On 06/27/2013 07:42 PM, Benjamin Herrenschmidt wrote:

On Thu, 2013-06-27 at 16:59 +1000, Stephen Rothwell wrote:

quoted

quoted

+/* Allows an external user (for example, KVM) to unlock an IOMMU

group */

quoted

+static void vfio_group_del_external_user(struct file *filep)
+{
+     struct vfio_group *group = filep->private_data;
+
+     BUG_ON(filep->f_op != &vfio_group_fops);

We usually reserve BUG_ON for situations where there is no way to
continue running or continuing will corrupt the running kernel.  Maybe
WARN_ON() and return?

Not even that. This is a user space provided "fd", we shouldn't oops the
kernel because we passed a wrong argument, just return -EINVAL or
something like that (add a return code).

I'll change to WARN_ON but...
This is going to be called on KVM exit on a file pointer previously
verified for correctness. If it is a wrong file*, then something went
terribly wrong.


-- 
Alexey