Re: [Qemu-devel] [PATCH v2 2/3] qdev: add cleanup logic in device_set_realized() to avoid resource leak

[Gonglei (Arei)]

Ping, please.

Any comments? Thanks.

Best regards,
-Gonglei


> -----Original Message-----
> From: Gonglei (Arei)
> Sent: Thursday, August 21, 2014 10:11 AM
> To: address@hidden
> Cc: address@hidden; Huangweidong (C); address@hidden;
> address@hidden; address@hidden; address@hidden;
> Huangpeng (Peter); Luonengjun; Gonglei (Arei)
> Subject: [PATCH v2 2/3] qdev: add cleanup logic in device_set_realized() to
> avoid resource leak
> 
> From: Gonglei <address@hidden>
> 
> At present, this function doesn't have partial cleanup implemented,
> which will cause resource leak in some scenarios.
> 
> 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.
> 
> Adding fuller cleanup logic which assure that function can
> goto appropriate error label as local_err population is
> detected as each relevant point.
> 
> Signed-off-by: Gonglei <address@hidden>
> ---
>  hw/core/qdev.c | 58
> ++++++++++++++++++++++++++++++++++++++--------------------
>  1 file changed, 38 insertions(+), 20 deletions(-)
> 
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 4a1ac5b..c1a36f0 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -834,12 +834,14 @@ 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) {
> +        if (local_err != NULL) {
> +            goto fail;
> +        }
> +
> +        if (dev->parent_bus && dev->parent_bus->hotplug_handler) {
>              hotplug_handler_plug(dev->parent_bus->hotplug_handler,
>                                   dev, &local_err);
> -        } else if (local_err == NULL &&
> -                   object_dynamic_cast(qdev_get_machine(),
> TYPE_MACHINE)) {
> +        } 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);
> @@ -852,21 +854,25 @@ static void device_set_realized(Object *obj, bool
> value, Error **errp)
>              }
>          }
> 
> -        if (qdev_get_vmsd(dev) && local_err == NULL) {
> +        if (local_err != NULL) {
> +            goto post_realize_fail;
> +        }
> +
> +        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);
>          }
> -        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;
> -                }
> +
> +        QLIST_FOREACH(bus, &dev->child_bus, sibling) {
> +            object_property_set_bool(OBJECT(bus), true, "realized",
> +                                     &local_err);
> +            if (local_err != NULL) {
> +                goto set_bool_fail;
>              }
>          }
> -        if (dev->hotplugged && local_err == NULL) {
> +
> +        if (dev->hotplugged) {
>              device_reset(dev);
>          }
>          dev->pending_deleted_event = false;
> @@ -875,24 +881,36 @@ static void device_set_realized(Object *obj, bool
> value, Error **errp)
>              object_property_set_bool(OBJECT(bus), false, "realized",
>                                       &local_err);
>              if (local_err != NULL) {
> -                break;
> +                goto fail;
>              }
>          }
> -        if (qdev_get_vmsd(dev) && local_err == NULL) {
> +        if (qdev_get_vmsd(dev)) {
>              vmstate_unregister(dev, qdev_get_vmsd(dev), dev);
>          }
> -        if (dc->unrealize && local_err == NULL) {
> +        if (dc->unrealize) {
>              dc->unrealize(dev, &local_err);
>          }
>          dev->pending_deleted_event = true;
> -    }
> 
> -    if (local_err != NULL) {
> -        error_propagate(errp, local_err);
> -        return;
> +        if (local_err != NULL) {
> +            goto fail;
> +        }
>      }
> 
>      dev->realized = value;
> +    return;
> +
> +set_bool_fail:
> +    if (qdev_get_vmsd(dev)) {
> +        vmstate_unregister(dev, qdev_get_vmsd(dev), dev);
> +    }
> +post_realize_fail:
> +    if (dc->unrealize) {
> +        dc->unrealize(dev, NULL);
> +    }
> +fail:
> +    error_propagate(errp, local_err);
> +    return;
>  }
> 
>  static bool device_get_hotpluggable(Object *obj, Error **errp)
> --
> 1.7.12.4
>