Re: [Qemu-arm] [Qemu-devel] [PATCH v2 10/16] hw/mips: Use object_initialize_child for correct reference 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:
> 
>  @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 Malta/Boston machines adopt the CPS child, and similarly
> the CPS adopts the ITU/CPC/GIC/GCR 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/mips/boston.c     |  4 ++--
>  hw/mips/cps.c        | 20 ++++++++------------
>  hw/mips/mips_malta.c |  4 ++--
>  3 files changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/mips/boston.c b/hw/mips/boston.c
> index cb3ea85fdc1..1ffccc8da92 100644
> --- a/hw/mips/boston.c
> +++ b/hw/mips/boston.c
> @@ -455,8 +455,8 @@ static void boston_mach_init(MachineState *machine)
>  
>      is_64b = cpu_supports_isa(machine->cpu_type, ISA_MIPS64);
>  
> -    object_initialize(&s->cps, sizeof(s->cps), TYPE_MIPS_CPS);
> -    qdev_set_parent_bus(DEVICE(&s->cps), sysbus_get_default());
> +    sysbus_init_child_obj(OBJECT(machine), "cps", OBJECT(&s->cps),
> +                          sizeof(s->cps), TYPE_MIPS_CPS);
>      object_property_set_str(OBJECT(&s->cps), machine->cpu_type, "cpu-type",
>                              &err);
>      object_property_set_int(OBJECT(&s->cps), smp_cpus, "num-vp", &err);
> diff --git a/hw/mips/cps.c b/hw/mips/cps.c
> index fc97f59af4c..649b35a76c5 100644
> --- a/hw/mips/cps.c
> +++ b/hw/mips/cps.c
> @@ -94,9 +94,8 @@ static void mips_cps_realize(DeviceState *dev, Error **errp)
>  
>      /* Inter-Thread Communication Unit */
>      if (itu_present) {
> -        object_initialize(&s->itu, sizeof(s->itu), TYPE_MIPS_ITU);
> -        qdev_set_parent_bus(DEVICE(&s->itu), sysbus_get_default());
> -
> +        sysbus_init_child_obj(OBJECT(dev), "itu", &s->itu, sizeof(s->itu),
> +                              TYPE_MIPS_ITU);
>          object_property_set_int(OBJECT(&s->itu), 16, "num-fifo", &err);
>          object_property_set_int(OBJECT(&s->itu), 16, "num-semaphores", &err);
>          object_property_set_bool(OBJECT(&s->itu), saar_present, 
> "saar-present",
> @@ -115,9 +114,8 @@ static void mips_cps_realize(DeviceState *dev, Error 
> **errp)
>      }
>  
>      /* Cluster Power Controller */
> -    object_initialize(&s->cpc, sizeof(s->cpc), TYPE_MIPS_CPC);
> -    qdev_set_parent_bus(DEVICE(&s->cpc), sysbus_get_default());
> -
> +    sysbus_init_child_obj(OBJECT(dev), "cpc", &s->cpc, sizeof(s->cpc),
> +                          TYPE_MIPS_CPC);
>      object_property_set_int(OBJECT(&s->cpc), s->num_vp, "num-vp", &err);
>      object_property_set_int(OBJECT(&s->cpc), 1, "vp-start-running", &err);
>      object_property_set_bool(OBJECT(&s->cpc), true, "realized", &err);
> @@ -130,9 +128,8 @@ static void mips_cps_realize(DeviceState *dev, Error 
> **errp)
>                              sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->cpc), 
> 0));
>  
>      /* Global Interrupt Controller */
> -    object_initialize(&s->gic, sizeof(s->gic), TYPE_MIPS_GIC);
> -    qdev_set_parent_bus(DEVICE(&s->gic), sysbus_get_default());
> -
> +    sysbus_init_child_obj(OBJECT(dev), "gic", &s->gic, sizeof(s->gic),
> +                          TYPE_MIPS_GIC);
>      object_property_set_int(OBJECT(&s->gic), s->num_vp, "num-vp", &err);
>      object_property_set_int(OBJECT(&s->gic), 128, "num-irq", &err);
>      object_property_set_bool(OBJECT(&s->gic), true, "realized", &err);
> @@ -147,9 +144,8 @@ static void mips_cps_realize(DeviceState *dev, Error 
> **errp)
>      /* Global Configuration Registers */
>      gcr_base = env->CP0_CMGCRBase << 4;
>  
> -    object_initialize(&s->gcr, sizeof(s->gcr), TYPE_MIPS_GCR);
> -    qdev_set_parent_bus(DEVICE(&s->gcr), sysbus_get_default());
> -
> +    sysbus_init_child_obj(OBJECT(dev), "gcr", &s->gcr, sizeof(s->gcr),
> +                          TYPE_MIPS_GCR);
>      object_property_set_int(OBJECT(&s->gcr), s->num_vp, "num-vp", &err);
>      object_property_set_int(OBJECT(&s->gcr), 0x800, "gcr-rev", &err);
>      object_property_set_int(OBJECT(&s->gcr), gcr_base, "gcr-base", &err);
> diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
> index 04f2117d71e..aff8464f2ac 100644
> --- a/hw/mips/mips_malta.c
> +++ b/hw/mips/mips_malta.c
> @@ -1151,8 +1151,8 @@ static void create_cps(MaltaState *s, const char 
> *cpu_type,
>  {
>      Error *err = NULL;
>  
> -    object_initialize(&s->cps, sizeof(s->cps), TYPE_MIPS_CPS);
> -    qdev_set_parent_bus(DEVICE(&s->cps), sysbus_get_default());
> +    sysbus_init_child_obj(OBJECT(s), "cps", OBJECT(&s->cps), sizeof(s->cps),
> +                          TYPE_MIPS_CPS);
>      object_property_set_str(OBJECT(&s->cps), cpu_type, "cpu-type", &err);
>      object_property_set_int(OBJECT(&s->cps), smp_cpus, "num-vp", &err);
>      object_property_set_bool(OBJECT(&s->cps), true, "realized", &err);
> 

Reviewed-by: Paolo Bonzini <address@hidden>