Re: [Qemu-devel] [PATCH 1/4] Replace acpi_pcihp_get_bsel with generic object_property_get_int

[Michael S. Tsirkin]

On Fri, Apr 18, 2014 at 06:30:37PM +0200, Andreas Färber wrote:
> Am 18.04.2014 15:41, schrieb Kirill Batuzov:
> > acpi_pcihp_get_bsel implements functionality of object_property_get_int for
> > specific property named ACPI_PCIHP_PROP_BSEL, but fails to decrement 
> > object's
> > reference counter properly. Replacing it with generic 
> > object_property_get_int
> > serves two purposes: reducing code duplication and fixing memory leak.
> > 
> > Signed-off-by: Kirill Batuzov <address@hidden>
> > ---
> >  hw/acpi/pcihp.c |   23 ++++++-----------------
> >  1 file changed, 6 insertions(+), 17 deletions(-)
> > 
> > diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
> > index f80c480..ff44aec 100644
> > --- a/hw/acpi/pcihp.c
> > +++ b/hw/acpi/pcihp.c
> > @@ -61,24 +61,11 @@ typedef struct AcpiPciHpFind {
> >      PCIBus *bus;
> >  } AcpiPciHpFind;
> >  
> > -static int acpi_pcihp_get_bsel(PCIBus *bus)
> > -{
> > -    QObject *o = object_property_get_qobject(OBJECT(bus),
> > -                                             ACPI_PCIHP_PROP_BSEL, NULL);
> > -    int64_t bsel = -1;
> > -    if (o) {
> > -        bsel = qint_get_int(qobject_to_qint(o));
> > -    }
> > -    if (bsel < 0) {
> > -        return -1;
> > -    }
> > -    return bsel;
> > -}
> > -
> >  static void acpi_pcihp_test_hotplug_bus(PCIBus *bus, void *opaque)
> >  {
> >      AcpiPciHpFind *find = opaque;
> > -    if (find->bsel == acpi_pcihp_get_bsel(bus)) {
> > +    if (find->bsel == object_property_get_int(OBJECT(bus),
> > +                                              ACPI_PCIHP_PROP_BSEL, NULL)) 
> > {
> >          find->bus = bus;
> >      }
> >  }
> 
> I note that the wrapper function was changing negative values up to be
> -1, which is getting dropped here. Not sure if it matters.

I think this was to ensure that we don't get an overflow.
I'm not sure why didn't I validate against ACPI_PCIHP_MAX_HOTPLUG_BUS
too.
How about making acpi_pcihp_get_bsel call object_property_get_int
and validate that value is between 0 and ACPI_PCIHP_MAX_HOTPLUG_BUS?


> > @@ -185,7 +172,8 @@ void acpi_pcihp_device_plug_cb(ACPIREGS *ar, qemu_irq 
> > irq, AcpiPciHpState *s,
> >  {
> >      PCIDevice *pdev = PCI_DEVICE(dev);
> >      int slot = PCI_SLOT(pdev->devfn);
> > -    int bsel = acpi_pcihp_get_bsel(pdev->bus);
> > +    int bsel = object_property_get_int(OBJECT(pdev->bus),
> > +                                       ACPI_PCIHP_PROP_BSEL, NULL);
> >      if (bsel < 0) {
> >          error_setg(errp, "Unsupported bus. Bus doesn't have property '"
> >                     ACPI_PCIHP_PROP_BSEL "' set");
> > @@ -210,7 +198,8 @@ void acpi_pcihp_device_unplug_cb(ACPIREGS *ar, qemu_irq 
> > irq, AcpiPciHpState *s,
> >  {
> >      PCIDevice *pdev = PCI_DEVICE(dev);
> >      int slot = PCI_SLOT(pdev->devfn);
> > -    int bsel = acpi_pcihp_get_bsel(pdev->bus);
> > +    int bsel = object_property_get_int(OBJECT(pdev->bus),
> > +                                       ACPI_PCIHP_PROP_BSEL, NULL);
> >      if (bsel < 0) {
> >          error_setg(errp, "Unsupported bus. Bus doesn't have property '"
> >                     ACPI_PCIHP_PROP_BSEL "' set");
> 
> These ones seem to just check for < 0, so look okay from reading the
> patch. CC'ing mst.

Hmm int is 32 bit and object_property_get_int can return a 64 bit one.

> The alternative would be to leave the wrapper around and just replace
> the ..._get_qobject() with the ..._get_int() inside.

Yes, I'd prefer that, and extra validation there too.

> Regards,
> Andreas
> 
> -- 
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