[Qemu-devel] [PATCH for-2.5] virtio-9p-device: add minimal unrealize handler

[Greg Kurz]

Since commit 4652f1640e029e1f2433fa77ba6af285 "virtio-9p: add savevm handlers",
if the user hot-unplugs a quiescent 9p device and live migrates, the source
QEMU crashes before migration completetion... This happens because virtio-9p
devices have a realize handler which calls virtio_init() and register_savevm().
Both calls store pointers to the device internals, that get dereferenced during
migration even if the device got unplugged.

This patch simply adds an unrealize handler to perform minimal cleanup and
avoid the crash. Hot unplug of non-quiescent 9p devices is still not supported
in QEMU, and not supported by linux guests either.

Signed-off-by: Greg Kurz <address@hidden>
---
 hw/9pfs/virtio-9p-device.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index 944b5f5e9fcc..b42d3b30a027 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -145,6 +145,17 @@ out:
     v9fs_path_free(&path);
 }
 
+static void virtio_9p_device_unrealize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    V9fsState *s = VIRTIO_9P(dev);
+
+    virtio_cleanup(vdev);
+    unregister_savevm(dev, "virtio-9p", s);
+    g_free(s->ctx.fs_root);
+    g_free(s->tag);
+}
+
 /* virtio-9p device */
 
 static Property virtio_9p_properties[] = {
@@ -161,6 +172,7 @@ static void virtio_9p_class_init(ObjectClass *klass, void 
*data)
     dc->props = virtio_9p_properties;
     set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
     vdc->realize = virtio_9p_device_realize;
+    vdc->unrealize = virtio_9p_device_unrealize;
     vdc->get_features = virtio_9p_get_features;
     vdc->get_config = virtio_9p_get_config;
 }