work_on_cpu_key(9)

🌸 NAME 🌸

okay so bestie, welcome to work_on_cpu_key(9) from the Kernel API Manual — the whole entire point is running a function in thread context on a particular cpu. No cap, that's the name.

work_on_cpu_key — run a function in thread context on a particular cpu. Slay. 💅

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✨ SYNOPSIS ✨

long work_on_cpu_key (int cpu , long (*fn)(void *) , void *arg , struct lock_class_key *key );

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🎀 ARGUMENTS 🎀

• cpu — the cpu to run on. Like, the actual cpu, bestie. ✨
• fn — the function to run. This is the main-character function, fr fr.
• arg — the function arg. It gets passed along to fn, no drama.
• key — the lock class key for lock debugging purposes. It's giving “debugging details,” and we respect it. 🫶

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🦋 DESCRIPTION 🦋

Okay so here's where responsibility enters the chat: it is up to the caller to ensure that the cpu doesn't go offline. Yep — the caller. Not fn. Not the vibe. You. 😭

And the caller must not hold any locks which would prevent fn from completing. That's a real one, bestie — do not be out here holding locks that block fn from finishing. Periodt. 💀

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💅 RETURN 💅

The value fn returns. That's it. That's the return. 🫶

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💖 SEE ALSO 💖

Kernel file ./kernel/workqueue.c is like the whole group chat, and these are all in it: for_each_pool(9), for_each_pool_worker(9), for_each_pwq(9), worker_pool_assign_id(9), unbound_effective_cpumask(9), get_work_pool(9), worker_set_flags(9), worker_clr_flags(9), worker_enter_idle(9), worker_leave_idle(9), find_worker_executing_work(9), move_linked_works(9), assign_work(9), kick_pool_pick(9), kick_pool(9), wq_worker_running(9), wq_worker_sleeping(9), wq_worker_tick(9), wq_worker_last_func(9), wq_node_nr_active(9), wq_update_node_max_active(9), get_pwq(9), put_pwq(9), put_pwq_unlocked(9), pwq_tryinc_nr_active(9), pwq_activate_first_inactive(9), unplug_oldest_pwq(9), node_activate_pending_pwq(9), pwq_dec_nr_active(9), pwq_dec_nr_in_flight(9), try_to_grab_pending(9), work_grab_pending(9), insert_work(9), queue_work_on(9), select_numa_node_cpu(9), queue_work_node(9), queue_delayed_work_on(9), mod_delayed_work_on(9), queue_rcu_work(9), worker_attach_to_pool(9), worker_detach_from_pool(9), create_worker(9), set_worker_dying(9), idle_worker_timeout(9), idle_cull_fn(9), maybe_create_worker(9), manage_workers(9), process_one_work(9), process_scheduled_works(9), worker_thread(9), rescuer_thread(9), check_flush_dependency(9), insert_wq_barrier(9), flush_workqueue_prep_pwqs(9), __flush_workqueue(9), drain_workqueue(9), flush_work(9), flush_delayed_work(9), flush_rcu_work(9), cancel_work_sync(9), cancel_delayed_work(9), cancel_delayed_work_sync(9), disable_work(9), disable_work_sync(9), enable_work(9), disable_delayed_work(9), disable_delayed_work_sync(9), enable_delayed_work(9), schedule_on_each_cpu(9), execute_in_process_context(9), free_workqueue_attrs(9), alloc_workqueue_attrs(9), init_worker_pool(9), put_unbound_pool(9), get_unbound_pool(9), wq_calc_pod_cpumask(9), apply_workqueue_attrs(9), unbound_wq_update_pwq(9), wq_adjust_max_active(9), destroy_workqueue(9), workqueue_set_max_active(9), workqueue_set_min_active(9), current_work(9), current_is_workqueue_rescuer(9), current_is_workqueue_mem_reclaim(9), workqueue_congested(9), work_busy(9), set_worker_desc(9), print_worker_info(9), show_one_workqueue(9), show_one_worker_pool(9), show_all_workqueues(9), show_freezable_workqueues(9), rebind_workers(9), restore_unbound_workers_cpumask(9), freeze_workqueues_begin(9), freeze_workqueues_busy(9), thaw_workqueues(9), workqueue_unbound_housekeeping_update(9), workqueue_set_unbound_cpumask(9), workqueue_sysfs_register(9), workqueue_sysfs_unregister(9), workqueue_init_early(9), workqueue_init(9), llc_count_cores(9), llc_populate_cpu_shard_id(9), precompute_cache_shard_ids(9), workqueue_init_topology(9).

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okay that's the page, bestie — source/version: ./kernel; date: October 2026; and it's all from the Kernel API Manual. Mwah 💋✨