[Intel-gfx] [PATCH] drm/i915/sw_fence: Replace private use of wq->flags with bit zero in wq->private

[Chris Wilson]

On Thu, Nov 03, 2016 at 08:33:58AM +0000, Tvrtko Ursulin wrote:
> On 02/11/2016 17:34, Chris Wilson wrote:
> >It looks ok, but I just don't see the point. wq->flags is private to the
> >wq->func callback.
> 
> A very superficial skim shows that wake_up_common at least looks at
> the flags. So I thought, as long as wake_up_something gets called
> form somewhere on these ones, it would be safer not to potentially
> silently collide with some core flag.
> 
> Or are you saying no one ever touches them outside i915_sw_fence.c ?

That would break the encapsulation of the waitqueue being inside the
fence. I was not intending for people to call wake_up_all(fence.wait),
kfence_wake_up_all() [bad name, I was trying to borrow the concept from
wake_up_all() but it is not the same, it is for the completion of a
deferred signal notify] completes the fence in addition to signaling its
waiters.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre