ct_nmi_enter(9)

💅 ct_nmi_enter(9) — like, the Kernel API Manual page, bestie 🎀

okay so this is a section 9 kernel API page, and honestly it's a tiny little icon. it's giving "short but essential." let's get into it ✨

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🌸 NAME 🌸

ct_nmi_enter — the function that tells RCU "hey girl, we just walked into NMI context" 💖

✨ SYNOPSIS ✨

void noinstr ct_nmi_enter (void );

🦋 ARGUMENTS 🦋

• void — literally no arguments. nothing. zero. nada. it takes nothing and it needs nothing 🫶

🔥 DESCRIPTION 🔥

okay so here's the vibe 👑

if the CPU was idle from RCU's point of view, this updates ct->state and ct->nmi_nesting so that the RCU grace-period handling knows the CPU is, in fact, active. like, "not me being awake actually, notice me" 😭

this implementation permits nested NMIs — yes, NMI inception, we love to see it — as long as the nesting level does not overflow an int. and honestly? you will probably run out of stack space first. 💀 so like, don't get too comfy with the nesting, bestie.

🚨 warning time: if you add or remove a call to ct_nmi_enter, be sure to test with CONFIG_RCU_EQS_DEBUG=y. no skipping the vibe check on this one, fr fr. 🔍

🌈 SEE ALSO 🌈

• the kernel file ./kernel/context_tracking.c (iconic source material, go read it) 📖
• ct_nmi_exit(9)
• ct_idle_enter(9)
• ct_idle_exit(9)
• ct_irq_enter(9)
• ct_irq_exit(9)
• __ct_user_enter(9)
• user_enter_callable(9)
• __ct_user_exit(9)
• user_exit_callable(9)

like, the whole context-tracking friend group tbh 🫶 the enter/exit squad is fully assembled.

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okay and for the cute sign-off 🌸 — this whole thing lives over in ./kernel, it's from October 2026, and it's the ct_nmi_enter(9) page itself. slay, documented, periodt. 💅✨