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virtio-9p-device: add minimal unrealize handler 

Since commit 4652f1640e "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 <gkurz@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20151208155457.27775.69441.stgit@bahia.huguette.org
[PMM: rewrapped long lines in commit message]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Greg Kurz 2015-12-08 16:54:57 +01:00 committed by Peter Maydell
parent c3626ca7df
commit 6cecf09373
1 changed files with 12 additions and 0 deletions
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12
hw/9pfs/virtio-9p-device.c
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@ -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;
}