Re: [Qemu-devel] [PATCH] RFC: pci-bus: add property ownership on bsel

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 28 Jul 2016 15:13:57 +0400
marcandre.lureau@redhat.com wrote:

> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> The property should own the allocated and unreferenced pointer. In case
> of error, it should also be freed.

acpi_setup() -> acpi_set_pci_info() -> acpi_set_bsel()
is called only once at machine done time
so if error happens it would be better to handle it instead of
just freeing bus_bsel pointer.
Since it's error path at machine startup time, typical reaction
to an unexpected error would be abort(), so following change
should be sufficient:

         object_property_add_uint32_ptr(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
-                                       bus_bsel, NULL);
+                                       bus_bsel, &error_abort);


> 
> RFC, because this patch triggers:
> /x86_64/qom/pc-i440fx-1.7:
> qemu-system-x86_64: attempt to add duplicate property 'acpi-pcihp-bsel' to object (type 'PCI')
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  hw/i386/acpi-build.c | 15 +++++++++++++--
>  include/qom/object.h |  4 ++++
>  qom/object.c         |  9 +++++++++
>  3 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 017bb51..2012007 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -425,6 +425,11 @@ build_madt(GArray *table_data, BIOSLinker *linker, PCMachineState *pcms)
>                   table_data->len - madt_start, 1, NULL, NULL);
>  }
>  
> +static void bsel_release(Object *obj, const char *name, void *opaque)
> +{
> +    g_free(opaque);
> +}
> +
>  /* Assign BSEL property to all buses.  In the future, this can be changed
>   * to only assign to buses that support hotplug.
>   */
> @@ -432,13 +437,19 @@ static void *acpi_set_bsel(PCIBus *bus, void *opaque)
>  {
>      unsigned *bsel_alloc = opaque;
>      unsigned *bus_bsel;
> +    Error *err = NULL;
>  
>      if (qbus_is_hotpluggable(BUS(bus))) {
>          bus_bsel = g_malloc(sizeof *bus_bsel);
>  
>          *bus_bsel = (*bsel_alloc)++;
> -        object_property_add_uint32_ptr(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
> -                                       bus_bsel, NULL);
> +        object_property_add_uint32_ptr_release(OBJECT(bus),
> +                                               ACPI_PCIHP_PROP_BSEL,
> +                                               bus_bsel, bsel_release, &err);
> +        if (err) {
> +            g_free(bus_bsel);
> +            error_report_err(err);
> +        }
>      }
>  
>      return bsel_alloc;
> diff --git a/include/qom/object.h b/include/qom/object.h
> index 5ecc2d1..41c1051 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -1488,6 +1488,10 @@ void object_class_property_add_uint16_ptr(ObjectClass *klass, const char *name,
>   */
>  void object_property_add_uint32_ptr(Object *obj, const char *name,
>                                      const uint32_t *v, Error **errp);
> +void object_property_add_uint32_ptr_release(Object *obj, const char *name,
> +                                            uint32_t *v,
> +                                            ObjectPropertyRelease *release,
> +                                            Error **errp);
>  void object_class_property_add_uint32_ptr(ObjectClass *klass, const char *name,
>                                            const uint32_t *v, Error **errp);
>  
> diff --git a/qom/object.c b/qom/object.c
> index 8166b7d..1635f57 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -2157,6 +2157,15 @@ void object_property_add_uint32_ptr(Object *obj, const char *name,
>                          NULL, NULL, (void *)v, errp);
>  }
>  
> +void object_property_add_uint32_ptr_release(Object *obj, const char *name,
> +                                            uint32_t *v,
> +                                            ObjectPropertyRelease *release,
> +                                            Error **errp)
> +{
> +    object_property_add(obj, name, "uint32", property_get_uint32_ptr,
> +                        NULL, release, (void *)v, errp);
> +}
> +
>  void object_class_property_add_uint32_ptr(ObjectClass *klass, const char *name,
>                                            const uint32_t *v, Error **errp)
>  {