The ordinal of the a set bit is simply the number of set bits before it; counting those doesn't need to be done one bit at a time. While at it, update the parameters to unsigned int.
It is not completely unthinkable that gcc would see pos as compile-time constant 0 in one of the uses of bitmap_pos_to_ord. Since the static inline frontend bitmap_weight doesn't handle nbits==0 correctly (it would behave exactly as if nbits==BITS_PER_LONG), use __bitmap_weight. Signed-off-by: Rasmus Villemoes <[email protected]> --- Notes: Alternatively, the last line could be spelled bitmap_weight(buf, pos+1)-1, but this is simpler. lib/bitmap.c | 22 ++++++---------------- 1 file changed, 6 insertions(+), 16 deletions(-) diff --git a/lib/bitmap.c b/lib/bitmap.c index 1807d089eda7..ab62a7e4d50f 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -713,10 +713,10 @@ EXPORT_SYMBOL(bitmap_parselist_user); /** * 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 < @bits) - * @bits: number of valid bit positions in @buf + * @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 @bits) to the + * 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. * @@ -728,22 +728,12 @@ EXPORT_SYMBOL(bitmap_parselist_user); * * 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) +static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits) { - int i, ord; - - if (pos < 0 || pos >= bits || !test_bit(pos, buf)) + if (pos >= nbits || !test_bit(pos, buf)) return -1; - i = find_first_bit(buf, bits); - ord = 0; - while (i < pos) { - i = find_next_bit(buf, bits, i + 1); - ord++; - } - BUG_ON(i != pos); - - return ord; + return __bitmap_weight(buf, pos); } /** -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
