1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 259ad282ae5d..c488da5db7c7 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -76,6 +76,7 @@ struct vfio_group {
         struct notifier_block           nb;
         struct list_head                vfio_next;
         struct list_head                container_next;
+        atomic_t                        opened;
 };
 
 struct vfio_device {
@@ -206,6 +207,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
         INIT_LIST_HEAD(&group->device_list);
         mutex_init(&group->device_lock);
         atomic_set(&group->container_users, 0);
+        atomic_set(&group->opened, 0);
         group->iommu_group = iommu_group;
 
         group->nb.notifier_call = vfio_iommu_group_notifier;
@@ -1236,12 +1238,22 @@ static long vfio_group_fops_compat_ioctl(struct file *filep,
 static int vfio_group_fops_open(struct inode *inode, struct file *filep)
 {
         struct vfio_group *group;
+        int opened;
 
         group = vfio_group_get_from_minor(iminor(inode));
         if (!group)
                 return -ENODEV;
 
+        /* Do we need multiple instances of the group open?  Seems not. */
+        opened = atomic_cmpxchg(&group->opened, 0, 1);
+        if (opened) {
+                vfio_group_put(group);
+                return -EBUSY;
+        }
+
+        /* Is something still in use from a previous open? */
         if (group->container) {
+                atomic_dec(&group->opened);
                 vfio_group_put(group);
                 return -EBUSY;
         }
@@ -1259,6 +1271,8 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep)
 
         vfio_group_try_dissolve_container(group);
 
+        atomic_dec(&group->opened);
+
         vfio_group_put(group);
 
         return 0;