for_each_cpu_andnot(9)

💅 for_each_cpu_andnot(9) — Kernel API Manual, but make it make sense 🎀

okay so bestie, welcome to the <pink>Kernel API Manual</pink> ✨ — this one's a macro, it's iconic, and it's about to save you so much temporary-mask drama. Let's get into it 🦋

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✨ NAME ✨

for_each_cpu_andnot — loop over every cpu that's chillin' in one mask but not in the other. it's giving "you're invited but she's not" 💅

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🌸 SYNOPSIS 🌸

for_each_cpu_andnot (cpu , mask1 , mask2 );

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🎀 ARGUMENTS 🎀

• cpu — the iterator, an (optionally unsigned) integer. it's the little counter that goes brrr through your cpus 🔥
• mask1 — pointer to the first cpumask. the "yes bestie" list 💖
• mask2 — pointer to the second cpumask. the "nope, excluded" list 🙈

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🦋 DESCRIPTION 🦋

so here's the tea ☕: this macro literally saves you from declaring a temporary CPU mask in, like, a million different places. no cap. it is equivalent to:

struct cpumask tmp; cpumask_andnot(tmp, mask1, mask2); for_each_cpu(cpu, tmp) ...

like, same energy, less clutter. obsessed 💜

lowkey important: after the loop finishes, cpu is >= nr_cpu_ids. fr fr, don't be surprised by that, it's by design ✨

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👑 SEE ALSO 👑

Kernel file ./include/linux/cpumask.h — and honestly, the whole cpumask friend group showed up. main character energy all around 🌈

• cpumask_pr_args(9), cpumask_first(9), cpumask_first_zero(9), cpumask_first_and(9), cpumask_first_andnot(9), cpumask_first_and_and(9), cpumask_last(9)
• cpumask_next(9), cpumask_next_zero(9), cpumask_next_and(9), cpumask_next_andnot(9), cpumask_next_and_wrap(9), cpumask_next_wrap(9), cpumask_random(9)
• for_each_cpu(9), for_each_cpu_wrap(9), for_each_cpu_and(9), for_each_cpu_or(9), for_each_cpu_from(9)
• cpumask_any_but(9), cpumask_any_and_but(9), cpumask_any_andnot_but(9)
• cpumask_nth(9), cpumask_nth_and(9), cpumask_nth_and_andnot(9)
• cpumask_set_cpu(9), cpumask_clear_cpus(9), cpumask_clear_cpu(9)
• cpumask_test_cpu(9), cpumask_test_and_set_cpu(9), cpumask_test_and_clear_cpu(9)
• cpumask_setall(9), cpumask_clear(9)
• cpumask_and(9), cpumask_or(9), cpumask_weighted_or(9), cpumask_xor(9), cpumask_andnot(9)
• cpumask_equal(9), cpumask_or_equal(9), cpumask_intersects(9), cpumask_subset(9)
• cpumask_empty(9), cpumask_full(9)
• cpumask_weight(9), cpumask_weight_and(9), cpumask_weight_andnot(9)
• cpumask_shift_right(9), cpumask_shift_left(9)
• cpumask_copy(9), cpumask_any(9), cpumask_any_and(9), cpumask_of(9)
• cpumask_parse_user(9), cpumask_parselist_user(9), cpumask_parse(9), cpulist_parse(9), cpumask_size(9)
• alloc_cpumask_var(9), to_cpumask(9), num_online_cpus(9)
• cpumap_print_bitmask_to_buf(9), cpumap_print_list_to_buf(9)

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and that's the whole page, bestie 🫶 this lil macro came from ./include/linux and it's dated October 2026 — go forth and iterate responsibly, mwah 💋✨