The way setting up CGroups for external helpers work, is: qemuExtDevicesHasDevice() is called first to determine whether there is a helper process running, the CGroup controller is created and then qemuExtDevicesSetupCgroup() is called to place helpers into the CGroup. But when one reads just qemuExtDevicesSetupCgroup() it's easy to miss this hidden logic. Therefore, add a warning at the beginning of the function. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_extdevice.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/qemu/qemu_extdevice.c b/src/qemu/qemu_extdevice.c index 47e97f3565..1c397972e4 100644 --- a/src/qemu/qemu_extdevice.c +++ b/src/qemu/qemu_extdevice.c @@ -331,6 +331,9 @@ qemuExtDevicesSetupCgroup(virQEMUDriver *driver, virDomainDef *def = vm->def; size_t i; + /* Don't forget to adjust qemuExtDevicesHasDevice() accordingly. + * Otherwise, this function might not be called at all. */ + if (qemuDBusSetupCgroup(driver, vm, cgroup) < 0) return -1; -- 2.39.1