Re: [PATCH v2 1/1] core/register: Specify instance_size in the TypeInfo

[Eduardo Habkost <ehabkost@redhat.com>]

On Tue, Aug 25, 2020 at 10:30:59AM -0700, Alistair Francis wrote:
> Reported-by: Eduardo Habkost <ehabkost@redhat.com>
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  hw/core/register.c | 31 +++++++++++++------------------
>  1 file changed, 13 insertions(+), 18 deletions(-)
> 
> diff --git a/hw/core/register.c b/hw/core/register.c
> index ddf91eb445..31038bd7cc 100644
> --- a/hw/core/register.c
> +++ b/hw/core/register.c
> @@ -176,17 +176,6 @@ void register_reset(RegisterInfo *reg)
>      }
>  }
>  
> -void register_init(RegisterInfo *reg)
> -{
> -    assert(reg);
> -
> -    if (!reg->data || !reg->access) {
> -        return;
> -    }
> -
> -    object_initialize((void *)reg, sizeof(*reg), TYPE_REGISTER);
> -}
> -
>  void register_write_memory(void *opaque, hwaddr addr,
>                             uint64_t value, unsigned size)
>  {
> @@ -269,13 +258,18 @@ static RegisterInfoArray *register_init_block(DeviceState *owner,
>          int index = rae[i].addr / data_size;
>          RegisterInfo *r = &ri[index];
>  
> -        *r = (RegisterInfo) {
> -            .data = data + data_size * index,
> -            .data_size = data_size,
> -            .access = &rae[i],
> -            .opaque = owner,
> -        };
> -        register_init(r);
> +        if (data + data_size * index == 0 || !&rae[i]) {

Do you know what's the goal of this check?

Can `data` or `rae` be NULL?  If not, it seems impossible for
this condition to be true.  If they can, this seems to be a weird
and fragile way of checking for NULL arguments.

> +            continue;
> +        }
> +
> +        /* Init the register, this will zero it. */
> +        object_initialize((void *)r, sizeof(*r), TYPE_REGISTER);
> +
> +        /* Set the properties of the register */
> +        r->data = data + data_size * index;
> +        r->data_size = data_size;
> +        r->access = &rae[i];
> +        r->opaque = owner;
>  
>          r_array->r[i] = r;
>      }
> @@ -329,6 +323,7 @@ static const TypeInfo register_info = {
>      .name  = TYPE_REGISTER,
>      .parent = TYPE_DEVICE,
>      .class_init = register_class_init,
> +    .instance_size = sizeof(RegisterInfo),
>  };
>  
>  static void register_register_types(void)
> -- 
> 2.28.0
> 

-- 
Eduardo