[Intel-gfx] [PATCH 05/16] drm/i915: Enable i915_gem_wait_for_idle() without holding struct_mutex

[Joonas Lahtinen]

On ma, 2016-08-01 at 20:28 +0100, Chris Wilson wrote:
> On Mon, Aug 01, 2016 at 07:22:27PM +0100, Chris Wilson wrote:
> > 
> > The principal motivation for this was to try and eliminate the
> > struct_mutex from i915_gem_suspend - but we still need to hold the mutex
> > current for the i915_gem_context_lost(). (The issue there is that there
> > may be an indirect lockdep cycle between cpu_hotplug (i.e. suspend) and
> > struct_mutex via the stop_machine().) For the moment, enabling last
> > request tracking for the engine, allows us to do busyness checking and
> > waiting without requiring the struct_mutex - which is useful in its own
> > right.
> Couple of mistakes here: stop-engines tweaking still from when this was
> only aiming at making i915_gem_suspend() lockless (now broken out to a
> separate patc) and more importantly, accessing
> dev_priv->mm.interruptible not under any controlling lock. That takes
> passing around bool interruptible and suddenly we have a bigger patch.
> :|

Not sure what to do with this information, will you send a new
revision?

Regards, Joonas

> -Chris
> 
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation