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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * lib/bitmap.c
  * Helper functions for bitmap.h.
  */
 
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 #include <linux/bug.h>
 #include <linux/ctype.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/thread_info.h>
 #include <linux/uaccess.h>
 
 #include <asm/page.h>
 
 #include "kstrtox.h"
 
 /**
  * DOC: bitmap introduction
  *
  * bitmaps provide an array of bits, implemented using an
  * array of unsigned longs.  The number of valid bits in a
  * given bitmap does _not_ need to be an exact multiple of
  * BITS_PER_LONG.
  *
  * The possible unused bits in the last, partially used word
  * of a bitmap are 'don't care'.  The implementation makes
  * no particular effort to keep them zero.  It ensures that
  * their value will not affect the results of any operation.
  * The bitmap operations that return Boolean (bitmap_empty,
  * for example) or scalar (bitmap_weight, for example) results
  * carefully filter out these unused bits from impacting their
  * results.
  *
  * The byte ordering of bitmaps is more natural on little
  * endian architectures.  See the big-endian headers
  * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
  * for the best explanations of this ordering.
  */
 
 bool __bitmap_equal(const unsigned long *bitmap1,
             const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k, lim = bits/BITS_PER_LONG;
     for (k = 0; k < lim; ++k)
         if (bitmap1[k] != bitmap2[k])
             return false;
 
     if (bits % BITS_PER_LONG)
         if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
             return false;
 
     return true;
 }
 EXPORT_SYMBOL(__bitmap_equal);
 
 bool __bitmap_or_equal(const unsigned long *bitmap1,
                const unsigned long *bitmap2,
                const unsigned long *bitmap3,
                unsigned int bits)
 {
     unsigned int k, lim = bits / BITS_PER_LONG;
     unsigned long tmp;
 
     for (k = 0; k < lim; ++k) {
         if ((bitmap1[k] | bitmap2[k]) != bitmap3[k])
             return false;
     }
 
     if (!(bits % BITS_PER_LONG))
         return true;
 
     tmp = (bitmap1[k] | bitmap2[k]) ^ bitmap3[k];
     return (tmp & BITMAP_LAST_WORD_MASK(bits)) == 0;
 }
 
 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
 {
     unsigned int k, lim = BITS_TO_LONGS(bits);
     for (k = 0; k < lim; ++k)
         dst[k] = ~src[k];
 }
 EXPORT_SYMBOL(__bitmap_complement);
 
 /**
  * __bitmap_shift_right - logical right shift of the bits in a bitmap
  *   @dst : destination bitmap
  *   @src : source bitmap
  *   @shift : shift by this many bits
  *   @nbits : bitmap size, in bits
  *
  * Shifting right (dividing) means moving bits in the MS -> LS bit
  * direction.  Zeros are fed into the vacated MS positions and the
  * LS bits shifted off the bottom are lost.
  */
 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
             unsigned shift, unsigned nbits)
 {
     unsigned k, lim = BITS_TO_LONGS(nbits);
     unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
     unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
     for (k = 0; off + k < lim; ++k) {
         unsigned long upper, lower;
 
         /*
          * If shift is not word aligned, take lower rem bits of
          * word above and make them the top rem bits of result.
          */
         if (!rem || off + k + 1 >= lim)
             upper = 0;
         else {
             upper = src[off + k + 1];
             if (off + k + 1 == lim - 1)
                 upper &= mask;
             upper <<= (BITS_PER_LONG - rem);
         }
         lower = src[off + k];
         if (off + k == lim - 1)
             lower &= mask;
         lower >>= rem;
         dst[k] = lower | upper;
     }
     if (off)
         memset(&dst[lim - off], 0, off*sizeof(unsigned long));
 }
 EXPORT_SYMBOL(__bitmap_shift_right);
 
 
 /**
  * __bitmap_shift_left - logical left shift of the bits in a bitmap
  *   @dst : destination bitmap
  *   @src : source bitmap
  *   @shift : shift by this many bits
  *   @nbits : bitmap size, in bits
  *
  * Shifting left (multiplying) means moving bits in the LS -> MS
  * direction.  Zeros are fed into the vacated LS bit positions
  * and those MS bits shifted off the top are lost.
  */
 
 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
             unsigned int shift, unsigned int nbits)
 {
     int k;
     unsigned int lim = BITS_TO_LONGS(nbits);
     unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
     for (k = lim - off - 1; k >= 0; --k) {
         unsigned long upper, lower;
 
         /*
          * If shift is not word aligned, take upper rem bits of
          * word below and make them the bottom rem bits of result.
          */
         if (rem && k > 0)
             lower = src[k - 1] >> (BITS_PER_LONG - rem);
         else
             lower = 0;
         upper = src[k] << rem;
         dst[k + off] = lower | upper;
     }
     if (off)
         memset(dst, 0, off*sizeof(unsigned long));
 }
 EXPORT_SYMBOL(__bitmap_shift_left);
 
 /**
  * bitmap_cut() - remove bit region from bitmap and right shift remaining bits
  * @dst: destination bitmap, might overlap with src
  * @src: source bitmap
  * @first: start bit of region to be removed
  * @cut: number of bits to remove
  * @nbits: bitmap size, in bits
  *
  * Set the n-th bit of @dst iff the n-th bit of @src is set and
  * n is less than @first, or the m-th bit of @src is set for any
  * m such that @first <= n < nbits, and m = n + @cut.
  *
  * In pictures, example for a big-endian 32-bit architecture:
  *
  * The @src bitmap is::
  *
  *   31                                   63
  *   |                                    |
  *   10000000 11000001 11110010 00010101  10000000 11000001 01110010 00010101
  *                   |  |              |                                    |
  *                  16  14             0                                   32
  *
  * if @cut is 3, and @first is 14, bits 14-16 in @src are cut and @dst is::
  *
  *   31                                   63
  *   |                                    |
  *   10110000 00011000 00110010 00010101  00010000 00011000 00101110 01000010
  *                      |              |                                    |
  *                      14 (bit 17     0                                   32
  *                          from @src)
  *
  * Note that @dst and @src might overlap partially or entirely.
  *
  * This is implemented in the obvious way, with a shift and carry
  * step for each moved bit. Optimisation is left as an exercise
  * for the compiler.
  */
 void bitmap_cut(unsigned long *dst, const unsigned long *src,
         unsigned int first, unsigned int cut, unsigned int nbits)
 {
     unsigned int len = BITS_TO_LONGS(nbits);
     unsigned long keep = 0, carry;
     int i;
 
