cpumask: add cpumask_weight_andnot()

Similarly to cpumask_weight_and(), cpumask_weight_andnot() is a handy
helper that may help to avoid creating an intermediate mask just to
calculate number of bits that set in a 1st given mask, and clear in 2nd
one.

Signed-off-by: Yury Norov <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 09522af227f1..b97692854966 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -348,6 +348,13 @@ unsigned int __bitmap_weight_and(const unsigned long *bitmap1,
 }
 EXPORT_SYMBOL(__bitmap_weight_and);
 
+unsigned int __bitmap_weight_andnot(const unsigned long *bitmap1,
+				const unsigned long *bitmap2, unsigned int bits)
+{
+	return BITMAP_WEIGHT(bitmap1[idx] & ~bitmap2[idx], bits);
+}
+EXPORT_SYMBOL(__bitmap_weight_andnot);
+
 void __bitmap_set(unsigned long *map, unsigned int start, int len)
 {
 	unsigned long *p = map + BIT_WORD(start);