stop_core_cpuslocked(9)

💅 stop_core_cpuslocked — kernel API manual, bestie edition 🎀

okay so real talk, this is a page straight out of the Kernel API Manual, and honestly? it's a baddie. it does one thing and it does it slayfully. let's get into it ✨

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✨ NAME ✨

stop_core_cpuslocked — stop all threads on just one core 🛑

like not the whole system, not every CPU, just one core. main character energy but make it hyper-localized 💅

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🌸 SYNOPSIS 🌸

int stop_core_cpuslocked (unsigned int cpu , cpu_stop_fn_t fn , void *data );

yeah that's the whole signature, she's compact and she knows it 🫶

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🦋 ARGUMENTS 🦋

• cpu — any cpu in the targeted core. literally any one of them, she'll figure out which core you mean, iykyk 💖
• fn — the function to run on each CPU in the core containing cpu. this is the whole errand, the thing you actually came here to do ✨
• data — the data ptr to pass to fn. the little care package you hand over 🎁

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🔥 DESCRIPTION 🔥

Same as above, but instead of every CPU, only the logical CPUs of the single core containing cpu are affected. 🌈

(and yes, "same as above" — she's referencing her sister function, keep scrolling to SEE ALSO, it's giving sequel energy 👑)

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💀 CONTEXT 💀

Must be called from within a cpus_read_lock protected region.

⚠️ bestie do NOT skip this. if you're not inside a cpus_read_lock protected region you are lowkey asking for chaos. it's not a vibe check you can fail, it's a rule 🙈

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⭐ RETURN ⭐

• 0 — returned if all invocations of fn return zero. everyone came back clean, we love a unanimous slay 🎉
• otherwise — the value returned by an arbitrarily chosen member of the set of calls to fn that returned non-zero. so like, one of the failures gets to speak for the group. arbitrary. chaotic. iconic. which one? don't ask, it's not telling 😭

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🧚 SEE ALSO 🧚

• Kernel file ./include/linux/stop_machine.h
• stop_machine(9)
• stop_machine_cpuslocked(9)

go read those next, they're the prequels and the lore runs deep 🍓

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okay that's the whole page, you're so welcome 💜 remember: one core only, lock held, fn returns zero everywhere or you get somebody's random non-zero back.

from ./include/linux — October 2026 — with love, the Kernel API Manual crew 🌸🫶✨