[PATCH v5 5/5] dma-buf/sync_file: only enable fence signalling on poll()

[Chris Wilson]

On Fri, Aug 05, 2016 at 08:28:15AM +0100, Chris Wilson wrote:
> On Thu, Aug 04, 2016 at 11:24:14PM -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
> > 
> > Signalling doesn't need to be enabled at sync_file creation, it is only
> > required if userspace waiting the fence to signal through poll().
> > 
> > Thus we delay fence_add_callback() until poll is called. It only adds the
> > callback the first time poll() is called. This avoid re-adding the same
> > callback multiple times.
> > 
> > v2: rebase and update to work with new fence support for sync_file
> > 
> > v3: use atomic operation to set enabled and protect fence_add_callback()
> > 
> > v4: use user bit from fence flags (comment from Chris Wilson)
> > 
> > Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
> > ---
> > +	if (!test_and_set_bit(POLL_ENABLED, &sync_file->fence->flags)) {
> > +		if (fence_add_callback(sync_file->fence, &sync_file->cb,
> > +				   fence_check_cb_func) < 0)
> > +			wake_up_all(&sync_file->wq);
> > +	}
> > +
> >  	status = fence_is_signaled(sync_file->fence);
> 
> status can only be true/false here.
> 	return fence_is_signaled(sync_file->fence) ? POLLIN : 0;
> 
> Reviwed-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by

/me goes back to drinking his coffee
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre