[Intel-gfx] [PATCH v2] drm/i915: Always mark the writer as also a read for busy ioctl

[Chris Wilson]

On Tue, Aug 09, 2016 at 06:08:25PM +0100, Chris Wilson wrote:
> One of the few guarantees we want the busy ioctl to provide is that the
> reported busy writer is included in the set of busy read engines. This
> should be provided by the ordering of setting and retiring the active
> trackers, but we can do better by explicitly setting the busy read
> engine flag for the last writer.
> 
> v2: More comments inside __busy_write_id() to explain why both fields
> are set.
> 
> Fixes: 3fdc13c7a3cb ("drm/i915: Remove (struct_mutex) locking for busy-ioctl")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com

>From irc, Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre