[v2,01/16] qom/object: Add a new function object_initialize_child()
diff mbox series

Message ID 1531470464-21522-2-git-send-email-thuth@redhat.com
State New
Headers show
Series
  • Fix crashes with introspection of ARM devices
Related show

Commit Message

Thomas Huth July 13, 2018, 8:27 a.m. UTC
A lot of code is using the object_initialize() function followed by a call
to object_property_add_child() to add the newly initialized object as a child
of the current object. Both functions increase the reference counter of the
new object, but many spots that call these two functions then forget to drop
one of the superfluous references. So the newly created object is often not
cleaned up correctly when the parent is destroyed. In the worst case, this
can cause crashes, e.g. because device objects are not correctly removed from
their parent_bus.

Since this is a common pattern between many code spots, let's introdcue a
new function that takes care of calling all three required initialization
functions, first object_initialize(), then object_property_add_child() and
finally object_unref().

And while we're at object.h, also fix some copy-n-paste errors in the
comments there ("to store the area" --> "to store the error").

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 include/qom/object.h | 23 +++++++++++++++++++++--
 qom/object.c         | 15 +++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

Comments

Paolo Bonzini July 13, 2018, 11:14 a.m. UTC | #1
On 13/07/2018 10:27, Thomas Huth wrote:
> A lot of code is using the object_initialize() function followed by a call
> to object_property_add_child() to add the newly initialized object as a child
> of the current object. Both functions increase the reference counter of the
> new object, but many spots that call these two functions then forget to drop
> one of the superfluous references. So the newly created object is often not
> cleaned up correctly when the parent is destroyed. In the worst case, this
> can cause crashes, e.g. because device objects are not correctly removed from
> their parent_bus.
> 
> Since this is a common pattern between many code spots, let's introdcue a
> new function that takes care of calling all three required initialization
> functions, first object_initialize(), then object_property_add_child() and
> finally object_unref().
> 
> And while we're at object.h, also fix some copy-n-paste errors in the
> comments there ("to store the area" --> "to store the error").

Even though I'd prefer the full cleanup, I can live with this. :)

Series

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

except for patch 6 for which I've sent a replacement.

Paolo

> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  include/qom/object.h | 23 +++++++++++++++++++++--
>  qom/object.c         | 15 +++++++++++++++
>  2 files changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/include/qom/object.h b/include/qom/object.h
> index f3d2308..3362db0 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -749,6 +749,25 @@ int object_set_propv(Object *obj,
>  void object_initialize(void *obj, size_t size, const char *typename);
>  
>  /**
> + * object_initialize_child:
> + * @parentobj: The parent object to add a property to
> + * @propname: The name of the property
> + * @childobj: A pointer to the memory to be used for the object.
> + * @size: The maximum size available at @obj for the object.
> + * @type: The name of the type of the object to instantiate.
> + * @errp: If an error occurs, a pointer to an area to store the error
> + *
> + * This function will initialize an object. The memory for the object should
> + * have already been allocated. The object will then be added as child property
> + * to a parent with object_property_add_child() function. The returned object
> + * has a reference count of 1 (for the "child<...>" property from the parent),
> + * so the object will get finalized automatically when the parent gets removed.
> + */
> +void object_initialize_child(Object *parentobj, const char *propname,
> +                             void *childobj, size_t size, const char *type,
> +                             Error **errp);
> +
> +/**
>   * object_dynamic_cast:
>   * @obj: The object to cast.
>   * @typename: The @typename to cast to.
> @@ -1382,7 +1401,7 @@ Object *object_resolve_path_component(Object *parent, const gchar *part);
>   * @obj: the object to add a property to
>   * @name: the name of the property
>   * @child: the child object
> - * @errp: if an error occurs, a pointer to an area to store the area
> + * @errp: if an error occurs, a pointer to an area to store the error
>   *
>   * Child properties form the composition tree.  All objects need to be a child
>   * of another object.  Objects can only be a child of one object.
> @@ -1420,7 +1439,7 @@ void object_property_allow_set_link(const Object *, const char *,
>   * @child: a pointer to where the link object reference is stored
>   * @check: callback to veto setting or NULL if the property is read-only
>   * @flags: additional options for the link
> - * @errp: if an error occurs, a pointer to an area to store the area
> + * @errp: if an error occurs, a pointer to an area to store the error
>   *
>   * Links establish relationships between objects.  Links are unidirectional
>   * although two links can be combined to form a bidirectional relationship
> diff --git a/qom/object.c b/qom/object.c
> index 4609e34..7be7638 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -392,6 +392,21 @@ void object_initialize(void *data, size_t size, const char *typename)
>      object_initialize_with_type(data, size, type);
>  }
>  
> +void object_initialize_child(Object *parentobj, const char *propname,
> +                             void *childobj, size_t size, const char *type,
> +                             Error **errp)
> +{
> +    object_initialize(childobj, size, type);
> +    object_property_add_child(parentobj, propname, OBJECT(childobj), errp);
> +    /*
> +     * Since object_property_add_child added a reference to the child object,
> +     * we can drop the reference added by object_initialize(), so the child
> +     * property will own the only reference to the object.
> +     */
> +    object_unref(OBJECT(childobj));
> +}
> +
> +
>  static inline bool object_property_is_child(ObjectProperty *prop)
>  {
>      return strstart(prop->type, "child<", NULL);
>
Eduardo Habkost July 13, 2018, 9:16 p.m. UTC | #2
On Fri, Jul 13, 2018 at 10:27:29AM +0200, Thomas Huth wrote:
> A lot of code is using the object_initialize() function followed by a call
> to object_property_add_child() to add the newly initialized object as a child
> of the current object. Both functions increase the reference counter of the
> new object, but many spots that call these two functions then forget to drop
> one of the superfluous references. So the newly created object is often not
> cleaned up correctly when the parent is destroyed. In the worst case, this
> can cause crashes, e.g. because device objects are not correctly removed from
> their parent_bus.
> 
> Since this is a common pattern between many code spots, let's introdcue a
> new function that takes care of calling all three required initialization
> functions, first object_initialize(), then object_property_add_child() and
> finally object_unref().
> 
> And while we're at object.h, also fix some copy-n-paste errors in the
> comments there ("to store the area" --> "to store the error").
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  include/qom/object.h | 23 +++++++++++++++++++++--
>  qom/object.c         | 15 +++++++++++++++
>  2 files changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/include/qom/object.h b/include/qom/object.h
> index f3d2308..3362db0 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -749,6 +749,25 @@ int object_set_propv(Object *obj,
>  void object_initialize(void *obj, size_t size, const char *typename);
>  
>  /**
> + * object_initialize_child:
> + * @parentobj: The parent object to add a property to
> + * @propname: The name of the property
> + * @childobj: A pointer to the memory to be used for the object.
> + * @size: The maximum size available at @obj for the object.
> + * @type: The name of the type of the object to instantiate.
> + * @errp: If an error occurs, a pointer to an area to store the error
> + *
> + * This function will initialize an object. The memory for the object should
> + * have already been allocated. The object will then be added as child property
> + * to a parent with object_property_add_child() function. The returned object
> + * has a reference count of 1 (for the "child<...>" property from the parent),
> + * so the object will get finalized automatically when the parent gets removed.
> + */
> +void object_initialize_child(Object *parentobj, const char *propname,
> +                             void *childobj, size_t size, const char *type,
> +                             Error **errp);

I wonder if we should deprecate object_initialize() and support
only object_initialize_child() later.  Initializing an object
contained inside another one without making it a child of the
parent object is a recipe for trouble.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Andreas Färber July 13, 2018, 9:29 p.m. UTC | #3
Am 13.07.2018 um 23:16 schrieb Eduardo Habkost:
> I wonder if we should deprecate object_initialize() and support
> only object_initialize_child() later.  Initializing an object
> contained inside another one without making it a child of the
> parent object is a recipe for trouble.

The root container object needs to be initialized, too.

Cheers,
Andreas
Eduardo Habkost July 13, 2018, 9:46 p.m. UTC | #4
On Fri, Jul 13, 2018 at 11:29:17PM +0200, Andreas Färber wrote:
> Am 13.07.2018 um 23:16 schrieb Eduardo Habkost:
> > I wonder if we should deprecate object_initialize() and support
> > only object_initialize_child() later.  Initializing an object
> > contained inside another one without making it a child of the
> > parent object is a recipe for trouble.
> 
> The root container object needs to be initialized, too.

If the object is not embedded in another struct, I would expect
it to be created using object_new() instead of
object_initialize().
Eduardo Habkost July 13, 2018, 10:57 p.m. UTC | #5
On Fri, Jul 13, 2018 at 10:27:29AM +0200, Thomas Huth wrote:
> A lot of code is using the object_initialize() function followed by a call
> to object_property_add_child() to add the newly initialized object as a child
> of the current object. Both functions increase the reference counter of the
> new object, but many spots that call these two functions then forget to drop
> one of the superfluous references. So the newly created object is often not
> cleaned up correctly when the parent is destroyed. In the worst case, this
> can cause crashes, e.g. because device objects are not correctly removed from
> their parent_bus.
> 
> Since this is a common pattern between many code spots, let's introdcue a
> new function that takes care of calling all three required initialization
> functions, first object_initialize(), then object_property_add_child() and
> finally object_unref().
> 
> And while we're at object.h, also fix some copy-n-paste errors in the
> comments there ("to store the area" --> "to store the error").
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Potential candidates for using the new function, found using the
following Coccinelle patch:

@@
expression child, size, type, parent, errp, propname;
@@
-object_initialize(child, size, type);
-object_property_add_child(
+object_initialize_child(
                           parent, propname, 
-                          OBJECT(child),
+                          child, size, type,
                           errp);

Some of them (very few) already call object_unref() and need to
be fixed manually.

Most of the remaining ~50 object_initialize() callers are also
candidates, even if they don't call object_property_add_child()
today.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
index bb9d33848d..e5923f85af 100644
--- a/hw/arm/aspeed.c
+++ b/hw/arm/aspeed.c
@@ -189,8 +189,8 @@ static void aspeed_board_init(MachineState *machine,
     DriveInfo *drive0 = drive_get(IF_MTD, 0, 0);
 
     bmc = g_new0(AspeedBoardState, 1);
-    object_initialize(&bmc->soc, (sizeof(bmc->soc)), cfg->soc_name);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&bmc->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &bmc->soc, (sizeof(bmc->soc)), cfg->soc_name,
                               &error_abort);
 
     sc = ASPEED_SOC_GET_CLASS(&bmc->soc);
diff --git a/hw/arm/aspeed_soc.c b/hw/arm/aspeed_soc.c
index e68911af0f..994262756f 100644
--- a/hw/arm/aspeed_soc.c
+++ b/hw/arm/aspeed_soc.c
@@ -106,11 +106,11 @@ static void aspeed_soc_init(Object *obj)
     AspeedSoCClass *sc = ASPEED_SOC_GET_CLASS(s);
     int i;
 
-    object_initialize(&s->cpu, sizeof(s->cpu), sc->info->cpu_type);
-    object_property_add_child(obj, "cpu", OBJECT(&s->cpu), NULL);
+    object_initialize_child(obj, "cpu",  &s->cpu, sizeof(s->cpu),
+                            sc->info->cpu_type, NULL);
 
-    object_initialize(&s->scu, sizeof(s->scu), TYPE_ASPEED_SCU);
-    object_property_add_child(obj, "scu", OBJECT(&s->scu), NULL);
+    object_initialize_child(obj, "scu",  &s->scu, sizeof(s->scu),
+                            TYPE_ASPEED_SCU, NULL);
     qdev_set_parent_bus(DEVICE(&s->scu), sysbus_get_default());
     qdev_prop_set_uint32(DEVICE(&s->scu), "silicon-rev",
                          sc->info->silicon_rev);
@@ -121,35 +121,34 @@ static void aspeed_soc_init(Object *obj)
     object_property_add_alias(obj, "hw-prot-key", OBJECT(&s->scu),
                               "hw-prot-key", &error_abort);
 
-    object_initialize(&s->vic, sizeof(s->vic), TYPE_ASPEED_VIC);
-    object_property_add_child(obj, "vic", OBJECT(&s->vic), NULL);
+    object_initialize_child(obj, "vic",  &s->vic, sizeof(s->vic),
+                            TYPE_ASPEED_VIC, NULL);
     qdev_set_parent_bus(DEVICE(&s->vic), sysbus_get_default());
 
-    object_initialize(&s->timerctrl, sizeof(s->timerctrl), TYPE_ASPEED_TIMER);
-    object_property_add_child(obj, "timerctrl", OBJECT(&s->timerctrl), NULL);
+    object_initialize_child(obj, "timerctrl",  &s->timerctrl,
+                            sizeof(s->timerctrl), TYPE_ASPEED_TIMER, NULL);
     object_property_add_const_link(OBJECT(&s->timerctrl), "scu",
                                    OBJECT(&s->scu), &error_abort);
     qdev_set_parent_bus(DEVICE(&s->timerctrl), sysbus_get_default());
 
-    object_initialize(&s->i2c, sizeof(s->i2c), TYPE_ASPEED_I2C);
-    object_property_add_child(obj, "i2c", OBJECT(&s->i2c), NULL);
+    object_initialize_child(obj, "i2c",  &s->i2c, sizeof(s->i2c),
+                            TYPE_ASPEED_I2C, NULL);
     qdev_set_parent_bus(DEVICE(&s->i2c), sysbus_get_default());
 
-    object_initialize(&s->fmc, sizeof(s->fmc), sc->info->fmc_typename);
-    object_property_add_child(obj, "fmc", OBJECT(&s->fmc), NULL);
+    object_initialize_child(obj, "fmc",  &s->fmc, sizeof(s->fmc),
+                            sc->info->fmc_typename, NULL);
     qdev_set_parent_bus(DEVICE(&s->fmc), sysbus_get_default());
     object_property_add_alias(obj, "num-cs", OBJECT(&s->fmc), "num-cs",
                               &error_abort);
 
     for (i = 0; i < sc->info->spis_num; i++) {
-        object_initialize(&s->spi[i], sizeof(s->spi[i]),
-                          sc->info->spi_typename[i]);
-        object_property_add_child(obj, "spi[*]", OBJECT(&s->spi[i]), NULL);
+        object_initialize_child(obj, "spi[*]",  &s->spi[i], sizeof(s->spi[i]),
+                                sc->info->spi_typename[i], NULL);
         qdev_set_parent_bus(DEVICE(&s->spi[i]), sysbus_get_default());
     }
 
-    object_initialize(&s->sdmc, sizeof(s->sdmc), TYPE_ASPEED_SDMC);
-    object_property_add_child(obj, "sdmc", OBJECT(&s->sdmc), NULL);
+    object_initialize_child(obj, "sdmc",  &s->sdmc, sizeof(s->sdmc),
+                            TYPE_ASPEED_SDMC, NULL);
     qdev_set_parent_bus(DEVICE(&s->sdmc), sysbus_get_default());
     qdev_prop_set_uint32(DEVICE(&s->sdmc), "silicon-rev",
                          sc->info->silicon_rev);
@@ -157,15 +156,15 @@ static void aspeed_soc_init(Object *obj)
                               "ram-size", &error_abort);
 
     for (i = 0; i < sc->info->wdts_num; i++) {
-        object_initialize(&s->wdt[i], sizeof(s->wdt[i]), TYPE_ASPEED_WDT);
-        object_property_add_child(obj, "wdt[*]", OBJECT(&s->wdt[i]), NULL);
+        object_initialize_child(obj, "wdt[*]",  &s->wdt[i], sizeof(s->wdt[i]),
+                                TYPE_ASPEED_WDT, NULL);
         qdev_set_parent_bus(DEVICE(&s->wdt[i]), sysbus_get_default());
         qdev_prop_set_uint32(DEVICE(&s->wdt[i]), "silicon-rev",
                                     sc->info->silicon_rev);
     }
 
-    object_initialize(&s->ftgmac100, sizeof(s->ftgmac100), TYPE_FTGMAC100);
-    object_property_add_child(obj, "ftgmac100", OBJECT(&s->ftgmac100), NULL);
+    object_initialize_child(obj, "ftgmac100",  &s->ftgmac100,
+                            sizeof(s->ftgmac100), TYPE_FTGMAC100, NULL);
     qdev_set_parent_bus(DEVICE(&s->ftgmac100), sysbus_get_default());
 }
 
diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c
index 6be7660e8c..0fbfd4e4fb 100644
--- a/hw/arm/bcm2835_peripherals.c
+++ b/hw/arm/bcm2835_peripherals.c
@@ -41,8 +41,8 @@ static void bcm2835_peripherals_init(Object *obj)
                        MBOX_CHAN_COUNT << MBOX_AS_CHAN_SHIFT);
 
     /* Interrupt Controller */
-    object_initialize(&s->ic, sizeof(s->ic), TYPE_BCM2835_IC);
-    object_property_add_child(obj, "ic", OBJECT(&s->ic), NULL);
+    object_initialize_child(obj, "ic",  &s->ic, sizeof(s->ic),
+                            TYPE_BCM2835_IC, NULL);
     qdev_set_parent_bus(DEVICE(&s->ic), sysbus_get_default());
 
     /* UART0 */
@@ -51,21 +51,21 @@ static void bcm2835_peripherals_init(Object *obj)
     qdev_set_parent_bus(DEVICE(s->uart0), sysbus_get_default());
 
     /* AUX / UART1 */
-    object_initialize(&s->aux, sizeof(s->aux), TYPE_BCM2835_AUX);
-    object_property_add_child(obj, "aux", OBJECT(&s->aux), NULL);
+    object_initialize_child(obj, "aux",  &s->aux, sizeof(s->aux),
+                            TYPE_BCM2835_AUX, NULL);
     qdev_set_parent_bus(DEVICE(&s->aux), sysbus_get_default());
 
     /* Mailboxes */
-    object_initialize(&s->mboxes, sizeof(s->mboxes), TYPE_BCM2835_MBOX);
-    object_property_add_child(obj, "mbox", OBJECT(&s->mboxes), NULL);
+    object_initialize_child(obj, "mbox",  &s->mboxes, sizeof(s->mboxes),
+                            TYPE_BCM2835_MBOX, NULL);
     qdev_set_parent_bus(DEVICE(&s->mboxes), sysbus_get_default());
 
     object_property_add_const_link(OBJECT(&s->mboxes), "mbox-mr",
                                    OBJECT(&s->mbox_mr), &error_abort);
 
     /* Framebuffer */
-    object_initialize(&s->fb, sizeof(s->fb), TYPE_BCM2835_FB);
-    object_property_add_child(obj, "fb", OBJECT(&s->fb), NULL);
+    object_initialize_child(obj, "fb",  &s->fb, sizeof(s->fb),
+                            TYPE_BCM2835_FB, NULL);
     object_property_add_alias(obj, "vcram-size", OBJECT(&s->fb), "vcram-size",
                               &error_abort);
     qdev_set_parent_bus(DEVICE(&s->fb), sysbus_get_default());
@@ -74,8 +74,8 @@ static void bcm2835_peripherals_init(Object *obj)
                                    OBJECT(&s->gpu_bus_mr), &error_abort);
 
     /* Property channel */
-    object_initialize(&s->property, sizeof(s->property), TYPE_BCM2835_PROPERTY);
-    object_property_add_child(obj, "property", OBJECT(&s->property), NULL);
+    object_initialize_child(obj, "property",  &s->property,
+                            sizeof(s->property), TYPE_BCM2835_PROPERTY, NULL);
     object_property_add_alias(obj, "board-rev", OBJECT(&s->property),
                               "board-rev", &error_abort);
     qdev_set_parent_bus(DEVICE(&s->property), sysbus_get_default());
@@ -86,31 +86,31 @@ static void bcm2835_peripherals_init(Object *obj)
                                    OBJECT(&s->gpu_bus_mr), &error_abort);
 
     /* Random Number Generator */
-    object_initialize(&s->rng, sizeof(s->rng), TYPE_BCM2835_RNG);
-    object_property_add_child(obj, "rng", OBJECT(&s->rng), NULL);
+    object_initialize_child(obj, "rng",  &s->rng, sizeof(s->rng),
+                            TYPE_BCM2835_RNG, NULL);
     qdev_set_parent_bus(DEVICE(&s->rng), sysbus_get_default());
 
     /* Extended Mass Media Controller */
-    object_initialize(&s->sdhci, sizeof(s->sdhci), TYPE_SYSBUS_SDHCI);
-    object_property_add_child(obj, "sdhci", OBJECT(&s->sdhci), NULL);
+    object_initialize_child(obj, "sdhci",  &s->sdhci, sizeof(s->sdhci),
+                            TYPE_SYSBUS_SDHCI, NULL);
     qdev_set_parent_bus(DEVICE(&s->sdhci), sysbus_get_default());
 
     /* SDHOST */
-    object_initialize(&s->sdhost, sizeof(s->sdhost), TYPE_BCM2835_SDHOST);
-    object_property_add_child(obj, "sdhost", OBJECT(&s->sdhost), NULL);
+    object_initialize_child(obj, "sdhost",  &s->sdhost, sizeof(s->sdhost),
+                            TYPE_BCM2835_SDHOST, NULL);
     qdev_set_parent_bus(DEVICE(&s->sdhost), sysbus_get_default());
 
     /* DMA Channels */
-    object_initialize(&s->dma, sizeof(s->dma), TYPE_BCM2835_DMA);
-    object_property_add_child(obj, "dma", OBJECT(&s->dma), NULL);
+    object_initialize_child(obj, "dma",  &s->dma, sizeof(s->dma),
+                            TYPE_BCM2835_DMA, NULL);
     qdev_set_parent_bus(DEVICE(&s->dma), sysbus_get_default());
 
     object_property_add_const_link(OBJECT(&s->dma), "dma-mr",
                                    OBJECT(&s->gpu_bus_mr), &error_abort);
 
     /* GPIO */
-    object_initialize(&s->gpio, sizeof(s->gpio), TYPE_BCM2835_GPIO);
-    object_property_add_child(obj, "gpio", OBJECT(&s->gpio), NULL);
+    object_initialize_child(obj, "gpio",  &s->gpio, sizeof(s->gpio),
+                            TYPE_BCM2835_GPIO, NULL);
     qdev_set_parent_bus(DEVICE(&s->gpio), sysbus_get_default());
 
     object_property_add_const_link(OBJECT(&s->gpio), "sdbus-sdhci",
diff --git a/hw/arm/digic.c b/hw/arm/digic.c
index 726abb9b48..90faca0710 100644
--- a/hw/arm/digic.c
+++ b/hw/arm/digic.c
@@ -35,8 +35,8 @@ static void digic_init(Object *obj)
     DeviceState *dev;
     int i;
 
-    object_initialize(&s->cpu, sizeof(s->cpu), "arm946-" TYPE_ARM_CPU);
-    object_property_add_child(obj, "cpu", OBJECT(&s->cpu), NULL);
+    object_initialize_child(obj, "cpu",  &s->cpu, sizeof(s->cpu),
+                            "arm946-" TYPE_ARM_CPU, NULL);
 
     for (i = 0; i < DIGIC4_NB_TIMERS; i++) {
 #define DIGIC_TIMER_NAME_MLEN    11
diff --git a/hw/arm/imx25_pdk.c b/hw/arm/imx25_pdk.c
index 9f3ee14739..76769531b2 100644
--- a/hw/arm/imx25_pdk.c
+++ b/hw/arm/imx25_pdk.c
@@ -72,8 +72,8 @@ static void imx25_pdk_init(MachineState *machine)
     unsigned int alias_offset;
     int i;
 
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_FSL_IMX25);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_FSL_IMX25,
                               &error_abort);
 
     object_property_set_bool(OBJECT(&s->soc), true, "realized", &error_fatal);
diff --git a/hw/arm/kzm.c b/hw/arm/kzm.c
index 864c7bd411..42f540fcdd 100644
--- a/hw/arm/kzm.c
+++ b/hw/arm/kzm.c
@@ -71,8 +71,8 @@ static void kzm_init(MachineState *machine)
     unsigned int alias_offset;
     unsigned int i;
 
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_FSL_IMX31);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_FSL_IMX31,
                               &error_abort);
 
     object_property_set_bool(OBJECT(&s->soc), true, "realized", &error_fatal);
diff --git a/hw/arm/mps2-tz.c b/hw/arm/mps2-tz.c
index 22180c56fb..4849f5a6d1 100644
--- a/hw/arm/mps2-tz.c
+++ b/hw/arm/mps2-tz.c
@@ -111,8 +111,8 @@ static void init_sysbus_child(Object *parent, const char *childname,
                               void *child, size_t childsize,
                               const char *childtype)
 {
-    object_initialize(child, childsize, childtype);
-    object_property_add_child(parent, childname, OBJECT(child), &error_abort);
+    object_initialize_child(parent, childname,  child, childsize, childtype,
+                            &error_abort);
     qdev_set_parent_bus(DEVICE(child), sysbus_get_default());
 
 }
@@ -301,10 +301,10 @@ static void mps2tz_common_init(MachineState *machine)
     /* The sec_resp_cfg output from the IoTKit must be split into multiple
      * lines, one for each of the PPCs we create here.
      */
-    object_initialize(&mms->sec_resp_splitter, sizeof(mms->sec_resp_splitter),
-                      TYPE_SPLIT_IRQ);
-    object_property_add_child(OBJECT(machine), "sec-resp-splitter",
-                              OBJECT(&mms->sec_resp_splitter), &error_abort);
+    object_initialize_child(OBJECT(machine), "sec-resp-splitter",
+                               &mms->sec_resp_splitter,
+                              sizeof(mms->sec_resp_splitter), TYPE_SPLIT_IRQ,
+                              &error_abort);
     object_property_set_int(OBJECT(&mms->sec_resp_splitter), 5,
                             "num-lines", &error_fatal);
     object_property_set_bool(OBJECT(&mms->sec_resp_splitter), true,
@@ -338,10 +338,10 @@ static void mps2tz_common_init(MachineState *machine)
      * Tx, Rx and "combined" IRQs are sent to the NVIC separately.
      * Create the OR gate for this.
      */
-    object_initialize(&mms->uart_irq_orgate, sizeof(mms->uart_irq_orgate),
-                      TYPE_OR_IRQ);
-    object_property_add_child(OBJECT(mms), "uart-irq-orgate",
-                              OBJECT(&mms->uart_irq_orgate), &error_abort);
+    object_initialize_child(OBJECT(mms), "uart-irq-orgate",
+                               &mms->uart_irq_orgate,
+                              sizeof(mms->uart_irq_orgate), TYPE_OR_IRQ,
+                              &error_abort);
     object_property_set_int(OBJECT(&mms->uart_irq_orgate), 10, "num-lines",
                             &error_fatal);
     object_property_set_bool(OBJECT(&mms->uart_irq_orgate), true,
diff --git a/hw/arm/raspi.c b/hw/arm/raspi.c
index 66899c28dc..6c9f89cbfd 100644
--- a/hw/arm/raspi.c
+++ b/hw/arm/raspi.c
@@ -175,9 +175,9 @@ static void raspi_init(MachineState *machine, int version)
     BusState *bus;
     DeviceState *carddev;
 
-    object_initialize(&s->soc, sizeof(s->soc),
-                      version == 3 ? TYPE_BCM2837 : TYPE_BCM2836);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc),
+                              version == 3 ? TYPE_BCM2837 : TYPE_BCM2836,
                               &error_abort);
 
     /* Allocate and map RAM */
diff --git a/hw/arm/sabrelite.c b/hw/arm/sabrelite.c
index ee140e5d9e..fe094c95d4 100644
--- a/hw/arm/sabrelite.c
+++ b/hw/arm/sabrelite.c
@@ -55,8 +55,8 @@ static void sabrelite_init(MachineState *machine)
         exit(1);
     }
 
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_FSL_IMX6);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_FSL_IMX6,
                               &error_abort);
 
     object_property_set_bool(OBJECT(&s->soc), true, "realized", &err);
diff --git a/hw/arm/xlnx-zcu102.c b/hw/arm/xlnx-zcu102.c
index b6bc6a93b8..1d5a4c6be8 100644
--- a/hw/arm/xlnx-zcu102.c
+++ b/hw/arm/xlnx-zcu102.c
@@ -91,8 +91,8 @@ static void xlnx_zcu102_init(MachineState *machine)
     memory_region_allocate_system_memory(&s->ddr_ram, NULL, "ddr-ram",
                                          ram_size);
 
