[libvirt] [PATCH v2 2/3] qemu: first wait all workers finish on state cleanup

[Nikolay Shirokovskiy]

This fix the crash [1]

This happens on race conditions of simultaneous exiting libvirtd and qemu process.
Let's just finish all workers that keep driver pointer before disposing
driver object or any of its members.

[1] crash backtrace: (bt is shortened a bit):

0  0x00007ffff7282f2b in virClassIsDerivedFrom (klass=0xdeadbeef, parent=0x55555581d650) at util/virobject.c:169
1  0x00007ffff72835fd in virObjectIsClass (anyobj=0x7fffd024f580, klass=0x55555581d650) at util/virobject.c:365
2  0x00007ffff7283498 in virObjectLock (anyobj=0x7fffd024f580) at util/virobject.c:317
3  0x00007ffff722f0a3 in virCloseCallbacksUnset (closeCallbacks=0x7fffd024f580, vm=0x7fffd0194db0,
    cb=0x7fffdf1af765 <qemuProcessAutoDestroy>) at util/virclosecallbacks.c:164
4  0x00007fffdf1afa7b in qemuProcessAutoDestroyRemove (driver=0x7fffd00f3a60, vm=0x7fffd0194db0)
    at qemu/qemu_process.c:6365
5  0x00007fffdf1adff1 in qemuProcessStop (driver=0x7fffd00f3a60, vm=0x7fffd0194db0,
    reason=VIR_DOMAIN_SHUTOFF_CRASHED, asyncJob=QEMU_ASYNC_JOB_NONE, flags=0) at qemu/qemu_process.c:5877
6  0x00007fffdf1f711c in processMonitorEOFEvent (driver=0x7fffd00f3a60, vm=0x7fffd0194db0)
    at qemu/qemu_driver.c:4545
7  0x00007fffdf1f7313 in qemuProcessEventHandler (data=0x555555832710, opaque=0x7fffd00f3a60)
    at qemu/qemu_driver.c:4589
8  0x00007ffff72a84c4 in virThreadPoolWorker (opaque=0x555555805da0) at util/virthreadpool.c:167

Thread 1 (Thread 0x7ffff7fb1880 (LWP 494472)):
1  0x00007ffff72a7898 in virCondWait (c=0x7fffd01c21f8, m=0x7fffd01c21a0) at util/virthread.c:154
2  0x00007ffff72a8a22 in virThreadPoolFree (pool=0x7fffd01c2160) at util/virthreadpool.c:290
3  0x00007fffdf1edd44 in qemuStateCleanup () at qemu/qemu_driver.c:1102
4  0x00007ffff736570a in virStateCleanup () at libvirt.c:807
5  0x000055555556f991 in main (argc=1, argv=0x7fffffffe458) at libvirtd.c:1660
---
 src/qemu/qemu_driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 12ddbc0..58753ea 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1068,6 +1068,7 @@ qemuStateCleanup(void)
     if (!qemu_driver)
         return -1;
 
+    virThreadPoolFree(qemu_driver->workerPool);
     virNWFilterUnRegisterCallbackDriver(&qemuCallbackDriver);
     virObjectUnref(qemu_driver->config);
     virObjectUnref(qemu_driver->hostdevMgr);
@@ -1099,7 +1100,6 @@ qemuStateCleanup(void)
     virLockManagerPluginUnref(qemu_driver->lockManager);
 
     virMutexDestroy(&qemu_driver->lock);
-    virThreadPoolFree(qemu_driver->workerPool);
     VIR_FREE(qemu_driver);
 
     return 0;
-- 
1.8.3.1