drm/ttm: once more fix ttm_buffer_object_transfer

commit 4d98e5ee upstream.

When the mutex is locked just in the moment we copy it we end up with a
warning that we release a locked mutex.

Fix this by properly reinitializing the mutex.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/ttm/ttm_bo_util.c

@@ -473,6 +473,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 	INIT_LIST_HEAD(&fbo->lru);
 	INIT_LIST_HEAD(&fbo->swap);
 	INIT_LIST_HEAD(&fbo->io_reserve_lru);
+	mutex_init(&fbo->wu_mutex);
 	fbo->moving = NULL;
 	drm_vma_node_reset(&fbo->vma_node);
 	atomic_set(&fbo->cpu_writers, 0);