cpumask_subset(9)

✨ cpumask_subset(9) ✨

okay so bestie, we're in the Kernel API Manual today and this page is literally about one tiny function that answers one iconic question: is this group of CPUs fully inside that other group of CPUs? That's it, that's the vibe. 💅

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🎀 NAME 🎀

cpumask_subset — literally (*src1p & ~*src2p) == 0 — no cap, that's the whole definition right there 🫶

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🌸 SYNOPSIS 🌸

bool cpumask_subset (const struct cpumask *src1p , const struct cpumask
       *src2p );

So it takes two const struct cpumask * pointers and hands you back a bool. Very demure, very mindful. ✨

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🦋 ARGUMENTS 🦋

• src1p — the first input 💖 (the one we're asking about — is this one a subset?)
• src2p — the second input 💜 (the one we're comparing against — does this one contain it?)

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⭐ RETURN ⭐

true if *src1p is a subset of *src2p, else it returns false. periodt. 👑

So like... if every CPU in src1p is also chillin' in src2p, you get true. If src1p has even one little CPU that src2p doesn't have, it's a false and honestly? fair. 🙈

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🌈 SEE ALSO 🌈

the whole cpumask friend group, assembled. not me listing every single one 😭 but fr fr, here they are:

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_andnot(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_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)

also the kernel file is ./include/linux/cpumask.h — that's where the source lives, go say hi 🧚

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okay that's the whole page!! tysm for reading, mwah 💋 — this one came straight out of ./include/linux, October 2026, and yes the page itself is cpumask_subset(9) because we keep it consistent, bestie 🍓💖