[PATCH] roundup_pow_of_two() 64-bit fix (962749af) · Commits · 戴 / test

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:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

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);

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