vfio: grab vfio_device reference *before* exposing the sucker via fd_install()

It's not critical (anymore) since another thread closing the file will block
on ->device_lock before it gets to dropping the final reference, but it's
definitely cleaner that way...

Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 887ae43..17830c9 100644 (file)
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1111,10 +1111,10 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
                 */
                filep->f_mode |= (FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
 
-               fd_install(ret, filep);
-
                vfio_device_get(device);
                atomic_inc(&group->container_users);
+
+               fd_install(ret, filep);
                break;
        }
        mutex_unlock(&group->device_lock);