lib/bitmap.c: simplify bitmap_ord_to_pos

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 95dcd2f76e1a155e59afd6927765d9a0c1b9ea38..1e74fe7aa167a873087120a919e6e6057d6a0f28 100644 (file)
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -171,7 +171,7 @@ 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);
 extern int bitmap_print_to_pagebuf(bool list, char *buf,
                                   const unsigned long *maskp, int nmaskbits);
 

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 84d20b5c6bf1f8bd77f2b2bd1e70f5774ffbf045..e8a38bde7af9e49224c18a1548419756915062ec 100644 (file)
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -771,34 +771,28 @@ 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;
 }