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In the forthcoming task migration support, a key calculation will be mapping cpu and node numbers from the old set to the new set while preserving cpuset-relative offset. For example, if a task and its pages on nodes 8-11 are being migrated to nodes 24-27, then pages on node 9 (the 2nd node in the old set) should be moved to node 25 (the 2nd node in the new set.) As with other bitmap operations, the proper way to code this is to provide the underlying calculation in lib/bitmap.c, and then to provide the usual cpumask and nodemask wrappers. This patch provides that. These operations are termed 'remap' operations. Both remapping a single bit and a set of bits is supported. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
761 lines
22 KiB
C
761 lines
22 KiB
C
/*
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* lib/bitmap.c
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* Helper functions for bitmap.h.
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/module.h>
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#include <linux/ctype.h>
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#include <linux/errno.h>
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#include <linux/bitmap.h>
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#include <linux/bitops.h>
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#include <asm/uaccess.h>
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/*
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* bitmaps provide an array of bits, implemented using an an
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* array of unsigned longs. The number of valid bits in a
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* given bitmap does _not_ need to be an exact multiple of
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* BITS_PER_LONG.
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*
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* The possible unused bits in the last, partially used word
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* of a bitmap are 'don't care'. The implementation makes
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* no particular effort to keep them zero. It ensures that
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* their value will not affect the results of any operation.
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* The bitmap operations that return Boolean (bitmap_empty,
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* for example) or scalar (bitmap_weight, for example) results
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* carefully filter out these unused bits from impacting their
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* results.
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*
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* These operations actually hold to a slightly stronger rule:
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* if you don't input any bitmaps to these ops that have some
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* unused bits set, then they won't output any set unused bits
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* in output bitmaps.
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*
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* The byte ordering of bitmaps is more natural on little
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* endian architectures. See the big-endian headers
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* include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
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* for the best explanations of this ordering.
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*/
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int __bitmap_empty(const unsigned long *bitmap, int bits)
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{
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int k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k)
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if (bitmap[k])
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return 0;
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if (bits % BITS_PER_LONG)
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if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
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return 0;
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return 1;
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}
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EXPORT_SYMBOL(__bitmap_empty);
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int __bitmap_full(const unsigned long *bitmap, int bits)
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{
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int k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k)
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if (~bitmap[k])
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return 0;
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if (bits % BITS_PER_LONG)
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if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
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return 0;
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return 1;
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}
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EXPORT_SYMBOL(__bitmap_full);
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int __bitmap_equal(const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k)
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if (bitmap1[k] != bitmap2[k])
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return 0;
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if (bits % BITS_PER_LONG)
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if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
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return 0;
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return 1;
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}
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EXPORT_SYMBOL(__bitmap_equal);
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void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
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{
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int k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k)
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dst[k] = ~src[k];
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if (bits % BITS_PER_LONG)
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dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
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}
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EXPORT_SYMBOL(__bitmap_complement);
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/*
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* __bitmap_shift_right - logical right shift of the bits in a bitmap
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* @dst - destination bitmap
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* @src - source bitmap
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* @nbits - shift by this many bits
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* @bits - bitmap size, in bits
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*
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* Shifting right (dividing) means moving bits in the MS -> LS bit
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* direction. Zeros are fed into the vacated MS positions and the
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* LS bits shifted off the bottom are lost.
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*/
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void __bitmap_shift_right(unsigned long *dst,
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const unsigned long *src, int shift, int bits)
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{
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int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
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int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
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unsigned long mask = (1UL << left) - 1;
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for (k = 0; off + k < lim; ++k) {
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unsigned long upper, lower;
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/*
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* If shift is not word aligned, take lower rem bits of
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* word above and make them the top rem bits of result.
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*/
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if (!rem || off + k + 1 >= lim)
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upper = 0;
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else {
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upper = src[off + k + 1];
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if (off + k + 1 == lim - 1 && left)
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upper &= mask;
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}
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lower = src[off + k];
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if (left && off + k == lim - 1)
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lower &= mask;
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dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
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if (left && k == lim - 1)
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dst[k] &= mask;
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}
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if (off)
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memset(&dst[lim - off], 0, off*sizeof(unsigned long));
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}
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EXPORT_SYMBOL(__bitmap_shift_right);
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/*
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* __bitmap_shift_left - logical left shift of the bits in a bitmap
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* @dst - destination bitmap
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* @src - source bitmap
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* @nbits - shift by this many bits
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* @bits - bitmap size, in bits
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*
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* Shifting left (multiplying) means moving bits in the LS -> MS
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* direction. Zeros are fed into the vacated LS bit positions
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* and those MS bits shifted off the top are lost.
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*/
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void __bitmap_shift_left(unsigned long *dst,
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const unsigned long *src, int shift, int bits)
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{
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int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
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int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
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for (k = lim - off - 1; k >= 0; --k) {
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unsigned long upper, lower;
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/*
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* If shift is not word aligned, take upper rem bits of
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* word below and make them the bottom rem bits of result.
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*/
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if (rem && k > 0)
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lower = src[k - 1];
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else
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lower = 0;
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upper = src[k];
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if (left && k == lim - 1)
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upper &= (1UL << left) - 1;
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dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem;
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if (left && k + off == lim - 1)
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dst[k + off] &= (1UL << left) - 1;
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}
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if (off)
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memset(dst, 0, off*sizeof(unsigned long));
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}
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EXPORT_SYMBOL(__bitmap_shift_left);
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void __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k;
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int nr = BITS_TO_LONGS(bits);
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for (k = 0; k < nr; k++)
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dst[k] = bitmap1[k] & bitmap2[k];
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}
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EXPORT_SYMBOL(__bitmap_and);
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void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k;
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int nr = BITS_TO_LONGS(bits);
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for (k = 0; k < nr; k++)
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dst[k] = bitmap1[k] | bitmap2[k];
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}
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EXPORT_SYMBOL(__bitmap_or);
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void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k;
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int nr = BITS_TO_LONGS(bits);
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for (k = 0; k < nr; k++)
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dst[k] = bitmap1[k] ^ bitmap2[k];
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}
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EXPORT_SYMBOL(__bitmap_xor);
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void __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k;
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int nr = BITS_TO_LONGS(bits);
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for (k = 0; k < nr; k++)
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dst[k] = bitmap1[k] & ~bitmap2[k];
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}
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EXPORT_SYMBOL(__bitmap_andnot);
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int __bitmap_intersects(const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k)
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if (bitmap1[k] & bitmap2[k])
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return 1;
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if (bits % BITS_PER_LONG)
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if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
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return 1;
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return 0;
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}
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EXPORT_SYMBOL(__bitmap_intersects);
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int __bitmap_subset(const unsigned long *bitmap1,
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const unsigned long *bitmap2, int bits)
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{
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int k, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; ++k)
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if (bitmap1[k] & ~bitmap2[k])
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return 0;
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if (bits % BITS_PER_LONG)
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if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
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return 0;
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return 1;
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}
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EXPORT_SYMBOL(__bitmap_subset);
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#if BITS_PER_LONG == 32
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int __bitmap_weight(const unsigned long *bitmap, int bits)
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{
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int k, w = 0, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; k++)
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w += hweight32(bitmap[k]);
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if (bits % BITS_PER_LONG)
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w += hweight32(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
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return w;
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}
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#else
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int __bitmap_weight(const unsigned long *bitmap, int bits)
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{
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int k, w = 0, lim = bits/BITS_PER_LONG;
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for (k = 0; k < lim; k++)
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w += hweight64(bitmap[k]);
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if (bits % BITS_PER_LONG)
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w += hweight64(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
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return w;
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}
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#endif
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EXPORT_SYMBOL(__bitmap_weight);
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/*
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* Bitmap printing & parsing functions: first version by Bill Irwin,
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* second version by Paul Jackson, third by Joe Korty.
