[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 1/2] spapr: introduce SPAPR_MACHINE_NOASSERT(
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] spapr: introduce SPAPR_MACHINE_NOASSERT() |
Date: |
Sun, 8 Oct 2017 21:05:37 +0100 |
On 8 October 2017 at 18:17, Greg Kurz <address@hidden> wrote:
> A spapr-cpu-core device can only be plugged into a pseries machine. This
> is checked in spapr_cpu_core_realize() with object_dynamic_cast() instead
> of the usual SPAPR_MACHINE() macro because we don't want QEMU to abort.
>
> This patch moves the gory details to a SPAPR_MACHINE_NOASSERT() macro
> that acts like the SPAPR_MACHINE() one, except it returns NULL instead
> of aborting if its argument doesn't point to a pseries machine type.
>
> This is done for two reasons:
> - it makes the code nicer
> - it may be used by other pseries-specific devices like PHBs for example
>
> Signed-off-by: Greg Kurz <address@hidden>
> ---
> hw/ppc/spapr_cpu_core.c | 7 +++----
> include/hw/ppc/spapr.h | 3 +++
> 2 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 37beb56e8b18..5fde07614218 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -199,7 +199,7 @@ error:
>
> static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
> {
> - sPAPRMachineState *spapr;
> + sPAPRMachineState *spapr = SPAPR_MACHINE_NOASSERT(qdev_get_machine());
> sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(dev));
> CPUCore *cc = CPU_CORE(OBJECT(dev));
> @@ -209,9 +209,8 @@ static void spapr_cpu_core_realize(DeviceState *dev,
> Error **errp)
> void *obj;
> int i, j;
>
> - spapr = (sPAPRMachineState *) qdev_get_machine();
> - if (!object_dynamic_cast((Object *) spapr, TYPE_SPAPR_MACHINE)) {
> - error_setg(errp, "spapr-cpu-core needs a pseries machine");
> + if (!spapr) {
> + error_setg(errp, TYPE_SPAPR_CPU_CORE " needs a pseries machine");
> return;
> }
>
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index c1b365f56431..4933da8083df 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -43,6 +43,9 @@ typedef struct sPAPRMachineClass sPAPRMachineClass;
> #define SPAPR_MACHINE_CLASS(klass) \
> OBJECT_CLASS_CHECK(sPAPRMachineClass, klass, TYPE_SPAPR_MACHINE)
>
> +#define SPAPR_MACHINE_NOASSERT(obj) \
> + ((sPAPRMachineState *) object_dynamic_cast(obj, TYPE_SPAPR_MACHINE))
> +
I don't think this is a great idea. Doing things with pointers
that might not be of the right type should be obvious, not hidden
under macros. An opencoded call to object_dynamic_cast is how the
rest of the codebase does this; it's a bit of a weird way
to write "isinstance()" but there you go. If we want to
improve the way we write this sort of thing we should do
so as a general improvement to the QOM APIs and conventions,
not just a single thing in SPAPR code.
thanks
-- PMM