[libvirt] [PATCH 3/4] daemon: keep daemon until all hypervisors drivers are cleaned up

This fix SEGV with next backtrace (shortened a bit): 1 0x00007fd3a791b2e6 in virCondWait (c=<optimized out>, m=<optimized out>) at util/virthread.c:154 2 0x00007fd3a791bcb0 in virThreadPoolFree (pool=0x7fd38024ee00) at util/virthreadpool.c:266 3 0x00007fd38edaa00e in qemuStateCleanup () at qemu/qemu_driver.c:1116 4 0x00007fd3a79abfeb in virStateCleanup () at libvirt.c:808 5 0x00007fd3a85f2c9e in main (argc=<optimized out>, argv=<optimized out>) at libvirtd.c:1660 Thread 1 (Thread 0x7fd38722d700 (LWP 32256)): 0 0x00007fd3a7900910 in virClassIsDerivedFrom (klass=0xdfd36058d4853, parent=0x7fd3a8f394d0) at util/virobject.c:169 1 0x00007fd3a7900c4e in virObjectIsClass (anyobj=anyobj@entry=0x7fd3a8f2f850, klass=<optimized out>) at util/virobject.c:365 2 0x00007fd3a7900c74 in virObjectLock (anyobj=0x7fd3a8f2f850) at util/virobject.c:317 3 0x00007fd3a7a24d5d in virNetDaemonRemoveShutdownInhibition (dmn=0x7fd3a8f2f850) at rpc/virnetdaemon.c:547 4 0x00007fd38ed722cf in qemuProcessStop (driver=driver@entry=0x7fd380103810, vm=vm@entry=0x7fd38025b6d0, reason=reason@entry=VIR_DOMAIN_SHUTOFF_SHUTDOWN, asyncJob=asyncJob@entry=QEMU_ASYNC_JOB_NONE, flags=flags@entry=0) at qemu/qemu_process.c:5786 5 0x00007fd38edd9428 in processMonitorEOFEvent (vm=0x7fd38025b6d0, driver=0x7fd380103810) at qemu/qemu_driver.c:4588 6 qemuProcessEventHandler (data=<optimized out>, opaque=0x7fd380103810) at qemu/qemu_driver.c:4632 7 0x00007fd3a791bb55 in virThreadPoolWorker (opaque=opaque@entry=0x7fd3a8f1e4c0) at util/virthreadpool.c:145 This happens due to race on simultaneous finishing of libvirtd and qemu process. We need to keep daemon object until all hypervisor drivers are cleaned up. The other option is to take reference to daemon in every hypervisor driver but this will take more work and we really don't need to. Drivers cleanup procedure is synchronous thus let's just remove last reference to daemon after drivers cleanup. --- daemon/libvirtd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/daemon/libvirtd.c b/daemon/libvirtd.c index 7fac7b2..97a7587 100644 --- a/daemon/libvirtd.c +++ b/daemon/libvirtd.c @@ -1631,7 +1631,6 @@ int main(int argc, char **argv) { /* we need to keep servers references up to here so that above function will not cause servers cleanup which can deadlock */ - virObjectUnref(dmn); virObjectUnref(srv); virObjectUnref(srvAdm); virNetlinkShutdown(); @@ -1661,6 +1660,9 @@ int main(int argc, char **argv) { driversInitialized = false; virStateCleanup(); } + /* unref daemon only here as hypervisor drivers can + call shutdown inhibition functions on cleanup */ + virObjectUnref(dmn); return ret; } -- 1.8.3.1