bpf_timer_cancel_async(9)

💅 bpf_timer_cancel_async — the gen-z guide to bailing on a timer

okay so you found bpf_timer_cancel_async(9) in the Kernel API Manual and you're like "bestie what does this even do" — don't worry, i gotchu. short version: it tries to deactivate a timer. that's the whole vibe. 🎀

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✨ NAME ✨

bpf_timer_cancel_async — try to deactivate a timer, no cap 🕰️

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🌸 SYNOPSIS 🌸

__bpf_kfunc int bpf_timer_cancel_async (struct bpf_timer *timer );

literally the entire signature, copy it exactly, don't be weird about the spacing 🫶

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🦋 ARGUMENTS 🦋

• timer — the bpf_timer you wanna stop. that's it. that's the arg. she's the main character of this function 💅

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🔥 DESCRIPTION 🔥

so you're calling this to try to deactivate a timer, and the function is gonna come back at you with one of these bad boys. read the return value carefully because it's giving very different energy depending on which one you get 👀

• 0 when the timer was not active 😴
• 1 when the timer was active ⚡
• -1 when the timer is currently executing the callback function and cannot be stopped 💀 like it's literally mid-callback, you cannot touch her
• -ECANCELED when the timer will be cancelled asynchronously 🕊️ ok so it's not done yet, but it's been handled — patience, bestie
• -ENOMEM when out of memory 😭 classic
• -EINVAL when the timer was not initialized 🚩 so you skipped a step, huh
• -ENOENT when this kfunc is racing with timer deletion 🏁 yes it's a race, no you're not winning it on purpose

ngl the difference between -1 and -ECANCELED is the whole personality of this function — one says "can't stop her", the other says "she's on her way out." know which one you got. 🙈

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💜 SEE ALSO 💜

kernel file ./kernel/bpf/helpers.c, plus the whole group chat:

• bpf_obj_new(9)
• bpf_percpu_obj_new(9)
• bpf_obj_drop(9)
• bpf_percpu_obj_drop(9)
• bpf_refcount_acquire(9)
• bpf_list_push_front(9)
• bpf_list_push_back(9)
• bpf_rbtree_add(9)
• bpf_task_acquire(9)
• bpf_task_release(9)
• bpf_cgroup_acquire(9)
• bpf_cgroup_release(9)
• bpf_cgroup_ancestor(9)
• bpf_cgroup_from_id(9)
• bpf_task_under_cgroup(9)
• bpf_task_get_cgroup1(9)
• bpf_task_from_pid(9)
• bpf_task_from_vpid(9)
• bpf_dynptr_slice(9)
• bpf_dynptr_slice_rdwr(9)
• bpf_dynptr_copy(9)
• bpf_dynptr_memset(9)
• bpf_iter_bits_new(9)
• bpf_iter_bits_next(9)
• bpf_iter_bits_destroy(9)
• bpf_copy_from_user_str(9)
• bpf_copy_from_user_task_str(9)
• bpf_strcmp(9)
• bpf_strcasecmp(9)
• bpf_strnchr(9)
• bpf_strchr(9)
• bpf_strchrnul(9)
• bpf_strrchr(9)
• bpf_strnlen(9)
• bpf_strlen(9)
• bpf_strspn(9)
• bpf_strcspn(9)
• bpf_strstr(9)
• bpf_strcasestr(9)
• bpf_strnstr(9)
• bpf_strncasestr(9)
• bpf_lookup_user_key(9)
• bpf_lookup_system_key(9)
• bpf_key_put(9)
• bpf_verify_pkcs7_signature(9)
• bpf_task_work_schedule_signal(9)
• bpf_task_work_schedule_resume(9)

like. all of them. every single one. go read them, i'll wait 🍓

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okay that's the whole page, go touch some bpf_timers 💖

sign-off time ✨ this one lives in ./kernel/bpf, dated October 2026, and we're officially done — slay, periodt, bye 🎀