Re: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq()
From: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Date: 2021-11-28 18:12:32
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On Sat, Nov 27, 2021 at 07:56:57PM -0800, Yury Norov wrote:
quoted hunk ↗ jump to hunk
Now as we have bitmap_weight_eq(), switch bitmap_full() and bitmap_empty() to using it. Signed-off-by: Yury Norov <yury.norov@gmail.com> --- include/linux/bitmap.h | 26 ++++++++++---------------- 1 file changed, 10 insertions(+), 16 deletions(-)diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 996041f771c8..2d951e4dc814 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h@@ -386,22 +386,6 @@ static inline int bitmap_subset(const unsigned long *src1, return __bitmap_subset(src1, src2, nbits); } -static inline bool bitmap_empty(const unsigned long *src, unsigned nbits) -{ - if (small_const_nbits(nbits)) - return ! (*src & BITMAP_LAST_WORD_MASK(nbits)); - - return find_first_bit(src, nbits) == nbits; -}
Since this is supposed to be an optimization, I would go all the way and
replace this with the trivial implementation instead:
bool bitmap_empty(long *bits, size_t nbits)
{
for (; nbits >= BITS_PER_LONG; ++bits, nbits -= BITS_PER_LONG)
if (*bits)
return false;
if (nbits && *bits & BITMAP_LAST_WORD_MASK(nbits))
return false;
return true;
}
Best Regards
Michał Mirosław