[Qemu-devel] [PATCH 28/37] virtio-blk: fix unplug + virsh reboot

[Michael Roth <mdroth@linux.vnet.ibm.com>]

From: Christian Borntraeger <borntraeger@de.ibm.com>

virtio-blk registers a vmstate change handler. Unfortunately this
handler is not unregistered on unplug, leading to some random
crashes if the system is restarted, e.g. via virsh reboot.
Lets unregister the vmstate change handler if the device is removed.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 69b302b2044a9a0f6d157d25b39a91ff7124c61f)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/virtio-blk.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 34913ee..f5e6ee9 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -36,6 +36,7 @@ typedef struct VirtIOBlock
     VirtIOBlkConf *blk;
     unsigned short sector_mask;
     DeviceState *qdev;
+    VMChangeStateEntry *change;
 #ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
     VirtIOBlockDataPlane *dataplane;
 #endif
@@ -681,7 +682,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
     }
 #endif
 
-    qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
+    s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
     s->qdev = dev;
     register_savevm(dev, "virtio-blk", virtio_blk_id++, 2,
                     virtio_blk_save, virtio_blk_load, s);
@@ -702,6 +703,7 @@ void virtio_blk_exit(VirtIODevice *vdev)
     virtio_blk_data_plane_destroy(s->dataplane);
     s->dataplane = NULL;
 #endif
+    qemu_del_vm_change_state_handler(s->change);
     unregister_savevm(s->qdev, "virtio-blk", s);
     blockdev_mark_auto_del(s->bs);
     virtio_cleanup(vdev);
-- 
1.7.9.5