Re: [Qemu-arm] [Qemu-devel] [PATCH v2 13/16] hw/microblaze/zynqmp: Use object_initialize_child for correct ref. counting

[Paolo Bonzini]

On 07/05/19 11:34, Philippe Mathieu-Daudé wrote:
> As explained in commit aff39be0ed97:
> 
>   Both functions, object_initialize() and object_property_add_child()
>   increase the reference counter of the new object, so one of the
>   references has to be dropped afterwards to get the reference
>   counting right. Otherwise the child object will not be properly
>   cleaned up when the parent gets destroyed.
>   Thus let's use now object_initialize_child() instead to get the
>   reference counting here right.
> 
> This patch was generated using the following Coccinelle script
> (then manually modified to use numbered IPI name)
> 
>  @use_sysbus_init_child_obj_missing_parent@
>  expression child_ptr;
>  expression child_type;
>  expression child_size;
>  @@
>  -   object_initialize(child_ptr, child_size, child_type);
>      ...
>  -   qdev_set_parent_bus(DEVICE(child_ptr), sysbus_get_default());
>      ...
>  ?-  object_unref(OBJECT(child_ptr));
>  +   sysbus_init_child_obj(OBJECT(PARENT_OBJ), "CHILD_NAME", child_ptr,
>  +                         child_size, child_type);
> 
> We let the SoC adopt the IPI children.
> 
> While the object_initialize() function doesn't take an
> 'Error *errp' argument, the object_initialize_child() does.
> Since this code is used when a machine is created (and is not
> yet running), we deliberately choose to use the &error_abort
> argument instead of ignoring errors if an object creation failed.
> This choice also matches when using sysbus_init_child_obj(),
> since its code is:
> 
>   void sysbus_init_child_obj(Object *parent,
>                              const char *childname, void *child,
>                              size_t childsize, const char *childtype)
>   {
>       object_initialize_child(parent, childname, child, childsize,
>                               childtype, &error_abort, NULL);
> 
>       qdev_set_parent_bus(DEVICE(child), sysbus_get_default());
>   }
> 
> Suggested-by: Eduardo Habkost <address@hidden>
> Inspired-by: Thomas Huth <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  hw/microblaze/xlnx-zynqmp-pmu.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/microblaze/xlnx-zynqmp-pmu.c b/hw/microblaze/xlnx-zynqmp-pmu.c
> index 20e973edf5f..0948b1fd5f2 100644
> --- a/hw/microblaze/xlnx-zynqmp-pmu.c
> +++ b/hw/microblaze/xlnx-zynqmp-pmu.c
> @@ -71,9 +71,10 @@ static void xlnx_zynqmp_pmu_soc_init(Object *obj)
>  
>      /* Create the IPI device */
>      for (int i = 0; i < XLNX_ZYNQMP_PMU_NUM_IPIS; i++) {
> -        object_initialize(&s->ipi[i], sizeof(XlnxZynqMPIPI),
> -                          TYPE_XLNX_ZYNQMP_IPI);
> -        qdev_set_parent_bus(DEVICE(&s->ipi[i]), sysbus_get_default());
> +        char *name = g_strdup_printf("ipi%d", i);
> +        sysbus_init_child_obj(obj, name, &s->ipi[i],
> +                              sizeof(XlnxZynqMPIPI), TYPE_XLNX_ZYNQMP_IPI);
> +        g_free(name);
>      }
>  }
>  
> 

Reviewed-by: Paolo Bonzini <address@hidden>