[PATCH 53/72] try_cmpxchg64

[Chris Wilson]

---
 drivers/gpu/drm/i915/i915_utils.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 54773371e6bd..0b5588e59740 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -456,4 +456,19 @@ static inline bool timer_expired(const struct timer_list *t)
  */
 #define IS_ACTIVE(config) ((config) != 0)
 
+#if IS_ENABLED(CONFIG_64BIT)
+#define try_cmpxchg64(_ptr, _pold, _new) try_cmpxchg(_ptr, _pold, _new)
+#else
+#define try_cmpxchg64(_ptr, _pold, _new)				\
+({									\
+	__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);		\
+	__typeof__(*(_ptr)) __old = *_old;				\
+	__typeof__(*(_ptr)) __cur = cmpxchg64(_ptr, __old, _new);	\
+	bool success = __cur == __old;					\
+	if (unlikely(!success))						\
+		*_old = __cur;						\
+	likely(success);						\
+})
+#endif
+
 #endif /* !__I915_UTILS_H */
-- 
2.20.1