The problem
-----------
QOM has a data model where class struct data is static: class
structs are initialized at class_init, and never changed again.
...except for a few rare cases where class data is changed
outside class_init. Those cases are:
qbus_realize(), code added by:
commit 61de36761b565a4138d8ad7ec75489ab28fe84b6
Date: Thu Feb 6 16:08:15 2014 +0100
qdev: Keep global allocation counter per bus
mips_jazz_init(), code added by:
commit 54e755588cf1e90f0b1460c4e8e6b6a54b6d3a32
Date: Mon Nov 4 23:26:17 2013 +0100
mips jazz: do not raise data bus exception when accessing invalid
addresses
xen_set_dynamic_sysbus(), code added by:
commit 3a6c9172ac5951e6dac2b3f6cbce3cfccdec5894
Date: Tue Nov 22 07:10:58 2016 +0100
xen: create qdev for each backend device
s390_cpu_realizefn(), code added by:
commit c6644fc88bed1176f67b4b7a9df691bcf25c0c5b
Date: Fri Mar 4 12:34:31 2016 -0500
s390x/cpu: Get rid of side effects when creating a vcpu
I want to prevent that from happening again.
Proposal
--------
I propose we make object_get_class() and *_GET_CLASS macros
return const pointers. This way, anybody willing to change class
structs outside class_init will (hopefully) be aware that they
are doing something unexpected.
This would be very simple and trivial, except that:
* OBJECT_CLASS_CHECK cast its return value to a different
(non-const) pointer type.
* OBJECT_CLASS_CHECK-based macros are used everywhere to
cast class pointers to different class types.
I have addressed this problem using C11's _Generic keyword.
_Generic allows us to make OBJECT_CLASS_CHECK and other macros
return a const pointer if its argument is a const pointer, and a
non-const pointer otherwise.
This series changes OBJECT_CLASS, OBJECT_CLASS_CHECK,
object_class_dynamic_cast_assert(), object_class_dynamic_cast(),
and object_class_get_parent() to exhibit this const-aware
behavior.
If the compiler doesn't support _Generic, we keep the old
behavior, and the cast macros will keep returning non-const
pointers.
---
Cc: Alexander Graf <ag...@suse.de>
Cc: Hervé Poussineau <hpous...@reactos.org>
Cc: Juergen Gross <jgr...@suse.com>
Cc: Matthew Rosato <mjros...@linux.vnet.ibm.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
Cc: Igor Mammedov <imamm...@redhat.com>
Cc: Andreas Färber <afaer...@suse.de>
Eduardo Habkost (9):
configure: test if _Generic works as expected
Simplify code using *MACHINE_GET_CLASS
qom: QUALIFIED_CAST helper macro
qom: Make object_class_get_parent() const-aware
Make class parameter const at some functions
Explicitly cast the *_GET_CLASS() value when we break the rules
Use const variables for *_GET_CLASS values
qom: Make class cast macros/functions const-aware
qom: Make object_get_class() return const pointer
configure | 20 +++++++++
include/qom/cpu.h | 12 +++---
include/qom/object.h | 94 ++++++++++++++++++++++++++++++++++-------
