[Intel-gfx] [PATCH 01/33] drm/i915: Add smp_rmb() to busy ioctl's RCU dance

[Joonas Lahtinen]

On ke, 2016-08-10 at 14:00 +0300, Joonas Lahtinen wrote:
> 
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> 
> I still think it's fragile, though. But lets see once the dust settles
> if we can make improvements.
> 

Daniel pointed out that the engine_id could still be different during
middle section when the engine_id is captured if the request is briefly
reused.

So backing off with the Reviewed-by, either we handle the possibly
wrong engine_id (no extra tests, so we might actually hit it in
testing) or we avoid it completely (with locking).

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation