From 87e24802586333fa861861f6493c76039872755b Mon Sep 17 00:00:00 2001 From: Paul Jackson Date: Fri, 24 Mar 2006 03:15:44 -0800 Subject: [PATCH] [PATCH] bitmap: region cleanup Paul Mundt says: This patch set implements a number of patches to clean up and restructure the bitmap region code, in addition to extending the interface to support multiword spanning allocations. The current implementation (before this patch set) is limited by only being able to allocate pages <= BITS_PER_LONG, as noted by the strategically positioned BUG_ON() at lib/bitmap.c:752: /* We don't do regions of pages > 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); As I seem to have been the first person to trigger this, the result ends up being the following patch set with the help of Paul Jackson. The final patch in the series eliminates quite a bit of code duplication, so the bitmap code size ends up being smaller than the current implementation as an added bonus. After these are applied, it should already be possible to do multiword allocations with dma_alloc_coherent() out of ranges established by dma_declare_coherent_memory() on x86 without having to change any of the code, and the SH store queue API will follow up on this as the other user that needs support for this. This patch: 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 Mundt Signed-off-by: Paul Jackson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/bitmap.h | 3 ++ lib/bitmap.c | 64 +++++++++++++++++++++++++----------------- 2 files changed, 41 insertions(+), 26 deletions(-) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 7d8ff97b3e92..d9ed27969855 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -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 */ /* diff --git a/lib/bitmap.c b/lib/bitmap.c index 48e708381d44..3fab1ce9ac65 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -677,39 +677,38 @@ int bitmap_bitremap(int oldbit, const unsigned long *old, EXPORT_SYMBOL(bitmap_bitremap); /** - * bitmap_find_free_region - find a contiguous aligned mem region + * bitmap_find_free_region - find a contiguous aligned mem region * @bitmap: an array of unsigned longs corresponding to the bitmap * @bits: number of bits in the bitmap * @order: region size to find (size is actually 1< 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 */ + if ((bitmap[index] & (mask << offset)) == 0) { + /* set region in bitmap */ bitmap[index] |= (mask << offset); return i; } @@ -719,7 +718,7 @@ int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) EXPORT_SYMBOL(bitmap_find_free_region); /** - * bitmap_release_region - release allocated bitmap region + * bitmap_release_region - release allocated bitmap region * @bitmap: a pointer to the bitmap * @pos: the beginning of the region * @order: the order of the bits to release (number is 1< 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; -- 2.20.1