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Subject[PATCH v3 0/5] lib/find: add find_nth_bit()
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Kernel lacks for a function that searches for Nth bit in a bitmap.
Usually people do it like this:
for_each_set_bit(bit, mask, size)
if (n-- == 0)
return bit;

Which is not so elegant and very slow.

This series adds fast routines for this task, and applies them where
appropriate.

v1: https://lore.kernel.org/lkml/20220706182300.70862-4-yury.norov@gmail.com/T/
v2: https://lore.kernel.org/lkml/CAAH8bW_RYG_Tbpip=BkSFAymDm2y3jJBqTi0PJWA=H-a-L_3tg@mail.gmail.com/T/
v3:
- add bitmap_weight_and() and use it in cpumask_local_spread();
- rework find_nth_bit() family: similarly to [1], introduce
FIND_NTH_BIT(), and optimize the function to return earlier when
it's known that the rest of bitmap can't meet the requirement.
- patch "lib/nodemask: inline next_node_in() and node_random()" has
been merged, so drop it from this series.

On top of:
[1] https://lore.kernel.org/lkml/20220915020730.852234-1-yury.norov@gmail.com/T/

Yury Norov (6):
lib/bitmap: don't call __bitmap_weight() in kernel code
lib/bitmap: add bitmap_weight_and()
lib: add find_nth(,and,andnot)_bit()
lib/bitmap: add tests for find_nth_bit()
lib/bitmap: remove bitmap_ord_to_pos
cpumask: add cpumask_nth_{,and,andnot}

fs/ntfs3/bitmap.c | 4 +-
include/linux/bitmap.h | 13 +++++-
include/linux/bitops.h | 19 +++++++++
include/linux/cpumask.h | 55 +++++++++++++++++++++++++
include/linux/find.h | 86 ++++++++++++++++++++++++++++++++++++++++
include/linux/nodemask.h | 3 +-
lib/bitmap.c | 68 ++++++++++++-------------------
lib/cpumask.c | 28 ++++++-------
lib/find_bit.c | 44 ++++++++++++++++++++
lib/find_bit_benchmark.c | 18 +++++++++
lib/test_bitmap.c | 47 +++++++++++++++++++++-
11 files changed, 320 insertions(+), 65 deletions(-)

--
2.34.1

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