f47b91148a
There is a possibility that qemu driver frees by unreferencing its closeCallbacks pointer as it has the only reference to the object, while in fact not all users of CloseCallbacks called thier virCloseCallbacksUnset. Backtrace is the following: Thread #1: 0 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 1 in virCondWait (c=<optimized out>, m=<optimized out>) at util/virthread.c:154 2 in virThreadPoolFree (pool=0x7f0810110b50) at util/virthreadpool.c:266 3 in qemuStateCleanup () at qemu/qemu_driver.c:1116 4 in virStateCleanup () at libvirt.c:808 5 in main (argc=<optimized out>, argv=<optimized out>) at libvirtd.c:1660 Thread #2: 0 in virClassIsDerivedFrom (klass=0xdeadbeef, parent=0x7f0837c694d0) at util/virobject.c:169 1 in virObjectIsClass (anyobj=anyobj@entry=0x7f08101d4760, klass=<optimized out>) at util/virobject.c:365 2 in virObjectLock (anyobj=0x7f08101d4760) at util/virobject.c:317 3 in virCloseCallbacksUnset (closeCallbacks=0x7f08101d4760, vm=vm@entry=0x7f08101d47b0, cb=cb@entry=0x7f081d078fc0 <qemuProcessAutoDestroy>) at util/virclosecallbacks.c:163 4 in qemuProcessAutoDestroyRemove (driver=driver@entry=0x7f081018be50, vm=vm@entry=0x7f08101d47b0) at qemu/qemu_process.c:6368 5 in qemuProcessStop (driver=driver@entry=0x7f081018be50, vm=vm@entry=0x7f08101d47b0, reason=reason@entry=VIR_DOMAIN_SHUTOFF_SHUTDOWN, asyncJob=asyncJob@entry=QEMU_ASYNC_JOB_NONE, flags=flags@entry=0) at qemu/qemu_process.c:5854 6 in processMonitorEOFEvent (vm=0x7f08101d47b0, driver=0x7f081018be50) at qemu/qemu_driver.c:4585 7 qemuProcessEventHandler (data=<optimized out>, opaque=0x7f081018be50) at qemu/qemu_driver.c:4629 8 in virThreadPoolWorker (opaque=opaque@entry=0x7f0837c4f820) at util/virthreadpool.c:145 9 in virThreadHelper (data=<optimized out>) at util/virthread.c:206 10 in start_thread () from /lib64/libpthread.so.0 Let's reference CloseCallbacks object in virCloseCallbacksSet and unreference in virCloseCallbacksUnset. Signed-off-by: Maxim Nestratov <mnestratov@virtuozzo.com>
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>