target/ppc/mmu-book3s-v3.h | 2 +-
target/ppc/mmu-hash64.h | 2 +-
target/s390x/cpu.h | 2 +-
backends/cryptodev.c | 10 ++---
backends/hostmem.c | 2 +-
backends/rng.c | 4 +-
backends/tpm.c | 28 ++++++------
chardev/char-mux.c | 2 +-
chardev/char.c | 10 ++---
cpu-exec.c | 14 +++---
device-hotplug.c | 2 +-
disas.c | 4 +-
exec.c | 6 +--
gdbstub.c | 12 +++---
hmp.c | 4 +-
hw/acpi/acpi_interface.c | 2 +-
hw/acpi/cpu.c | 8 ++--
hw/acpi/cpu_hotplug.c | 4 +-
hw/acpi/ipmi.c | 2 +-
hw/acpi/memory_hotplug.c | 2 +-
hw/acpi/nvdimm.c | 4 +-
hw/acpi/pcihp.c | 4 +-
hw/arm/aspeed.c | 2 +-
hw/arm/aspeed_soc.c | 4 +-
hw/arm/boot.c | 2 +-
hw/arm/exynos4_boards.c | 2 +-
hw/arm/vexpress.c | 2 +-
hw/arm/virt-acpi-build.c | 6 +--
hw/arm/virt.c | 6 +--
hw/audio/cs4231a.c | 10 ++---
hw/audio/gus.c | 6 +--
hw/audio/intel-hda.c | 8 ++--
hw/audio/sb16.c | 6 +--
hw/block/dataplane/virtio-blk.c | 6 +--
hw/block/fdc.c | 8 ++--
hw/block/m25p80.c | 2 +-
hw/char/serial-pci.c | 2 +-
hw/char/virtio-console.c | 6 +--
hw/char/virtio-serial-bus.c | 18 ++++----
hw/core/bus.c | 4 +-
hw/core/fw-path-provider.c | 2 +-
hw/core/generic-loader.c | 2 +-
hw/core/hotplug.c | 8 ++--
hw/core/loader.c | 4 +-
hw/core/machine.c | 5 +--
hw/core/nmi.c | 2 +-
hw/core/qdev-properties.c | 4 +-
hw/core/qdev.c | 32 +++++++-------
hw/core/stream.c | 4 +-
hw/core/sysbus.c | 6 +--
hw/display/cirrus_vga.c | 2 +-
hw/i2c/core.c | 10 ++---
hw/i2c/smbus.c | 8 ++--
hw/i386/acpi-build.c | 16 +++----
hw/i386/kvm/i8254.c | 2 +-
hw/i386/kvm/i8259.c | 2 +-
hw/i386/pc.c | 32 +++++++-------
hw/i386/pc_piix.c | 4 +-
hw/i386/pc_q35.c | 4 +-
hw/i386/x86-iommu.c | 2 +-
hw/ide/microdrive.c | 4 +-
hw/ide/qdev.c | 2 +-
hw/input/adb.c | 6 +--
hw/input/virtio-input.c | 12 +++---
hw/intc/apic_common.c | 26 ++++++------
hw/intc/arm_gic.c | 2 +-
hw/intc/arm_gic_common.c | 4 +-
hw/intc/arm_gic_kvm.c | 4 +-
hw/intc/arm_gicv3.c | 2 +-
hw/intc/arm_gicv3_common.c | 4 +-
hw/intc/arm_gicv3_its_common.c | 6 +--
hw/intc/arm_gicv3_kvm.c | 4 +-
hw/intc/i8259.c | 2 +-
hw/intc/i8259_common.c | 4 +-
hw/intc/ioapic_common.c | 6 +--
hw/intc/xics.c | 26 ++++++------
hw/ipack/ipack.c | 4 +-
hw/ipack/tpci200.c | 12 +++---
hw/ipmi/ipmi_bmc_extern.c | 12 +++---
hw/ipmi/ipmi_bmc_sim.c | 24 +++++------
hw/ipmi/isa_ipmi_bt.c | 22 +++++-----
hw/ipmi/isa_ipmi_kcs.c | 20 ++++-----
hw/mem/pc-dimm.c | 10 ++---
hw/mips/mips_jazz.c | 2 +-
hw/misc/imx_ccm.c | 2 +-
hw/net/e1000.c | 2 +-
hw/net/vhost_net.c | 4 +-
hw/net/vmxnet3.c | 2 +-
hw/nvram/fw_cfg.c | 2 +-
hw/pci-bridge/pcie_root_port.c | 8 ++--
hw/pci/pci.c | 17 ++++----
hw/pcmcia/pxa2xx.c | 16 +++----
hw/ppc/pnv.c | 14 +++---
hw/ppc/pnv_core.c | 2 +-
hw/ppc/pnv_xscom.c | 6 +--
hw/ppc/prep.c | 8 ++--
hw/ppc/spapr.c | 50 +++++++++++-----------
hw/ppc/spapr_cpu_core.c | 4 +-
hw/ppc/spapr_drc.c | 20 ++++-----
hw/ppc/spapr_events.c | 6 +--
