hw/core/vm-change-state-handler.c

   1 /*
   2  *  qdev vm change state handlers
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License,
   7  *  or (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include "qemu/osdep.h"
  19 #include "hw/qdev.h"
  20
  21 static int qdev_get_dev_tree_depth(DeviceState *dev)
  22 {
  23     int depth;
  24
  25     for (depth = 0; dev; depth++) {
  26         BusState *bus = dev->parent_bus;
  27
  28         if (!bus) {
  29             break;
  30         }
  31
  32         dev = bus->parent;
  33     }
  34
  35     return depth;
  36 }
  37
  38 /**
  39  * qdev_add_vm_change_state_handler:
  40  * @dev: the device that owns this handler
  41  * @cb: the callback function to be invoked
  42  * @opaque: user data passed to the callback function
  43  *
  44  * This function works like qemu_add_vm_change_state_handler() except callbacks
  45  * are invoked in qdev tree depth order.  Ordering is desirable when callbacks
  46  * of children depend on their parent's callback having completed first.
  47  *
  48  * For example, when qdev_add_vm_change_state_handler() is used, a host
  49  * controller's callback is invoked before the children on its bus when the VM
  50  * starts running.  The order is reversed when the VM stops running.
  51  *
  52  * Returns: an entry to be freed with qemu_del_vm_change_state_handler()
  53  */
  54 VMChangeStateEntry *qdev_add_vm_change_state_handler(DeviceState *dev,
  55                                                      VMChangeStateHandler *cb,
  56                                                      void *opaque)
  57 {
  58     int depth = qdev_get_dev_tree_depth(dev);
  59
  60     return qemu_add_vm_change_state_handler_prio(cb, opaque, depth);
  61 }