[ 83/91] tile: fix bug where fls(0) was not returning 0
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2012-05-27 01:20:35
Also in:
lkml
3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Metcalf <redacted> 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 <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- 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)