[Intel-gfx] [PATCH v3 08/12] drm/i915: Fix struct mutex vs. RPS lock inversion

[Chris Wilson]

On Tue, Feb 02, 2016 at 02:46:58PM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> RPS lock must be taken before the struct_mutex to avoid
> locking inversion. So stop grabbing it for the whole
> powersave initialization and instead only take it during
> the sections which need it.
> 
> Also, struct_mutex is not needed any more since dedicated
> RPS lock was added in:
> 
>    commit 4fc688ce79772496503d22263d61b071a8fb596e
>    Author: Jesse Barnes <jbarnes at virtuousgeek.org>
>    Date:   Fri Nov 2 11:14:01 2012 -0700
> 
>        drm/i915: protect RPS/RC6 related accesses (including PCU) with a new mutex
> 
> Based on prototype patch by Chris Wilson and a subsequent
> mailing list discussion involving Ville, Imre, Chris and
> Daniel.
> 
> v2: More details in the commit.
> 
> v3: Use drm_gem_object_unreference_unlocked. (Chris Wilson)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre