libvirt/libvirt-qemu_migration_params-Avoid-deadlock-in-qemuMigrationParamsReset.patch

From 0022c9aef2ecf60e9091e6df57e56065b14b67c5 Mon Sep 17 00:00:00 2001
Message-Id: <0022c9aef2ecf60e9091e6df57e56065b14b67c5@dist-git>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Thu, 28 Jul 2022 15:35:45 +0200
Subject: [PATCH] qemu_migration_params: Avoid deadlock in
 qemuMigrationParamsReset

In my recent comnmit v8.5.0-188-gc47f1abb81 I accidentally moved
qemuMigrationParamsResetTLS after qemuDomainObjEnterMonitorAsync not
noticing qemuMigrationParamsResetTLS will try to enter the monitor
again. The second call will time out and return with a domain object
locked. But we're still in monitor section and the object should be
unlocked which means qemuDomainObjExitMonitor will deadlock trying to
lock it again.

Fixes: c47f1abb81194461377a0c608a7ecd87f9ce9146
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
(cherry picked from commit 8cb19a9b9a56ab6ebefc1f913c545e0bb86d4364)

https://bugzilla.redhat.com/show_bug.cgi?id=2107892

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_migration_params.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_migration_params.c b/src/qemu/qemu_migration_params.c
index 4a824ff5e1..4766d16e64 100644
--- a/src/qemu/qemu_migration_params.c
+++ b/src/qemu/qemu_migration_params.c
@@ -1291,6 +1291,7 @@ qemuMigrationParamsReset(virQEMUDriver *driver,
 {
     virErrorPtr err;
     g_autoptr(virBitmap) clearCaps = NULL;
+    int rc;
 
     virErrorPreserveLast(&err);
 
@@ -1305,11 +1306,16 @@ qemuMigrationParamsReset(virQEMUDriver *driver,
 
     clearCaps = virBitmapNew(0);
 
-    if (qemuMigrationParamsApplyCaps(vm, clearCaps) == 0 &&
-        qemuMigrationParamsApplyValues(vm, origParams, false) == 0)
-        qemuMigrationParamsResetTLS(driver, vm, asyncJob, origParams, apiFlags);
+    rc = 0;
+    if (qemuMigrationParamsApplyCaps(vm, clearCaps) < 0 ||
+        qemuMigrationParamsApplyValues(vm, origParams, false) < 0)
+        rc = -1;
 
     qemuDomainObjExitMonitor(vm);
+    if (rc < 0)
+        goto cleanup;
+
+    qemuMigrationParamsResetTLS(driver, vm, asyncJob, origParams, apiFlags);
 
  cleanup:
     virErrorRestore(&err);
-- 
2.35.1