1 files changed, 12 insertions, 1 deletions

diff --git a/include/linux/log2.h b/include/linux/log2.h
index fd7ff3d91e6a..ef3d4f67118c 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -203,6 +203,17 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
  *  ... and so on.
  */
 
-#define order_base_2(n) ilog2(roundup_pow_of_two(n))
+static inline __attribute_const__
+int __order_base_2(unsigned long n)
+{
+        return n > 1 ? ilog2(n - 1) + 1 : 0;
+}
 
+#define order_base_2(n)                         \
+(                                               \
+        __builtin_constant_p(n) ? (             \
+                ((n) == 0 || (n) == 1) ? 0 :    \
+                ilog2((n) - 1) + 1) :           \
+        __order_base_2(n)                       \
+)
 #endif /* _LINUX_LOG2_H */