lib: bitmap: make the start index of bitmap_set unsigned

The compiler can generate slightly smaller and simpler code when it
knows that "start" is non-negative.

Also, use the names "start" and "len" for the two parameters in both
header file and implementation, instead of the previous mix.

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>

lib/bitmap.c

@@ -274,21 +274,21 @@ int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
-void bitmap_set(unsigned long *map, int start, int nr)
+void bitmap_set(unsigned long *map, unsigned int start, int len)
 {
 	unsigned long *p = map + BIT_WORD(start);
-	const int size = start + nr;
+	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 (nr - bits_to_set >= 0) {
+	while (len - bits_to_set >= 0) {
 		*p |= mask_to_set;
-		nr -= bits_to_set;
+		len -= bits_to_set;
 		bits_to_set = BITS_PER_LONG;
 		mask_to_set = ~0UL;
 		p++;
 	}
-	if (nr) {
+	if (len) {
 		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 		*p |= mask_to_set;
 	}