Merge tag 'vfio-v3.11' of git://github.com/awilliam/linux-vfio

[platform/adaptation/renesas_rcar/renesas_kernel.git] / drivers / vfio / vfio.c

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 259ad28..c488da5 100644 (file)
--- 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;