Re: [Qemu-devel] [PATCH 22/22] core/sysbus: remove the SysBusDeviceClass::initpath

[maozy]

Hi, Eduardo

On 11/20/18 7:31 AM, Eduardo Habkost wrote:
> On Mon, Nov 19, 2018 at 08:08:20PM +0800, Mao Zhongyi wrote:
> > Currently, all sysbus devices have been converted to realize(),
> > so remove this path.
> >
> > Cc: address@hidden
> > Cc: address@hidden
> > Cc: address@hidden
> > Cc: address@hidden
> > Cc: address@hidden
> > Cc: address@hidden
> > Cc: address@hidden
> >
> > Signed-off-by: Mao Zhongyi <address@hidden>
> > Signed-off-by: Zhang Shengju <address@hidden>
> > ---
> >   hw/core/sysbus.c    | 15 ---------------
> >   include/hw/sysbus.h |  3 ---
> >   2 files changed, 18 deletions(-)
> >
> > diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c
> > index 7ac36ad3e7..030ad426c1 100644
> > --- a/hw/core/sysbus.c
> > +++ b/hw/core/sysbus.c
> > @@ -201,20 +201,6 @@ void sysbus_init_ioports(SysBusDevice *dev, uint32_t 
> > ioport, uint32_t size)
> >       }
> >   }
> >   
> > -/* TODO remove once all sysbus devices have been converted to realize */
> > -static void sysbus_realize(DeviceState *dev, Error **errp)
> > -{
> > -    SysBusDevice *sd = SYS_BUS_DEVICE(dev);
> > -    SysBusDeviceClass *sbc = SYS_BUS_DEVICE_GET_CLASS(sd);
> > -
> > -    if (!sbc->init) {
> > -        return;
> > -    }
> > -    if (sbc->init(sd) < 0) {
> > -        error_setg(errp, "Device initialization failed");
> > -    }
> > -}
>
> Nice.  :)
>
>
> > -
> >   DeviceState *sysbus_create_varargs(const char *name,
> >                                      hwaddr addr, ...)
> >   {
> > @@ -327,7 +313,6 @@ MemoryRegion *sysbus_address_space(SysBusDevice *dev)
> >   static void sysbus_device_class_init(ObjectClass *klass, void *data)
> >   {
> >       DeviceClass *k = DEVICE_CLASS(klass);
> > -    k->realize = sysbus_realize;
>
> Have you ensured this won't break any subclasses that
> saved the original realize function on a parent_realize field?

Thanks for the catch.

> Now they will have parent_realize set to NULL.

In order to void the subclasses whose parent_realize field is
set to NULL, the k->realize function must be retained even
though it doesn't do anything practical. Just like this:


-/* TODO remove once all sysbus devices have been converted to realize*/
 static void sysbus_realize(DeviceState *dev, Error **errp)
 {
-    SysBusDevice *sd = SYS_BUS_DEVICE(dev);
-    SysBusDeviceClass *sbc = SYS_BUS_DEVICE_GET_CLASS(sd);
-
-    if (!sbc->init) {
-        return;
-    }
-    if (sbc->init(sd) < 0) {
-        error_setg(errp, "Device initialization failed");
-    }
 }

it doesn't look elegant, but I didn't think of a better way, if you
can give me some hints, I really appreciate it. :)

Thanks,
Mao


> Most of them use device_class_set_parent_realize() to implement
> that.
>
> >       k->bus_type = TYPE_SYSTEM_BUS;
> >       /*
> >        * device_add plugs devices into a suitable bus.  For "real" buses,
> > diff --git a/include/hw/sysbus.h b/include/hw/sysbus.h
> > index 0b59a3b8d6..1aedcf05c9 100644
> > --- a/include/hw/sysbus.h
> > +++ b/include/hw/sysbus.h
> > @@ -38,9 +38,6 @@ typedef struct SysBusDevice SysBusDevice;
> >   typedef struct SysBusDeviceClass {
> >       /*< private >*/
> >       DeviceClass parent_class;
> > -    /*< public >*/
> > -
> > -    int (*init)(SysBusDevice *dev);
> >   
> >       /*
> >        * Let the sysbus device format its own non-PIO, non-MMIO unit address.
> > --
> > 2.17.1