[PATCH] dma-buf: avoid scheduling on fence status query

Dave Airlie airlied at gmail.com
Wed Apr 26 09:59:05 UTC 2017


On 26 April 2017 at 17:20, Christian K├Ânig <deathsimple at vodafone.de> wrote:
> NAK, I'm wondering how often I have to reject that change. We should
> probably add a comment here.
>
> Even with a zero timeout we still need to enable signaling, otherwise some
> fence will never signal if userspace just polls on them.
>
> If a caller is only interested in the fence status without enabling the
> signaling it should call dma_fence_is_signaled() instead.

Can we not move the return 0 (with spin unlock) down after we enabling
signalling, but before
we enter the schedule_timeout(1)?

Dave.


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