hrtimer_update_function(9)

🎀 NAME 🎀

okay so bestie, this is hrtimer_update_function(9) from the Kernel API Manual — and it literally does what it says on the tin: it updates the timer's callback function. no cap 💅✨

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✨ SYNOPSIS ✨

void hrtimer_update_function (struct hrtimer *timer , enum
       hrtimer_restart (*function)(struct hrtimer *) );

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🦋 ARGUMENTS 🦋

• timer — the timer you're updating, periodt 🫶
• function — the new callback function, the main character of this glow-up 🌟

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💖 DESCRIPTION 💖

Okay so the vibe check here is strict: this is only safe to call if the timer is not enqueued. That's the whole rule, bestie — do not skip it 🙈

It can be called in the callback function if the timer is not enqueued at the same time (see the comments above HRTIMER_STATE_ENQUEUED). iykyk 👑

🚨 lowkey important: not enqueued = safe to call; enqueued = not the move. fr fr 💀

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🌈 SEE ALSO 🌈

Kernel file ./kernel/time/hrtimer.c — and these iconic little references, all present and accounted for 🎀:

• hrtimer_forward(9)
• hrtimer_start_range_ns(9)
• hrtimer_start_range_ns_user(9)
• hrtimer_try_to_cancel(9)
• hrtimer_cancel(9)
• __hrtimer_get_remaining(9)
• hrtimer_get_next_event(9)
• hrtimer_next_event_without(9)
• hrtimer_setup(9)
• hrtimer_setup_on_stack(9)
• hrtimer_sleeper_start_expires(9)
• hrtimer_setup_sleeper_on_stack(9)

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that’s the page, bestie 🫶 — source/version: ./kernel/time; date: October 2026; manual title: hrtimer_update_function(9) 💖✨