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*/
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#define CHUNKSZ 32
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#define nbits_to_hold_value(val) fls(val)
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#define unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
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#define BASEDEC 10 /* fancier cpuset lists input in decimal */
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/**
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* bitmap_scnprintf - convert bitmap to an ASCII hex string.
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* @buf: byte buffer into which string is placed
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* @buflen: reserved size of @buf, in bytes
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* @maskp: pointer to bitmap to convert
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* @nmaskbits: size of bitmap, in bits
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*
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* Exactly @nmaskbits bits are displayed. Hex digits are grouped into
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* comma-separated sets of eight digits per set.
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*/
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int bitmap_scnprintf(char *buf, unsigned int buflen,
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const unsigned long *maskp, int nmaskbits)
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{
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int i, word, bit, len = 0;
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unsigned long val;
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const char *sep = "";
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int chunksz;
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u32 chunkmask;
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chunksz = nmaskbits & (CHUNKSZ - 1);
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if (chunksz == 0)
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chunksz = CHUNKSZ;
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i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
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for (; i >= 0; i -= CHUNKSZ) {
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chunkmask = ((1ULL << chunksz) - 1);
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word = i / BITS_PER_LONG;
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bit = i % BITS_PER_LONG;
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val = (maskp[word] >> bit) & chunkmask;
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len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
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(chunksz+3)/4, val);
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chunksz = CHUNKSZ;
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sep = ",";
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}
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return len;
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}
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EXPORT_SYMBOL(bitmap_scnprintf);
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/**
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* bitmap_parse - convert an ASCII hex string into a bitmap.
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* @buf: pointer to buffer in user space containing string.
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* @buflen: buffer size in bytes. If string is smaller than this
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* then it must be terminated with a \0.
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* @maskp: pointer to bitmap array that will contain result.
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* @nmaskbits: size of bitmap, in bits.
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*
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* Commas group hex digits into chunks. Each chunk defines exactly 32
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* bits of the resultant bitmask. No chunk may specify a value larger
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* than 32 bits (-EOVERFLOW), and if a chunk specifies a smaller value
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* then leading 0-bits are prepended. -EINVAL is returned for illegal
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* characters and for grouping errors such as "1,,5", ",44", "," and "".
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* Leading and trailing whitespace accepted, but not embedded whitespace.
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*/
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int bitmap_parse(const char __user *ubuf, unsigned int ubuflen,
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unsigned long *maskp, int nmaskbits)
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{
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int c, old_c, totaldigits, ndigits, nchunks, nbits;
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u32 chunk;
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bitmap_zero(maskp, nmaskbits);
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nchunks = nbits = totaldigits = c = 0;
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do {
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chunk = ndigits = 0;
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/* Get the next chunk of the bitmap */
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while (ubuflen) {
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old_c = c;
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if (get_user(c, ubuf++))
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return -EFAULT;
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ubuflen--;
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if (isspace(c))
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continue;
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/*
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* If the last character was a space and the current
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* character isn't '\0', we've got embedded whitespace.
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* This is a no-no, so throw an error.
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*/
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if (totaldigits && c && isspace(old_c))
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return -EINVAL;
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/* A '\0' or a ',' signal the end of the chunk */
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if (c == '\0' || c == ',')
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break;
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if (!isxdigit(c))
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return -EINVAL;
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/*
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* Make sure there are at least 4 free bits in 'chunk'.
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* If not, this hexdigit will overflow 'chunk', so
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* throw an error.
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*/
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if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
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return -EOVERFLOW;
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chunk = (chunk << 4) | unhex(c);
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ndigits++; totaldigits++;
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}
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if (ndigits == 0)
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return -EINVAL;
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if (nchunks == 0 && chunk == 0)
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continue;
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__bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
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*maskp |= chunk;
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nchunks++;
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nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
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if (nbits > nmaskbits)
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return -EOVERFLOW;
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} while (ubuflen && c == ',');
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return 0;
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}
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EXPORT_SYMBOL(bitmap_parse);
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/*
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* bscnl_emit(buf, buflen, rbot, rtop, bp)
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*
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* Helper routine for bitmap_scnlistprintf(). Write decimal number
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* or range to buf, suppressing output past buf+buflen, with optional
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* comma-prefix. Return len of what would be written to buf, if it
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* all fit.
