lib/bitmap: add bitmap_weight_and()

The function calculates Hamming weight of (bitmap1 & bitmap2). Now we
have to do like this:
	tmp = bitmap_alloc(nbits);
	bitmap_and(tmp, map1, map2, nbits);
	weight = bitmap_weight(tmp, nbits);
	bitmap_free(tmp);

This requires additional memory, adds pressure on alloc subsystem, and
way less cache-friendly than just:
	weight = bitmap_weight_and(map1, map2, nbits);

The following patches apply it for cpumask functions.

Signed-off-by: Yury Norov <yury.norov@gmail.com>

1 files changed, 21 insertions, 9 deletions

diff --git a/lib/bitmap.c b/lib/bitmap.c
index d56e275db73e..3fc2e338ec30 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -333,20 +333,32 @@ bool __bitmap_subset(const unsigned long *bitmap1,
 }
 EXPORT_SYMBOL(__bitmap_subset);
 
+#define BITMAP_WEIGHT(FETCH, bits)	\
+({										\
+	unsigned int __bits = (bits), idx, w = 0;				\
+										\
+	for (idx = 0; idx < __bits / BITS_PER_LONG; idx++)			\
+		w += hweight_long(FETCH);					\
+										\
+	if (__bits % BITS_PER_LONG)						\
+		w += hweight_long((FETCH) & BITMAP_LAST_WORD_MASK(__bits));	\
+										\
+	w;									\
+})
+
 unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
 {
-	unsigned int k, lim = bits/BITS_PER_LONG, w = 0;
-
-	for (k = 0; k < lim; k++)
-		w += hweight_long(bitmap[k]);
-
-	if (bits % BITS_PER_LONG)
-		w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
-
-	return w;
+	return BITMAP_WEIGHT(bitmap[idx], bits);
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
+unsigned int __bitmap_weight_and(const unsigned long *bitmap1,
+				const unsigned long *bitmap2, unsigned int bits)
+{
+	return BITMAP_WEIGHT(bitmap1[idx] & bitmap2[idx], bits);
+}
+EXPORT_SYMBOL(__bitmap_weight_and);
+
 void __bitmap_set(unsigned long *map, unsigned int start, int len)
 {
 	unsigned long *p = map + BIT_WORD(start);