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Commit 962749af authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
Browse files

[PATCH] roundup_pow_of_two() 64-bit fix 



fls() takes an integer, so roundup_pow_of_two() is busted for ulongs larger
than 2^32-1.

Fix this by implementing and using fls_long().

(Why does roundup_pow_of_two() return a long?)

(Why is roundup_pow_of_two() __attribute_const__ whereas long_log2() is
__attribute_pure__?)

(Why does long_log2() suck so much?  Because we were missing fls_long()?)

Cc: Roland Dreier <rdreier@cisco.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: John Hawkes <hawkes@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 231bed20

include/linux/bitops.h

+7 −0
Original line number Diff line number Diff line
@@ -175,4 +175,11 @@ static inline __u32 ror32(__u32 word, unsigned int shift) 
	return (word >> shift) | (word << (32 - shift));

}



static inline unsigned fls_long(unsigned long l)

{

	if (sizeof(l) == 4)

		return fls(l);

	return fls64(l);

}



#endif

include/linux/kernel.h

+3 −2
Original line number Diff line number Diff line
@@ -154,9 +154,10 @@ static inline int __attribute_pure__ long_log2(unsigned long x) 
	return r;

}



static inline unsigned long __attribute_const__ roundup_pow_of_two(unsigned long x)

static inline unsigned long

__attribute_const__ roundup_pow_of_two(unsigned long x)

{

	return (1UL << fls(x - 1));

	return 1UL << fls_long(x - 1);

}



extern int printk_ratelimit(void);