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*/
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static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
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{
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if (len > 0)
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len += scnprintf(buf + len, buflen - len, ",");
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if (rbot == rtop)
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len += scnprintf(buf + len, buflen - len, "%d", rbot);
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else
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len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
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return len;
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}
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/**
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* bitmap_scnlistprintf - convert bitmap to list format ASCII string
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* @buf: byte buffer into which string is placed
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* @buflen: reserved size of @buf, in bytes
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* @maskp: pointer to bitmap to convert
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* @nmaskbits: size of bitmap, in bits
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*
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* Output format is a comma-separated list of decimal numbers and
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* ranges. Consecutively set bits are shown as two hyphen-separated
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* decimal numbers, the smallest and largest bit numbers set in
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* the range. Output format is compatible with the format
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* accepted as input by bitmap_parselist().
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*
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* The return value is the number of characters which would be
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* generated for the given input, excluding the trailing '\0', as
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* per ISO C99.
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*/
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int bitmap_scnlistprintf(char *buf, unsigned int buflen,
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const unsigned long *maskp, int nmaskbits)
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{
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int len = 0;
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/* current bit is 'cur', most recently seen range is [rbot, rtop] */
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int cur, rbot, rtop;
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rbot = cur = find_first_bit(maskp, nmaskbits);
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while (cur < nmaskbits) {
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rtop = cur;
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cur = find_next_bit(maskp, nmaskbits, cur+1);
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if (cur >= nmaskbits || cur > rtop + 1) {
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len = bscnl_emit(buf, buflen, rbot, rtop, len);
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rbot = cur;
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}
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}
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return len;
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}
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EXPORT_SYMBOL(bitmap_scnlistprintf);
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/**
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* bitmap_parselist - convert list format ASCII string to bitmap
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* @buf: read nul-terminated user string from this buffer
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* @mask: write resulting mask here
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* @nmaskbits: number of bits in mask to be written
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*
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* Input format is a comma-separated list of decimal numbers and
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* ranges. Consecutively set bits are shown as two hyphen-separated
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* decimal numbers, the smallest and largest bit numbers set in
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* the range.
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*
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* Returns 0 on success, -errno on invalid input strings:
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* -EINVAL: second number in range smaller than first
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* -EINVAL: invalid character in string
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* -ERANGE: bit number specified too large for mask
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*/
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int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
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{
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unsigned a, b;
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|
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bitmap_zero(maskp, nmaskbits);
|
|
do {
|
|
if (!isdigit(*bp))
|
|
return -EINVAL;
|
|
b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
|
|
if (*bp == '-') {
|
|
bp++;
|
|
if (!isdigit(*bp))
|
|
return -EINVAL;
|
|
b = simple_strtoul(bp, (char **)&bp, BASEDEC);
|
|
}
|
|
if (!(a <= b))
|
|
return -EINVAL;
|
|
if (b >= nmaskbits)
|
|
return -ERANGE;
|
|
while (a <= b) {
|
|
set_bit(a, maskp);
|
|
a++;
|
|
}
|
|
if (*bp == ',')
|
|
bp++;
|
|
} while (*bp != '\0' && *bp != '\n');
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(bitmap_parselist);
|
|
|
|
/*
|
|
* bitmap_pos_to_ord(buf, pos, bits)
|
|
* @buf: pointer to a bitmap
|
|
* @pos: a bit position in @buf (0 <= @pos < @bits)
|
|
* @bits: number of valid bit positions in @buf
|
|
*
|
|
* Map the bit at position @pos in @buf (of length @bits) to the
|
|
* ordinal of which set bit it is. If it is not set or if @pos
|
|
* is not a valid bit position, map to zero (0).