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_XLNX_ZYNQMP);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_XLNX_ZYNQMP,
                               &error_abort);
 
     object_property_set_link(OBJECT(&s->soc), OBJECT(&s->ddr_ram),
diff --git a/hw/arm/xlnx-zynqmp.c b/hw/arm/xlnx-zynqmp.c
index a1365b44a0..f0420df8c4 100644
--- a/hw/arm/xlnx-zynqmp.c
+++ b/hw/arm/xlnx-zynqmp.c
@@ -133,10 +133,9 @@ static void xlnx_zynqmp_create_rpu(XlnxZynqMPState *s, const char *boot_cpu,
     for (i = 0; i < num_rpus; i++) {
         char *name;
 
-        object_initialize(&s->rpu_cpu[i], sizeof(s->rpu_cpu[i]),
-                          "cortex-r5f-" TYPE_ARM_CPU);
-        object_property_add_child(OBJECT(s), "rpu-cpu[*]",
-                                  OBJECT(&s->rpu_cpu[i]), &error_abort);
+        object_initialize_child(OBJECT(s), "rpu-cpu[*]",
+                                   &s->rpu_cpu[i], sizeof(s->rpu_cpu[i]),
+                                  "cortex-r5f-" TYPE_ARM_CPU, &error_abort);
 
         name = object_get_canonical_path_component(OBJECT(&s->rpu_cpu[i]));
         if (strcmp(name, boot_cpu)) {
diff --git a/hw/microblaze/xlnx-zynqmp-pmu.c b/hw/microblaze/xlnx-zynqmp-pmu.c
index 999a5657cf..62f2e43707 100644
--- a/hw/microblaze/xlnx-zynqmp-pmu.c
+++ b/hw/microblaze/xlnx-zynqmp-pmu.c
@@ -62,9 +62,8 @@ static void xlnx_zynqmp_pmu_soc_init(Object *obj)
 {
     XlnxZynqMPPMUSoCState *s = XLNX_ZYNQMP_PMU_SOC(obj);
 
-    object_initialize(&s->cpu, sizeof(s->cpu),
-                      TYPE_MICROBLAZE_CPU);
-    object_property_add_child(obj, "pmu-cpu", OBJECT(&s->cpu),
+    object_initialize_child(obj, "pmu-cpu",
+                              &s->cpu, sizeof(s->cpu), TYPE_MICROBLAZE_CPU,
                               &error_abort);
 
     object_initialize(&s->intc, sizeof(s->intc), TYPE_XLNX_PMU_IO_INTC);
@@ -163,9 +162,9 @@ static void xlnx_zynqmp_pmu_init(MachineState *machine)
                                 pmu_ram);
 
     /* Create the PMU device */
-    object_initialize(pmu, sizeof(XlnxZynqMPPMUSoCState), TYPE_XLNX_ZYNQMP_PMU_SOC);
-    object_property_add_child(OBJECT(machine), "pmu", OBJECT(pmu),
-                              &error_abort);
+    object_initialize_child(OBJECT(machine), "pmu",
+                              pmu, sizeof(XlnxZynqMPPMUSoCState),
+                              TYPE_XLNX_ZYNQMP_PMU_SOC, &error_abort);
     object_property_set_bool(OBJECT(pmu), true, "realized", &error_fatal);
 
     for (i = 0; i < 32; i++) {
diff --git a/hw/pci-host/designware.c b/hw/pci-host/designware.c
index 29ea313798..8590ec657b 100644
--- a/hw/pci-host/designware.c
+++ b/hw/pci-host/designware.c
@@ -721,8 +721,8 @@ static void designware_pcie_host_init(Object *obj)
     DesignwarePCIEHost *s = DESIGNWARE_PCIE_HOST(obj);
     DesignwarePCIERoot *root = &s->root;
 
-    object_initialize(root, sizeof(*root), TYPE_DESIGNWARE_PCIE_ROOT);
-    object_property_add_child(obj, "root", OBJECT(root), NULL);
+    object_initialize_child(obj, "root",  root, sizeof(*root),
+                            TYPE_DESIGNWARE_PCIE_ROOT, NULL);
     qdev_prop_set_int32(DEVICE(root), "addr", PCI_DEVFN(0, 0));
     qdev_prop_set_bit(DEVICE(root), "multifunction", false);
 }
diff --git a/hw/pci-host/gpex.c b/hw/pci-host/gpex.c
index 2583b151a4..060e80930b 100644
--- a/hw/pci-host/gpex.c
+++ b/hw/pci-host/gpex.c
@@ -120,8 +120,8 @@ static void gpex_host_initfn(Object *obj)
     GPEXHost *s = GPEX_HOST(obj);
     GPEXRootState *root = &s->gpex_root;
 
-    object_initialize(root, sizeof(*root), TYPE_GPEX_ROOT_DEVICE);
-    object_property_add_child(obj, "gpex_root", OBJECT(root), NULL);
+    object_initialize_child(obj, "gpex_root",  root, sizeof(*root),
+                            TYPE_GPEX_ROOT_DEVICE, NULL);
     qdev_prop_set_int32(DEVICE(root), "addr", PCI_DEVFN(0, 0));
     qdev_prop_set_bit(DEVICE(root), "multifunction", false);
 }
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 02f9576588..d590035659 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -205,8 +205,8 @@ static void q35_host_initfn(Object *obj)
     memory_region_init_io(&phb->data_mem, obj, &pci_host_data_le_ops, phb,
                           "pci-conf-data", 4);
 
-    object_initialize(&s->mch, sizeof(s->mch), TYPE_MCH_PCI_DEVICE);
-    object_property_add_child(OBJECT(s), "mch", OBJECT(&s->mch), NULL);
+    object_initialize_child(OBJECT(s), "mch",  &s->mch, sizeof(s->mch),
+                            TYPE_MCH_PCI_DEVICE, NULL);
     qdev_prop_set_int32(DEVICE(&s->mch), "addr", PCI_DEVFN(0, 0));
     qdev_prop_set_bit(DEVICE(&s->mch), "multifunction", false);
     /* mch's object_initialize resets the default value, set it again */
diff --git a/hw/pci-host/xilinx-pcie.c b/hw/pci-host/xilinx-pcie.c
index 60309afe9e..f82d3f3e33 100644
--- a/hw/pci-host/xilinx-pcie.c
+++ b/hw/pci-host/xilinx-pcie.c
@@ -149,8 +149,8 @@ static void xilinx_pcie_host_init(Object *obj)
     XilinxPCIEHost *s = XILINX_PCIE_HOST(obj);
     XilinxPCIERoot *root = &s->root;
 
-    object_initialize(root, sizeof(*root), TYPE_XILINX_PCIE_ROOT);
-    object_property_add_child(obj, "root", OBJECT(root), NULL);
+    object_initialize_child(obj, "root",  root, sizeof(*root),
+                            TYPE_XILINX_PCIE_ROOT, NULL);
     qdev_prop_set_int32(DEVICE(root), "addr", PCI_DEVFN(0, 0));
     qdev_prop_set_bit(DEVICE(root), "multifunction", false);
 }
diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 0989f6a05f..93eb2948cc 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -726,18 +726,18 @@ static void pnv_chip_power8_instance_init(Object *obj)
 {
     Pnv8Chip *chip8 = PNV8_CHIP(obj);
 
