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    Subject[PATCH 7/8] lib: bitmap: Simplify bitmap_ord_to_pos
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    Make the return value and the ord and nbits parameters of
    bitmap_ord_to_pos unsigned.

    Also, simplify the implementation and as a side effect make the result
    fully defined, returning nbits for ord >= weight, in analogy with what
    find_{first,next}_bit does. This is a better sentinel than the former
    ("unofficial") 0. No current users are affected by this change.

    Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
    ---
    include/linux/bitmap.h | 2 +-
    lib/bitmap.c | 28 +++++++++++-----------------
    2 files changed, 12 insertions(+), 18 deletions(-)

    diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
    index 85e8fb091ed7..e854934cdbf9 100644
    --- a/include/linux/bitmap.h
    +++ b/include/linux/bitmap.h
    @@ -144,7 +144,7 @@ extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int
    extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
    extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
    extern void bitmap_copy_le(void *dst, const unsigned long *src, int nbits);
    -extern int bitmap_ord_to_pos(const unsigned long *bitmap, int n, int bits);
    +extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);

    #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
    #define BITMAP_LAST_WORD_MASK(nbits) \
    diff --git a/lib/bitmap.c b/lib/bitmap.c
    index ab62a7e4d50f..89b61e42f173 100644
    --- a/lib/bitmap.c
    +++ b/lib/bitmap.c
    @@ -740,34 +740,28 @@ static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigne
    * 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)
    - * @bits: number of valid bit positions in @buf
    + * @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), else
    - * results are undefined.
    + * 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 return undefined values. When @ord value 3
    + * 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 @bits are valid positions in @buf.
    + * The bit positions 0 through @nbits-1 are valid positions in @buf.
    */
    -int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
    +unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
    {
    - int pos = 0;
    + unsigned int pos;

    - 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;
    - }
    + for (pos = find_first_bit(buf, nbits);
    + pos < nbits && ord;
    + pos = find_next_bit(buf, nbits, pos + 1))
    + ord--;

    return pos;
    }
    --
    2.1.3


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