Virtio wants to release used indices after the corresponding
virtio device has been unregistered. However, virtio does not
hold an extra reference, giving up its last reference with
device_unregister(), making accessing dev->index afterwards
invalid.
I actually saw problems when testing my (not-yet-merged)
virtio-ccw code:
- device_add virtio-net,id=xxx
-> creates device virtio<n> with n>0
- device_del xxx
-> deletes virtio<n>, but calls ida_simple_remove with an
index of 0
- device_add virtio-net,id=xxx
-> tries to add virtio0, which is still in use...
So let's save the index we want to release before calling
device_unregister().
Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
---
drivers/virtio/virtio.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 1e8659c..809b0de 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -225,8 +225,10 @@ EXPORT_SYMBOL_GPL(register_virtio_device);
void unregister_virtio_device(struct virtio_device *dev)
{
+ int index = dev->index; /* save for after device release */
+
device_unregister(&dev->dev);
- ida_simple_remove(&virtio_index_ida, dev->index);
+ ida_simple_remove(&virtio_index_ida, index);
}
EXPORT_SYMBOL_GPL(unregister_virtio_device);
--
1.7.12.4
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