Messages in this thread Patch in this message | | | From | Cornelia Huck <> | Subject | [PATCH] virtio: Don't access index after unregister. | Date | Thu, 8 Nov 2012 11:43:47 +0100 |
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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@de.ibm.com> --- 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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