[Qemu-devel] [PATCH v2 02/16] hw/misc/macio: Use object_initialize_child for correct ref. counting

Philippe Mathieu-Daudé posted 16 patches 6 years, 9 months ago
[Qemu-devel] [PATCH v2 02/16] hw/misc/macio: Use object_initialize_child for correct ref. counting
Posted by Philippe Mathieu-Daudé 6 years, 9 months ago
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
(with a bit of manual fix-up for overly long lines):

 @use_object_initialize_child@
 expression parent_obj;
 expression child_ptr;
 expression child_name;
 expression child_type;
 expression child_size;
 expression errp;
 @@
 (
 -   object_initialize(child_ptr, child_size, child_type);
 +   object_initialize_child(parent_obj, child_name,  child_ptr, child_size,
 +                           child_type, &error_abort, NULL);
     ... when != parent_obj
 -   object_property_add_child(parent_obj, child_name, OBJECT(child_ptr), NULL);
     ...
 ?-  object_unref(OBJECT(child_ptr));
 |
 -   object_initialize(child_ptr, child_size, child_type);
 +   object_initialize_child(parent_obj, child_name,  child_ptr, child_size,
 +                            child_type, errp, NULL);
     ... when != parent_obj
 -   object_property_add_child(parent_obj, child_name, OBJECT(child_ptr), errp);
     ...
 ?-  object_unref(OBJECT(child_ptr));
 )

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.

Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Inspired-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/misc/macio/macio.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/misc/macio/macio.c b/hw/misc/macio/macio.c
index 94da85c8d7d..b726c73022c 100644
--- a/hw/misc/macio/macio.c
+++ b/hw/misc/macio/macio.c
@@ -346,12 +346,12 @@ static void macio_newworld_realize(PCIDevice *d, Error **errp)
         object_property_set_bool(OBJECT(&ns->gpio), true, "realized", &err);
 
         /* PMU */
-        object_initialize(&s->pmu, sizeof(s->pmu), TYPE_VIA_PMU);
+        object_initialize_child(OBJECT(s), "pmu", &s->pmu, sizeof(s->pmu),
+                                TYPE_VIA_PMU, &error_abort, NULL);
         object_property_set_link(OBJECT(&s->pmu), OBJECT(sysbus_dev), "gpio",
                                  &error_abort);
         qdev_prop_set_bit(DEVICE(&s->pmu), "has-adb", ns->has_adb);
         qdev_set_parent_bus(DEVICE(&s->pmu), BUS(&s->macio_bus));
-        object_property_add_child(OBJECT(s), "pmu", OBJECT(&s->pmu), NULL);
 
         object_property_set_bool(OBJECT(&s->pmu), true, "realized", &err);
         if (err) {
@@ -365,9 +365,9 @@ static void macio_newworld_realize(PCIDevice *d, Error **errp)
                                     sysbus_mmio_get_region(sysbus_dev, 0));
     } else {
         /* CUDA */
-        object_initialize(&s->cuda, sizeof(s->cuda), TYPE_CUDA);
+        object_initialize_child(OBJECT(s), "cuda", &s->cuda, sizeof(s->cuda),
+                                TYPE_CUDA, &error_abort, NULL);
         qdev_set_parent_bus(DEVICE(&s->cuda), BUS(&s->macio_bus));
-        object_property_add_child(OBJECT(s), "cuda", OBJECT(&s->cuda), NULL);
         qdev_prop_set_uint64(DEVICE(&s->cuda), "timebase-frequency",
                              s->frequency);
 
-- 
2.20.1


Re: [Qemu-devel] [PATCH v2 02/16] hw/misc/macio: Use object_initialize_child for correct ref. counting
Posted by David Gibson 6 years, 9 months ago
On Tue, May 07, 2019 at 06:34:02PM +0200, 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
> (with a bit of manual fix-up for overly long lines):
> 
>  @use_object_initialize_child@
>  expression parent_obj;
>  expression child_ptr;
>  expression child_name;
>  expression child_type;
>  expression child_size;
>  expression errp;
>  @@
>  (
>  -   object_initialize(child_ptr, child_size, child_type);
>  +   object_initialize_child(parent_obj, child_name,  child_ptr, child_size,
>  +                           child_type, &error_abort, NULL);
>      ... when != parent_obj
>  -   object_property_add_child(parent_obj, child_name, OBJECT(child_ptr), NULL);
>      ...
>  ?-  object_unref(OBJECT(child_ptr));
>  |
>  -   object_initialize(child_ptr, child_size, child_type);
>  +   object_initialize_child(parent_obj, child_name,  child_ptr, child_size,
>  +                            child_type, errp, NULL);
>      ... when != parent_obj
>  -   object_property_add_child(parent_obj, child_name, OBJECT(child_ptr), errp);
>      ...
>  ?-  object_unref(OBJECT(child_ptr));
>  )
> 
> 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.
> 
> Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
> Inspired-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/misc/macio/macio.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/misc/macio/macio.c b/hw/misc/macio/macio.c
> index 94da85c8d7d..b726c73022c 100644
> --- a/hw/misc/macio/macio.c
> +++ b/hw/misc/macio/macio.c
> @@ -346,12 +346,12 @@ static void macio_newworld_realize(PCIDevice *d, Error **errp)
>          object_property_set_bool(OBJECT(&ns->gpio), true, "realized", &err);
>  
>          /* PMU */
> -        object_initialize(&s->pmu, sizeof(s->pmu), TYPE_VIA_PMU);
> +        object_initialize_child(OBJECT(s), "pmu", &s->pmu, sizeof(s->pmu),
> +                                TYPE_VIA_PMU, &error_abort, NULL);
>          object_property_set_link(OBJECT(&s->pmu), OBJECT(sysbus_dev), "gpio",
>                                   &error_abort);
>          qdev_prop_set_bit(DEVICE(&s->pmu), "has-adb", ns->has_adb);
>          qdev_set_parent_bus(DEVICE(&s->pmu), BUS(&s->macio_bus));
> -        object_property_add_child(OBJECT(s), "pmu", OBJECT(&s->pmu), NULL);
>  
>          object_property_set_bool(OBJECT(&s->pmu), true, "realized", &err);
>          if (err) {
> @@ -365,9 +365,9 @@ static void macio_newworld_realize(PCIDevice *d, Error **errp)
>                                      sysbus_mmio_get_region(sysbus_dev, 0));
>      } else {
>          /* CUDA */
> -        object_initialize(&s->cuda, sizeof(s->cuda), TYPE_CUDA);
> +        object_initialize_child(OBJECT(s), "cuda", &s->cuda, sizeof(s->cuda),
> +                                TYPE_CUDA, &error_abort, NULL);
>          qdev_set_parent_bus(DEVICE(&s->cuda), BUS(&s->macio_bus));
> -        object_property_add_child(OBJECT(s), "cuda", OBJECT(&s->cuda), NULL);
>          qdev_prop_set_uint64(DEVICE(&s->cuda), "timebase-frequency",
>                               s->frequency);
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson