1 // SPDX-License-Identifier: GPL-2.0
3 * Basic worker thread pool for io_uring
5 * Copyright (C) 2019 Jens Axboe
8 #include <linux/kernel.h>
9 #include <linux/init.h>
10 #include <linux/errno.h>
11 #include <linux/sched/signal.h>
12 #include <linux/percpu.h>
13 #include <linux/slab.h>
14 #include <linux/rculist_nulls.h>
15 #include <linux/cpu.h>
16 #include <linux/tracehook.h>
17 #include <uapi/linux/io_uring.h>
21 #define WORKER_IDLE_TIMEOUT (5 * HZ)
24 IO_WORKER_F_UP = 1, /* up and active */
25 IO_WORKER_F_RUNNING = 2, /* account as running */
26 IO_WORKER_F_FREE = 4, /* worker on free list */
27 IO_WORKER_F_BOUND = 8, /* is doing bounded work */
31 IO_WQ_BIT_EXIT = 0, /* wq exiting */
35 IO_ACCT_STALLED_BIT = 0, /* stalled on hash */
39 * One for each thread in a wqe pool
44 struct hlist_nulls_node nulls_node;
45 struct list_head all_list;
46 struct task_struct *task;
49 struct io_wq_work *cur_work;
52 struct completion ref_done;
54 unsigned long create_state;
55 struct callback_head create_work;
60 struct work_struct work;
64 #if BITS_PER_LONG == 64
65 #define IO_WQ_HASH_ORDER 6
67 #define IO_WQ_HASH_ORDER 5
70 #define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
77 struct io_wq_work_list work_list;
88 * Per-node worker thread pool
92 struct io_wqe_acct acct[2];
96 struct hlist_nulls_head free_list;
97 struct list_head all_list;
99 struct wait_queue_entry wait;
102 struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
104 cpumask_var_t cpu_mask;
113 free_work_fn *free_work;
114 io_wq_work_fn *do_work;
116 struct io_wq_hash *hash;
118 atomic_t worker_refs;
119 struct completion worker_done;
121 struct hlist_node cpuhp_node;
123 struct task_struct *task;
125 struct io_wqe *wqes[];
128 static enum cpuhp_state io_wq_online;
130 struct io_cb_cancel_data {
138 static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index);
139 static void io_wqe_dec_running(struct io_worker *worker);
140 static bool io_acct_cancel_pending_work(struct io_wqe *wqe,
141 struct io_wqe_acct *acct,
142 struct io_cb_cancel_data *match);
143 static void create_worker_cb(struct callback_head *cb);
144 static void io_wq_cancel_tw_create(struct io_wq *wq);
146 static bool io_worker_get(struct io_worker *worker)
148 return refcount_inc_not_zero(&worker->ref);
151 static void io_worker_release(struct io_worker *worker)
153 if (refcount_dec_and_test(&worker->ref))
154 complete(&worker->ref_done);
157 static inline struct io_wqe_acct *io_get_acct(struct io_wqe *wqe, bool bound)
159 return &wqe->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
162 static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
163 struct io_wq_work *work)
165 return io_get_acct(wqe, !(work->flags & IO_WQ_WORK_UNBOUND));
168 static inline struct io_wqe_acct *io_wqe_get_acct(struct io_worker *worker)
170 return io_get_acct(worker->wqe, worker->flags & IO_WORKER_F_BOUND);
173 static void io_worker_ref_put(struct io_wq *wq)
175 if (atomic_dec_and_test(&wq->worker_refs))
176 complete(&wq->worker_done);
179 static void io_worker_cancel_cb(struct io_worker *worker)
181 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
182 struct io_wqe *wqe = worker->wqe;
183 struct io_wq *wq = wqe->wq;
185 atomic_dec(&acct->nr_running);
186 raw_spin_lock(&worker->wqe->lock);
188 raw_spin_unlock(&worker->wqe->lock);
189 io_worker_ref_put(wq);
190 clear_bit_unlock(0, &worker->create_state);
191 io_worker_release(worker);
194 static bool io_task_worker_match(struct callback_head *cb, void *data)
196 struct io_worker *worker;
198 if (cb->func != create_worker_cb)
200 worker = container_of(cb, struct io_worker, create_work);
201 return worker == data;
204 static void io_worker_exit(struct io_worker *worker)
206 struct io_wqe *wqe = worker->wqe;
207 struct io_wq *wq = wqe->wq;
210 struct callback_head *cb = task_work_cancel_match(wq->task,
211 io_task_worker_match, worker);
215 io_worker_cancel_cb(worker);
218 if (refcount_dec_and_test(&worker->ref))
219 complete(&worker->ref_done);
220 wait_for_completion(&worker->ref_done);
222 raw_spin_lock(&wqe->lock);
223 if (worker->flags & IO_WORKER_F_FREE)
224 hlist_nulls_del_rcu(&worker->nulls_node);
225 list_del_rcu(&worker->all_list);
227 io_wqe_dec_running(worker);
229 current->flags &= ~PF_IO_WORKER;
231 raw_spin_unlock(&wqe->lock);
233 kfree_rcu(worker, rcu);
234 io_worker_ref_put(wqe->wq);
238 static inline bool io_acct_run_queue(struct io_wqe_acct *acct)
240 if (!wq_list_empty(&acct->work_list) &&
241 !test_bit(IO_ACCT_STALLED_BIT, &acct->flags))
247 * Check head of free list for an available worker. If one isn't available,
248 * caller must create one.
250 static bool io_wqe_activate_free_worker(struct io_wqe *wqe,
251 struct io_wqe_acct *acct)
254 struct hlist_nulls_node *n;
255 struct io_worker *worker;
258 * Iterate free_list and see if we can find an idle worker to
259 * activate. If a given worker is on the free_list but in the process
260 * of exiting, keep trying.
262 hlist_nulls_for_each_entry_rcu(worker, n, &wqe->free_list, nulls_node) {
263 if (!io_worker_get(worker))
265 if (io_wqe_get_acct(worker) != acct) {
266 io_worker_release(worker);
269 if (wake_up_process(worker->task)) {
270 io_worker_release(worker);
273 io_worker_release(worker);
280 * We need a worker. If we find a free one, we're good. If not, and we're
281 * below the max number of workers, create one.
283 static bool io_wqe_create_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
286 * Most likely an attempt to queue unbounded work on an io_wq that
287 * wasn't setup with any unbounded workers.
289 if (unlikely(!acct->max_workers))
290 pr_warn_once("io-wq is not configured for unbound workers");
292 raw_spin_lock(&wqe->lock);
293 if (acct->nr_workers >= acct->max_workers) {
294 raw_spin_unlock(&wqe->lock);
298 raw_spin_unlock(&wqe->lock);
299 atomic_inc(&acct->nr_running);
300 atomic_inc(&wqe->wq->worker_refs);
301 return create_io_worker(wqe->wq, wqe, acct->index);
304 static void io_wqe_inc_running(struct io_worker *worker)
306 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
308 atomic_inc(&acct->nr_running);
311 static void create_worker_cb(struct callback_head *cb)
313 struct io_worker *worker;
316 struct io_wqe_acct *acct;
317 bool do_create = false;
319 worker = container_of(cb, struct io_worker, create_work);
322 acct = &wqe->acct[worker->create_index];
323 raw_spin_lock(&wqe->lock);
324 if (acct->nr_workers < acct->max_workers) {
328 raw_spin_unlock(&wqe->lock);
330 create_io_worker(wq, wqe, worker->create_index);
332 atomic_dec(&acct->nr_running);
333 io_worker_ref_put(wq);
335 clear_bit_unlock(0, &worker->create_state);
336 io_worker_release(worker);
339 static bool io_queue_worker_create(struct io_worker *worker,
340 struct io_wqe_acct *acct,
341 task_work_func_t func)
343 struct io_wqe *wqe = worker->wqe;
344 struct io_wq *wq = wqe->wq;
346 /* raced with exit, just ignore create call */
347 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
349 if (!io_worker_get(worker))
352 * create_state manages ownership of create_work/index. We should
353 * only need one entry per worker, as the worker going to sleep
354 * will trigger the condition, and waking will clear it once it
355 * runs the task_work.
357 if (test_bit(0, &worker->create_state) ||
358 test_and_set_bit_lock(0, &worker->create_state))
361 atomic_inc(&wq->worker_refs);
362 init_task_work(&worker->create_work, func);
363 worker->create_index = acct->index;
364 if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
366 * EXIT may have been set after checking it above, check after
367 * adding the task_work and remove any creation item if it is
368 * now set. wq exit does that too, but we can have added this
369 * work item after we canceled in io_wq_exit_workers().
371 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
372 io_wq_cancel_tw_create(wq);
373 io_worker_ref_put(wq);
376 io_worker_ref_put(wq);
377 clear_bit_unlock(0, &worker->create_state);
379 io_worker_release(worker);
381 atomic_dec(&acct->nr_running);
382 io_worker_ref_put(wq);
386 static void io_wqe_dec_running(struct io_worker *worker)
387 __must_hold(wqe->lock)
389 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
390 struct io_wqe *wqe = worker->wqe;
392 if (!(worker->flags & IO_WORKER_F_UP))
395 if (atomic_dec_and_test(&acct->nr_running) && io_acct_run_queue(acct)) {
396 atomic_inc(&acct->nr_running);
397 atomic_inc(&wqe->wq->worker_refs);
398 raw_spin_unlock(&wqe->lock);
399 io_queue_worker_create(worker, acct, create_worker_cb);
400 raw_spin_lock(&wqe->lock);
405 * Worker will start processing some work. Move it to the busy list, if
406 * it's currently on the freelist
408 static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
409 struct io_wq_work *work)
410 __must_hold(wqe->lock)
412 if (worker->flags & IO_WORKER_F_FREE) {
413 worker->flags &= ~IO_WORKER_F_FREE;
414 hlist_nulls_del_init_rcu(&worker->nulls_node);
419 * No work, worker going to sleep. Move to freelist, and unuse mm if we
420 * have one attached. Dropping the mm may potentially sleep, so we drop
421 * the lock in that case and return success. Since the caller has to
422 * retry the loop in that case (we changed task state), we don't regrab
423 * the lock if we return success.
425 static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
426 __must_hold(wqe->lock)
428 if (!(worker->flags & IO_WORKER_F_FREE)) {
429 worker->flags |= IO_WORKER_F_FREE;
430 hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
434 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
436 return work->flags >> IO_WQ_HASH_SHIFT;
439 static bool io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
441 struct io_wq *wq = wqe->wq;
444 spin_lock_irq(&wq->hash->wait.lock);
445 if (list_empty(&wqe->wait.entry)) {
446 __add_wait_queue(&wq->hash->wait, &wqe->wait);
447 if (!test_bit(hash, &wq->hash->map)) {
448 __set_current_state(TASK_RUNNING);
449 list_del_init(&wqe->wait.entry);
453 spin_unlock_irq(&wq->hash->wait.lock);
457 static struct io_wq_work *io_get_next_work(struct io_wqe_acct *acct,
458 struct io_worker *worker)
459 __must_hold(wqe->lock)
461 struct io_wq_work_node *node, *prev;
462 struct io_wq_work *work, *tail;
463 unsigned int stall_hash = -1U;
464 struct io_wqe *wqe = worker->wqe;
466 wq_list_for_each(node, prev, &acct->work_list) {
469 work = container_of(node, struct io_wq_work, list);
471 /* not hashed, can run anytime */
472 if (!io_wq_is_hashed(work)) {
473 wq_list_del(&acct->work_list, node, prev);
477 hash = io_get_work_hash(work);
478 /* all items with this hash lie in [work, tail] */
479 tail = wqe->hash_tail[hash];
481 /* hashed, can run if not already running */
482 if (!test_and_set_bit(hash, &wqe->wq->hash->map)) {
483 wqe->hash_tail[hash] = NULL;
484 wq_list_cut(&acct->work_list, &tail->list, prev);
487 if (stall_hash == -1U)
489 /* fast forward to a next hash, for-each will fix up @prev */
493 if (stall_hash != -1U) {
497 * Set this before dropping the lock to avoid racing with new
498 * work being added and clearing the stalled bit.
500 set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
501 raw_spin_unlock(&wqe->lock);
502 unstalled = io_wait_on_hash(wqe, stall_hash);
503 raw_spin_lock(&wqe->lock);
505 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
506 if (wq_has_sleeper(&wqe->wq->hash->wait))
507 wake_up(&wqe->wq->hash->wait);
514 static bool io_flush_signals(void)
516 if (test_thread_flag(TIF_NOTIFY_SIGNAL) || current->task_works) {
517 __set_current_state(TASK_RUNNING);
518 tracehook_notify_signal();
524 static void io_assign_current_work(struct io_worker *worker,
525 struct io_wq_work *work)
532 spin_lock(&worker->lock);
533 worker->cur_work = work;
534 spin_unlock(&worker->lock);
537 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
539 static void io_worker_handle_work(struct io_worker *worker)
540 __releases(wqe->lock)
542 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
543 struct io_wqe *wqe = worker->wqe;
544 struct io_wq *wq = wqe->wq;
545 bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state);
548 struct io_wq_work *work;
551 * If we got some work, mark us as busy. If we didn't, but
552 * the list isn't empty, it means we stalled on hashed work.
553 * Mark us stalled so we don't keep looking for work when we
554 * can't make progress, any work completion or insertion will
555 * clear the stalled flag.
557 work = io_get_next_work(acct, worker);
559 __io_worker_busy(wqe, worker, work);
561 raw_spin_unlock(&wqe->lock);
564 io_assign_current_work(worker, work);
565 __set_current_state(TASK_RUNNING);
567 /* handle a whole dependent link */
569 struct io_wq_work *next_hashed, *linked;
570 unsigned int hash = io_get_work_hash(work);
572 next_hashed = wq_next_work(work);
574 if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND))
575 work->flags |= IO_WQ_WORK_CANCEL;
577 io_assign_current_work(worker, NULL);
579 linked = wq->free_work(work);
581 if (!work && linked && !io_wq_is_hashed(linked)) {
585 io_assign_current_work(worker, work);
587 io_wqe_enqueue(wqe, linked);
589 if (hash != -1U && !next_hashed) {
590 /* serialize hash clear with wake_up() */
591 spin_lock_irq(&wq->hash->wait.lock);
592 clear_bit(hash, &wq->hash->map);
593 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
594 spin_unlock_irq(&wq->hash->wait.lock);
595 if (wq_has_sleeper(&wq->hash->wait))
596 wake_up(&wq->hash->wait);
597 raw_spin_lock(&wqe->lock);
598 /* skip unnecessary unlock-lock wqe->lock */
601 raw_spin_unlock(&wqe->lock);
605 raw_spin_lock(&wqe->lock);
609 static int io_wqe_worker(void *data)
611 struct io_worker *worker = data;
612 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
613 struct io_wqe *wqe = worker->wqe;
614 struct io_wq *wq = wqe->wq;
615 bool last_timeout = false;
616 char buf[TASK_COMM_LEN];
618 worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
620 snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
621 set_task_comm(current, buf);
623 while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
626 set_current_state(TASK_INTERRUPTIBLE);
628 raw_spin_lock(&wqe->lock);
629 if (io_acct_run_queue(acct)) {
630 io_worker_handle_work(worker);
633 /* timed out, exit unless we're the last worker */
634 if (last_timeout && acct->nr_workers > 1) {
636 raw_spin_unlock(&wqe->lock);
637 __set_current_state(TASK_RUNNING);
640 last_timeout = false;
641 __io_worker_idle(wqe, worker);
642 raw_spin_unlock(&wqe->lock);
643 if (io_flush_signals())
645 ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
646 if (signal_pending(current)) {
649 if (!get_signal(&ksig))
656 if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
657 raw_spin_lock(&wqe->lock);
658 io_worker_handle_work(worker);
661 io_worker_exit(worker);
666 * Called when a worker is scheduled in. Mark us as currently running.
668 void io_wq_worker_running(struct task_struct *tsk)
670 struct io_worker *worker = tsk->pf_io_worker;
674 if (!(worker->flags & IO_WORKER_F_UP))
676 if (worker->flags & IO_WORKER_F_RUNNING)
678 worker->flags |= IO_WORKER_F_RUNNING;
679 io_wqe_inc_running(worker);
683 * Called when worker is going to sleep. If there are no workers currently
684 * running and we have work pending, wake up a free one or create a new one.
686 void io_wq_worker_sleeping(struct task_struct *tsk)
688 struct io_worker *worker = tsk->pf_io_worker;
692 if (!(worker->flags & IO_WORKER_F_UP))
694 if (!(worker->flags & IO_WORKER_F_RUNNING))
697 worker->flags &= ~IO_WORKER_F_RUNNING;
699 raw_spin_lock(&worker->wqe->lock);
700 io_wqe_dec_running(worker);
701 raw_spin_unlock(&worker->wqe->lock);
704 static void io_init_new_worker(struct io_wqe *wqe, struct io_worker *worker,
705 struct task_struct *tsk)
707 tsk->pf_io_worker = worker;
709 set_cpus_allowed_ptr(tsk, wqe->cpu_mask);
710 tsk->flags |= PF_NO_SETAFFINITY;
712 raw_spin_lock(&wqe->lock);
713 hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
714 list_add_tail_rcu(&worker->all_list, &wqe->all_list);
715 worker->flags |= IO_WORKER_F_FREE;
716 raw_spin_unlock(&wqe->lock);
717 wake_up_new_task(tsk);
720 static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
725 static inline bool io_should_retry_thread(long err)
728 * Prevent perpetual task_work retry, if the task (or its group) is
731 if (fatal_signal_pending(current))
737 case -ERESTARTNOINTR:
738 case -ERESTARTNOHAND:
745 static void create_worker_cont(struct callback_head *cb)
747 struct io_worker *worker;
748 struct task_struct *tsk;
751 worker = container_of(cb, struct io_worker, create_work);
752 clear_bit_unlock(0, &worker->create_state);
754 tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
756 io_init_new_worker(wqe, worker, tsk);
757 io_worker_release(worker);
759 } else if (!io_should_retry_thread(PTR_ERR(tsk))) {
760 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
762 atomic_dec(&acct->nr_running);
763 raw_spin_lock(&wqe->lock);
765 if (!acct->nr_workers) {
766 struct io_cb_cancel_data match = {
767 .fn = io_wq_work_match_all,
771 while (io_acct_cancel_pending_work(wqe, acct, &match))
772 raw_spin_lock(&wqe->lock);
774 raw_spin_unlock(&wqe->lock);
775 io_worker_ref_put(wqe->wq);
780 /* re-create attempts grab a new worker ref, drop the existing one */
781 io_worker_release(worker);
782 schedule_work(&worker->work);
785 static void io_workqueue_create(struct work_struct *work)
787 struct io_worker *worker = container_of(work, struct io_worker, work);
788 struct io_wqe_acct *acct = io_wqe_get_acct(worker);
790 if (!io_queue_worker_create(worker, acct, create_worker_cont))
794 static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
796 struct io_wqe_acct *acct = &wqe->acct[index];
797 struct io_worker *worker;
798 struct task_struct *tsk;
800 __set_current_state(TASK_RUNNING);
802 worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
805 atomic_dec(&acct->nr_running);
806 raw_spin_lock(&wqe->lock);
808 raw_spin_unlock(&wqe->lock);
809 io_worker_ref_put(wq);
813 refcount_set(&worker->ref, 1);
815 spin_lock_init(&worker->lock);
816 init_completion(&worker->ref_done);
818 if (index == IO_WQ_ACCT_BOUND)
819 worker->flags |= IO_WORKER_F_BOUND;
821 tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
823 io_init_new_worker(wqe, worker, tsk);
824 } else if (!io_should_retry_thread(PTR_ERR(tsk))) {
828 INIT_WORK(&worker->work, io_workqueue_create);
829 schedule_work(&worker->work);
836 * Iterate the passed in list and call the specific function for each
837 * worker that isn't exiting
839 static bool io_wq_for_each_worker(struct io_wqe *wqe,
840 bool (*func)(struct io_worker *, void *),
843 struct io_worker *worker;
846 list_for_each_entry_rcu(worker, &wqe->all_list, all_list) {
847 if (io_worker_get(worker)) {
848 /* no task if node is/was offline */
850 ret = func(worker, data);
851 io_worker_release(worker);
860 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
862 set_notify_signal(worker->task);
863 wake_up_process(worker->task);
867 static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
869 struct io_wq *wq = wqe->wq;
872 work->flags |= IO_WQ_WORK_CANCEL;
874 work = wq->free_work(work);
878 static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work)
880 struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
882 struct io_wq_work *tail;
884 if (!io_wq_is_hashed(work)) {
886 wq_list_add_tail(&work->list, &acct->work_list);
890 hash = io_get_work_hash(work);
891 tail = wqe->hash_tail[hash];
892 wqe->hash_tail[hash] = work;
896 wq_list_add_after(&work->list, &tail->list, &acct->work_list);
899 static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
904 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
906 struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
907 unsigned work_flags = work->flags;
911 * If io-wq is exiting for this task, or if the request has explicitly
912 * been marked as one that should not get executed, cancel it here.
914 if (test_bit(IO_WQ_BIT_EXIT, &wqe->wq->state) ||
915 (work->flags & IO_WQ_WORK_CANCEL)) {
916 io_run_cancel(work, wqe);
920 raw_spin_lock(&wqe->lock);
921 io_wqe_insert_work(wqe, work);
922 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
925 do_create = !io_wqe_activate_free_worker(wqe, acct);
928 raw_spin_unlock(&wqe->lock);
930 if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
931 !atomic_read(&acct->nr_running))) {
934 did_create = io_wqe_create_worker(wqe, acct);
935 if (likely(did_create))
938 raw_spin_lock(&wqe->lock);
939 /* fatal condition, failed to create the first worker */
940 if (!acct->nr_workers) {
941 struct io_cb_cancel_data match = {
942 .fn = io_wq_work_match_item,
947 if (io_acct_cancel_pending_work(wqe, acct, &match))
948 raw_spin_lock(&wqe->lock);
950 raw_spin_unlock(&wqe->lock);
954 void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
956 struct io_wqe *wqe = wq->wqes[numa_node_id()];
958 io_wqe_enqueue(wqe, work);
962 * Work items that hash to the same value will not be done in parallel.
963 * Used to limit concurrent writes, generally hashed by inode.
965 void io_wq_hash_work(struct io_wq_work *work, void *val)
969 bit = hash_ptr(val, IO_WQ_HASH_ORDER);
970 work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
973 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
975 struct io_cb_cancel_data *match = data;
978 * Hold the lock to avoid ->cur_work going out of scope, caller
979 * may dereference the passed in work.
981 spin_lock(&worker->lock);
982 if (worker->cur_work &&
983 match->fn(worker->cur_work, match->data)) {
984 set_notify_signal(worker->task);
987 spin_unlock(&worker->lock);
989 return match->nr_running && !match->cancel_all;
992 static inline void io_wqe_remove_pending(struct io_wqe *wqe,
993 struct io_wq_work *work,
994 struct io_wq_work_node *prev)
996 struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
997 unsigned int hash = io_get_work_hash(work);
998 struct io_wq_work *prev_work = NULL;
1000 if (io_wq_is_hashed(work) && work == wqe->hash_tail[hash]) {
1002 prev_work = container_of(prev, struct io_wq_work, list);
1003 if (prev_work && io_get_work_hash(prev_work) == hash)
1004 wqe->hash_tail[hash] = prev_work;
1006 wqe->hash_tail[hash] = NULL;
1008 wq_list_del(&acct->work_list, &work->list, prev);
1011 static bool io_acct_cancel_pending_work(struct io_wqe *wqe,
1012 struct io_wqe_acct *acct,
1013 struct io_cb_cancel_data *match)
1014 __releases(wqe->lock)
1016 struct io_wq_work_node *node, *prev;
1017 struct io_wq_work *work;
1019 wq_list_for_each(node, prev, &acct->work_list) {
1020 work = container_of(node, struct io_wq_work, list);
1021 if (!match->fn(work, match->data))
1023 io_wqe_remove_pending(wqe, work, prev);
1024 raw_spin_unlock(&wqe->lock);
1025 io_run_cancel(work, wqe);
1026 match->nr_pending++;
1027 /* not safe to continue after unlock */
1034 static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
1035 struct io_cb_cancel_data *match)
1039 raw_spin_lock(&wqe->lock);
1040 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1041 struct io_wqe_acct *acct = io_get_acct(wqe, i == 0);
1043 if (io_acct_cancel_pending_work(wqe, acct, match)) {
1044 if (match->cancel_all)
1049 raw_spin_unlock(&wqe->lock);
1052 static void io_wqe_cancel_running_work(struct io_wqe *wqe,
1053 struct io_cb_cancel_data *match)
1056 io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
1060 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
1061 void *data, bool cancel_all)
1063 struct io_cb_cancel_data match = {
1066 .cancel_all = cancel_all,
1071 * First check pending list, if we're lucky we can just remove it
1072 * from there. CANCEL_OK means that the work is returned as-new,
1073 * no completion will be posted for it.
1075 for_each_node(node) {
1076 struct io_wqe *wqe = wq->wqes[node];
1078 io_wqe_cancel_pending_work(wqe, &match);
1079 if (match.nr_pending && !match.cancel_all)
1080 return IO_WQ_CANCEL_OK;
1084 * Now check if a free (going busy) or busy worker has the work
1085 * currently running. If we find it there, we'll return CANCEL_RUNNING
1086 * as an indication that we attempt to signal cancellation. The
1087 * completion will run normally in this case.
1089 for_each_node(node) {
1090 struct io_wqe *wqe = wq->wqes[node];
1092 io_wqe_cancel_running_work(wqe, &match);
1093 if (match.nr_running && !match.cancel_all)
1094 return IO_WQ_CANCEL_RUNNING;
1097 if (match.nr_running)
1098 return IO_WQ_CANCEL_RUNNING;
1099 if (match.nr_pending)
1100 return IO_WQ_CANCEL_OK;
1101 return IO_WQ_CANCEL_NOTFOUND;
1104 static int io_wqe_hash_wake(struct wait_queue_entry *wait, unsigned mode,
1105 int sync, void *key)
1107 struct io_wqe *wqe = container_of(wait, struct io_wqe, wait);
1110 list_del_init(&wait->entry);
1113 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1114 struct io_wqe_acct *acct = &wqe->acct[i];
1116 if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags))
1117 io_wqe_activate_free_worker(wqe, acct);
1123 struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
1128 if (WARN_ON_ONCE(!data->free_work || !data->do_work))
1129 return ERR_PTR(-EINVAL);
1130 if (WARN_ON_ONCE(!bounded))
1131 return ERR_PTR(-EINVAL);
1133 wq = kzalloc(struct_size(wq, wqes, nr_node_ids), GFP_KERNEL);
1135 return ERR_PTR(-ENOMEM);
1136 ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1140 refcount_inc(&data->hash->refs);
1141 wq->hash = data->hash;
1142 wq->free_work = data->free_work;
1143 wq->do_work = data->do_work;
1146 for_each_node(node) {
1148 int alloc_node = node;
1150 if (!node_online(alloc_node))
1151 alloc_node = NUMA_NO_NODE;
1152 wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
1155 wq->wqes[node] = wqe;
1156 if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL))
1158 cpumask_copy(wqe->cpu_mask, cpumask_of_node(node));
1159 wqe->node = alloc_node;
1160 wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
1161 wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
1162 task_rlimit(current, RLIMIT_NPROC);
1163 INIT_LIST_HEAD(&wqe->wait.entry);
1164 wqe->wait.func = io_wqe_hash_wake;
1165 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1166 struct io_wqe_acct *acct = &wqe->acct[i];
1169 atomic_set(&acct->nr_running, 0);
1170 INIT_WQ_LIST(&acct->work_list);
1173 raw_spin_lock_init(&wqe->lock);
1174 INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
1175 INIT_LIST_HEAD(&wqe->all_list);
1178 wq->task = get_task_struct(data->task);
1179 atomic_set(&wq->worker_refs, 1);
1180 init_completion(&wq->worker_done);
1183 io_wq_put_hash(data->hash);
1184 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1185 for_each_node(node) {
1186 if (!wq->wqes[node])
1188 free_cpumask_var(wq->wqes[node]->cpu_mask);
1189 kfree(wq->wqes[node]);
1193 return ERR_PTR(ret);
1196 static bool io_task_work_match(struct callback_head *cb, void *data)
1198 struct io_worker *worker;
1200 if (cb->func != create_worker_cb && cb->func != create_worker_cont)
1202 worker = container_of(cb, struct io_worker, create_work);
1203 return worker->wqe->wq == data;
1206 void io_wq_exit_start(struct io_wq *wq)
1208 set_bit(IO_WQ_BIT_EXIT, &wq->state);
1211 static void io_wq_cancel_tw_create(struct io_wq *wq)
1213 struct callback_head *cb;
1215 while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
1216 struct io_worker *worker;
1218 worker = container_of(cb, struct io_worker, create_work);
1219 io_worker_cancel_cb(worker);
1221 * Only the worker continuation helper has worker allocated and
1222 * hence needs freeing.