-    object_initialize(&chip8->psi, sizeof(chip8->psi), TYPE_PNV_PSI);
-    object_property_add_child(obj, "psi", OBJECT(&chip8->psi), NULL);
+    object_initialize_child(obj, "psi",  &chip8->psi, sizeof(chip8->psi),
+                            TYPE_PNV_PSI, NULL);
     object_property_add_const_link(OBJECT(&chip8->psi), "xics",
                                    OBJECT(qdev_get_machine()), &error_abort);
 
-    object_initialize(&chip8->lpc, sizeof(chip8->lpc), TYPE_PNV_LPC);
-    object_property_add_child(obj, "lpc", OBJECT(&chip8->lpc), NULL);
+    object_initialize_child(obj, "lpc",  &chip8->lpc, sizeof(chip8->lpc),
+                            TYPE_PNV_LPC, NULL);
     object_property_add_const_link(OBJECT(&chip8->lpc), "psi",
                                    OBJECT(&chip8->psi), &error_abort);
 
-    object_initialize(&chip8->occ, sizeof(chip8->occ), TYPE_PNV_OCC);
-    object_property_add_child(obj, "occ", OBJECT(&chip8->occ), NULL);
+    object_initialize_child(obj, "occ",  &chip8->occ, sizeof(chip8->occ),
+                            TYPE_PNV_OCC, NULL);
     object_property_add_const_link(OBJECT(&chip8->occ), "psi",
                                    OBJECT(&chip8->psi), &error_abort);
 }
@@ -975,9 +975,8 @@ static void pnv_chip_core_realize(PnvChip *chip, Error **errp)
         }
 
         snprintf(core_name, sizeof(core_name), "core[%d]", core_hwid);
-        object_initialize(pnv_core, typesize, typename);
-        object_property_add_child(OBJECT(chip), core_name, OBJECT(pnv_core),
-                                  &error_fatal);
+        object_initialize_child(OBJECT(chip), core_name,
+                                  pnv_core, typesize, typename, &error_fatal);
         object_property_set_int(OBJECT(pnv_core), smp_threads, "nr-threads",
                                 &error_fatal);
         object_property_set_int(OBJECT(pnv_core), core_hwid,
diff --git a/hw/ppc/pnv_psi.c b/hw/ppc/pnv_psi.c
index 5b969127c3..2e29089e66 100644
--- a/hw/ppc/pnv_psi.c
+++ b/hw/ppc/pnv_psi.c
@@ -445,8 +445,8 @@ static void pnv_psi_init(Object *obj)
 {
     PnvPsi *psi = PNV_PSI(obj);
 
-    object_initialize(&psi->ics, sizeof(psi->ics), TYPE_ICS_SIMPLE);
-    object_property_add_child(obj, "ics-psi", OBJECT(&psi->ics), NULL);
+    object_initialize_child(obj, "ics-psi",  &psi->ics, sizeof(psi->ics),
+                            TYPE_ICS_SIMPLE, NULL);
 }
 
 static const uint8_t irq_to_xivr[] = {
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 3f5e1d3ec2..8c4bdb147a 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1700,8 +1700,8 @@ static void spapr_create_nvram(sPAPRMachineState *spapr)
 
 static void spapr_rtc_create(sPAPRMachineState *spapr)
 {
-    object_initialize(&spapr->rtc, sizeof(spapr->rtc), TYPE_SPAPR_RTC);
-    object_property_add_child(OBJECT(spapr), "rtc", OBJECT(&spapr->rtc),
+    object_initialize_child(OBJECT(spapr), "rtc",
+                              &spapr->rtc, sizeof(spapr->rtc), TYPE_SPAPR_RTC,
                               &error_fatal);
     object_property_set_bool(OBJECT(&spapr->rtc), true, "realized",
                               &error_fatal);
diff --git a/hw/riscv/sifive_e.c b/hw/riscv/sifive_e.c
index 8a8dbe1c00..b323eac391 100644
--- a/hw/riscv/sifive_e.c
+++ b/hw/riscv/sifive_e.c
@@ -105,8 +105,8 @@ static void riscv_sifive_e_init(MachineState *machine)
     int i;
 
     /* Initialize SoC */
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_RISCV_E_SOC);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_RISCV_E_SOC,
                               &error_abort);
     object_property_set_bool(OBJECT(&s->soc), true, "realized",
                             &error_abort);
@@ -139,9 +139,9 @@ static void riscv_sifive_e_soc_init(Object *obj)
 {
     SiFiveESoCState *s = RISCV_E_SOC(obj);
 
-    object_initialize(&s->cpus, sizeof(s->cpus), TYPE_RISCV_HART_ARRAY);
-    object_property_add_child(obj, "cpus", OBJECT(&s->cpus),
-                              &error_abort);
+    object_initialize_child(obj, "cpus",
+                              &s->cpus, sizeof(s->cpus),
+                              TYPE_RISCV_HART_ARRAY, &error_abort);
     object_property_set_str(OBJECT(&s->cpus), SIFIVE_E_CPU, "cpu-type",
                             &error_abort);
     object_property_set_int(OBJECT(&s->cpus), smp_cpus, "num-harts",
diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index 3a6ffeb437..c94900f345 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -244,8 +244,8 @@ static void riscv_sifive_u_init(MachineState *machine)
     int i;
 
     /* Initialize SoC */
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_RISCV_U_SOC);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_RISCV_U_SOC,
                               &error_abort);
     object_property_set_bool(OBJECT(&s->soc), true, "realized",
                             &error_abort);
@@ -303,9 +303,9 @@ static void riscv_sifive_u_soc_init(Object *obj)
 {
     SiFiveUSoCState *s = RISCV_U_SOC(obj);
 
-    object_initialize(&s->cpus, sizeof(s->cpus), TYPE_RISCV_HART_ARRAY);
-    object_property_add_child(obj, "cpus", OBJECT(&s->cpus),
-                              &error_abort);
+    object_initialize_child(obj, "cpus",
+                              &s->cpus, sizeof(s->cpus),
+                              TYPE_RISCV_HART_ARRAY, &error_abort);
     object_property_set_str(OBJECT(&s->cpus), SIFIVE_U_CPU, "cpu-type",
                             &error_abort);
     object_property_set_int(OBJECT(&s->cpus), smp_cpus, "num-harts",
diff --git a/hw/riscv/spike.c b/hw/riscv/spike.c
index f94e2b6707..44639a8c99 100644
--- a/hw/riscv/spike.c
+++ b/hw/riscv/spike.c
@@ -171,8 +171,8 @@ static void spike_v1_10_0_board_init(MachineState *machine)
     int i;
 
     /* Initialize SOC */
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY,
                               &error_abort);
     object_property_set_str(OBJECT(&s->soc), SPIKE_V1_10_0_CPU, "cpu-type",
                             &error_abort);
@@ -254,8 +254,8 @@ static void spike_v1_09_1_board_init(MachineState *machine)
     int i;
 
     /* Initialize SOC */
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY,
                               &error_abort);
     object_property_set_str(OBJECT(&s->soc), SPIKE_V1_09_1_CPU, "cpu-type",
                             &error_abort);
diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index aeada2498d..d597916885 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -274,8 +274,8 @@ static void riscv_virt_board_init(MachineState *machine)
     void *fdt;
 
