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bitmap: fix bitmap_count_one

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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/qemu-devel@nongnu.org/msg554316.html
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
CC: Juan Quintela <quintela@redhat.com>
CC: Dr. David Alan Gilbert <dgilbert@redhat.com>
CC: Peter Xu <peterx@redhat.com>
Message-Id: <1544516693-5395-2-git-send-email-wei.w.wang@intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Wei Wang 2018-12-11 16:24:47 +08:00 committed by Dr. David Alan Gilbert
parent 609d384407
commit e7c91368d2
1 changed files with 4 additions and 0 deletions
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4
include/qemu/bitmap.h
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@ -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 {