css_from_id(9)

🎀 css_from_id(9) 🎀

okay bestie, welcome to the Kernel API Manual — we're looking at css_from_id today and honestly? she's short, she's sweet, she's a lil lookup function. let's go 💅

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✨ NAME ✨

css_from_id — lookup css by id 🦋

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🌸 SYNOPSIS 🌸

struct cgroup_subsys_state * css_from_id (int id , struct cgroup_subsys
*ss );

that's it. that's the whole vibe check. no cap.

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💖 ARGUMENTS 💖

• id — the cgroup id 🏷️ like, the number you're hunting for
• ss — cgroup subsys to be looked into 🔍 the subsystem you're snooping around inside

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🧚 DESCRIPTION 🧚

So here's the tea ☕ — css_from_id returns the css if there's a valid one with id, otherwise it returns NULL. That's literally it, that's the whole plot.

⚠️ important bestie: it should be called under rcu_read_lock. do not skip this. this is not a suggestion, this is the rule 🙈

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👑 SEE ALSO 👑

Kernel file ./kernel/cgroup/cgroup.c, and hoo boy, the friend group is large — presenting, in all their glory: cgroup_ssid_enabled(9), cgroup_on_dfl(9), cgroup_e_css_by_mask(9), cgroup_e_css(9), cgroup_get_e_css(9), __cgroup_task_count(9), cgroup_task_count(9), for_each_css(9), do_each_subsys_mask(9), css_set_populated(9), css_update_populated(9), css_set_update_populated(9), css_set_move_task(9), compare_css_sets(9), find_existing_css_set(9), allocate_cgrp_cset_links(9), link_css_set(9), find_css_set(9), cgroup_file_mode(9), cgroup_calc_subtree_ss_mask(9), cgroup_kn_unlock(9), cgroup_kn_lock_live(9), css_clear_dir(9), css_populate_dir(9), cgroup_attach_lock(9), cgroup_attach_unlock(9), cgroup_migrate_add_task(9), cgroup_taskset_first(9), cgroup_taskset_next(9), cgroup_migrate_execute(9), cgroup_migrate_vet_dst(9), cgroup_migrate_finish(9), cgroup_migrate_add_src(9), cgroup_migrate_prepare_dst(9), cgroup_migrate(9), cgroup_attach_task(9), cgroup_update_dfl_csses(9), cgroup_lock_and_drain_offline(9), cgroup_save_control(9), cgroup_propagate_control(9), cgroup_restore_control(9), cgroup_apply_control_enable(9), cgroup_apply_control_disable(9), cgroup_apply_control(9), cgroup_finalize_control(9), cgroup_enable_threaded(9), cgroup_tryget_css(9), cgroup_addrm_files(9), cgroup_rm_cftypes(9), cgroup_add_cftypes(9), cgroup_add_dfl_cftypes(9), cgroup_add_legacy_cftypes(9), cgroup_file_notify(9), cgroup_file_show(9), css_next_child(9), css_next_descendant_pre(9), css_rightmost_descendant(9), css_next_descendant_post(9), css_has_online_children(9), css_task_iter_advance_css_set(9), css_task_iter_start(9), css_task_iter_next(9), css_task_iter_end(9), css_create(9), kill_css_sync(9), kill_css_finish(9), cgroup_destroy_locked(9), cgroup_init_early(9), cgroup_init(9), cgroup_fork(9), cgroup_v1v2_get_from_file(9), cgroup_get_from_file(9), cgroup_css_set_fork(9), cgroup_css_set_put_fork(9), cgroup_can_fork(9), cgroup_cancel_fork(9), cgroup_post_fork(9), cgroup_task_exit(9), css_tryget_online_from_dir(9), cgroup_get_from_path(9), cgroup_v1v2_get_from_fd(9), cgroup_get_from_fd(9), cgroup_parse_float(9).

like I said. huge friend group. go click through them, iykyk 💜

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and that's the whole page, bestie — this one came to you from ./kernel/cgroup in October 2026, signed, sealed, and slayed 🫶🎀✨