Messages in this thread Patch in this message | | | Date | Thu, 19 Jan 2006 18:07:57 -0800 (PST) | From | Paul Jackson <> | Subject | [TEST PATCH 1/3] lib bitmap region cleanup |
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From Paul Jackson <pj@sgi.com>
Some code cleanup on the lib/bitmap.c bitmap_*_region() routines: * spacing * variable names * comments
Has no change to code function.
Signed-off-by: Paul Jackson <pj@sgi.com>
---
This compiles, but has not been tested past that. I am hoping that Paul Mundt will be able to test.
include/linux/bitmap.h | 3 ++ lib/bitmap.c | 57 ++++++++++++++++++++++++++++++------------------- 2 files changed, 38 insertions(+), 22 deletions(-)
--- 2.6.15-mm2.orig/include/linux/bitmap.h 2006-01-18 23:31:05.859645986 -0800 +++ 2.6.15-mm2/include/linux/bitmap.h 2006-01-18 23:39:53.505381843 -0800 @@ -46,6 +46,9 @@ * bitmap_parse(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf * bitmap_scnlistprintf(buf, len, src, nbits) Print bitmap src as list to buf * bitmap_parselist(buf, dst, nbits) Parse bitmap dst from list + * bitmap_find_free_region(bitmap, bits, order) Find and allocate bit region + * bitmap_release_region(bitmap, pos, order) Free specified bit region + * bitmap_allocate_region(bitmap, pos, order) Allocate specified bit region */ /* --- 2.6.15-mm2.orig/lib/bitmap.c 2006-01-18 23:39:46.282642389 -0800 +++ 2.6.15-mm2/lib/bitmap.c 2006-01-18 23:40:23.342639589 -0800 @@ -682,34 +682,34 @@ EXPORT_SYMBOL(bitmap_bitremap); * @bits: number of bits in the bitmap * @order: region size to find (size is actually 1<<order) * - * This is used to allocate a memory region from a bitmap. The idea is - * that the region has to be 1<<order sized and 1<<order aligned (this - * makes the search algorithm much faster). + * Find a sequence of free (zero) bits in a bitmap and allocate + * them (set them to one). Only consider sequences of length a + * power ('order') of two, alligned to that power of two, which + * makes the search algorithm much faster. * - * The region is marked as set bits in the bitmap if a free one is - * found. + * Return the bit offset in bitmap of the allocated sequence, + * or -errno on failure. * - * Returns either beginning of region or negative error */ int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) { unsigned long mask; - int pages = 1 << order; + int nbits = 1 << order; int i; - if(pages > BITS_PER_LONG) + if(nbits > BITS_PER_LONG) return -EINVAL; /* make a mask of the order */ - mask = (1ul << (pages - 1)); + mask = (1UL << (nbits - 1)); mask += mask - 1; - /* run up the bitmap pages bits at a time */ - for (i = 0; i < bits; i += pages) { - int index = i/BITS_PER_LONG; + /* run up the bitmap nbits at a time */ + for (i = 0; i < bits; i += nbits) { + int index = i / BITS_PER_LONG; int offset = i - (index * BITS_PER_LONG); if((bitmap[index] & (mask << offset)) == 0) { - /* set region in bimap */ + /* set region in bitmap */ bitmap[index] |= (mask << offset); return i; } @@ -729,27 +729,40 @@ EXPORT_SYMBOL(bitmap_find_free_region); */ void bitmap_release_region(unsigned long *bitmap, int pos, int order) { - int pages = 1 << order; - unsigned long mask = (1ul << (pages - 1)); - int index = pos/BITS_PER_LONG; + int nbits = 1 << order; + unsigned long mask = (1UL << (nbits - 1)); + int index = pos / BITS_PER_LONG; int offset = pos - (index * BITS_PER_LONG); + mask += mask - 1; bitmap[index] &= ~(mask << offset); } EXPORT_SYMBOL(bitmap_release_region); +/** + * bitmap_allocate_region - allocate bitmap region + * @bitmap: a pointer to the bitmap + * @pos: the beginning of the region + * @order: the order of the bits to allocate (number is 1<<order) + * + * Allocate (set bits in) a specified region of a bitmap. + * Return 0 on success, or -EBUSY if specified region wasn't + * free (not all bits were zero). + */ int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) { - int pages = 1 << order; - unsigned long mask = (1ul << (pages - 1)); - int index = pos/BITS_PER_LONG; + int nbits = 1 << order; + unsigned long mask = (1UL << (nbits - 1)); + int index = pos / BITS_PER_LONG; int offset = pos - (index * BITS_PER_LONG); - /* We don't do regions of pages > BITS_PER_LONG. The + /* + * We don't do regions of nbits > BITS_PER_LONG. The * algorithm would be a simple look for multiple zeros in the * array, but there's no driver today that needs this. If you - * trip this BUG(), you get to code it... */ - BUG_ON(pages > BITS_PER_LONG); + * trip this BUG(), you get to code it... + */ + BUG_ON(nbits > BITS_PER_LONG); mask += mask - 1; if (bitmap[index] & (mask << offset)) return -EBUSY; -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <pj@sgi.com> 1.650.933.1373 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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