From: Dave Airlie <airlied@redhat.com>
Date: Tue, 3 Oct 2017 12:38:57 +1000
Subject: amdgpu/dc: convert dc_transfer to use a kref.
Git-commit: 93052132568aedb5eda04deae51d6034738a4800
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Rolling your own atomic ref counts is frowned upon.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_surface.c |   17 +++++++++--------
 drivers/gpu/drm/amd/display/dc/dc.h              |    2 +-
 drivers/gpu/drm/amd/display/dc/os_types.h        |    2 ++
 3 files changed, 12 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
@@ -161,17 +161,18 @@ alloc_fail:
 
 void dc_transfer_func_retain(struct dc_transfer_func *tf)
 {
-	ASSERT(atomic_read(&tf->ref_count) > 0);
-	atomic_inc(&tf->ref_count);
+	kref_get(&tf->refcount);
 }
 
-void dc_transfer_func_release(struct dc_transfer_func *tf)
+static void dc_transfer_func_free(struct kref *kref)
 {
-	ASSERT(atomic_read(&tf->ref_count) > 0);
-	atomic_dec(&tf->ref_count);
+	struct dc_transfer_func *tf = container_of(kref, struct dc_transfer_func, refcount);
+	kfree(tf);
+}
 
-	if (atomic_read(&tf->ref_count) == 0)
-		kfree(tf);
+void dc_transfer_func_release(struct dc_transfer_func *tf)
+{
+	kref_put(&tf->refcount, dc_transfer_func_free);
 }
 
 struct dc_transfer_func *dc_create_transfer_func()
@@ -181,7 +182,7 @@ struct dc_transfer_func *dc_create_trans
 	if (tf == NULL)
 		goto alloc_fail;
 
-	atomic_inc(&tf->ref_count);
+	kref_init(&tf->refcount);
 
 	return tf;
 
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -330,11 +330,11 @@ enum dc_transfer_func_predefined {
 };
 
 struct dc_transfer_func {
+	struct kref refcount;
 	struct dc_transfer_func_distributed_points tf_pts;
 	enum dc_transfer_func_type type;
 	enum dc_transfer_func_predefined tf;
 	struct dc_context *ctx;
-	atomic_t ref_count;
 };
 
 /*
--- a/drivers/gpu/drm/amd/display/dc/os_types.h
+++ b/drivers/gpu/drm/amd/display/dc/os_types.h
@@ -32,6 +32,8 @@
 #include <linux/types.h>
 #include <drm/drmP.h>
 
+#include <linux/kref.h>
+
 #include "cgs_linux.h"
 
 #if defined(__BIG_ENDIAN) && !defined(BIGENDIAN_CPU)