[PATCH 2/4] drm/i915: Avoid tainting i915_gem_park() with wakeref.lock

Chris Wilson
2019-06-13T06:20:27Z

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>
---
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 f68c0ad1aa47..03af78151aeb 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;

- 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)