Message ID | 1408441305-11044-3-git-send-email-arei.gonglei@huawei.com |
---|---|
State | New |
Headers | show |
On Tue, Aug 19, 2014 at 7:41 PM, <arei.gonglei@huawei.com> wrote: > From: Gonglei <arei.gonglei@huawei.com> > > At present, the local variable local_err is reused at multi-places, > Which will cause resource leak in some scenarios. > The problem isn't really the local_err reusage. It's the fact that this function doesn't have partial cleanup implemented (the dc->unrealize call you add here is needed but not in original code at all). Doing a fuller audit of the function, it seems to have outgrown the simplistic if (!local_err) approach to error handling. I think the goto-fallthrough system might be a cleaner alternative. Perhaps finish the fn with: dev->realized = value; return; post_realize_fail: if (dc->unrealize) { dc->unrealize(dev, NULL); } fail: if (local_err != NULL) { error_propagate(errp, local_err); return; } } Then goto the appropriate error label as local_err population is detected as each relevant point. Regards, Peter > Example: > > 1. Assuming that "dc->realize(dev, &local_err)" execute successful > and local_err == NULL; > 2. Executing device hotplug in hotplug_handler_plug(), but failed > (It is prone to occur). Then local_err != NULL; > 3. error_propagate(errp, local_err) and return. But the resources > which been allocated in dc->realize() will be leaked. > Simple backtrace: > dc->realize() > |->device_realize > |->pci_qdev_init() > |->do_pci_register_device() > |->etc. > > To avoid the resource leak, using some different local error variables. > For different error conditions, release the corresponding resources. > > Signed-off-by: Gonglei <arei.gonglei@huawei.com> > --- > hw/core/qdev.c | 75 +++++++++++++++++++++++++++++++++++----------------------- > 1 file changed, 46 insertions(+), 29 deletions(-) > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c > index 3e7085e..b3a463b 100644 > --- a/hw/core/qdev.c > +++ b/hw/core/qdev.c > @@ -839,41 +839,58 @@ static void device_set_realized(Object *obj, bool value, Error **errp) > dc->realize(dev, &local_err); > } > > - if (dev->parent_bus && dev->parent_bus->hotplug_handler && > - local_err == NULL) { > - hotplug_handler_plug(dev->parent_bus->hotplug_handler, > - dev, &local_err); > - } else if (local_err == NULL && > - object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) { > - HotplugHandler *hotplug_ctrl; > - MachineState *machine = MACHINE(qdev_get_machine()); > - MachineClass *mc = MACHINE_GET_CLASS(machine); > - > - if (mc->get_hotplug_handler) { > - hotplug_ctrl = mc->get_hotplug_handler(machine, dev); > - if (hotplug_ctrl) { > - hotplug_handler_plug(hotplug_ctrl, dev, &local_err); > + if (local_err == NULL) { > + Error *hotplug_err = NULL; > + > + if (dev->parent_bus && dev->parent_bus->hotplug_handler) { > + hotplug_handler_plug(dev->parent_bus->hotplug_handler, > + dev, &hotplug_err); > + } else if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) { > + HotplugHandler *hotplug_ctrl; > + MachineState *machine = MACHINE(qdev_get_machine()); > + MachineClass *mc = MACHINE_GET_CLASS(machine); > + > + if (mc->get_hotplug_handler) { > + hotplug_ctrl = mc->get_hotplug_handler(machine, dev); > + if (hotplug_ctrl) { > + hotplug_handler_plug(hotplug_ctrl, dev, &hotplug_err); > + } > } > } > - } > > - if (qdev_get_vmsd(dev) && local_err == NULL) { > - vmstate_register_with_alias_id(dev, -1, qdev_get_vmsd(dev), dev, > - dev->instance_id_alias, > - dev->alias_required_for_version); > - } > - if (local_err == NULL) { > - QLIST_FOREACH(bus, &dev->child_bus, sibling) { > - object_property_set_bool(OBJECT(bus), true, "realized", > - &local_err); > - if (local_err != NULL) { > - break; > + if (hotplug_err == NULL) { > + Error *err = NULL; > + if (qdev_get_vmsd(dev)) { > + vmstate_register_with_alias_id(dev, -1, qdev_get_vmsd(dev), > + dev, dev->instance_id_alias, > + dev->alias_required_for_version); > } > + > + QLIST_FOREACH(bus, &dev->child_bus, sibling) { > + object_property_set_bool(OBJECT(bus), true, "realized", > + &err); > + if (err != NULL) { > + if (qdev_get_vmsd(dev)) { > + vmstate_unregister(dev, qdev_get_vmsd(dev), dev); > + } > + > + break; > + } > + } > + > + if (dev->hotplugged && err == NULL) { > + device_reset(dev); > + } > + error_free(err); > + } else { > + if (dc->unrealize) { > + dc->unrealize(dev, NULL); > + } > + > + error_propagate(errp, hotplug_err); > + return; > } > } > - if (dev->hotplugged && local_err == NULL) { > - device_reset(dev); > - } > dev->pending_deleted_event = false; > } else if (!value && dev->realized) { > QLIST_FOREACH(bus, &dev->child_bus, sibling) { > -- > 1.7.12.4 > > >
> -----Original Message----- > From: peter.crosthwaite@petalogix.com > On Tue, Aug 19, 2014 at 7:41 PM, <arei.gonglei@huawei.com> wrote: > > From: Gonglei <arei.gonglei@huawei.com> > > > > At present, the local variable local_err is reused at multi-places, > > Which will cause resource leak in some scenarios. > > > > The problem isn't really the local_err reusage. It's the fact that > this function doesn't have partial cleanup implemented (the > dc->unrealize call you add here is needed but not in original code at > all). Doing a fuller audit of the function, it seems to have outgrown > the simplistic if (!local_err) approach to error handling. I think the > goto-fallthrough system might be a cleaner alternative. Perhaps finish > the fn with: > > dev->realized = value; > return; > > post_realize_fail: > if (dc->unrealize) { > dc->unrealize(dev, NULL); > } > fail: > if (local_err != NULL) { > error_propagate(errp, local_err); > return; > } > > } > > Then goto the appropriate error label as local_err population is > detected as each relevant point. > Hi, Peter. I know your mean. vmstate_unregister() also should be called, beside dc->unrealized(). I will re-realize as your suggestion. Thanks! Best regards, -Gonglei
diff --git a/hw/core/qdev.c b/hw/core/qdev.c index 3e7085e..b3a463b 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -839,41 +839,58 @@ static void device_set_realized(Object *obj, bool value, Error **errp) dc->realize(dev, &local_err); } - if (dev->parent_bus && dev->parent_bus->hotplug_handler && - local_err == NULL) { - hotplug_handler_plug(dev->parent_bus->hotplug_handler, - dev, &local_err); - } else if (local_err == NULL && - object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) { - HotplugHandler *hotplug_ctrl; - MachineState *machine = MACHINE(qdev_get_machine()); - MachineClass *mc = MACHINE_GET_CLASS(machine); - - if (mc->get_hotplug_handler) { - hotplug_ctrl = mc->get_hotplug_handler(machine, dev); - if (hotplug_ctrl) { - hotplug_handler_plug(hotplug_ctrl, dev, &local_err); + if (local_err == NULL) { + Error *hotplug_err = NULL; + + if (dev->parent_bus && dev->parent_bus->hotplug_handler) { + hotplug_handler_plug(dev->parent_bus->hotplug_handler, + dev, &hotplug_err); + } else if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) { + HotplugHandler *hotplug_ctrl; + MachineState *machine = MACHINE(qdev_get_machine()); + MachineClass *mc = MACHINE_GET_CLASS(machine); + + if (mc->get_hotplug_handler) { + hotplug_ctrl = mc->get_hotplug_handler(machine, dev); + if (hotplug_ctrl) { + hotplug_handler_plug(hotplug_ctrl, dev, &hotplug_err); + } } } - } - if (qdev_get_vmsd(dev) && local_err == NULL) { - vmstate_register_with_alias_id(dev, -1, qdev_get_vmsd(dev), dev, - dev->instance_id_alias, - dev->alias_required_for_version); - } - if (local_err == NULL) { - QLIST_FOREACH(bus, &dev->child_bus, sibling) { - object_property_set_bool(OBJECT(bus), true, "realized", - &local_err); - if (local_err != NULL) { - break; + if (hotplug_err == NULL) { + Error *err = NULL; + if (qdev_get_vmsd(dev)) { + vmstate_register_with_alias_id(dev, -1, qdev_get_vmsd(dev), + dev, dev->instance_id_alias, + dev->alias_required_for_version); } + + QLIST_FOREACH(bus, &dev->child_bus, sibling) { + object_property_set_bool(OBJECT(bus), true, "realized", + &err); + if (err != NULL) { + if (qdev_get_vmsd(dev)) { + vmstate_unregister(dev, qdev_get_vmsd(dev), dev); + } + + break; + } + } + + if (dev->hotplugged && err == NULL) { + device_reset(dev); + } + error_free(err); + } else { + if (dc->unrealize) { + dc->unrealize(dev, NULL); + } + + error_propagate(errp, hotplug_err); + return; } } - if (dev->hotplugged && local_err == NULL) { - device_reset(dev); - } dev->pending_deleted_event = false; } else if (!value && dev->realized) { QLIST_FOREACH(bus, &dev->child_bus, sibling) {