     /* Initialize SOC */
-    object_initialize(&s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY);
-    object_property_add_child(OBJECT(machine), "soc", OBJECT(&s->soc),
+    object_initialize_child(OBJECT(machine), "soc",
+                              &s->soc, sizeof(s->soc), TYPE_RISCV_HART_ARRAY,
                               &error_abort);
     object_property_set_str(OBJECT(&s->soc), VIRT_CPU, "cpu-type",
                             &error_abort);
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index d4e4d98b59..acf7b4e40e 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2232,8 +2232,8 @@ void virtio_instance_init_common(Object *proxy_obj, void *data,
 {
     DeviceState *vdev = data;
 
-    object_initialize(vdev, vdev_size, vdev_name);
-    object_property_add_child(proxy_obj, "virtio-backend", OBJECT(vdev), NULL);
+    object_initialize_child(proxy_obj, "virtio-backend",  vdev, vdev_size,
+                            vdev_name, NULL);
     object_unref(OBJECT(vdev));
     qdev_alias_all_properties(vdev, proxy_obj);
 }
diff --git a/qom/object.c b/qom/object.c
index 7be7638db1..91ff795b38 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -396,8 +396,7 @@ void object_initialize_child(Object *parentobj, const char *propname,
                              void *childobj, size_t size, const char *type,
                              Error **errp)
 {
-    object_initialize(childobj, size, type);
-    object_property_add_child(parentobj, propname, OBJECT(childobj), errp);
+    object_initialize_child(parentobj, propname,  childobj, size, type, errp);
     /*
      * Since object_property_add_child added a reference to the child object,
      * we can drop the reference added by object_initialize(), so the child
Thomas Huth July 16, 2018, 7:05 a.m. UTC | #6
On 13.07.2018 23:46, Eduardo Habkost wrote:
> On Fri, Jul 13, 2018 at 11:29:17PM +0200, Andreas Färber wrote:
>> Am 13.07.2018 um 23:16 schrieb Eduardo Habkost:
>>> I wonder if we should deprecate object_initialize() and support
>>> only object_initialize_child() later.  Initializing an object
>>> contained inside another one without making it a child of the
>>> parent object is a recipe for trouble.
>>
>> The root container object needs to be initialized, too.
> 
> If the object is not embedded in another struct, I would expect
> it to be created using object_new() instead of
> object_initialize().

True. So I guess having a closer look at code that calls
object_initialize() only is something for our TODO lists once 3.0 has
been released...

 Thomas
Thomas Huth July 16, 2018, 7:16 a.m. UTC | #7
On 14.07.2018 00:57, Eduardo Habkost wrote:
> On Fri, Jul 13, 2018 at 10:27:29AM +0200, Thomas Huth wrote:
>> A lot of code is using the object_initialize() function followed by a call
>> to object_property_add_child() to add the newly initialized object as a child
>> of the current object. Both functions increase the reference counter of the
>> new object, but many spots that call these two functions then forget to drop
>> one of the superfluous references. So the newly created object is often not
>> cleaned up correctly when the parent is destroyed. In the worst case, this
>> can cause crashes, e.g. because device objects are not correctly removed from
>> their parent_bus.
>>
>> Since this is a common pattern between many code spots, let's introdcue a
>> new function that takes care of calling all three required initialization
>> functions, first object_initialize(), then object_property_add_child() and
>> finally object_unref().
>>
>> And while we're at object.h, also fix some copy-n-paste errors in the
>> comments there ("to store the area" --> "to store the error").
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
> 
> Potential candidates for using the new function, found using the
> following Coccinelle patch:
> 
> @@
> expression child, size, type, parent, errp, propname;
> @@
> -object_initialize(child, size, type);
> -object_property_add_child(
> +object_initialize_child(
>                            parent, propname, 
> -                          OBJECT(child),
> +                          child, size, type,
>                            errp);
> 
> Some of them (very few) already call object_unref() and need to
> be fixed manually.
> 
> Most of the remaining ~50 object_initialize() callers are also
> candidates, even if they don't call object_property_add_child()
> today.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
> index bb9d33848d..e5923f85af 100644
> --- a/hw/arm/aspeed.c
> +++ b/hw/arm/aspeed.c
> @@ -189,8 +189,8 @@ static void aspeed_board_init(MachineState *machine,
>      DriveInfo *drive0 = drive_get(IF_MTD, 0, 0);
>  
>      bmc = g_new0(AspeedBoardState, 1);
> -    object_initialize(&bmc->soc, (sizeof(bmc->soc)), cfg->soc_name);
> -    object_property_add_child(OBJECT(machine), "soc", OBJECT(&bmc->soc),
> +    object_initialize_child(OBJECT(machine), "soc",
> +                              &bmc->soc, (sizeof(bmc->soc)), cfg->soc_name,
>                                &error_abort);
>  
>      sc = ASPEED_SOC_GET_CLASS(&bmc->soc);
> diff --git a/hw/arm/aspeed_soc.c b/hw/arm/aspeed_soc.c
> index e68911af0f..994262756f 100644
> --- a/hw/arm/aspeed_soc.c
> +++ b/hw/arm/aspeed_soc.c
> @@ -106,11 +106,11 @@ static void aspeed_soc_init(Object *obj)
>      AspeedSoCClass *sc = ASPEED_SOC_GET_CLASS(s);
>      int i;
>  
> -    object_initialize(&s->cpu, sizeof(s->cpu), sc->info->cpu_type);
> -    object_property_add_child(obj, "cpu", OBJECT(&s->cpu), NULL);
> +    object_initialize_child(obj, "cpu",  &s->cpu, sizeof(s->cpu),
> +                            sc->info->cpu_type, NULL);
>  
> -    object_initialize(&s->scu, sizeof(s->scu), TYPE_ASPEED_SCU);
> -    object_property_add_child(obj, "scu", OBJECT(&s->scu), NULL);
> +    object_initialize_child(obj, "scu",  &s->scu, sizeof(s->scu),
> +                            TYPE_ASPEED_SCU, NULL);
>      qdev_set_parent_bus(DEVICE(&s->scu), sysbus_get_default());
>      qdev_prop_set_uint32(DEVICE(&s->scu), "silicon-rev",

Thanks, that's definitely something we should do for 3.1! But for 3.0, I
think we better only focus on the ones that cause reproducible problem.

And the spots that also use qdev_set_parent_bus(...,
sysbus_get_default()) should use sysbus_init_child_obj() instead.

