[Intel-gfx] [PATCH 3/4] drm/i915: Clear hangcheck score if engine is idle

[Chris Wilson]

On Mon, Nov 30, 2015 at 06:53:08PM +0200, Mika Kuoppala wrote:
> If we have accumulated hangcheck score before reaching
> engine idle, that score will remain and is transferred to
> the next set of batches. This is wrong as idle is a quite clear
> boundary to prevent hangcheck score manipulation across batches.
> 
> Fix this by clearing the score if engine reaches idle.

The hangcheck accumulation is to detect denial of service by a
sequence of batches that each take more than a hangcheck interval, being
idle doesn't mean anything with respect to the slow dos. The only
question is whether trying to do that at all is sensible.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre