cpumask_last(9)

📦 version 7.3.1, in nixpkgs unstable

💅 cpumask_last(9) — like, the last CPU standing 🎀

okay bestie, welcome to the kernel API manual, section 9 (9 — kernel API, iykyk). today's main character is cpumask_last, and honestly? she's a tiny little function with one job and she does it. no notes. 💖

✨ NAME ✨

cpumask_last — get the last CPU in a cpumask 🌸

like, the actual last one. the final girl. the one at the end of the bitmask. periodt.

✨ SYNOPSIS ✨

unsigned int cpumask_last (const struct cpumask *srcp );

that's it. that's the whole signature. she's not complicated, she's just focused. 👑

✨ ARGUMENTS ✨

  • srcp — the cpumask pointer. literally just a pointer to the cpumask you want her to look at. hand her the mask, she finds the last set CPU in it. 🫶

✨ RETURN ✨

she gives you back >= nr_cpumask_bits if there are no CPUs set 😭

⚠️ okay this is the important bit, don't skip it — an empty mask does not get you a cute little 0 or a -1. you get a value that's >= nr_cpumask_bits, and that's your signal that there was nothing to find. check for it, bestie. fr fr.

✨ SEE ALSO ✨

the whole cpumask extended universe is right here, living in the kernel file ./include/linux/cpumask.h — go say hi to the fam 💜

that's the whole page, bestie, you ate that 🍓 this lil drop came from ./include/linux and is dated October 2026 — so like, mark your calendar, this manual is lowkey from the future 💅✨ bye ily 🧚💖

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