 Thomas
Thomas Huth Aug. 16, 2018, 11:59 a.m. UTC | #8
On 07/14/2018 12:57 AM, Eduardo Habkost wrote:
> On Fri, Jul 13, 2018 at 10:27:29AM +0200, Thomas Huth wrote:
>> A lot of code is using the object_initialize() function followed by a call
>> to object_property_add_child() to add the newly initialized object as a child
>> of the current object. Both functions increase the reference counter of the
>> new object, but many spots that call these two functions then forget to drop
>> one of the superfluous references. So the newly created object is often not
>> cleaned up correctly when the parent is destroyed. In the worst case, this
>> can cause crashes, e.g. because device objects are not correctly removed from
>> their parent_bus.
>>
>> Since this is a common pattern between many code spots, let's introdcue a
>> new function that takes care of calling all three required initialization
>> functions, first object_initialize(), then object_property_add_child() and
>> finally object_unref().
>>
>> And while we're at object.h, also fix some copy-n-paste errors in the
>> comments there ("to store the area" --> "to store the error").
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
> 
> Potential candidates for using the new function, found using the
> following Coccinelle patch:
> 
> @@
> expression child, size, type, parent, errp, propname;
> @@
> -object_initialize(child, size, type);
> -object_property_add_child(
> +object_initialize_child(
>                            parent, propname, 
> -                          OBJECT(child),
> +                          child, size, type,
>                            errp);
> 
> Some of them (very few) already call object_unref() and need to
> be fixed manually.
> 
> Most of the remaining ~50 object_initialize() callers are also
> candidates, even if they don't call object_property_add_child()
> today.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

Care to turn this into a proper patch, now that we left the freeze period?

> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index d4e4d98b59..acf7b4e40e 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2232,8 +2232,8 @@ void virtio_instance_init_common(Object *proxy_obj, void *data,
>  {
>      DeviceState *vdev = data;
>  
> -    object_initialize(vdev, vdev_size, vdev_name);
> -    object_property_add_child(proxy_obj, "virtio-backend", OBJECT(vdev), NULL);
> +    object_initialize_child(proxy_obj, "virtio-backend",  vdev, vdev_size,
> +                            vdev_name, NULL);
>      object_unref(OBJECT(vdev));
>      qdev_alias_all_properties(vdev, proxy_obj);
>  }
> diff --git a/qom/object.c b/qom/object.c
> index 7be7638db1..91ff795b38 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -396,8 +396,7 @@ void object_initialize_child(Object *parentobj, const char *propname,
>                               void *childobj, size_t size, const char *type,
>                               Error **errp)
>  {
> -    object_initialize(childobj, size, type);
> -    object_property_add_child(parentobj, propname, OBJECT(childobj), errp);
> +    object_initialize_child(parentobj, propname,  childobj, size, type, errp);
>      /*
>       * Since object_property_add_child added a reference to the child object,
>       * we can drop the reference added by object_initialize(), so the child

At least these two hunks need manual adjustment.

 Thomas
Eduardo Habkost Aug. 17, 2018, 1:40 a.m. UTC | #9
On Thu, Aug 16, 2018 at 01:59:49PM +0200, Thomas Huth wrote:
> On 07/14/2018 12:57 AM, Eduardo Habkost wrote:
> > On Fri, Jul 13, 2018 at 10:27:29AM +0200, Thomas Huth wrote:
> >> A lot of code is using the object_initialize() function followed by a call
> >> to object_property_add_child() to add the newly initialized object as a child
> >> of the current object. Both functions increase the reference counter of the
> >> new object, but many spots that call these two functions then forget to drop
> >> one of the superfluous references. So the newly created object is often not
> >> cleaned up correctly when the parent is destroyed. In the worst case, this
> >> can cause crashes, e.g. because device objects are not correctly removed from
> >> their parent_bus.
> >>
> >> Since this is a common pattern between many code spots, let's introdcue a
> >> new function that takes care of calling all three required initialization
> >> functions, first object_initialize(), then object_property_add_child() and
> >> finally object_unref().
> >>
> >> And while we're at object.h, also fix some copy-n-paste errors in the
> >> comments there ("to store the area" --> "to store the error").
> >>
> >> Signed-off-by: Thomas Huth <thuth@redhat.com>
> > 
> > Potential candidates for using the new function, found using the
> > following Coccinelle patch:
> > 
> > @@
> > expression child, size, type, parent, errp, propname;
> > @@
> > -object_initialize(child, size, type);
> > -object_property_add_child(
> > +object_initialize_child(
> >                            parent, propname, 
> > -                          OBJECT(child),
> > +                          child, size, type,
> >                            errp);
> > 
> > Some of them (very few) already call object_unref() and need to
> > be fixed manually.
> > 
> > Most of the remaining ~50 object_initialize() callers are also
> > candidates, even if they don't call object_property_add_child()
> > today.
> > 
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> 
> Care to turn this into a proper patch, now that we left the freeze period?

It's possible, but we need a volunteer to review each hunk
because the existing code might be (correctly) calling
object_unref() (either immediately or when parent is finalized).

I will keep this in my TODO list, but it's not my top priority
right now.

Patch
diff mbox series

diff --git a/include/qom/object.h b/include/qom/object.h
index f3d2308..3362db0 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -749,6 +749,25 @@  int object_set_propv(Object *obj,
 void object_initialize(void *obj, size_t size, const char *typename);
 
 /**
+ * object_initialize_child:
+ * @parentobj: The parent object to add a property to
+ * @propname: The name of the property
+ * @childobj: A pointer to the memory to be used for the object.
+ * @size: The maximum size available at @obj for the object.
+ * @type: The name of the type of the object to instantiate.
+ * @errp: If an error occurs, a pointer to an area to store the error
+ *
+ * This function will initialize an object. The memory for the object should
+ * have already been allocated. The object will then be added as child property
+ * to a parent with object_property_add_child() function. The returned object
+ * has a reference count of 1 (for the "child<...>" property from the parent),
+ * so the object will get finalized automatically when the parent gets removed.
+ */
+void object_initialize_child(Object *parentobj, const char *propname,
+                             void *childobj, size_t size, const char *type,
+                             Error **errp);
+
+/**
  * object_dynamic_cast:
  * @obj: The object to cast.
  * @typename: The @typename to cast to.
@@ -1382,7 +1401,7 @@  Object *object_resolve_path_component(Object *parent, const gchar *part);
  * @obj: the object to add a property to
  * @name: the name of the property
  * @child: the child object
- * @errp: if an error occurs, a pointer to an area to store the area
+ * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Child properties form the composition tree.  All objects need to be a child
  * of another object.  Objects can only be a child of one object.
@@ -1420,7 +1439,7 @@  void object_property_allow_set_link(const Object *, const char *,
  * @child: a pointer to where the link object reference is stored
  * @check: callback to veto setting or NULL if the property is read-only
  * @flags: additional options for the link
- * @errp: if an error occurs, a pointer to an area to store the area
+ * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Links establish relationships between objects.  Links are unidirectional
  * although two links can be combined to form a bidirectional relationship
diff --git a/qom/object.c b/qom/object.c
index 4609e34..7be7638 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -392,6 +392,21 @@  void object_initialize(void *data, size_t size, const char *typename)
     object_initialize_with_type(data, size, type);
 }
 
+void object_initialize_child(Object *parentobj, const char *propname,
+                             void *childobj, size_t size, const char *type,
+                             Error **errp)
+{
+    object_initialize(childobj, size, type);
+    object_property_add_child(parentobj, propname, OBJECT(childobj), errp);
+    /*
+     * Since object_property_add_child added a reference to the child object,
+     * we can drop the reference added by object_initialize(), so the child
+     * property will own the only reference to the object.
+     */
+    object_unref(OBJECT(childobj));
+}
+
+
 static inline bool object_property_is_child(ObjectProperty *prop)
 {
     return strstart(prop->type, "child<", NULL);