bpf_cpumask_create(9)

💅 bpf_cpumask_create(9) — the Kernel API Manual moment

okay bestie, so this is bpf_cpumask_create from section 9 of the Kernel API Manual, and honestly? it's iconic. it's giving "i make cpumasks so your BPF program can have a little autonomy." let's get into it 🎀

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✨ NAME ✨

bpf_cpumask_create — Create a mutable BPF cpumask. literally that's the whole vibe. mutable. BPF. cpumask. slay 💅

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🌸 SYNOPSIS 🌸

__bpf_kfunc struct bpf_cpumask * bpf_cpumask_create (void );

no cap, that's the signature. __bpf_kfunc, returns a struct bpf_cpumask *, takes void. periodt.

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🦋 ARGUMENTS 🦋

• void — no arguments. none. zero. she takes nothing and she gives you a cpumask. main character energy fr fr 💖

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🧚 DESCRIPTION 🧚

okay so here's the tea 👑

bpf_cpumask_create allocates a cpumask that can be queried, mutated, acquired, and released by a BPF program. like, she's fully featured. she does it all.

🚨 IMPORTANT CAVEAT, bestie, do not skip this: the cpumask returned by this function must either be embedded in a map as a kptr, or freed with bpf_cpumask_release. there is no third option. you cannot just vibe and forget about her 😭

and listen — bpf_cpumask_create allocates memory using the BPF memory allocator, and it will not block. so she's not gonna sit there making you wait, she's non-blocking, she's efficient, we love her for it 🫶

but also… she may return NULL if no memory is available. so like. check your returns. ngl that's just good manners 💀

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🔥 RETURN 🔥

• A pointer to a new struct bpf_cpumask instance on success. 🎉 she ate.
• NULL if the BPF memory allocator is out of memory. 😭 she tried her best.

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👑 SEE ALSO 👑

okay this is the part where she name-drops her whole friend group and honestly every single one of them is a baddie. the source of truth is the kernel file ./kernel/bpf/cpumask.c. go read it, iykyk 💜

• struct bpf_cpumask(9)
• bpf_cpumask_acquire(9)
• bpf_cpumask_release(9)
• bpf_cpumask_first(9)
• bpf_cpumask_first_zero(9)
• bpf_cpumask_first_and(9)
• bpf_cpumask_set_cpu(9)
• bpf_cpumask_clear_cpu(9)
• bpf_cpumask_test_cpu(9)
• bpf_cpumask_test_and_set_cpu(9)
• bpf_cpumask_test_and_clear_cpu(9)
• bpf_cpumask_setall(9)
• bpf_cpumask_clear(9)
• bpf_cpumask_and(9)
• bpf_cpumask_or(9)
• bpf_cpumask_xor(9)
• bpf_cpumask_equal(9)
• bpf_cpumask_intersects(9)
• bpf_cpumask_subset(9)
• bpf_cpumask_empty(9)
• bpf_cpumask_full(9)
• bpf_cpumask_copy(9)
• bpf_cpumask_any_distribute(9)
• bpf_cpumask_any_and_distribute(9)
• bpf_cpumask_weight(9)
• bpf_cpumask_populate(9)

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🌈 the cute sign-off 🌈

this little masterpiece lives in ./kernel/bpf, and she's dated October 2026 — yeah, from the future, she's ahead of her time ✨ and the page itself is bpf_cpumask_create(9), obviously, because she's the moment, she's the legend 🎀

anyway bestie go free your cpumasks with bpf_cpumask_release or embed them as a kptr, drink some water, and stan non-blocking allocation 💖🦋🌸