flush_workqueue_prep_pwqs(9)

💖 flush_workqueue_prep_pwqs — NAME ✨

flush_workqueue_prep_pwqs — prepare pwqs for workqueue flushing, bestie. This is the flush_workqueue_prep_pwqs(9) page from the Kernel API Manual, and yes, we’re getting into the workqueue girlie lore 💅

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🌸 SYNOPSIS 🌸

bool flush_workqueue_prep_pwqs (struct workqueue_struct *wq , int
flush_color , int work_color );

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🎀 ARGUMENTS 🎀

• wq — the workqueue being flushed. That’s the main character here 👑
• flush_color — new flush color, < 0 for no-op. So if it’s negative, we’re literally not doing that update.
• work_color — new work color, < 0 for no-op. Same vibe: negative means skip it.

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🦋 DESCRIPTION 🦋

Okay so the whole point: prepare pwqs for workqueue flushing.

If flush_color is non-negative, flush_color on all pwqs should be -1. If no pwq has in-flight commands at the specified color, all pwq->flush_color's stay at -1 and false is returned. If any pwq has in flight commands, its pwq->flush_color is set to flush_color, wq->nr_pwqs_to_flush is updated accordingly, pwq wakeup logic is armed and true is returned. No cap, that’s the whole flow ✨

The caller should have initialized wq->first_flusher prior to calling this function with non-negative flush_color. So like, do that first, bestie 🫶 If flush_color is negative, no flush color update is done and false is returned.

If work_color is non-negative, all pwqs should have the same work_color which is previous to work_color and all will be advanced to work_color. Slay, they all move together 💫

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🔥 CONTEXT 🔥

It’s giving locked-down energy:

mutex_lock(wq->mutex).

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⭐ RETURN ⭐

true if flush_color >= 0 and there’s something to flush. false otherwise. That’s it, that’s the answer 💅

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🌈 SEE ALSO 🌈

Kernel file ./kernel/workqueue.c

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(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), work_on_cpu_key(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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💖 cute little sign-off: source/version is ./kernel, date is October 2026, and this whole page is flush_workqueue_prep_pwqs(9) — periodt, mwah 🧚✨