[PATCH] dma-fence: Make dma_fence_add_callback() fail if signaled with error

[Chris Wilson]

Quoting Ezequiel Garcia (2018-05-09 21:14:49)
> Change how dma_fence_add_callback() behaves, when the fence
> has error-signaled by the time it is being add. After this commit,
> dma_fence_add_callback() returns the fence error, if it
> has error-signaled before dma_fence_add_callback() is called.

Why? What problem are you trying to solve? fence->error does not imply
that the fence has yet been signaled, and the caller wants a callback
when it is signaled.
-Chris