|
|
*
|
|
* If for example, just bits 4 through 7 are set in @buf, then @pos
|
|
* values 4 through 7 will get mapped to 0 through 3, respectively,
|
|
* and other @pos values will get mapped to 0. When @pos value 7
|
|
* gets mapped to (returns) @ord value 3 in this example, that means
|
|
* that bit 7 is the 3rd (starting with 0th) set bit in @buf.
|
|
*
|
|
* The bit positions 0 through @bits are valid positions in @buf.
|
|
*/
|
|
static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
|
|
{
|
|
int ord = 0;
|
|
|
|
if (pos >= 0 && pos < bits) {
|
|
int i;
|
|
|
|
for (i = find_first_bit(buf, bits);
|
|
i < pos;
|
|
i = find_next_bit(buf, bits, i + 1))
|
|
ord++;
|
|
if (i > pos)
|
|
ord = 0;
|
|
}
|
|
return ord;
|
|
}
|
|
|
|
/**
|
|
* bitmap_ord_to_pos(buf, ord, bits)
|
|
* @buf: pointer to bitmap
|
|
* @ord: ordinal bit position (n-th set bit, n >= 0)
|
|
* @bits: number of valid bit positions in @buf
|
|
*
|
|
* Map the ordinal offset of bit @ord in @buf to its position in @buf.
|
|
* If @ord is not the ordinal offset of a set bit in @buf, map to zero (0).
|
|
*
|
|
* If for example, just bits 4 through 7 are set in @buf, then @ord
|
|
* values 0 through 3 will get mapped to 4 through 7, respectively,
|
|
* and all other @ord valuds will get mapped to 0. When @ord value 3
|
|
* gets mapped to (returns) @pos value 7 in this example, that means
|
|
* that the 3rd set bit (starting with 0th) is at position 7 in @buf.
|
|
*
|
|
* The bit positions 0 through @bits are valid positions in @buf.
|
|
*/
|
|
static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
|
|
{
|
|
int pos = 0;
|
|
|
|
if (ord >= 0 && ord < bits) {
|
|
int i;
|
|
|
|
for (i = find_first_bit(buf, bits);
|
|
i < bits && ord > 0;
|
|
i = find_next_bit(buf, bits, i + 1))
|
|
ord--;
|
|
if (i < bits && ord == 0)
|
|
pos = i;
|
|
}
|
|
|
|
return pos;
|
|
}
|
|
|
|
/**
|
|
* bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
|
|
* @src: subset to be remapped
|
|
* @dst: remapped result
|
|
* @old: defines domain of map
|
|
* @new: defines range of map
|
|
* @bits: number of bits in each of these bitmaps
|
|
*
|
|
* Let @old and @new define a mapping of bit positions, such that
|
|
* whatever position is held by the n-th set bit in @old is mapped
|
|
* to the n-th set bit in @new. In the more general case, allowing
|
|
* for the possibility that the weight 'w' of @new is less than the
|
|
* weight of @old, map the position of the n-th set bit in @old to
|
|
* the position of the m-th set bit in @new, where m == n % w.
|
|
*
|
|
* If either of the @old and @new bitmaps are empty, or if@src and @dst
|
|
* point to the same location, then this routine does nothing.
|
|
*
|
|
* The positions of unset bits in @old are mapped to the position of
|
|
* the first set bit in @new.
|
|
*
|
|
* Apply the above specified mapping to @src, placing the result in
|
|
* @dst, clearing any bits previously set in @dst.
|
|
*
|
|
* The resulting value of @dst will have either the same weight as
|
|
* @src, or less weight in the general case that the mapping wasn't
|
|
* injective due to the weight of @new being less than that of @old.
|
|
* The resulting value of @dst will never have greater weight than
|
|
* that of @src, except perhaps in the case that one of the above
|
|
* conditions was not met and this routine just returned.
|
|
*
|
|
* For example, lets say that @old has bits 4 through 7 set, and
|
|
* @new has bits 12 through 15 set. This defines the mapping of bit
|
|
* position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
|
|
* bit positions to 12 (the first set bit in @new. So if say @src
|
|
* comes into this routine with bits 1, 5 and 7 set, then @dst should
|
|
* leave with bits 12, 13 and 15 set.
