dma_fence_get_rcu_safe
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);
struct dma_fence *dma_fence_get_rcu_safe(struct dma_fence **);