8.2.3, freeze on 2024-04-20, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 01/87] Revert "configure: run plugin TCG tests again", Michael Tokarev, 2024/04/10
- [Stable-8.2.3 02/87] configure: run plugin TCG tests again, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 03/87] tcg/aarch64: Apple does not align __int128_t in even registers, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 05/87] gitlab: update FreeBSD Cirrus CI image to 13.3, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 04/87] linux-user: Remove pgb_dynamic alignment assertion, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 06/87] ui/cocoa: Fix window clipping on macOS 14, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 07/87] target/arm: Fix 32-bit SMOPA, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 08/87] hw/rtc/sun4v-rtc: Relicense to GPLv2-or-later, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 09/87] system/qdev-monitor: move drain_call_rcu call under if (!dev) in qmp_device_add(),
Michael Tokarev <=
- [Stable-8.2.3 10/87] hw/scsi/lsi53c895a: stop script on phase mismatch, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 11/87] hw/scsi/lsi53c895a: add timer to scripts processing, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 13/87] migration/rdma: Fix a memory issue for migration, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 12/87] make-release: switch to .xz format by default, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 15/87] e1000e: fix link state on resume, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 14/87] igb: fix link state on resume, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 16/87] Avoid unaligned fetch in ladr_match(), Michael Tokarev, 2024/04/10
- [Stable-8.2.3 17/87] xen: Drop out of coroutine context xen_invalidate_map_cache_entry, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 19/87] hw/nvme: fix invalid check on mcl, Michael Tokarev, 2024/04/10
- [Stable-8.2.3 18/87] hw/nvme: separate 'serial' property for VFs, Michael Tokarev, 2024/04/10