percpu_ref_init(9)

💅 percpu_ref_init — the Kernel API Manual glow-up ✨

okay so before we even start: this page is from the Kernel API Manual, section 9, and it's literally about waking a percpu refcount up from its beauty sleep. bestie, let's get into it 🎀

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🌸 NAME 🌸

percpu_ref_init — initialize a percpu refcount. that's it. that's the whole vibe. she sets it up so it's ready to be counted on 🫶

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✨ SYNOPSIS ✨

int percpu_ref_init (struct percpu_ref *ref , percpu_ref_func_t *release
, unsigned int flags , gfp_t gfp );

four args, one int coming back at you. no cap, that's the whole signature 💅

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🦋 ARGUMENTS 🦋

• ref — the percpu_ref you're initializing. this is the main character right here 👑
• release — the function that gets called when the refcount hits 0. like, the cleanup crew that shows up when the party's over 🎉→😭
• flags — your PERCPU_REF_INIT_* flags. yes, the star-asterisk, they all live in that family 🌈
• gfp — the allocation mask to use. the memory-allocation mood board, basically 🧚

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💖 DESCRIPTION 💖

so percpu_ref_init initializes ref. and like — plot twist — ref starts out in percpu mode with a refcount of 1 💀 yes, one. she comes out the box already at 1, unless flags contains PERCPU_REF_INIT_ATOMIC or PERCPU_REF_INIT_DEAD 🙈

those two flags change the start state to atomic, and the latter one — PERCPU_REF_INIT_DEAD — also sets the initial refcount to 0. so like, born dead, iconic energy fr fr 💀✨

for the actual flag behaviors, go read the definitions of the PERCPU_REF_INIT_* flags. that's where the lore lives, iykyk 📖

and listen — release must not sleep 😴🚫 this is highkey important, not me being dramatic. it may potentially be called from RCU callback context by percpu_ref_kill, so if your release tries to nap in there, that's a whole mess. don't do it bestie 🫶

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🔥 SEE ALSO 🔥

the whole friend group 💜 the kernel file ./lib/percpu-refcount.c, plus:

• percpu_ref_exit(9)
• percpu_ref_switch_to_atomic(9)
• percpu_ref_switch_to_atomic_sync(9)
• percpu_ref_switch_to_percpu(9)
• percpu_ref_kill_and_confirm(9)
• percpu_ref_is_zero(9)
• percpu_ref_reinit(9)
• percpu_ref_resurrect(9)

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⭐ and that's the page!! brought to you by ./lib, dated October 2026, in the Kernel API Manual — periodt 💅🎀🦋