[Qemu-devel] [PATCH v2 2/5] qdev: add the HotUnpluggable handler

[Greg Kurz]

This handler allows to ask a device instance if it can be hot-unplugged. It
is to be defined in device classes where hot-unpluggability depends on the
device state (for example, virtio-9p devices cannot be unplugged if the 9p
share is mounted in the guest).

Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
---
 hw/core/qdev.c         |    4 ++++
 include/hw/qdev-core.h |    4 ++++
 2 files changed, 8 insertions(+)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 4ab04aa31e78..2b2339c7c6ad 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -287,6 +287,10 @@ void qdev_unplug(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (dc->unpluggable && !dc->unpluggable(dev, errp)) {
+        return;
+    }
+
     qdev_hot_removed = true;
 
     hotplug_ctrl = qdev_get_hotplug_handler(dev);
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 038b54d94b27..5df0db1a5b68 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -38,6 +38,7 @@ typedef void (*DeviceRealize)(DeviceState *dev, Error **errp);
 typedef void (*DeviceUnrealize)(DeviceState *dev, Error **errp);
 typedef void (*BusRealize)(BusState *bus, Error **errp);
 typedef void (*BusUnrealize)(BusState *bus, Error **errp);
+typedef bool (*HotUnpluggable)(DeviceState *dev, Error **errp);
 
 struct VMStateDescription;
 
@@ -48,6 +49,8 @@ struct VMStateDescription;
  * property is changed to %true. The default invokes @init if not %NULL.
  * @unrealize: Callback function invoked when the #DeviceState:realized
  * property is changed to %false.
+ * @unpluggable: Callback function invoked by qdev_unplug(). Return %false
+ * to block hotunplug.
  * @init: Callback function invoked when the #DeviceState::realized property
  * is changed to %true. Deprecated, new types inheriting directly from
  * TYPE_DEVICE should use @realize instead, new leaf types should consult
@@ -120,6 +123,7 @@ typedef struct DeviceClass {
     void (*reset)(DeviceState *dev);
     DeviceRealize realize;
     DeviceUnrealize unrealize;
+    HotUnpluggable unpluggable;
 
     /* device state */
     const struct VMStateDescription *vmsd;