smp_call_on_cpu(9)

💅 smp_call_on_cpu(9) — the Kernel API Manual, bestie edition 🎀

Okay so picture this: you've got a function, right? And you've got one specific CPU in mind. And you're like "girl, I need this to run there and I need to wait for it." That's literally this whole thing. It's smp_call_on_cpu from the Kernel API Manual, and it's giving "call a function on a specific CPU and wait for it to return." Main character energy, no cap. ✨

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🌸 NAME 🌸

smp_call_on_cpu — Call a function on a specific CPU and wait for it to return.

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✨ SYNOPSIS ✨

int smp_call_on_cpu (unsigned int cpu , int (*func)(void *) , void *par
, bool phys );

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🦋 ARGUMENTS 🦋

• cpu — The CPU to run on. That's the whole vibe check: which CPU you're targeting. 👑
• func — The function to run. The actual star of the show. 💅
• par — An arbitrary pointer parameter for func. Like, whatever pointer you want to hand it — it's arbitrary, it's yours, it's giving "pass it through." 🫶
• phys — If true, force to run on physical cpu. See struct smp_call_on_cpu_struct for more info. So like, true = physical CPU, periodt. 🌈

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💀 RETURN 💀

-ENXIO if the cpu is invalid; otherwise the return value from func.

So if the CPU you picked is a no-go, you get -ENXIO back (rough). Otherwise you get whatever func decided to give you — literally just passing it through. 😭

Not me calling out that "otherwise" — yeah, the success path is just func's own return value. That's it. That's the whole deal. 🙈

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🧚 SEE ALSO 🧚

Kernel file ./kernel/smp.c 💖 and these iconic neighbors:

• csd_lock_is_stuck(9)
• generic_smp_call_function_single_interrupt(9)
• __flush_smp_call_function_queue(9)
• flush_smp_call_function_queue(9)
• smp_call_function_single(9)
• smp_call_function_single_async(9)
• smp_call_function_any(9)
• smp_call_function_many(9)
• smp_call_function(9)
• on_each_cpu_cond_mask(9)
• kick_all_cpus_sync(9)
• wake_up_all_idle_cpus(9)
• cpus_peek_for_pending_ipi(9)
• struct smp_call_on_cpu_struct(9)

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💖 that's the page, bestie 💖

Sign-off time 🎀: this one lives in ./kernel, dated October 2026, and it's page smp_call_on_cpu(9) of the Kernel API Manual. Go run your function on a CPU and slay. 💜🌸🦋