|
|
*/
|
|
void bitmap_remap(unsigned long *dst, const unsigned long *src,
|
|
const unsigned long *old, const unsigned long *new,
|
|
int bits)
|
|
{
|
|
int s;
|
|
|
|
if (bitmap_weight(old, bits) == 0)
|
|
return;
|
|
if (bitmap_weight(new, bits) == 0)
|
|
return;
|
|
if (dst == src) /* following doesn't handle inplace remaps */
|
|
return;
|
|
|
|
bitmap_zero(dst, bits);
|
|
for (s = find_first_bit(src, bits);
|
|
s < bits;
|
|
s = find_next_bit(src, bits, s + 1)) {
|
|
int x = bitmap_pos_to_ord(old, s, bits);
|
|
int y = bitmap_ord_to_pos(new, x, bits);
|
|
set_bit(y, dst);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(bitmap_remap);
|
|
|
|
/**
|
|
* bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
|
|
* @oldbit - bit position to be mapped
|
|
* @old: defines domain of map
|
|
* @new: defines range of map
|
|
* @bits: number of bits in each of these bitmaps
|
|
*
|
|
* Let @old and @new define a mapping of bit positions, such that
|
|
* whatever position is held by the n-th set bit in @old is mapped
|
|
* to the n-th set bit in @new. In the more general case, allowing
|
|
* for the possibility that the weight 'w' of @new is less than the
|
|
* weight of @old, map the position of the n-th set bit in @old to
|
|
* the position of the m-th set bit in @new, where m == n % w.
|
|
*
|
|
* The positions of unset bits in @old are mapped to the position of
|
|
* the first set bit in @new.
|
|
*
|
|
* Apply the above specified mapping to bit position @oldbit, returning
|
|
* the new bit position.
|
|
*
|
|
* For example, lets say that @old has bits 4 through 7 set, and
|
|
* @new has bits 12 through 15 set. This defines the mapping of bit
|
|
* position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
|
|
* bit positions to 12 (the first set bit in @new. So if say @oldbit
|
|
* is 5, then this routine returns 13.
|
|
*/
|
|
int bitmap_bitremap(int oldbit, const unsigned long *old,
|
|
const unsigned long *new, int bits)
|
|
{
|
|
int x = bitmap_pos_to_ord(old, oldbit, bits);
|
|
return bitmap_ord_to_pos(new, x, bits);
|
|
}
|
|
EXPORT_SYMBOL(bitmap_bitremap);
|
|
|
|
/**
|
|
* 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<<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).
|
|
*
|
|
* The region is marked as set bits in the bitmap if a free one is
|
|
* found.
|
|
*
|
|
* 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 i;
|
|
|
|
if(pages > BITS_PER_LONG)
|
|
return -EINVAL;
|
|
|
|
/* make a mask of the order */
|
|
mask = (1ul << (pages - 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;
|
|
int offset = i - (index * BITS_PER_LONG);
|
|
if((bitmap[index] & (mask << offset)) == 0) {
|
|
/* set region in bimap */
|
|
bitmap[index] |= (mask << offset);
|
|
return i;
|
|
}
|
|
}
|
|
return -ENOMEM;
|
|
}
|
|
EXPORT_SYMBOL(bitmap_find_free_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<<order)
|
|
*
|
|
* This is the complement to __bitmap_find_free_region and releases
|
|
* the found region (by clearing it in the bitmap).
|
|
*/
|
|
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 offset = pos - (index * BITS_PER_LONG);
|
|
mask += mask - 1;
|
|
bitmap[index] &= ~(mask << offset);
|
|
}
|
|
EXPORT_SYMBOL(bitmap_release_region);
|
|
|
|
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 offset = pos - (index * BITS_PER_LONG);
|
|
|
|
/* 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);
|
|
mask += mask - 1;
|
|
if (bitmap[index] & (mask << offset))
|
|
return -EBUSY;
|
|
bitmap[index] |= (mask << offset);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(bitmap_allocate_region);
|