1224 if (cb->func == create_worker_cont)
1229 static void io_wq_exit_workers(struct io_wq *wq)
1236 io_wq_cancel_tw_create(wq);
1239 for_each_node(node) {
1240 struct io_wqe *wqe = wq->wqes[node];
1242 io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL);
1245 io_worker_ref_put(wq);
1246 wait_for_completion(&wq->worker_done);
1248 for_each_node(node) {
1249 spin_lock_irq(&wq->hash->wait.lock);
1250 list_del_init(&wq->wqes[node]->wait.entry);
1251 spin_unlock_irq(&wq->hash->wait.lock);
1253 put_task_struct(wq->task);
1257 static void io_wq_destroy(struct io_wq *wq)
1261 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1263 for_each_node(node) {
1264 struct io_wqe *wqe = wq->wqes[node];
1265 struct io_cb_cancel_data match = {
1266 .fn = io_wq_work_match_all,
1269 io_wqe_cancel_pending_work(wqe, &match);
1270 free_cpumask_var(wqe->cpu_mask);
1273 io_wq_put_hash(wq->hash);
1277 void io_wq_put_and_exit(struct io_wq *wq)
1279 WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
1281 io_wq_exit_workers(wq);
1285 struct online_data {
1290 static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
1292 struct online_data *od = data;
1295 cpumask_set_cpu(od->cpu, worker->wqe->cpu_mask);
1297 cpumask_clear_cpu(od->cpu, worker->wqe->cpu_mask);
1301 static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online)
1303 struct online_data od = {
1311 io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, &od);
1316 static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
1318 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1320 return __io_wq_cpu_online(wq, cpu, true);
1323 static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
1325 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1327 return __io_wq_cpu_online(wq, cpu, false);
1330 int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask)
1336 struct io_wqe *wqe = wq->wqes[i];
1339 cpumask_copy(wqe->cpu_mask, mask);
1341 cpumask_copy(wqe->cpu_mask, cpumask_of_node(i));
1348 * Set max number of unbounded workers, returns old value. If new_count is 0,
1349 * then just return the old value.
1351 int io_wq_max_workers(struct io_wq *wq, int *new_count)
1353 int prev[IO_WQ_ACCT_NR];
1354 bool first_node = true;
1357 BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND != (int) IO_WQ_BOUND);
1358 BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
1359 BUILD_BUG_ON((int) IO_WQ_ACCT_NR != 2);
1361 for (i = 0; i < 2; i++) {
1362 if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
1363 new_count[i] = task_rlimit(current, RLIMIT_NPROC);
1366 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1370 for_each_node(node) {
1371 struct io_wqe *wqe = wq->wqes[node];
1372 struct io_wqe_acct *acct;
1374 raw_spin_lock(&wqe->lock);
1375 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1376 acct = &wqe->acct[i];
1378 prev[i] = max_t(int, acct->max_workers, prev[i]);
1380 acct->max_workers = new_count[i];
1382 raw_spin_unlock(&wqe->lock);
1387 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1388 new_count[i] = prev[i];
1393 static __init int io_wq_init(void)
1397 ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
1398 io_wq_cpu_online, io_wq_cpu_offline);
1404 subsys_initcall(io_wq_init);