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authorAlex Williamson <alex.williamson@redhat.com>2017-03-21 13:19:09 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-03-30 09:44:08 +0200
commit8b0219e35b43cb6ceb592a1fb35af5a9d5d91b5d (patch)
tree37052878dadfe5909ef571edf46031ad58bfcbe0
parent0d05871e5e4319e846a9596dd24b7546b1c81eb7 (diff)
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vfio: Rework group release notifier warning
commit 65b1adebfe43c642dfe3b109edb5d992db5fbe72 upstream. The intent of the original warning is make sure that the mdev vendor driver has removed any group notifiers at the point where the group is closed by the user. Theoretically this would be through an orderly shutdown where any devices are release prior to the group release. We can't always count on an orderly shutdown, the user can close the group before the notifier can be removed or the user task might be killed. We'd like to add this sanity test when the group is idle and the only references are from the devices within the group themselves, but we don't have a good way to do that. Instead check both when the group itself is removed and when the group is opened. A bit later than we'd prefer, but better than the current over aggressive approach. Fixes: ccd46dbae77d ("vfio: support notifier chain in vfio_group") Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Cc: Jike Song <jike.song@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/vfio/vfio.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 9901c4671e2f..6e10325596b6 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);