hw/ppc/spapr_hcall.c | 2 +-
hw/ppc/spapr_pci.c | 14 +++---
hw/ppc/spapr_rtas.c | 8 ++--
hw/ppc/spapr_vio.c | 12 +++---
hw/s390x/css-bridge.c | 2 +-
hw/s390x/css.c | 6 +--
hw/s390x/event-facility.c | 14 +++---
hw/s390x/s390-skeys-kvm.c | 2 +-
hw/s390x/s390-skeys.c | 8 ++--
hw/s390x/s390-virtio-ccw.c | 8 ++--
hw/s390x/sclp.c | 10 ++---
hw/s390x/virtio-ccw.c | 12 +++---
hw/scsi/megasas.c | 8 ++--
hw/scsi/mptconfig.c | 6 +--
hw/scsi/scsi-bus.c | 8 ++--
hw/scsi/vhost-scsi.c | 4 +-
hw/scsi/virtio-scsi-dataplane.c | 6 +--
hw/scsi/vmw_pvscsi.c | 2 +-
hw/sd/core.c | 18 ++++----
hw/sh4/sh7750.c | 2 +-
hw/smbios/smbios_type_38.c | 2 +-
hw/sparc/sun4m.c | 2 +-
hw/sparc64/sun4u.c | 2 +-
hw/ssi/aspeed_smc.c | 2 +-
hw/ssi/ssi.c | 8 ++--
hw/ssi/xilinx_spips.c | 2 +-
hw/timer/i8254.c | 2 +-
hw/timer/i8254_common.c | 10 ++---
hw/timer/m48t59-isa.c | 2 +-
hw/timer/m48t59.c | 2 +-
hw/usb/bus.c | 32 +++++++-------
hw/usb/dev-smartcard-reader.c | 8 ++--
hw/usb/hcd-ehci-pci.c | 2 +-
hw/usb/hcd-ehci-sysbus.c | 2 +-
hw/usb/hcd-uhci.c | 2 +-
hw/vfio/amd-xgbe.c | 2 +-
hw/vfio/calxeda-xgmac.c | 2 +-
hw/virtio/vhost-vsock.c | 4 +-
hw/virtio/vhost.c | 2 +-
hw/virtio/virtio-bus.c | 24 +++++------
hw/virtio/virtio-mmio.c | 2 +-
hw/virtio/virtio-pci.c | 20 ++++-----
hw/virtio/virtio.c | 62 +++++++++++++--------------
hw/xen/xen_backend.c | 3 +-
io/channel.c | 20 ++++-----
kvm-all.c | 2 +-
migration/migration.c | 2 +-
migration/savevm.c | 2 +-
monitor.c | 2 +-
net/filter.c | 6 +--
qdev-monitor.c | 12 +++---
qmp.c | 4 +-
qom/cpu.c | 26 ++++++------
qom/object.c | 31 +++++++-------
qom/object_interfaces.c | 4 +-
target/alpha/cpu.c | 2 +-
target/arm/cpu.c | 8 ++--
target/arm/kvm.c | 2 +-
target/cris/cpu.c | 10 ++---
target/cris/helper.c | 2 +-
target/hppa/cpu.c | 2 +-
target/i386/cpu.c | 10 ++---
target/i386/kvm.c | 2 +-
target/i386/machine.c | 3 +-
target/lm32/cpu.c | 4 +-
target/lm32/gdbstub.c | 2 +-
target/m68k/cpu.c | 4 +-
target/microblaze/cpu.c | 4 +-
target/microblaze/gdbstub.c | 2 +-
target/mips/cpu.c | 4 +-
target/moxie/cpu.c | 4 +-
target/nios2/cpu.c | 8 ++--
target/openrisc/cpu.c | 4 +-
target/openrisc/gdbstub.c | 2 +-
target/ppc/arch_dump.c | 2 +-
target/ppc/compat.c | 4 +-
target/ppc/excp_helper.c | 2 +-
target/ppc/mmu-hash64.c | 6 +--
target/ppc/mmu_helper.c | 2 +-
target/ppc/translate_init.c | 14 +++---
target/s390x/cpu.c | 6 +--
target/s390x/cpu_models.c | 4 +-
target/s390x/kvm.c | 4 +-
target/s390x/mem_helper.c | 6 +--
target/s390x/misc_helper.c | 6 +--
target/s390x/mmu_helper.c | 2 +-
target/sh4/cpu.c | 4 +-
target/sparc/cpu.c | 4 +-
target/tilegx/cpu.c | 4 +-
target/tricore/cpu.c | 4 +-
target/unicore32/cpu.c | 2 +-
target/xtensa/cpu.c | 6 +--
tests/check-qom-interface.c | 2 +-
user-exec.c | 2 +-
vl.c | 2 +-
198 files changed, 800 insertions(+), 721 deletions(-)
--
2.11.0.259.g40922b1
