On Wed, Jan 28, 2015 at 11:00:23AM +0100, Igor Mammedov wrote:
> On Wed, 28 Jan 2015 09:56:26 +0200
> "Michael S. Tsirkin" <m...@redhat.com> wrote:
>
> > > I've tried redo series with passing alloc list as first argument,
> > > looks ugly as hell
> >
> > I tried too. Not too bad at all. See below:
> >
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index f66da5d..820504a 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -491,14 +491,14 @@ static void acpi_set_pci_info(void)
> > }
> > }
> >
> > -static void build_append_pcihp_notify_entry(AcpiAml *method, int slot)
> > +static void build_append_pcihp_notify_entry(AmlPool *p, AcpiAml *method,
> > int slot)
> > {
> > - AcpiAml if_ctx;
> > + AcpiAml *if_ctx;
> > int32_t devfn = PCI_DEVFN(slot, 0);
> >
> > - if_ctx = acpi_if(acpi_and(acpi_arg0(), acpi_int(0x1U << slot)));
> > - aml_append(&if_ctx, acpi_notify(acpi_name("S%.02X", devfn),
> > acpi_arg1()));
> > - aml_append(method, if_ctx);
> > + if_ctx = acpi_if(p, acpi_and(p, acpi_arg0(), acpi_int(p, 0x1U <<
> > slot)));
> > + aml_append(p, if_ctx, acpi_notify(p, acpi_name(p, "S%.02X", devfn),
> > acpi_arg1(p)));
> > + aml_append(p, method, if_ctx);
> > }
> >
> > static void build_append_pci_bus_devices(AcpiAml *parent_scope, PCIBus
> > *bus,
> >
> > What exactly is the problem? A tiny bit more verbose but the lifetime
> > of all objects is now explicit.
> every usage of aml_foo()/build_append_pcihp_notify_entry() tags along
> extra pointer which is not really necessary for user to know.
It's necessary to make memory management explicit. Consider:
alloc_pool();
acpi_arg0();
free_pool();
acpi_arg1();
Looks ok but isn't because acpi_arg1 silently allocates memory.
p = alloc_pool();
acpi_arg0(p);
free_pool(p);
acpi_arg1(p);
It's obvious what's wrong here: p is used after it's freed.
Come on, it's 3 characters per call. I think it's a reasonable
compromize.
--
MST
