BITMAP_LAST_WORD_MASK(nbits) returns 0xffffffff when "nbits=0", which
makes bitmap_count_one fail to handle the "nbits=0" case. It appears to be
preferred to remain BITMAP_LAST_WORD_MASK identical to the kernel
implementation that it is ported from.
So this patch fixes bitmap_count_one to handle the nbits=0 case.
Inital Discussion Link:
https://www.mail-archive.com/[email protected]/msg554316.html
Signed-off-by: Wei Wang <>
CC: Juan Quintela <>
CC: Dr. David Alan Gilbert <>
CC: Peter Xu <>
---
include/qemu/bitmap.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
index 509eedd..679f1bd 100644
--- a/include/qemu/bitmap.h
+++ b/include/qemu/bitmap.h
@@ -221,6 +221,10 @@ static inline int bitmap_intersects(const unsigned long *src1,
static inline long bitmap_count_one(const unsigned long *bitmap, long nbits)
{
+ if (unlikely(!nbits)) {
+ return 0;
+ }
+
if (small_nbits(nbits)) {
return ctpopl(*bitmap & BITMAP_LAST_WORD_MASK(nbits));
} else {
--
1.8.3.1
