dma_fence_get_rcu_safe
prev = dma_fence_get_rcu_safe(&chain->prev);
f2 = dma_fence_get_rcu_safe(&t->fences[!t->id]);
fence = dma_fence_get_rcu_safe(&adev->gang_submit);
old = dma_fence_get_rcu_safe(ptr);
ef = dma_fence_get_rcu_safe(&p->ef);
fence = dma_fence_get_rcu_safe(&active->fence);
fence = dma_fence_get_rcu_safe(&vma->active.excl.fence);
fence = dma_fence_get_rcu_safe(&syncobj->fence);