drm/i915: Add getter/setter for i915_gem_object->frontbuffer

Add getter/setter for i915_gem_object->frontbuffer and use it instead of
directly touching i915_gem_object->frontbuffer frontbuffer pointer.

v3:
 - Fix intel_frontbuffer_get return value
 - s/front_ret/cur/
v2: Move getter/setter into i915_gem_object.h

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230727064142.751976-3-jouni.hogander@intel.com

2 files changed, 7 insertions, 40 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
index 3ce0436a0c7d..56f45370fee0 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
@@ -237,7 +237,7 @@ static void frontbuffer_release(struct kref *ref)
 	}
 	spin_unlock(&obj->vma.lock);
 
-	RCU_INIT_POINTER(obj->frontbuffer, NULL);
+	i915_gem_object_set_frontbuffer(obj, NULL);
 	spin_unlock(&intel_bo_to_i915(obj)->display.fb_tracking.lock);
 
 	i915_active_fini(&front->write);
@@ -250,9 +250,9 @@ struct intel_frontbuffer *
 intel_frontbuffer_get(struct drm_i915_gem_object *obj)
 {
 	struct drm_i915_private *i915 = intel_bo_to_i915(obj);
-	struct intel_frontbuffer *front;
+	struct intel_frontbuffer *front, *cur;
 
-	front = __intel_frontbuffer_get(obj);
+	front = i915_gem_object_get_frontbuffer(obj);
 	if (front)
 		return front;
 
@@ -269,17 +269,11 @@ intel_frontbuffer_get(struct drm_i915_gem_object *obj)
 			 I915_ACTIVE_RETIRE_SLEEPS);
 
 	spin_lock(&i915->display.fb_tracking.lock);
-	if (rcu_access_pointer(obj->frontbuffer)) {
-		kfree(front);
-		front = rcu_dereference_protected(obj->frontbuffer, true);
-		kref_get(&front->ref);
-	} else {
-		i915_gem_object_get(obj);
-		rcu_assign_pointer(obj->frontbuffer, front);
-	}
+	cur = i915_gem_object_set_frontbuffer(obj, front);
 	spin_unlock(&i915->display.fb_tracking.lock);
-
-	return front;
+	if (cur != front)
+		kfree(front);
+	return cur;
 }
 
 void intel_frontbuffer_put(struct intel_frontbuffer *front)
diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.h b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
index 3c474ed937fb..eeccc847331d 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.h
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
@@ -75,33 +75,6 @@ void intel_frontbuffer_flip(struct drm_i915_private *i915,
 
 void intel_frontbuffer_put(struct intel_frontbuffer *front);
 
-static inline struct intel_frontbuffer *
-__intel_frontbuffer_get(const struct drm_i915_gem_object *obj)
-{
-	struct intel_frontbuffer *front;
-
-	if (likely(!rcu_access_pointer(obj->frontbuffer)))
-		return NULL;
-
-	rcu_read_lock();
-	do {
-		front = rcu_dereference(obj->frontbuffer);
-		if (!front)
-			break;
-
-		if (unlikely(!kref_get_unless_zero(&front->ref)))
-			continue;
-
-		if (likely(front == rcu_access_pointer(obj->frontbuffer)))
-			break;
-
-		intel_frontbuffer_put(front);
-	} while (1);
-	rcu_read_unlock();
-
-	return front;
-}
-
 struct intel_frontbuffer *
 intel_frontbuffer_get(struct drm_i915_gem_object *obj);