tree 5647eca5f1a28297b023fd1a7b9b1c37030de9a6
parent 906ee99dd2a5c819c1171ce5eaf6c080c027e58c
author Alex Williamson <alex.williamson@redhat.com> 1360875733 -0700
committer Alex Williamson <alex.williamson@redhat.com> 1360875733 -0700

vfio: Protect vfio_dev_present against device_del

vfio_dev_present is meant to give us a wait_event callback so that we
can block removing a device from vfio until it becomes unused.  The
root of this check depends on being able to get the iommu group from
the device.  Unfortunately if the BUS_NOTIFY_DEL_DEVICE notifier has
fired then the device-group reference is no longer searchable and we
fail the lookup.

We don't need to go to such extents for this though.  We have a
reference to the device, from which we can acquire a reference to the
group.  We can then use the group reference to search for the device
and properly block removal.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>