     if (first % BITS_PER_LONG) {
         keep = src[first / BITS_PER_LONG] &
                (~0UL >> (BITS_PER_LONG - first % BITS_PER_LONG));
     }
 
     memmove(dst, src, len * sizeof(*dst));
 
     while (cut--) {
         for (i = first / BITS_PER_LONG; i < len; i++) {
             if (i < len - 1)
                 carry = dst[i + 1] & 1UL;
             else
                 carry = 0;
 
             dst[i] = (dst[i] >> 1) | (carry << (BITS_PER_LONG - 1));
         }
     }
 
     dst[first / BITS_PER_LONG] &= ~0UL << (first % BITS_PER_LONG);
     dst[first / BITS_PER_LONG] |= keep;
 }
 EXPORT_SYMBOL(bitmap_cut);
 
 bool __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
                 const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k;
     unsigned int lim = bits/BITS_PER_LONG;
     unsigned long result = 0;
 
     for (k = 0; k < lim; k++)
         result |= (dst[k] = bitmap1[k] & bitmap2[k]);
     if (bits % BITS_PER_LONG)
         result |= (dst[k] = bitmap1[k] & bitmap2[k] &
                BITMAP_LAST_WORD_MASK(bits));
     return result != 0;
 }
 EXPORT_SYMBOL(__bitmap_and);
 
 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
                 const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k;
     unsigned int nr = BITS_TO_LONGS(bits);
 
     for (k = 0; k < nr; k++)
         dst[k] = bitmap1[k] | bitmap2[k];
 }
 EXPORT_SYMBOL(__bitmap_or);
 
 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
                 const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k;
     unsigned int nr = BITS_TO_LONGS(bits);
 
     for (k = 0; k < nr; k++)
         dst[k] = bitmap1[k] ^ bitmap2[k];
 }
 EXPORT_SYMBOL(__bitmap_xor);
 
 bool __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
                 const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k;
     unsigned int lim = bits/BITS_PER_LONG;
     unsigned long result = 0;
 
     for (k = 0; k < lim; k++)
         result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
     if (bits % BITS_PER_LONG)
         result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
                BITMAP_LAST_WORD_MASK(bits));
     return result != 0;
 }
 EXPORT_SYMBOL(__bitmap_andnot);
 
 void __bitmap_replace(unsigned long *dst,
               const unsigned long *old, const unsigned long *new,
               const unsigned long *mask, unsigned int nbits)
 {
     unsigned int k;
     unsigned int nr = BITS_TO_LONGS(nbits);
 
     for (k = 0; k < nr; k++)
         dst[k] = (old[k] & ~mask[k]) | (new[k] & mask[k]);
 }
 EXPORT_SYMBOL(__bitmap_replace);
 
 bool __bitmap_intersects(const unsigned long *bitmap1,
              const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k, lim = bits/BITS_PER_LONG;
     for (k = 0; k < lim; ++k)
         if (bitmap1[k] & bitmap2[k])
             return true;
 
     if (bits % BITS_PER_LONG)
         if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
             return true;
     return false;
 }
 EXPORT_SYMBOL(__bitmap_intersects);
 
 bool __bitmap_subset(const unsigned long *bitmap1,
              const unsigned long *bitmap2, unsigned int bits)
 {
     unsigned int k, lim = bits/BITS_PER_LONG;
     for (k = 0; k < lim; ++k)
         if (bitmap1[k] & ~bitmap2[k])
             return false;
 
     if (bits % BITS_PER_LONG)
         if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
             return false;
     return true;
 }
 EXPORT_SYMBOL(__bitmap_subset);
 
 unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
 {
     unsigned int k, lim = bits/BITS_PER_LONG, w = 0;
 
     for (k = 0; k < lim; k++)
         w += hweight_long(bitmap[k]);
 
     if (bits % BITS_PER_LONG)
         w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
 
     return w;
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
 void __bitmap_set(unsigned long *map, unsigned int start, int len)
 {
     unsigned long *p = map + BIT_WORD(start);
     const unsigned int size = start + len;
     int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
 
     while (len - bits_to_set >= 0) {
         *p |= mask_to_set;
         len -= bits_to_set;
         bits_to_set = BITS_PER_LONG;
         mask_to_set = ~0UL;
         p++;
     }
     if (len) {
         mask_to_set &= BITMAP_LAST_WORD_MASK(size);
         *p |= mask_to_set;
     }
 }
 EXPORT_SYMBOL(__bitmap_set);
 
 void __bitmap_clear(unsigned long *map, unsigned int start, int len)
 {
     unsigned long *p = map + BIT_WORD(start);
     const unsigned int size = start + len;
     int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
     unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 
     while (len - bits_to_clear >= 0) {
         *p &= ~mask_to_clear;
         len -= bits_to_clear;
         bits_to_clear = BITS_PER_LONG;
         mask_to_clear = ~0UL;
         p++;
     }
     if (len) {
         mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
         *p &= ~mask_to_clear;
     }
 }
 EXPORT_SYMBOL(__bitmap_clear);
 
 /**
  * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
  * @map: The address to base the search on
  * @size: The bitmap size in bits
  * @start: The bitnumber to start searching at
  * @nr: The number of zeroed bits we're looking for
  * @align_mask: Alignment mask for zero area
  * @align_offset: Alignment offset for zero area.
  *
  * The @align_mask should be one less than a power of 2; the effect is that
  * the bit offset of all zero areas this function finds plus @align_offset
  * is multiple of that power of 2.
  */
 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
                          unsigned long size,
                          unsigned long start,
                          unsigned int nr,
                          unsigned long align_mask,
                          unsigned long align_offset)
 {
     unsigned long index, end, i;
 again:
     index = find_next_zero_bit(map, size, start);
 
     /* Align allocation */
     index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
 
     end = index + nr;
     if (end > size)
         return end;
     i = find_next_bit(map, end, index);
     if (i < end) {
         start = i + 1;
         goto again;
     }
     return index;
 }
 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
 
 /*
  * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
  * second version by Paul Jackson, third by Joe Korty.
  */
 
 /**
  * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
  *
  * @ubuf: pointer to user buffer containing string.
  * @ulen: buffer size in bytes.  If string is smaller than this
  *    then it must be terminated with a \0.
  * @maskp: pointer to bitmap array that will contain result.
  * @nmaskbits: size of bitmap, in bits.
  */
 int bitmap_parse_user(const char __user *ubuf,
             unsigned int ulen, unsigned long *maskp,
             int nmaskbits)
 {
     char *buf;
     int ret;
 
     buf = memdup_user_nul(ubuf, ulen);
     if (IS_ERR(buf))
         return PTR_ERR(buf);
 
     ret = bitmap_parse(buf, UINT_MAX, maskp, nmaskbits);
 
     kfree(buf);
     return ret;
 }
 EXPORT_SYMBOL(bitmap_parse_user);
 
 /**
  * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
  * @list: indicates whether the bitmap must be list
  * @buf: page aligned buffer into which string is placed
  * @maskp: pointer to bitmap to convert
  * @nmaskbits: size of bitmap, in bits
  *
  * Output format is a comma-separated list of decimal numbers and
  * ranges if list is specified or hex digits grouped into comma-separated
  * sets of 8 digits/set. Returns the number of characters written to buf.
  *
  * It is assumed that @buf is a pointer into a PAGE_SIZE, page-aligned
  * area and that sufficient storage remains at @buf to accommodate the
  * bitmap_print_to_pagebuf() output. Returns the number of characters
  * actually printed to @buf, excluding terminating '\0'.
  */
 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
                 int nmaskbits)
 {
     ptrdiff_t len = PAGE_SIZE - offset_in_page(buf);
 
     return list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
               scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
 }
 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
 
 /**
  * bitmap_print_to_buf  - convert bitmap to list or hex format ASCII string
  * @list: indicates whether the bitmap must be list
  *      true:  print in decimal list format
  *      false: print in hexadecimal bitmask format
  * @buf: buffer into which string is placed
  * @maskp: pointer to bitmap to convert
  * @nmaskbits: size of bitmap, in bits
  * @off: in the string from which we are copying, We copy to @buf
  * @count: the maximum number of bytes to print
  */
 static int bitmap_print_to_buf(bool list, char *buf, const unsigned long *maskp,
         int nmaskbits, loff_t off, size_t count)
 {
     const char *fmt = list ? "%*pbl\n" : "%*pb\n";
     ssize_t size;
     void *data;
 
     data = kasprintf(GFP_KERNEL, fmt, nmaskbits, maskp);
     if (!data)
         return -ENOMEM;
 
     size = memory_read_from_buffer(buf, count, &off, data, strlen(data) + 1);
     kfree(data);
 
     return size;
 }
 
 /**
  * bitmap_print_bitmask_to_buf  - convert bitmap to hex bitmask format ASCII string
  * @buf: buffer into which string is placed
  * @maskp: pointer to bitmap to convert
  * @nmaskbits: size of bitmap, in bits
  * @off: in the string from which we are copying, We copy to @buf
  * @count: the maximum number of bytes to print
  *
  * The bitmap_print_to_pagebuf() is used indirectly via its cpumap wrapper
  * cpumap_print_to_pagebuf() or directly by drivers to export hexadecimal
  * bitmask and decimal list to userspace by sysfs ABI.
  * Drivers might be using a normal attribute for this kind of ABIs. A
  * normal attribute typically has show entry as below::
  *
  *   static ssize_t example_attribute_show(struct device *dev,
  *      struct device_attribute *attr, char *buf)
  *   {
  *  ...
  *  return bitmap_print_to_pagebuf(true, buf, &mask, nr_trig_max);
  *   }
  *
  * show entry of attribute has no offset and count parameters and this
  * means the file is limited to one page only.
  * bitmap_print_to_pagebuf() API works terribly well for this kind of
  * normal attribute with buf parameter and without offset, count::
  *
  *   bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
  *             int nmaskbits)
  *   {
  *   }
  *
  * The problem is once we have a large bitmap, we have a chance to get a
  * bitmask or list more than one page. Especially for list, it could be
  * as complex as 0,3,5,7,9,... We have no simple way to know it exact size.
  * It turns out bin_attribute is a way to break this limit. bin_attribute
  * has show entry as below::
  *
  *   static ssize_t
  *   example_bin_attribute_show(struct file *filp, struct kobject *kobj,
  *      struct bin_attribute *attr, char *buf,
  *      loff_t offset, size_t count)
  *   {
  *  ...
  *   }
  *
  * With the new offset and count parameters, this makes sysfs ABI be able
  * to support file size more than one page. For example, offset could be
  * >= 4096.
  * bitmap_print_bitmask_to_buf(), bitmap_print_list_to_buf() wit their
  * cpumap wrapper cpumap_print_bitmask_to_buf(), cpumap_print_list_to_buf()
  * make those drivers be able to support large bitmask and list after they
  * move to use bin_attribute. In result, we have to pass the corresponding
  * parameters such as off, count from bin_attribute show entry to this API.
  *
  * The role of cpumap_print_bitmask_to_buf() and cpumap_print_list_to_buf()
  * is similar with cpumap_print_to_pagebuf(),  the difference is that
  * bitmap_print_to_pagebuf() mainly serves sysfs attribute with the assumption
  * the destination buffer is exactly one page and won't be more than one page.
  * cpumap_print_bitmask_to_buf() and cpumap_print_list_to_buf(), on the other
  * hand, mainly serves bin_attribute which doesn't work with exact one page,
  * and it can break the size limit of converted decimal list and hexadecimal
  * bitmask.
  *
  * WARNING!
  *
  * This function is not a replacement for sprintf() or bitmap_print_to_pagebuf().
  * It is intended to workaround sysfs limitations discussed above and should be
  * used carefully in general case for the following reasons:
  *
  *  - Time complexity is O(nbits^2/count), comparing to O(nbits) for snprintf().
  *  - Memory complexity is O(nbits), comparing to O(1) for snprintf().
  *  - @off and @count are NOT offset and number of bits to print.
  *  - If printing part of bitmap as list, the resulting string is not a correct
  *    list representation of bitmap. Particularly, some bits within or out of
  *    related interval may be erroneously set or unset. The format of the string
  *    may be broken, so bitmap_parselist-like parser may fail parsing it.
  *  - If printing the whole bitmap as list by parts, user must ensure the order
  *    of calls of the function such that the offset is incremented linearly.
  *  - If printing the whole bitmap as list by parts, user must keep bitmap
  *    unchanged between the very first and very last call. Otherwise concatenated
  *    result may be incorrect, and format may be broken.
  *
  * Returns the number of characters actually printed to @buf
  */
 int bitmap_print_bitmask_to_buf(char *buf, const unsigned long *maskp,
                 int nmaskbits, loff_t off, size_t count)
 {
     return bitmap_print_to_buf(false, buf, maskp, nmaskbits, off, count);
 }
 EXPORT_SYMBOL(bitmap_print_bitmask_to_buf);
 
 /**
  * bitmap_print_list_to_buf  - convert bitmap to decimal list format ASCII string
  * @buf: buffer into which string is placed
  * @maskp: pointer to bitmap to convert
  * @nmaskbits: size of bitmap, in bits
  * @off: in the string from which we are copying, We copy to @buf
  * @count: the maximum number of bytes to print
  *
  * Everything is same with the above bitmap_print_bitmask_to_buf() except
  * the print format.
  */
 int bitmap_print_list_to_buf(char *buf, const unsigned long *maskp,
                  int nmaskbits, loff_t off, size_t count)
 {
     return bitmap_print_to_buf(true, buf, maskp, nmaskbits, off, count);
 }
 EXPORT_SYMBOL(bitmap_print_list_to_buf);
 
 /*
  * Region 9-38:4/10 describes the following bitmap structure:
  * 0       9  12    18          38       N
  * .........****......****......****..................
  *      ^  ^     ^           ^       ^
  *      start  off   group_len         end   nbits
  */
 struct region {
     unsigned int start;
     unsigned int off;
     unsigned int group_len;
     unsigned int end;
     unsigned int nbits;
 };
 
 static void bitmap_set_region(const struct region *r, unsigned long *bitmap)
 {
     unsigned int start;
 
     for (start = r->start; start <= r->end; start += r->group_len)
         bitmap_set(bitmap, start, min(r->end - start + 1, r->off));
 }
 
 static int bitmap_check_region(const struct region *r)
 {
     if (r->start > r->end || r->group_len == 0 || r->off > r->group_len)
         return -EINVAL;
 
     if (r->end >= r->nbits)
         return -ERANGE;
 
     return 0;
 }
 
 static const char *bitmap_getnum(const char *str, unsigned int *num,
                  unsigned int lastbit)
 {
     unsigned long long n;
     unsigned int len;
 
     if (str[0] == 'N') {
         *num = lastbit;
         return str + 1;
     }
 
     len = _parse_integer(str, 10, &n);
     if (!len)
         return ERR_PTR(-EINVAL);
     if (len & KSTRTOX_OVERFLOW || n != (unsigned int)n)
         return ERR_PTR(-EOVERFLOW);
 
     *num = n;
     return str + len;
 }
 
 static inline bool end_of_str(char c)
 {
     return c == '\0' || c == '\n';
 }
 
 static inline bool __end_of_region(char c)
 {
     return isspace(c) || c == ',';
 }
 
 static inline bool end_of_region(char c)
 {
     return __end_of_region(c) || end_of_str(c);
 }
 
 /*
  * The format allows commas and whitespaces at the beginning
  * of the region.
  */
 static const char *bitmap_find_region(const char *str)
 {
     while (__end_of_region(*str))
         str++;
 
     return end_of_str(*str) ? NULL : str;
 }
 
 static const char *bitmap_find_region_reverse(const char *start, const char *end)
 {
     while (start <= end && __end_of_region(*end))
         end--;
 
     return end;
 }
 
 static const char *bitmap_parse_region(const char *str, struct region *r)
 {
     unsigned int lastbit = r->nbits - 1;
 
     if (!strncasecmp(str, "all", 3)) {
         r->start = 0;
         r->end = lastbit;
         str += 3;
 
         goto check_pattern;
     }
 
     str = bitmap_getnum(str, &r->start, lastbit);
     if (IS_ERR(str))
         return str;
 
     if (end_of_region(*str))
         goto no_end;
 
     if (*str != '-')
         return ERR_PTR(-EINVAL);
 
     str = bitmap_getnum(str + 1, &r->end, lastbit);
     if (IS_ERR(str))
         return str;
 
 check_pattern:
     if (end_of_region(*str))
         goto no_pattern;
 
     if (*str != ':')
         return ERR_PTR(-EINVAL);
 
     str = bitmap_getnum(str + 1, &r->off, lastbit);
     if (IS_ERR(str))
         return str;
 
     if (*str != '/')
         return ERR_PTR(-EINVAL);
 
     return bitmap_getnum(str + 1, &r->group_len, lastbit);
 
 no_end:
     r->end = r->start;
 no_pattern:
     r->off = r->end + 1;
     r->group_len = r->end + 1;
 
     return end_of_str(*str) ? NULL : str;
 }
 
 /**
  * bitmap_parselist - convert list format ASCII string to bitmap
  * @buf: read user string from this buffer; must be terminated
  *    with a \0 or \n.
  * @maskp: write resulting mask here
  * @nmaskbits: number of bits in mask to be written
  *
  * Input format is a comma-separated list of decimal numbers and
  * ranges.  Consecutively set bits are shown as two hyphen-separated
  * decimal numbers, the smallest and largest bit numbers set in
  * the range.
  * Optionally each range can be postfixed to denote that only parts of it
  * should be set. The range will divided to groups of specific size.
  * From each group will be used only defined amount of bits.
  * Syntax: range:used_size/group_size
  * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
  * The value 'N' can be used as a dynamically substituted token for the
  * maximum allowed value; i.e (nmaskbits - 1).  Keep in mind that it is
  * dynamic, so if system changes cause the bitmap width to change, such
  * as more cores in a CPU list, then any ranges using N will also change.
  *
  * Returns: 0 on success, -errno on invalid input strings. Error values:
  *
  *   - ``-EINVAL``: wrong region format
  *   - ``-EINVAL``: invalid character in string
  *   - ``-ERANGE``: bit number specified too large for mask
  *   - ``-EOVERFLOW``: integer overflow in the input parameters
  */
 int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
 {
     struct region r;
     long ret;
 
     r.nbits = nmaskbits;
     bitmap_zero(maskp, r.nbits);
 
     while (buf) {
         buf = bitmap_find_region(buf);
         if (buf == NULL)
             return 0;
 
         buf = bitmap_parse_region(buf, &r);
         if (IS_ERR(buf))
             return PTR_ERR(buf);
 
         ret = bitmap_check_region(&r);
         if (ret)
             return ret;
 
         bitmap_set_region(&r, maskp);
     }
 
     return 0;
 }
 EXPORT_SYMBOL(bitmap_parselist);
 
 
 /**
  * bitmap_parselist_user() - convert user buffer's list format ASCII
  * string to bitmap
  *
  * @ubuf: pointer to user buffer containing string.
  * @ulen: buffer size in bytes.  If string is smaller than this
  *    then it must be terminated with a \0.
  * @maskp: pointer to bitmap array that will contain result.
  * @nmaskbits: size of bitmap, in bits.
  *
  * Wrapper for bitmap_parselist(), providing it with user buffer.
  */
 int bitmap_parselist_user(const char __user *ubuf,
             unsigned int ulen, unsigned long *maskp,
             int nmaskbits)
 {
     char *buf;
     int ret;
 
     buf = memdup_user_nul(ubuf, ulen);
     if (IS_ERR(buf))
         return PTR_ERR(buf);
 
     ret = bitmap_parselist(buf, maskp, nmaskbits);
 
     kfree(buf);
     return ret;
 }
 EXPORT_SYMBOL(bitmap_parselist_user);
 
 static const char *bitmap_get_x32_reverse(const char *start,
                     const char *end, u32 *num)
 {
     u32 ret = 0;
     int c, i;
 
     for (i = 0; i < 32; i += 4) {
         c = hex_to_bin(*end--);
         if (c < 0)
             return ERR_PTR(-EINVAL);
 
         ret |= c << i;
 
         if (start > end || __end_of_region(*end))
             goto out;
     }
 
     if (hex_to_bin(*end--) >= 0)
         return ERR_PTR(-EOVERFLOW);
 out:
     *num = ret;
     return end;
 }
 
 /**
  * bitmap_parse - convert an ASCII hex string into a bitmap.
  * @start: pointer to buffer containing string.
  * @buflen: buffer size in bytes.  If string is smaller than this
  *    then it must be terminated with a \0 or \n. In that case,
  *    UINT_MAX may be provided instead of string length.
  * @maskp: pointer to bitmap array that will contain result.
  * @nmaskbits: size of bitmap, in bits.
  *
  * Commas group hex digits into chunks.  Each chunk defines exactly 32
  * bits of the resultant bitmask.  No chunk may specify a value larger
  * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
  * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
  * characters. Grouping such as "1,,5", ",44", "," or "" is allowed.
  * Leading, embedded and trailing whitespace accepted.
  */
 int bitmap_parse(const char *start, unsigned int buflen,
         unsigned long *maskp, int nmaskbits)
 {
     const char *end = strnchrnul(start, buflen, '\n') - 1;
     int chunks = BITS_TO_U32(nmaskbits);
     u32 *bitmap = (u32 *)maskp;
     int unset_bit;
     int chunk;
 
     for (chunk = 0; ; chunk++) {
         end = bitmap_find_region_reverse(start, end);
         if (start > end)
             break;
 
         if (!chunks--)
             return -EOVERFLOW;
 
 #if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
         end = bitmap_get_x32_reverse(start, end, &bitmap[chunk ^ 1]);
 #else
         end = bitmap_get_x32_reverse(start, end, &bitmap[chunk]);
 #endif
         if (IS_ERR(end))
             return PTR_ERR(end);
     }
 
     unset_bit = (BITS_TO_U32(nmaskbits) - chunks) * 32;
     if (unset_bit < nmaskbits) {
         bitmap_clear(maskp, unset_bit, nmaskbits - unset_bit);
         return 0;
     }
 
     if (find_next_bit(maskp, unset_bit, nmaskbits) != unset_bit)
         return -EOVERFLOW;
 
     return 0;
 }
 EXPORT_SYMBOL(bitmap_parse);
 
 /**
  * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
  *  @buf: pointer to a bitmap
  *  @pos: a bit position in @buf (0 <= @pos < @nbits)
  *  @nbits: number of valid bit positions in @buf
  *
  * Map the bit at position @pos in @buf (of length @nbits) 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 -1.
  *
  * 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 -1.  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, unsigned int pos, unsigned int nbits)
 {
     if (pos >= nbits || !test_bit(pos, buf))
         return -1;
 
     return __bitmap_weight(buf, pos);
 }
 
 /**
  * bitmap_ord_to_pos - find position of n-th set bit in bitmap
  *  @buf: pointer to bitmap
  *  @ord: ordinal bit position (n-th set bit, n >= 0)
  *  @nbits: number of valid bit positions in @buf
  *
  * Map the ordinal offset of bit @ord in @buf to its position in @buf.
  * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
  * >= weight(buf), returns @nbits.
  *
  * 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 values returns @nbits.  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 @nbits-1 are valid positions in @buf.
  */
 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
 {
     unsigned int pos;
 
     for (pos = find_first_bit(buf, nbits);
          pos < nbits && ord;
          pos = find_next_bit(buf, nbits, pos + 1))
         ord--;
 
     return pos;
 }
 
 /**
  * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
  *  @dst: remapped result
  *  @src: subset to be remapped
  *  @old: defines domain of map
  *  @new: defines range of map
  *  @nbits: 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 copies @src
  * to @dst.
  *
  * The positions of unset bits in @old are mapped to themselves
  * (the identify map).
  *
  * Apply the above specified mapping to @src, placing the result in
  * @dst, clearing any bits previously set in @dst.
  *
  * 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 unchanged.  So if say @src comes into this routine
  * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
  * 13 and 15 set.
  */
 void bitmap_remap(unsigned long *dst, const unsigned long *src,
         const unsigned long *old, const unsigned long *new,
         unsigned int nbits)
 {
     unsigned int oldbit, w;
 
     if (dst == src)     /* following doesn't handle inplace remaps */
         return;
     bitmap_zero(dst, nbits);
 
     w = bitmap_weight(new, nbits);
     for_each_set_bit(oldbit, src, nbits) {
         int n = bitmap_pos_to_ord(old, oldbit, nbits);
 
         if (n < 0 || w == 0)
             set_bit(oldbit, dst);   /* identity map */
         else
             set_bit(bitmap_ord_to_pos(new, n % w, nbits), 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 themselves
  * (the identify map).
  *
  * 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 unchanged.  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 w = bitmap_weight(new, bits);
     int n = bitmap_pos_to_ord(old, oldbit, bits);
     if (n < 0 || w == 0)
         return oldbit;
     else
         return bitmap_ord_to_pos(new, n % w, bits);
 }
 EXPORT_SYMBOL(bitmap_bitremap);
 
 #ifdef CONFIG_NUMA
 /**
  * bitmap_onto - translate one bitmap relative to another
  *  @dst: resulting translated bitmap
  *  @orig: original untranslated bitmap
  *  @relmap: bitmap relative to which translated
  *  @bits: number of bits in each of these bitmaps
  *
  * Set the n-th bit of @dst iff there exists some m such that the
  * n-th bit of @relmap is set, the m-th bit of @orig is set, and
  * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
  * (If you understood the previous sentence the first time your
  * read it, you're overqualified for your current job.)
  *
  * In other words, @orig is mapped onto (surjectively) @dst,
  * using the map { <n, m> | the n-th bit of @relmap is the
  * m-th set bit of @relmap }.
  *
  * Any set bits in @orig above bit number W, where W is the
  * weight of (number of set bits in) @relmap are mapped nowhere.
  * In particular, if for all bits m set in @orig, m >= W, then
  * @dst will end up empty.  In situations where the possibility
  * of such an empty result is not desired, one way to avoid it is
  * to use the bitmap_fold() operator, below, to first fold the
  * @orig bitmap over itself so that all its set bits x are in the
  * range 0 <= x < W.  The bitmap_fold() operator does this by
  * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
  *
  * Example [1] for bitmap_onto():
  *  Let's say @relmap has bits 30-39 set, and @orig has bits
  *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
  *  @dst will have bits 31, 33, 35, 37 and 39 set.
  *
  *  When bit 0 is set in @orig, it means turn on the bit in
  *  @dst corresponding to whatever is the first bit (if any)
  *  that is turned on in @relmap.  Since bit 0 was off in the
  *  above example, we leave off that bit (bit 30) in @dst.
  *
  *  When bit 1 is set in @orig (as in the above example), it
  *  means turn on the bit in @dst corresponding to whatever
  *  is the second bit that is turned on in @relmap.  The second
  *  bit in @relmap that was turned on in the above example was
  *  bit 31, so we turned on bit 31 in @dst.
  *
  *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
  *  because they were the 4th, 6th, 8th and 10th set bits
  *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
  *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
  *
  *  When bit 11 is set in @orig, it means turn on the bit in
  *  @dst corresponding to whatever is the twelfth bit that is
  *  turned on in @relmap.  In the above example, there were
  *  only ten bits turned on in @relmap (30..39), so that bit
  *  11 was set in @orig had no affect on @dst.
  *
  * Example [2] for bitmap_fold() + bitmap_onto():
  *  Let's say @relmap has these ten bits set::
  *
  *      40 41 42 43 45 48 53 61 74 95
  *
  *  (for the curious, that's 40 plus the first ten terms of the
  *  Fibonacci sequence.)
  *
  *  Further lets say we use the following code, invoking
  *  bitmap_fold() then bitmap_onto, as suggested above to
  *  avoid the possibility of an empty @dst result::
  *
  *  unsigned long *tmp; // a temporary bitmap's bits
  *
  *  bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
  *  bitmap_onto(dst, tmp, relmap, bits);
  *
  *  Then this table shows what various values of @dst would be, for
  *  various @orig's.  I list the zero-based positions of each set bit.
  *  The tmp column shows the intermediate result, as computed by
  *  using bitmap_fold() to fold the @orig bitmap modulo ten
  *  (the weight of @relmap):
  *
  *      =============== ============== =================
  *      @orig           tmp            @dst
  *      0                0             40
  *      1                1             41
  *      9                9             95
  *      10               0             40 [#f1]_
  *      1 3 5 7          1 3 5 7       41 43 48 61
  *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
  *      0 9 18 27        0 9 8 7       40 61 74 95
  *      0 10 20 30       0             40
  *      0 11 22 33       0 1 2 3       40 41 42 43
  *      0 12 24 36       0 2 4 6       40 42 45 53
  *      78 102 211       1 2 8         41 42 74 [#f1]_
  *      =============== ============== =================
  *
  * .. [#f1]
  *
  *     For these marked lines, if we hadn't first done bitmap_fold()
  *     into tmp, then the @dst result would have been empty.
  *
  * If either of @orig or @relmap is empty (no set bits), then @dst
  * will be returned empty.
  *
  * If (as explained above) the only set bits in @orig are in positions
  * m where m >= W, (where W is the weight of @relmap) then @dst will
  * once again be returned empty.
  *
  * All bits in @dst not set by the above rule are cleared.
  */
 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
             const unsigned long *relmap, unsigned int bits)
 {
     unsigned int n, m;  /* same meaning as in above comment */
 
     if (dst == orig)    /* following doesn't handle inplace mappings */
         return;
     bitmap_zero(dst, bits);
 
     /*
      * The following code is a more efficient, but less
      * obvious, equivalent to the loop:
      *  for (m = 0; m < bitmap_weight(relmap, bits); m++) {
      *      n = bitmap_ord_to_pos(orig, m, bits);
      *      if (test_bit(m, orig))
      *          set_bit(n, dst);
      *  }
      */
 
     m = 0;
     for_each_set_bit(n, relmap, bits) {
         /* m == bitmap_pos_to_ord(relmap, n, bits) */
         if (test_bit(m, orig))
             set_bit(n, dst);
         m++;
     }
 }
 
 /**
  * bitmap_fold - fold larger bitmap into smaller, modulo specified size
  *  @dst: resulting smaller bitmap
  *  @orig: original larger bitmap
  *  @sz: specified size
  *  @nbits: number of bits in each of these bitmaps
  *
  * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
  * Clear all other bits in @dst.  See further the comment and
  * Example [2] for bitmap_onto() for why and how to use this.
  */
 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
             unsigned int sz, unsigned int nbits)
 {
     unsigned int oldbit;
 
     if (dst == orig)    /* following doesn't handle inplace mappings */
         return;
     bitmap_zero(dst, nbits);
 
     for_each_set_bit(oldbit, orig, nbits)
         set_bit(oldbit % sz, dst);
 }
 #endif /* CONFIG_NUMA */
 
 /*
  * Common code for bitmap_*_region() routines.
  *  bitmap: array of unsigned longs corresponding to the bitmap
  *  pos: the beginning of the region
  *  order: region size (log base 2 of number of bits)
  *  reg_op: operation(s) to perform on that region of bitmap
  *
  * Can set, verify and/or release a region of bits in a bitmap,
  * depending on which combination of REG_OP_* flag bits is set.
  *
  * A region of a bitmap is a sequence of bits in the bitmap, of
  * some size '1 << order' (a power of two), aligned to that same
  * '1 << order' power of two.
  *
  * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
  * Returns 0 in all other cases and reg_ops.
  */
 
 enum {
     REG_OP_ISFREE,      /* true if region is all zero bits */
     REG_OP_ALLOC,       /* set all bits in region */
     REG_OP_RELEASE,     /* clear all bits in region */
 };
 
 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
 {
     int nbits_reg;      /* number of bits in region */
     int index;      /* index first long of region in bitmap */
     int offset;     /* bit offset region in bitmap[index] */
     int nlongs_reg;     /* num longs spanned by region in bitmap */
     int nbitsinlong;    /* num bits of region in each spanned long */
     unsigned long mask; /* bitmask for one long of region */
     int i;          /* scans bitmap by longs */
     int ret = 0;        /* return value */
 
     /*
      * Either nlongs_reg == 1 (for small orders that fit in one long)
      * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
      */
     nbits_reg = 1 << order;
     index = pos / BITS_PER_LONG;
     offset = pos - (index * BITS_PER_LONG);
     nlongs_reg = BITS_TO_LONGS(nbits_reg);
     nbitsinlong = min(nbits_reg,  BITS_PER_LONG);
 
     /*
      * Can't do "mask = (1UL << nbitsinlong) - 1", as that
      * overflows if nbitsinlong == BITS_PER_LONG.
      */
     mask = (1UL << (nbitsinlong - 1));
     mask += mask - 1;
     mask <<= offset;
 
     switch (reg_op) {
     case REG_OP_ISFREE:
         for (i = 0; i < nlongs_reg; i++) {
             if (bitmap[index + i] & mask)
                 goto done;
         }
         ret = 1;    /* all bits in region free (zero) */
         break;
 
     case REG_OP_ALLOC:
         for (i = 0; i < nlongs_reg; i++)
             bitmap[index + i] |= mask;
         break;
 
     case REG_OP_RELEASE:
         for (i = 0; i < nlongs_reg; i++)
             bitmap[index + i] &= ~mask;
         break;
     }
 done:
     return ret;
 }
 
 /**
  * bitmap_find_free_region - find a contiguous aligned mem region
  *  @bitmap: array of unsigned longs corresponding to the bitmap
  *  @bits: number of bits in the bitmap
  *  @order: region size (log base 2 of number of bits) to find
  *
  * Find a region of free (zero) bits in a @bitmap of @bits bits and
  * allocate them (set them to one).  Only consider regions of length
  * a power (@order) of two, aligned to that power of two, which
  * makes the search algorithm much faster.
  *
  * Return the bit offset in bitmap of the allocated region,
  * or -errno on failure.
  */
 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
 {
     unsigned int pos, end;      /* scans bitmap by regions of size order */
 
     for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
         if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
             continue;
         __reg_op(bitmap, pos, order, REG_OP_ALLOC);
         return pos;
     }
     return -ENOMEM;
 }
 EXPORT_SYMBOL(bitmap_find_free_region);
 
 /**
  * bitmap_release_region - release allocated bitmap region
  *  @bitmap: array of unsigned longs corresponding to the bitmap
  *  @pos: beginning of bit region to release
  *  @order: region size (log base 2 of number of bits) to release
  *
  * This is the complement to __bitmap_find_free_region() and releases
  * the found region (by clearing it in the bitmap).
  *
  * No return value.
  */
 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
 {
     __reg_op(bitmap, pos, order, REG_OP_RELEASE);
 }
 EXPORT_SYMBOL(bitmap_release_region);
 
 /**
  * bitmap_allocate_region - allocate bitmap region
  *  @bitmap: array of unsigned longs corresponding to the bitmap
  *  @pos: beginning of bit region to allocate
  *  @order: region size (log base 2 of number of bits) to allocate
  *
  * 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, unsigned int pos, int order)
 {
     if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
         return -EBUSY;
     return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
 }
 EXPORT_SYMBOL(bitmap_allocate_region);
 
 /**
  * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
  * @dst:   destination buffer
  * @src:   bitmap to copy
  * @nbits: number of bits in the bitmap
  *
  * Require nbits % BITS_PER_LONG == 0.
  */
 #ifdef __BIG_ENDIAN
 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
 {
     unsigned int i;
 
     for (i = 0; i < nbits/BITS_PER_LONG; i++) {
         if (BITS_PER_LONG == 64)
             dst[i] = cpu_to_le64(src[i]);
         else
             dst[i] = cpu_to_le32(src[i]);
     }
 }
 EXPORT_SYMBOL(bitmap_copy_le);
 #endif
 
 unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
 {
     return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
                  flags);
 }
 EXPORT_SYMBOL(bitmap_alloc);
 
 unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
 {
     return bitmap_alloc(nbits, flags | __GFP_ZERO);
 }
 EXPORT_SYMBOL(bitmap_zalloc);
 
 unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node)
 {
     return kmalloc_array_node(BITS_TO_LONGS(nbits), sizeof(unsigned long),
                   flags, node);
 }
 EXPORT_SYMBOL(bitmap_alloc_node);
 
 unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node)
 {
     return bitmap_alloc_node(nbits, flags | __GFP_ZERO, node);
 }
 EXPORT_SYMBOL(bitmap_zalloc_node);
 
 void bitmap_free(const unsigned long *bitmap)
 {
     kfree(bitmap);
 }
 EXPORT_SYMBOL(bitmap_free);
 
 static void devm_bitmap_free(void *data)
 {
     unsigned long *bitmap = data;
 
     bitmap_free(bitmap);
 }
 
 unsigned long *devm_bitmap_alloc(struct device *dev,
                  unsigned int nbits, gfp_t flags)
 {
     unsigned long *bitmap;
     int ret;
 
     bitmap = bitmap_alloc(nbits, flags);
     if (!bitmap)
         return NULL;
 
     ret = devm_add_action_or_reset(dev, devm_bitmap_free, bitmap);
     if (ret)
         return NULL;
 
     return bitmap;
 }
 EXPORT_SYMBOL_GPL(devm_bitmap_alloc);
 
 unsigned long *devm_bitmap_zalloc(struct device *dev,
                   unsigned int nbits, gfp_t flags)
 {
     return devm_bitmap_alloc(dev, nbits, flags | __GFP_ZERO);
 }
 EXPORT_SYMBOL_GPL(devm_bitmap_zalloc);
 
 #if BITS_PER_LONG == 64
 /**
  * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
  *  @bitmap: array of unsigned longs, the destination bitmap
  *  @buf: array of u32 (in host byte order), the source bitmap
  *  @nbits: number of bits in @bitmap
  */
 void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits)
 {
     unsigned int i, halfwords;
 
     halfwords = DIV_ROUND_UP(nbits, 32);
     for (i = 0; i < halfwords; i++) {
         bitmap[i/2] = (unsigned long) buf[i];
         if (++i < halfwords)
             bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
     }
 
     /* Clear tail bits in last word beyond nbits. */
     if (nbits % BITS_PER_LONG)
         bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
 }
 EXPORT_SYMBOL(bitmap_from_arr32);
 
 /**
  * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
  *  @buf: array of u32 (in host byte order), the dest bitmap
  *  @bitmap: array of unsigned longs, the source bitmap
  *  @nbits: number of bits in @bitmap
  */
 void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
 {
     unsigned int i, halfwords;
 
     halfwords = DIV_ROUND_UP(nbits, 32);
     for (i = 0; i < halfwords; i++) {
         buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
         if (++i < halfwords)
             buf[i] = (u32) (bitmap[i/2] >> 32);
     }
 
     /* Clear tail bits in last element of array beyond nbits. */
     if (nbits % BITS_PER_LONG)
         buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
 }
 EXPORT_SYMBOL(bitmap_to_arr32);
 #endif
 
 #if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN)
 /**
  * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap
  *  @bitmap: array of unsigned longs, the destination bitmap
  *  @buf: array of u64 (in host byte order), the source bitmap
  *  @nbits: number of bits in @bitmap
  */
 void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits)
 {
     int n;
 
     for (n = nbits; n > 0; n -= 64) {
         u64 val = *buf++;
 
         *bitmap++ = val;
         if (n > 32)
             *bitmap++ = val >> 32;
     }
 
     /*
      * Clear tail bits in the last word beyond nbits.
      *
      * Negative index is OK because here we point to the word next
      * to the last word of the bitmap, except for nbits == 0, which
      * is tested implicitly.
      */
     if (nbits % BITS_PER_LONG)
         bitmap[-1] &= BITMAP_LAST_WORD_MASK(nbits);
 }
 EXPORT_SYMBOL(bitmap_from_arr64);
 
 /**
  * bitmap_to_arr64 - copy the contents of bitmap to a u64 array of bits
  *  @buf: array of u64 (in host byte order), the dest bitmap
  *  @bitmap: array of unsigned longs, the source bitmap
  *  @nbits: number of bits in @bitmap
  */
 void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits)
 {
     const unsigned long *end = bitmap + BITS_TO_LONGS(nbits);
 
     while (bitmap < end) {
         *buf = *bitmap++;
         if (bitmap < end)
             *buf |= (u64)(*bitmap++) << 32;
         buf++;
     }
 
     /* Clear tail bits in the last element of array beyond nbits. */
     if (nbits % 64)
         buf[-1] &= GENMASK_ULL((nbits - 1) % 64, 0);
 }
 EXPORT_SYMBOL(bitmap_to_arr64);
 #endif

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