Re: [Qemu-devel] [PATCH qom-next v2 3/5] target-arm: Use parent classes for reset + realize

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jul 11, 2013 at 11:47:59AM +0200, Igor Mammedov wrote:
> On Thu, 11 Jul 2013 11:47:16 +1000
> peter.crosthwaite@xilinx.com wrote:
> 
> > From: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> > 
> > ARMCPUClass is only needed for parent-class abstract function access.
> > Just use parent classes for reset and realize access and remove
> > ARMCPUClass completely.
> > 
> > Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> > ---
> > 
> >  target-arm/cpu-qom.h | 20 --------------------
> >  target-arm/cpu.c     | 16 +++++++---------
> >  2 files changed, 7 insertions(+), 29 deletions(-)
> > 
> > diff --git a/target-arm/cpu-qom.h b/target-arm/cpu-qom.h
> > index ef6261f..bdad93a 100644
> > --- a/target-arm/cpu-qom.h
> > +++ b/target-arm/cpu-qom.h
> > @@ -24,28 +24,8 @@
> >  
> >  #define TYPE_ARM_CPU "arm-cpu"
> >  
> > -#define ARM_CPU_CLASS(klass) \
> > -    OBJECT_CLASS_CHECK(ARMCPUClass, (klass), TYPE_ARM_CPU)
> >  #define ARM_CPU(obj) \
> >      OBJECT_CHECK(ARMCPU, (obj), TYPE_ARM_CPU)
> > -#define ARM_CPU_GET_CLASS(obj) \
> > -    OBJECT_GET_CLASS(ARMCPUClass, (obj), TYPE_ARM_CPU)
> > -
> > -/**
> > - * ARMCPUClass:
> > - * @parent_realize: The parent class' realize handler.
> > - * @parent_reset: The parent class' reset handler.
> > - *
> > - * An ARM CPU model.
> > - */
> > -typedef struct ARMCPUClass {
> > -    /*< private >*/
> > -    CPUClass parent_class;
> > -    /*< public >*/
> > -
> > -    DeviceRealize parent_realize;
> > -    void (*parent_reset)(CPUState *cpu);
> > -} ARMCPUClass;
> >  
> >  /**
> >   * ARMCPU:
> > diff --git a/target-arm/cpu.c b/target-arm/cpu.c
> > index ed53df8..ad5ec7b 100644
> > --- a/target-arm/cpu.c
> > +++ b/target-arm/cpu.c
> > @@ -60,7 +60,8 @@ static void cp_reg_reset(gpointer key, gpointer value, gpointer opaque)
> >  static void arm_cpu_reset(CPUState *s)
> >  {
> >      ARMCPU *cpu = ARM_CPU(s);
> > -    ARMCPUClass *acc = ARM_CPU_GET_CLASS(cpu);
> > +    CPUClass *cc_parent =
> > +            CPU_CLASS(object_class_get_parent_by_name(TYPE_ARM_CPU));
> Maybe object_class_get_parent_of_type() would be less confusing?
> 
> This usage assumes that parent of TYPE_ARM_CPU is TYPE_CPU and if
> another TYPE_X added between them, it might break if TYPE_X doesn't
> re-implement this logic in its reset.

If what's needed is TYPE_CPU, you can just look up the class by name.

> Could reset be modeled like DEVICE.instance_init() instead? Then
> no explicit access to parent from child would be needed and it
> still leaves possibility to override resets if parent->child
> propagation order is not desirable for a particular device.
> 
> >      CPUARMState *env = &cpu->env;
> >  
> >      if (qemu_loglevel_mask(CPU_LOG_RESET)) {
> > @@ -68,7 +69,7 @@ static void arm_cpu_reset(CPUState *s)
> >          log_cpu_state(env, 0);
> >      }
> >  
> > -    acc->parent_reset(s);
> > +    cc_parent->reset(s);
> >  
> >      memset(env, 0, offsetof(CPUARMState, breakpoints));
> >      g_hash_table_foreach(cpu->cp_regs, cp_reg_reset, cpu);
> > @@ -158,7 +159,8 @@ static void arm_cpu_finalizefn(Object *obj)
> >  static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
> >  {
> >      ARMCPU *cpu = ARM_CPU(dev);
> > -    ARMCPUClass *acc = ARM_CPU_GET_CLASS(dev);
> > +    DeviceClass *dc_parent =
> > +            DEVICE_CLASS(object_class_get_parent_by_name(TYPE_ARM_CPU));
> >      CPUARMState *env = &cpu->env;
> >  
> >      /* Some features automatically imply others: */
> > @@ -209,7 +211,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
> >  
> >      cpu_reset(CPU(cpu));
> >  
> > -    acc->parent_realize(dev, errp);
> > +    dc_parent->realize(dev, errp);
> >  }
> >  
> >  /* CPU models */
> > @@ -803,14 +805,11 @@ static const ARMCPUInfo arm_cpus[] = {
> >  
> >  static void arm_cpu_class_init(ObjectClass *oc, void *data)
> >  {
> > -    ARMCPUClass *acc = ARM_CPU_CLASS(oc);
> > -    CPUClass *cc = CPU_CLASS(acc);
> > +    CPUClass *cc = CPU_CLASS(oc);
> >      DeviceClass *dc = DEVICE_CLASS(oc);
> >  
> > -    acc->parent_realize = dc->realize;
> >      dc->realize = arm_cpu_realizefn;
> >  
> > -    acc->parent_reset = cc->reset;
> >      cc->reset = arm_cpu_reset;
> >  
> >      cc->class_by_name = arm_cpu_class_by_name;
> > @@ -839,7 +838,6 @@ static const TypeInfo arm_cpu_type_info = {
> >      .instance_init = arm_cpu_initfn,
> >      .instance_finalize = arm_cpu_finalizefn,
> >      .abstract = true,
> > -    .class_size = sizeof(ARMCPUClass),
> >      .class_init = arm_cpu_class_init,
> >  };
> >