[ 83/91] tile: fix bug where fls(0) was not returning 0

[Greg KH]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Metcalf <cmetcalf@xxxxxxxxxx>

commit 9f1d62bed7f015d11b9164078b7fea433b474114 upstream.

This is because __builtin_clz(0) returns 64 for the "undefined" case
of 0, since the builtin just does a right-shift 32 and "clz" instruction.
So, use the alpha approach of casting to u32 and using __builtin_clzll().

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/tile/include/asm/bitops.h |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/arch/tile/include/asm/bitops.h
+++ b/arch/tile/include/asm/bitops.h
@@ -77,6 +77,11 @@ static inline int ffs(int x)
 	return __builtin_ffs(x);
 }
 
+static inline int fls64(__u64 w)
+{
+	return (sizeof(__u64) * 8) - __builtin_clzll(w);
+}
+
 /**
  * fls - find last set bit in word
  * @x: the word to search
@@ -90,12 +95,7 @@ static inline int ffs(int x)
  */
 static inline int fls(int x)
 {
-	return (sizeof(int) * 8) - __builtin_clz(x);
-}
-
-static inline int fls64(__u64 w)
-{
-	return (sizeof(__u64) * 8) - __builtin_clzll(w);
+	return fls64((unsigned int) x);
 }
 
 static inline unsigned int __arch_hweight32(unsigned int w)


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/