[PATCH] drm/vgem: Allow root to inject hanging fences onto dmabufs

[Chris Wilson]

On Wed, Jul 20, 2016 at 04:28:40PM -0700, Kristian Høgsberg wrote:
> Why is this useful if only root can use it?

> > When performing driver testing, one factor we want to test is how we
> > handle a foreign fence that is never signaled. We can wait on that fence
> > indefinitely, in which case the driver appears hung, or we can take some
> > remedial action (with risks regarding the state of any shared content).
> > Whatever the action choosen by the driver, in order to perform the test
> > we want to disable the safety feature of vgem fence (which is then used
> > to test implicit dma-buf fencing). This is regarded as a highly
> > dangerous feature and so hidden behind an expert config option and only
> > available to root when enabled.

-- 
Chris Wilson, Intel Open Source Technology Centre