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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2015-02-12 15:02:07 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:14 -0800
commitdf1d80a9eb16d98002673f68a7ebbe881f6e6946 (patch)
tree354e5cd242fdd024e258f40460887d231d48e2aa
parentb26ad5836c3a0a9d456eb60b9f841ca15403ee59 (diff)
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lib/bitmap.c: simplify bitmap_pos_to_ord
The ordinal of 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. Alternatively, the last line could be spelled bitmap_weight(buf, pos+1)-1, but this is simpler. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/bitmap.c22
1 files changed, 6 insertions, 16 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c
index b0d3e823dab3..84d20b5c6bf1 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -744,10 +744,10 @@ 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.
*
@@ -759,22 +759,12 @@ 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);
}
/**