[Intel-gfx] [PATCH 03/39] drm/i915: Avoid tainting i915_gem_park() with wakeref.lock

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> While we need to flush the wakeref before parking, we do not need to
> perform the i915_gem_park() itself underneath the wakeref lock, merely
> the struct_mutex. If we rearrange the locks, we can avoid the unnecessary
> tainting.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_pm.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pm.c b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
> index 6e75702c5671..a33f69610d6f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_pm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
> @@ -30,23 +30,22 @@ static void idle_work_handler(struct work_struct *work)
>  {
>  	struct drm_i915_private *i915 =
>  		container_of(work, typeof(*i915), gem.idle_work);
> -	bool restart = true;
> +	bool park;
>

can_park...meh.

> -	cancel_delayed_work(&i915->gem.retire_work);
> +	cancel_delayed_work_sync(&i915->gem.retire_work);
>  	mutex_lock(&i915->drm.struct_mutex);
>  
>  	intel_wakeref_lock(&i915->gt.wakeref);
> -	if (!intel_wakeref_active(&i915->gt.wakeref) && !work_pending(work)) {
> -		i915_gem_park(i915);
> -		restart = false;
> -	}
> +	park = !intel_wakeref_active(&i915->gt.wakeref) && !work_pending(work);
>  	intel_wakeref_unlock(&i915->gt.wakeref);
> -
> -	mutex_unlock(&i915->drm.struct_mutex);
> -	if (restart)
> +	if (park)
> +		i915_gem_park(i915);

Did not find anything beneath gem park that would need wakeref.

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> +	else
>  		queue_delayed_work(i915->wq,
>  				   &i915->gem.retire_work,
>  				   round_jiffies_up_relative(HZ));
> +
> +	mutex_unlock(&i915->drm.struct_mutex);
>  }
>  
>  static void retire_work_handler(struct work_struct *work)
> -- 
> 2.20.1
>
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