diff --git a/[refs] b/[refs]
index b7bfb72c3cb4..7891366f715b 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7df2457db83bc922fcc8b462526b77f1ffe8c84b
+refs/heads/master: 63c2f782e8f6aafbc11b14b2cb291b3dc9fc217d
diff --git a/trunk/arch/powerpc/mm/pgtable_32.c b/trunk/arch/powerpc/mm/pgtable_32.c
index 1891dbeeb8e9..bd02272bcb0f 100644
--- a/trunk/arch/powerpc/mm/pgtable_32.c
+++ b/trunk/arch/powerpc/mm/pgtable_32.c
@@ -294,11 +294,8 @@ void __init mapin_ram(void)
 	}
 }
 
-/* is x a power of 2? */
-#define is_power_of_2(x)	((x) != 0 && (((x) & ((x) - 1)) == 0))
-
 /* is x a power of 4? */
-#define is_power_of_4(x)	((x) != 0 && (((x) & (x-1)) == 0) && (ffs(x) & 1))
+#define is_power_of_4(x)	is_power_of_2(x) && (ffs(x) & 1))
 
 /*
  * Set up a mapping for a block of I/O.
diff --git a/trunk/arch/ppc/mm/pgtable.c b/trunk/arch/ppc/mm/pgtable.c
index 354a9408f024..82b06a1ef95d 100644
--- a/trunk/arch/ppc/mm/pgtable.c
+++ b/trunk/arch/ppc/mm/pgtable.c
@@ -313,11 +313,8 @@ void __init mapin_ram(void)
 	}
 }
 
-/* is x a power of 2? */
-#define is_power_of_2(x)	((x) != 0 && (((x) & ((x) - 1)) == 0))
-
 /* is x a power of 4? */
-#define is_power_of_4(x)	((x) != 0 && (((x) & (x-1)) == 0) && (ffs(x) & 1))
+#define is_power_of_4(x)	is_power_of_2(x) && (ffs(x) & 1))
 
 /*
  * Set up a mapping for a block of I/O.
diff --git a/trunk/arch/ppc/syslib/ppc85xx_rio.c b/trunk/arch/ppc/syslib/ppc85xx_rio.c
index 05b0e9415085..2b097800cdd9 100644
--- a/trunk/arch/ppc/syslib/ppc85xx_rio.c
+++ b/trunk/arch/ppc/syslib/ppc85xx_rio.c
@@ -59,8 +59,6 @@
 #define DBELL_TID(x)		(*(u8 *)(x + DOORBELL_TID_OFFSET))
 #define DBELL_INF(x)		(*(u16 *)(x + DOORBELL_INFO_OFFSET))
 
-#define is_power_of_2(x)	(((x) & ((x) - 1)) == 0)
-
 struct rio_atmu_regs {
 	u32 rowtar;
 	u32 pad1;
diff --git a/trunk/drivers/net/gianfar_ethtool.c b/trunk/drivers/net/gianfar_ethtool.c
index 6d71bea5e900..0d6943d67096 100644
--- a/trunk/drivers/net/gianfar_ethtool.c
+++ b/trunk/drivers/net/gianfar_ethtool.c
@@ -42,8 +42,6 @@
 
 #include "gianfar.h"
 
-#define is_power_of_2(x)        ((x) != 0 && (((x) & ((x) - 1)) == 0))
-
 extern void gfar_start(struct net_device *dev);
 extern int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit);
 
diff --git a/trunk/include/linux/log2.h b/trunk/include/linux/log2.h
index d02e1a547a7e..99922bedfcc9 100644
--- a/trunk/include/linux/log2.h
+++ b/trunk/include/linux/log2.h
@@ -43,6 +43,17 @@ int __ilog2_u64(u64 n)
 }
 #endif
 
+/*
+ *  Determine whether some value is a power of two, where zero is
+ * *not* considered a power of two.
+ */
+
+static inline __attribute__((const))
+bool is_power_of_2(unsigned long n)
+{
+	return (n != 0 && ((n & (n - 1)) == 0));
+}
+
 /*
  * round up to nearest power of two
  */