tree 4e7c1e3590d1ca21715a00930c1554c4a5eac8cf
parent 945399a8c78ac225cdbaece0f94c0d8741b4e1d8
author Sasha Levin <sasha.levin@oracle.com> 1420228060 -0500
committer Michael S. Tsirkin <mst@redhat.com> 1420554936 +0200

virtio_pci: defer kfree until release callback

A struct device which has just been unregistered can live on past the
point at which a driver decides to drop it's initial reference to the
kobject gained on allocation.

This implies that when releasing a virtio device, we can't free a struct
virtio_device until the underlying struct device has been released,
which might not happen immediately on device_unregister().

Unfortunately, this is exactly what virtio pci does:
it has an empty release callback, and frees memory immediately
after unregistering the device.

This causes an easy to reproduce crash if CONFIG_DEBUG_KOBJECT_RELEASE
it enabled.

To fix, free the memory only once we know the device is gone in the release
callback.

Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>