Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 312a0c17 authored by David Howells's avatar David Howells Committed by Linus Torvalds
Browse files

[PATCH] LOG2: Alter roundup_pow_of_two() so that it can use a ilog2() on a constant 



Alter roundup_pow_of_two() so that it can make use of ilog2() on a constant to
produce a constant value, retaining the ability for an arch to override it in
the non-const case.

This permits the function to be used to initialise variables.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f0d1b0b3

include/linux/kernel.h

+0 −6
Original line number Diff line number Diff line
@@ -158,12 +158,6 @@ static inline int printk(const char *s, ...) { return 0; } 


unsigned long int_sqrt(unsigned long);



static inline unsigned long

__attribute_const__ roundup_pow_of_two(unsigned long x)

{

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

}



extern int printk_ratelimit(void);

extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst);

extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,

include/linux/log2.h

+26 −0
Original line number Diff line number Diff line
@@ -43,6 +43,15 @@ int __ilog2_u64(u64 n) 
}

#endif



/*

 * round up to nearest power of two

 */

static inline __attribute__((const))

unsigned long __roundup_pow_of_two(unsigned long n)

{

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

}



/**

 * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value

 * @n - parameter
@@ -128,4 +137,21 @@ int __ilog2_u64(u64 n) 
	__ilog2_u64(n)				\

 )



/**

 * roundup_pow_of_two - round the given value up to nearest power of two

 * @n - parameter

 *

 * round the given balue up to the nearest power of two

 * - the result is undefined when n == 0

 * - this can be used to initialise global variables from constant data

 */

#define roundup_pow_of_two(n)			\

(						\

	__builtin_constant_p(n) ? (		\

		(n == 1) ? 0 :			\

		(1UL << (ilog2((n) - 1) + 1))	\

				   ) :		\

	__roundup_pow_of_two(n)			\

 )



#endif /* _LINUX_LOG2_H */