do_each_subsys_mask(9)

✨ NAME ✨

okay bestie, this is do_each_subsys_mask(9) from the Kernel API Manual 💖 — it’s the filter for for_each_subsys with a bitmask, and it’s lowkey iconic.

🎀 SYNOPSIS 🎀

do_each_subsys_mask (ss , ssid , ss_mask );

🌸 ARGUMENTS 🌸

• ss — the iteration cursor. It’s the main character moving through the loop ✨
• ssid — the index of ss, and it’s CGROUP_SUBSYS_COUNT after reaching the end. Track it, periodt.
• ss_mask — the bitmask. No notes 💅

🦋 DESCRIPTION 🦋

okay so here’s the tea: the block will only run for cases where the ssid-th bit — that’s (1 << ssid) — of ss_mask is set. That’s the whole filter vibe, fr fr 🌈

💅 SEE ALSO 💅

Kernel file ./kernel/cgroup/cgroup.c is part of the squad, and here’s the full SEE ALSO crew in order, bestie:

• 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), 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), css_from_id(9), cgroup_get_from_path(9)
• cgroup_v1v2_get_from_fd(9), cgroup_get_from_fd(9), cgroup_parse_float(9)

xoxo, ./kernel/cgroup — October 2026 — do_each_subsys_mask(9) 🫶💅