Hi Jouni,
On 5/29/2023 8:27 AM, Jouni Högander wrote:
Add getter/setter for i915_gem_object->frontbuffer and use it instead of
directly touching i915_gem_object->frontbuffer frontbuffer pointer.
Signed-off-by: Jouni Högander <jouni.hogander@xxxxxxxxx>
---
.../gpu/drm/i915/display/intel_frontbuffer.c | 18 ++---
.../gpu/drm/i915/display/intel_frontbuffer.h | 27 -------
drivers/gpu/drm/i915/gem/i915_gem_object.c | 70 ++++++++++++++++++-
drivers/gpu/drm/i915/gem/i915_gem_object.h | 6 ++
drivers/gpu/drm/i915/i915_vma.c | 2 +-
5 files changed, 81 insertions(+), 42 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
index 3ce0436a0c7d..41ac65c98720 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, *front_ret;
- front = __intel_frontbuffer_get(obj);
+ front = i915_gem_object_get_frontbuffer(obj);
if (front)
return front;
@@ -269,16 +269,10 @@ 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);
- }
+ front_ret = i915_gem_object_set_frontbuffer(obj, front);
spin_unlock(&i915->display.fb_tracking.lock);
-
+ if (front_ret != front)
+ kfree(front);
return front;
Should be "return front_ret" here or better s/front_ret/cur/
}
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);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 46a19b099ec8..6945e903e106 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -463,7 +463,7 @@ void __i915_gem_object_flush_frontbuffer(struct drm_i915_gem_object *obj,
{
struct intel_frontbuffer *front;
- front = __intel_frontbuffer_get(obj);
+ front = i915_gem_object_get_frontbuffer(obj);
if (front) {
intel_frontbuffer_flush(front, origin);
intel_frontbuffer_put(front);
@@ -475,7 +475,7 @@ void __i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj,
{
struct intel_frontbuffer *front;
- front = __intel_frontbuffer_get(obj);
+ front = i915_gem_object_get_frontbuffer(obj);
if (front) {
intel_frontbuffer_invalidate(front, origin);
intel_frontbuffer_put(front);
@@ -952,6 +952,72 @@ bool i915_gem_object_has_unknown_state(struct drm_i915_gem_object *obj)
return obj->mm.unknown_state;
}
+/**
+ * i915_gem_object_get_frontbuffer - Get the object's frontbuffer
+ * @obj: The object whose frontbuffer to get.
+ *
+ * Get pointer to object's frontbuffer if such exists. Please note that RCU
+ * mechanism is used to handle e.g. ongoing removal of frontbuffer pointer.
+ *
+ * Return: pointer to object's frontbuffer is such exists or NULL
+ */
+struct intel_frontbuffer *
+i915_gem_object_get_frontbuffer(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;
+}
+
+/**
+ * i915_gem_object_set_frontbuffer - Set the object's frontbuffer
+ * @obj: The object whose frontbuffer to set.
+ * @front: The frontbuffer to set
+ *
+ * Set object's frontbuffer pointer. If frontbuffer is already set for the
+ * object keep it and return it's pointer to the caller. Please note that RCU
+ * mechanism is used to handle e.g. ongoing removal of frontbuffer pointer.
+ *
+ * Return: pointer to frontbuffer which was set.
+ */
+struct intel_frontbuffer *
+i915_gem_object_set_frontbuffer(struct drm_i915_gem_object *obj,
+ struct intel_frontbuffer *front)
+{
+ struct intel_frontbuffer *front_ret = front;
+
+ if (!front) {
+ RCU_INIT_POINTER(obj->frontbuffer, NULL);
+ } else if (rcu_access_pointer(obj->frontbuffer)) {
+ front_ret = rcu_dereference_protected(obj->frontbuffer, true);
Could you please add a comment here stating that this function is
protected by i915->display.fb_tracking.lock or consider moving the lock
handling to this function?
Otherwise this is bit confusing.
Regards,
Nirmo
+ kref_get(&front_ret->ref);
+ } else {
+ drm_gem_object_get(&intel_bo_to_drm_bo(obj));
+ rcu_assign_pointer(obj->frontbuffer, front);
+ }
+
+ return front_ret;
+}
+
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/huge_gem_object.c"
#include "selftests/huge_pages.c"
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 884a17275b3a..69c5fa91152a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -891,4 +891,10 @@ static inline int i915_gem_object_userptr_validate(struct drm_i915_gem_object *o
#endif
+struct intel_frontbuffer *
+i915_gem_object_get_frontbuffer(const struct drm_i915_gem_object *obj);
+struct intel_frontbuffer *
+i915_gem_object_set_frontbuffer(struct drm_i915_gem_object *obj,
+ struct intel_frontbuffer *front);
+
#endif
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index ffb425ba591c..c66ff2157f6a 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -1908,7 +1908,7 @@ int _i915_vma_move_to_active(struct i915_vma *vma,
if (flags & EXEC_OBJECT_WRITE) {
struct intel_frontbuffer *front;
- front = __intel_frontbuffer_get(obj);
+ front = i915_gem_object_get_frontbuffer(obj);
if (unlikely(front)) {
if (intel_frontbuffer_invalidate(front, ORIGIN_CS))
i915_active_add_request(&front->write, rq);
