ide: Fix memory leak in ide_register_restart_cb()

Fix a memory leak in ide_register_restart_cb() in hw/ide/core.c and add
idebus_unrealize() in hw/ide/qdev.c to have calls to
qemu_del_vm_change_state_handler() to deal with the dangling change
state handler during hot-unplugging ide devices which might lead to a
crash.

Signed-off-by: Ashijeet Acharya <ashijeetacharya@gmail.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1474995212-10580-1-git-send-email-ashijeetacharya@gmail.com
[Minor whitespace fix --js]
Signed-off-by: John Snow <jsnow@redhat.com>
(cherry picked from commit ca44141)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

hw/ide/core.c

@@ -2582,7 +2582,7 @@ static void ide_restart_cb(void *opaque, int running, RunState state)
 void ide_register_restart_cb(IDEBus *bus)
 {
     if (bus->dma->ops->restart_dma) {
-        qemu_add_vm_change_state_handler(ide_restart_cb, bus);
+        bus->vmstate = qemu_add_vm_change_state_handler(ide_restart_cb, bus);
     }
 }
 

hw/ide/qdev.c

@@ -31,6 +31,7 @@
 /* --------------------------------- */
 
 static char *idebus_get_fw_dev_path(DeviceState *dev);
+static void idebus_unrealize(DeviceState *qdev, Error **errp);
 
 static Property ide_props[] = {
     DEFINE_PROP_UINT32("unit", IDEDevice, unit, -1),
@@ -44,6 +45,15 @@ static void ide_bus_class_init(ObjectClass *klass, void *data)
     k->get_fw_dev_path = idebus_get_fw_dev_path;
 }
 
+static void idebus_unrealize(DeviceState *qdev, Error **errp)
+{
+    IDEBus *bus = DO_UPCAST(IDEBus, qbus, qdev->parent_bus);
+
+    if (bus->vmstate) {
+        qemu_del_vm_change_state_handler(bus->vmstate);
+    }
+}
+
 static const TypeInfo ide_bus_info = {
     .name = TYPE_IDE_BUS,
     .parent = TYPE_BUS,
@@ -345,6 +355,7 @@ static void ide_device_class_init(ObjectClass *klass, void *data)
     k->init = ide_qdev_init;
     set_bit(DEVICE_CATEGORY_STORAGE, k->categories);
     k->bus_type = TYPE_IDE_BUS;
+    k->unrealize = idebus_unrealize;
     k->props = ide_props;
 }
 

include/hw/ide/internal.h

@@ -482,6 +482,7 @@ struct IDEBus {
     uint32_t retry_nsector;
     PortioList portio_list;
     PortioList portio2_list;
+    VMChangeStateEntry *vmstate;
 };
 
 #define TYPE_IDE_DEVICE "ide-device"