From: Mark Charlebois <charlebm@xxxxxxxxx> The call to __builtin_log2 presumes there is a double log2(double x) function defined in the kernel. The call to hash_log is a call to hash_64 which is defined in include/linux/hash.h static __always_inline u64 hash_64(u64 val, unsigned int bits) That means that __builtin_log2(NR_BG_LOCKS) is converting NR_BG_LOCKS to a double and returning a double and then that is converted to an unsigned int. Using ilog2 is much more appropriate and efficient. Another side effect of using __builtin_log2 is that is uses __aeabi_* functions for ARM that require linking with libgcc.a. Author: Mark Charlebois <charlebm@xxxxxxxxx> Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx> Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx> --- fs/mbcache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/mbcache.c b/fs/mbcache.c index bf166e3..2c0752b 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -93,7 +93,7 @@ #define MB_CACHE_WRITER ((unsigned short)~0U >> 1) -#define MB_CACHE_ENTRY_LOCK_BITS __builtin_log2(NR_BG_LOCKS) +#define MB_CACHE_ENTRY_LOCK_BITS ilog2(NR_BG_LOCKS) #define MB_CACHE_ENTRY_LOCK_INDEX(ce) \ (hash_long((unsigned long)ce, MB_CACHE_ENTRY_LOCK_BITS)) -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
