drm/i915: Avoid tainting i915_gem_park() with wakeref.lock

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@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190614220616.24932-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pm.c b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
index 141f3ea..05011d4 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_pm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
@@ -48,23 +48,22 @@ 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;
 
-       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);
+       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)