kernel/linux.git/include/linux/find.h, branch v6.19.11

cpumask: Remove unnecessary cpumask_nth_andnot()

2025-07-31T15:28:03+00:00

Commit 94f753143028("x86/resctrl: Optimize cpumask_any_housekeeping()") switched the only user of cpumask_nth_andnot() to other cpumask functions, but left the function cpumask_nth_andnot() unused. This makes function find_nth_andnot_bit() unused as well. Delete them. Signed-off-by: Shaopeng Tan Signed-off-by: Yury Norov [NVIDIA]

bitmap: generalize node_random()

2025-07-08T23:11:57+00:00

Generalize node_random() and make it available to general bitmaps and cpumasks users. Notice, find_first_bit() is generally faster than find_nth_bit(), and we employ it when there's a single set bit in the bitmap. See commit 3e061d924fe9c7b4 ("lib/nodemask: optimize node_random for nodemask with single NUMA node"). CC: Andrew Morton Signed-off-by: "Yury Norov [NVIDIA]"

find: Add find_first_andnot_bit()

2025-05-15T18:24:40+00:00

The function helps to implement cpumask_andnot() APIs. Signed-off-by: Yury Norov [NVIDIA] Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: James Morse Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Tested-by: James Morse Tested-by: Tony Luck Tested-by: Fenghua Yu Link: https://lore.kernel.org/20250515165855.31452-3-james.morse@arm.com

find: Switch from inline to __always_inline

2024-08-18T17:07:59+00:00

'inline' keyword is only a recommendation for compiler. If it decides to not inline find_bit nodemask functions, the whole small_const_nbits() machinery doesn't work. This is how a standard GCC 11.3.0 does for my x86_64 build now. This patch replaces 'inline' directive with unconditional '__always_inline' to make sure that there's always a chance for compile-time optimization. It doesn't change size of kernel image, according to bloat-o-meter. [[ Brian: split out from: Subject: [PATCH 1/3] bitmap: switch from inline to __always_inline https://lore.kernel.org/all/20221027043810.350460-2-yury.norov@gmail.com/ But rewritten, as there were too many conflicts. ]] Co-developed-by: Brian Norris Signed-off-by: Brian Norris Reviewed-by: Kees Cook Reviewed-by: Nathan Chancellor Signed-off-by: Yury Norov

Merge tag 'bitmap-for-6.10v2' of https://github.com/norov/linux

2024-05-21T22:29:01+00:00

Pull bitmap updates from Yury Norov: - topology_span_sane() optimization from Kyle Meyer - fns() rework from Kuan-Wei Chiu (used in cpumask_local_spread() and other places) - headers cleanup from Andy - add a MAINTAINERS record for bitops API * tag 'bitmap-for-6.10v2' of https://github.com/norov/linux: usercopy: Don't use "proxy" headers bitops: Move aligned_byte_mask() to wordpart.h MAINTAINERS: add BITOPS API record bitmap: relax find_nth_bit() limitation on return value lib: make test_bitops compilable into the kernel image bitops: Optimize fns() for improved performance lib/test_bitops: Add benchmark test for fns() Compiler Attributes: Add __always_used macro sched/topology: Optimize topology_span_sane() cpumask: Add for_each_cpu_from()

bitmap: relax find_nth_bit() limitation on return value

2024-05-09T16:25:08+00:00

The function claims to return the bitmap size, if Nth bit doesn't exist. This rule is violated in inline case because the fns() that is used there doesn't know anything about size of the bitmap. So, relax this requirement to '>= size', and make the outline implementation a bit cheaper. All in-tree kernel users of find_nth_bit() are safe against that. Reported-by: Rasmus Villemoes Closes: https://lore.kernel.org/all/Zi50cAgR8nZvgLa3@yury-ThinkPad/T/#m6da806a0525e74dcc91f35e5f20766ed4e853e8a Signed-off-by: Yury Norov

cpumask: Introduce cpumask_first_and_and()

2024-04-24T19:23:49+00:00

Introduce cpumask_first_and_and() to get intersection between 3 cpumasks, free of any intermediate cpumask variable. Instead, cpumask_first_and_and() works in-place with all inputs and produces desired output directly. Signed-off-by: Dawei Li Signed-off-by: Thomas Gleixner Acked-by: Yury Norov Link: https://lore.kernel.org/r/20240416085454.3547175-2-dawei.li@shingroup.cn

lib/find: optimize find_*_bit_wrap

2023-12-03T18:28:17+00:00

When an offset is 0, there's no need to search a bitmap from the beginning after the 1st search failed, because each bit has already been tested. Signed-off-by: Yury Norov

lib/find_bit: Fix the code comments about find_next_bit_wrap

2023-12-03T18:28:16+00:00

The function find_next_bit_wrap only has one memory region to search on. Adjust the comments. Signed-off-by: Guanjun Signed-off-by: Yury Norov

cpumask: introduce for_each_cpu_or

2023-03-19T17:02:04+00:00

Equivalent of for_each_cpu_and, except it ORs the two masks together so it iterates all the CPUs present in either mask. Signed-off-by: Dave Chinner Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong