Re: Races / crashes in shutdown of libvirtd daemon

On 4/27/20 5:54 PM, Daniel P. Berrangé wrote: And there is another one: https://bugzilla.redhat.com/show_bug.cgi?id=1895359 The problem is that when host is shutting down we get PrepareForShutdown() signal on dbus and spawn a thread that will eventually call qemuStateStop(). But before it gets a chance to run the main thread quits the event loop and calls qemuStateCleanup() freeing the qemu driver. After all this the dbus signal handling thread gets to run only to find qemu_driver=0x0 and thus crash. From the fact that the event loop quit I deduct that we were sent a SIGTERM which means there was no guest running otherwise we would inhibit the shutdown, so qemuStateStop() would be a NOP anyway. So maybe the fix for this particular case indeed is to check whether qemu_driver == 0x0. Anyway, I think your idea is sound. Michal