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author | David Howells <dhowells@redhat.com> | 2012-02-20 22:39:18 (GMT) |
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committer | H. Peter Anvin <hpa@zytor.com> | 2012-02-20 22:46:55 (GMT) |
commit | e0891a9816316b5e05fd5b0453ffe9fd6a56f489 (patch) | |
tree | 3a600ed8fe7285749059d7fccf247d8ca910e0ac /include/asm-generic/getorder.h | |
parent | 7931d493051ea9b09e4fddee2dc40b2eb88d62b9 (diff) | |
download | linux-fsl-qoriq-e0891a9816316b5e05fd5b0453ffe9fd6a56f489.tar.xz |
bitops: Adjust the comment on get_order() to describe the size==0 case
Adjust the comment on get_order() to note that the result of passing a size of
0 results in an undefined value.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120220223917.16199.9416.stgit@warthog.procyon.org.uk
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'include/asm-generic/getorder.h')
-rw-r--r-- | include/asm-generic/getorder.h | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/include/asm-generic/getorder.h b/include/asm-generic/getorder.h index 67e7245..76e9687 100644 --- a/include/asm-generic/getorder.h +++ b/include/asm-generic/getorder.h @@ -5,7 +5,28 @@ #include <linux/compiler.h> -/* Pure 2^n version of get_order */ +/** + * get_order - Determine the allocation order of a memory size + * @size: The size for which to get the order + * + * Determine the allocation order of a particular sized block of memory. This + * is on a logarithmic scale, where: + * + * 0 -> 2^0 * PAGE_SIZE and below + * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1 + * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1 + * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1 + * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1 + * ... + * + * The order returned is used to find the smallest allocation granule required + * to hold an object of the specified size. + * + * The result is undefined if the size is 0. + * + * This function may be used to initialise variables with compile time + * evaluations of constants. + */ static inline __attribute_const__ int get_order(unsigned long size) { int order; |