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

[Michael S. Tsirkin]

On Tue, Apr 22, 2014 at 11:04:37AM +0200, Igor Mammedov wrote:
> On Sun, 20 Apr 2014 11:32:23 +0300
> "Michael S. Tsirkin" <address@hidden> wrote:
> 
> > 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?
> We need acpi_pcihp_get_bsel() since not every bus might have
> ACPI_PCIHP_PROP_BSEL, so blindly replacing it with object_property_get_int()
> would be wrong.

object_property_get_int returns -1 on failure or am I misreading the code?

> > 
> > 
> > > > @@ -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
> > > 
> > > -- 
> > > SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
> > > GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
> >