bpf_cgroup_from_id(9)

💖 bpf_cgroup_from_id(9) 💖

okay so this is a page from the Kernel API Manual — yep, the kernel has its own manual, she's fancy like that — and today's main character is bpf_cgroup_from_id, a kfunc that goes and finds you a cgroup if you hand it the right ID. 🎀

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✨ NAME ✨

bpf_cgroup_from_id — find a cgroup from its ID.

Real talk though, bestie, this is the part you cannot skip: a cgroup returned by this kfunc which is not subsequently stored in a map must be released by calling bpf_cgroup_release(). So if you're not immediately tucking that cgroup into a map, you gotta clean up after yourself. No leaving it lying around. 💅

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🦋 SYNOPSIS 🦋

__bpf_kfunc struct cgroup * bpf_cgroup_from_id (u64 cgid );

That's the whole vibe: you give it a u64, you get back a struct cgroup *. Slay. ✨

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🌸 ARGUMENTS 🌸

• cgid — the cgroup id. that's it, that's the argument. hand over the id, get a cgroup (and remember the release rule up top, ok? 🫶).

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👑 SEE ALSO 👑

Kernel file ./kernel/bpf/helpers.c, plus literally the entire squad — these kfuncs all hang out together so here's the full friend group, no gatekeeping:

• 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_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)
• bpf_timer_cancel_async(9)

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🫶 friendly reminder, one last time, because it matters: not stored in a map? then call bpf_cgroup_release(). periodt. 💀

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and that's the page, diva 💜 — brought to you by the source path ./kernel/bpf, dated October 2026, filed under bpf_cgroup_from_id(9). go forth and release your cgroups 🌈⭐