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authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-03-06 22:38:01 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-03-06 22:38:01 -0500
commit38f3323037de22bb0089d08be27be01196e7148b (patch)
treea4614cbaf4880b3f782b74df91bbfcac8c3308f2 /include/asm-generic/page.h
parent5d6deb940f880140fbcf5ec42e92534e78785e99 (diff)
Revert "[PATCH] LOG2: Alter get_order() so that it can make use of ilog2() on a constant"
This reverts commit 39d61db0edb34d60b83c5e0d62d0e906578cc707. The commit was buggy in multiple ways: - the conversion to ilog2() was incorrect to begin with - it tested the wrong #defines, so on all architectures but FRV you'd never see the bug except for constant arguments. - the new "get_order()" macro used its arguments multiple times, and didn't even parenthesize them properly - despite the comments, it was not true that you could use it for constant initializers, since not all architectures even use the generic page.h header file. All of the problems are individually fixable, but it all boils down to: better just revert it, and re-do it from scratch. Cc: David Howells <dhowells@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-generic/page.h')
-rw-r--r--include/asm-generic/page.h38
1 files changed, 4 insertions, 34 deletions
diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h
index b55052ce2330..a96b5d986b6e 100644
--- a/include/asm-generic/page.h
+++ b/include/asm-generic/page.h
@@ -4,51 +4,21 @@
4#ifdef __KERNEL__ 4#ifdef __KERNEL__
5#ifndef __ASSEMBLY__ 5#ifndef __ASSEMBLY__
6 6
7#include <linux/log2.h> 7#include <linux/compiler.h>
8 8
9/* 9/* Pure 2^n version of get_order */
10 * non-const pure 2^n version of get_order 10static __inline__ __attribute_const__ int get_order(unsigned long size)
11 * - the arch may override these in asm/bitops.h if they can be implemented
12 * more efficiently than using the arch log2 routines
13 * - we use the non-const log2() instead if the arch has defined one suitable
14 */
15#ifndef ARCH_HAS_GET_ORDER
16static inline __attribute__((const))
17int __get_order(unsigned long size, int page_shift)
18{ 11{
19#if BITS_PER_LONG == 32 && defined(ARCH_HAS_ILOG2_U32)
20 int order = __ilog2_u32(size) - page_shift;
21 return order >= 0 ? order : 0;
22#elif BITS_PER_LONG == 64 && defined(ARCH_HAS_ILOG2_U64)
23 int order = __ilog2_u64(size) - page_shift;
24 return order >= 0 ? order : 0;
25#else
26 int order; 12 int order;
27 13
28 size = (size - 1) >> (page_shift - 1); 14 size = (size - 1) >> (PAGE_SHIFT - 1);
29 order = -1; 15 order = -1;
30 do { 16 do {
31 size >>= 1; 17 size >>= 1;
32 order++; 18 order++;
33 } while (size); 19 } while (size);
34 return order; 20 return order;
35#endif
36} 21}
37#endif
38
39/**
40 * get_order - calculate log2(pages) to hold a block of the specified size
41 * @n - size
42 *
43 * calculate allocation order based on the current page size
44 * - this can be used to initialise global variables from constant data
45 */
46#define get_order(n) \
47( \
48 __builtin_constant_p(n) ? \
49 ((n < (1UL << PAGE_SHIFT)) ? 0 : ilog2(n) - PAGE_SHIFT) : \
50 __get_order(n, PAGE_SHIFT) \
51 )
52 22
53#endif /* __ASSEMBLY__ */ 23#endif /* __ASSEMBLY__ */
54#endif /* __KERNEL__ */ 24#endif /* __KERNEL__ */