Merge tag 'vfio-v4.11-rc4' of git://github.com/awilliam/linux-vfio

Pull VFIO fix from Alex Williamson:
 "Rework sanity check for mdev driver group notifier de-registration
  (Alex Williamson)"

* tag 'vfio-v4.11-rc4' of git://github.com/awilliam/linux-vfio:
  vfio: Rework group release notifier warning

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 609f4f982c74..561084ab387f 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -403,6 +403,7 @@ static void vfio_group_release(struct kref *kref)
         struct iommu_group *iommu_group = group->iommu_group;
 
         WARN_ON(!list_empty(&group->device_list));
+        WARN_ON(group->notifier.head);
 
         list_for_each_entry_safe(unbound, tmp,
                                  &group->unbound_list, unbound_next) {
@@ -1573,6 +1574,10 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep)
                 return -EBUSY;
         }
 
+        /* Warn if previous user didn't cleanup and re-init to drop them */
+        if (WARN_ON(group->notifier.head))
+                BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);
+
         filep->private_data = group;
 
         return 0;
@@ -1584,9 +1589,6 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep)
 
         filep->private_data = NULL;
 
-        /* Any user didn't unregister? */
-        WARN_ON(group->notifier.head);
-
         vfio_group_try_dissolve_container(group);
 
         atomic_dec(&group->opened);