qdev: add qdev_add_vm_change_state_handler()

Children sometimes depend on their parent's vm change state handler
having completed.  Add a vm change state handler API for devices that
guarantees tree depth ordering.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-06-20 18:37:08 +01:00 committed by Kevin Wolf
parent 60dbc5a1c5
commit e965ffa70a
3 changed files with 67 additions and 0 deletions

View file

@ -7,6 +7,7 @@ common-obj-$(CONFIG_SOFTMMU) += fw-path-provider.o
common-obj-y += irq.o
common-obj-y += hotplug.o
common-obj-$(CONFIG_SOFTMMU) += nmi.o
common-obj-$(CONFIG_SOFTMMU) += vm-change-state-handler.o
common-obj-$(CONFIG_EMPTY_SLOT) += empty_slot.o
common-obj-$(CONFIG_XILINX_AXI) += stream.o

View file

@ -0,0 +1,61 @@
/*
* qdev vm change state handlers
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License,
* or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "hw/qdev.h"
static int qdev_get_dev_tree_depth(DeviceState *dev)
{
int depth;
for (depth = 0; dev; depth++) {
BusState *bus = dev->parent_bus;
if (!bus) {
break;
}
dev = bus->parent;
}
return depth;
}
/**
* qdev_add_vm_change_state_handler:
* @dev: the device that owns this handler
* @cb: the callback function to be invoked
* @opaque: user data passed to the callback function
*
* This function works like qemu_add_vm_change_state_handler() except callbacks
* are invoked in qdev tree depth order. Ordering is desirable when callbacks
* of children depend on their parent's callback having completed first.
*
* For example, when qdev_add_vm_change_state_handler() is used, a host
* controller's callback is invoked before the children on its bus when the VM
* starts running. The order is reversed when the VM stops running.
*
* Returns: an entry to be freed with qemu_del_vm_change_state_handler()
*/
VMChangeStateEntry *qdev_add_vm_change_state_handler(DeviceState *dev,
VMChangeStateHandler *cb,
void *opaque)
{
int depth = qdev_get_dev_tree_depth(dev);
return qemu_add_vm_change_state_handler_prio(cb, opaque, depth);
}

View file

@ -6,6 +6,7 @@
#include "qom/object.h"
#include "hw/irq.h"
#include "hw/hotplug.h"
#include "sysemu/sysemu.h"
enum {
DEV_NVECTORS_UNSPECIFIED = -1,
@ -450,4 +451,8 @@ static inline bool qbus_is_hotpluggable(BusState *bus)
void device_listener_register(DeviceListener *listener);
void device_listener_unregister(DeviceListener *listener);
VMChangeStateEntry *qdev_add_vm_change_state_handler(DeviceState *dev,
VMChangeStateHandler *cb,
void *opaque);
#endif