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>
13 #include <linux/sched/mm.h>
14 #include <linux/percpu.h>
15 #include <linux/slab.h>
16 #include <linux/kthread.h>
17 #include <linux/rculist_nulls.h>
18 #include <linux/fs_struct.h>
19 #include <linux/task_work.h>
20 #include <linux/blk-cgroup.h>
21 #include <linux/audit.h>
22 #include <linux/cpu.h>
24 #include "../kernel/sched/sched.h"
27 #define WORKER_IDLE_TIMEOUT (5 * HZ)
30 IO_WORKER_F_UP = 1, /* up and active */
31 IO_WORKER_F_RUNNING = 2, /* account as running */
32 IO_WORKER_F_FREE = 4, /* worker on free list */
33 IO_WORKER_F_FIXED = 8, /* static idle worker */
34 IO_WORKER_F_BOUND = 16, /* is doing bounded work */
38 IO_WQ_BIT_EXIT = 0, /* wq exiting */
39 IO_WQ_BIT_ERROR = 1, /* error on setup */
43 IO_WQE_FLAG_STALLED = 1, /* stalled on hash */
47 * One for each thread in a wqe pool
52 struct hlist_nulls_node nulls_node;
53 struct list_head all_list;
54 struct task_struct *task;
57 struct io_wq_work *cur_work;
62 #ifdef CONFIG_BLK_CGROUP
63 struct cgroup_subsys_state *blkcg_css;
65 const struct cred *cur_creds;
66 const struct cred *saved_creds;
67 struct files_struct *restore_files;
68 struct nsproxy *restore_nsproxy;
69 struct fs_struct *restore_fs;
72 #if BITS_PER_LONG == 64
73 #define IO_WQ_HASH_ORDER 6
75 #define IO_WQ_HASH_ORDER 5
78 #define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
92 * Per-node worker thread pool
97 struct io_wq_work_list work_list;
98 unsigned long hash_map;
100 } ____cacheline_aligned_in_smp;
103 struct io_wqe_acct acct[2];
105 struct hlist_nulls_head free_list;
106 struct list_head all_list;
109 struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
116 struct io_wqe **wqes;
119 free_work_fn *free_work;
120 io_wq_work_fn *do_work;
122 struct task_struct *manager;
123 struct user_struct *user;
125 struct completion done;
127 struct hlist_node cpuhp_node;
132 static enum cpuhp_state io_wq_online;
134 static bool io_worker_get(struct io_worker *worker)
136 return refcount_inc_not_zero(&worker->ref);
139 static void io_worker_release(struct io_worker *worker)
141 if (refcount_dec_and_test(&worker->ref))
142 wake_up_process(worker->task);
146 * Note: drops the wqe->lock if returning true! The caller must re-acquire
147 * the lock in that case. Some callers need to restart handling if this
148 * happens, so we can't just re-acquire the lock on behalf of the caller.
150 static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker)
152 bool dropped_lock = false;
154 if (worker->saved_creds) {
155 revert_creds(worker->saved_creds);
156 worker->cur_creds = worker->saved_creds = NULL;
159 if (current->files != worker->restore_files) {
160 __acquire(&wqe->lock);
161 raw_spin_unlock_irq(&wqe->lock);
165 current->files = worker->restore_files;
166 current->nsproxy = worker->restore_nsproxy;
167 task_unlock(current);
170 if (current->fs != worker->restore_fs)
171 current->fs = worker->restore_fs;
174 * If we have an active mm, we need to drop the wq lock before unusing
175 * it. If we do, return true and let the caller retry the idle loop.
179 __acquire(&wqe->lock);
180 raw_spin_unlock_irq(&wqe->lock);
183 __set_current_state(TASK_RUNNING);
184 kthread_unuse_mm(worker->mm);
189 #ifdef CONFIG_BLK_CGROUP
190 if (worker->blkcg_css) {
191 kthread_associate_blkcg(NULL);
192 worker->blkcg_css = NULL;
195 if (current->signal->rlim[RLIMIT_FSIZE].rlim_cur != RLIM_INFINITY)
196 current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
200 static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
201 struct io_wq_work *work)
203 if (work->flags & IO_WQ_WORK_UNBOUND)
204 return &wqe->acct[IO_WQ_ACCT_UNBOUND];
206 return &wqe->acct[IO_WQ_ACCT_BOUND];
209 static inline struct io_wqe_acct *io_wqe_get_acct(struct io_wqe *wqe,
210 struct io_worker *worker)
212 if (worker->flags & IO_WORKER_F_BOUND)
213 return &wqe->acct[IO_WQ_ACCT_BOUND];
215 return &wqe->acct[IO_WQ_ACCT_UNBOUND];
218 static void io_worker_exit(struct io_worker *worker)
220 struct io_wqe *wqe = worker->wqe;
221 struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
224 * If we're not at zero, someone else is holding a brief reference
225 * to the worker. Wait for that to go away.
227 set_current_state(TASK_INTERRUPTIBLE);
228 if (!refcount_dec_and_test(&worker->ref))
230 __set_current_state(TASK_RUNNING);
233 current->flags &= ~PF_IO_WORKER;
234 if (worker->flags & IO_WORKER_F_RUNNING)
235 atomic_dec(&acct->nr_running);
236 if (!(worker->flags & IO_WORKER_F_BOUND))
237 atomic_dec(&wqe->wq->user->processes);
241 raw_spin_lock_irq(&wqe->lock);
242 hlist_nulls_del_rcu(&worker->nulls_node);
243 list_del_rcu(&worker->all_list);
244 if (__io_worker_unuse(wqe, worker)) {
245 __release(&wqe->lock);
246 raw_spin_lock_irq(&wqe->lock);
249 raw_spin_unlock_irq(&wqe->lock);
251 kfree_rcu(worker, rcu);
252 if (refcount_dec_and_test(&wqe->wq->refs))
253 complete(&wqe->wq->done);
256 static inline bool io_wqe_run_queue(struct io_wqe *wqe)
257 __must_hold(wqe->lock)
259 if (!wq_list_empty(&wqe->work_list) &&
260 !(wqe->flags & IO_WQE_FLAG_STALLED))
266 * Check head of free list for an available worker. If one isn't available,
267 * caller must wake up the wq manager to create one.
269 static bool io_wqe_activate_free_worker(struct io_wqe *wqe)
272 struct hlist_nulls_node *n;
273 struct io_worker *worker;
275 n = rcu_dereference(hlist_nulls_first_rcu(&wqe->free_list));
279 worker = hlist_nulls_entry(n, struct io_worker, nulls_node);
280 if (io_worker_get(worker)) {
281 wake_up_process(worker->task);
282 io_worker_release(worker);
290 * We need a worker. If we find a free one, we're good. If not, and we're
291 * below the max number of workers, wake up the manager to create one.
293 static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
298 * Most likely an attempt to queue unbounded work on an io_wq that
299 * wasn't setup with any unbounded workers.
301 WARN_ON_ONCE(!acct->max_workers);
304 ret = io_wqe_activate_free_worker(wqe);
307 if (!ret && acct->nr_workers < acct->max_workers)
308 wake_up_process(wqe->wq->manager);
311 static void io_wqe_inc_running(struct io_wqe *wqe, struct io_worker *worker)
313 struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
315 atomic_inc(&acct->nr_running);
318 static void io_wqe_dec_running(struct io_wqe *wqe, struct io_worker *worker)
319 __must_hold(wqe->lock)
321 struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
323 if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe))
324 io_wqe_wake_worker(wqe, acct);
327 static void io_worker_start(struct io_wqe *wqe, struct io_worker *worker)
329 allow_kernel_signal(SIGINT);
331 current->flags |= PF_IO_WORKER;
333 worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
334 worker->restore_files = current->files;
335 worker->restore_nsproxy = current->nsproxy;
336 worker->restore_fs = current->fs;
337 io_wqe_inc_running(wqe, worker);
341 * Worker will start processing some work. Move it to the busy list, if
342 * it's currently on the freelist
344 static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
345 struct io_wq_work *work)
346 __must_hold(wqe->lock)
348 bool worker_bound, work_bound;
350 if (worker->flags & IO_WORKER_F_FREE) {
351 worker->flags &= ~IO_WORKER_F_FREE;
352 hlist_nulls_del_init_rcu(&worker->nulls_node);
356 * If worker is moving from bound to unbound (or vice versa), then
357 * ensure we update the running accounting.
359 worker_bound = (worker->flags & IO_WORKER_F_BOUND) != 0;
360 work_bound = (work->flags & IO_WQ_WORK_UNBOUND) == 0;
361 if (worker_bound != work_bound) {
362 io_wqe_dec_running(wqe, worker);
364 worker->flags |= IO_WORKER_F_BOUND;
365 wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers--;
366 wqe->acct[IO_WQ_ACCT_BOUND].nr_workers++;
367 atomic_dec(&wqe->wq->user->processes);
369 worker->flags &= ~IO_WORKER_F_BOUND;
370 wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers++;
371 wqe->acct[IO_WQ_ACCT_BOUND].nr_workers--;
372 atomic_inc(&wqe->wq->user->processes);
374 io_wqe_inc_running(wqe, worker);
379 * No work, worker going to sleep. Move to freelist, and unuse mm if we
380 * have one attached. Dropping the mm may potentially sleep, so we drop
381 * the lock in that case and return success. Since the caller has to
382 * retry the loop in that case (we changed task state), we don't regrab
383 * the lock if we return success.
385 static bool __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
386 __must_hold(wqe->lock)
388 if (!(worker->flags & IO_WORKER_F_FREE)) {
389 worker->flags |= IO_WORKER_F_FREE;
390 hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
393 return __io_worker_unuse(wqe, worker);
396 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
398 return work->flags >> IO_WQ_HASH_SHIFT;
401 static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
402 __must_hold(wqe->lock)
404 struct io_wq_work_node *node, *prev;
405 struct io_wq_work *work, *tail;
408 wq_list_for_each(node, prev, &wqe->work_list) {
409 work = container_of(node, struct io_wq_work, list);
411 /* not hashed, can run anytime */
412 if (!io_wq_is_hashed(work)) {
413 wq_list_del(&wqe->work_list, node, prev);
417 /* hashed, can run if not already running */
418 hash = io_get_work_hash(work);
419 if (!(wqe->hash_map & BIT(hash))) {
420 wqe->hash_map |= BIT(hash);
421 /* all items with this hash lie in [work, tail] */
422 tail = wqe->hash_tail[hash];
423 wqe->hash_tail[hash] = NULL;
424 wq_list_cut(&wqe->work_list, &tail->list, prev);
432 static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work)
435 kthread_unuse_mm(worker->mm);
440 if (mmget_not_zero(work->identity->mm)) {
441 kthread_use_mm(work->identity->mm);
442 worker->mm = work->identity->mm;
446 /* failed grabbing mm, ensure work gets cancelled */
447 work->flags |= IO_WQ_WORK_CANCEL;
450 static inline void io_wq_switch_blkcg(struct io_worker *worker,
451 struct io_wq_work *work)
453 #ifdef CONFIG_BLK_CGROUP
454 if (!(work->flags & IO_WQ_WORK_BLKCG))
456 if (work->identity->blkcg_css != worker->blkcg_css) {
457 kthread_associate_blkcg(work->identity->blkcg_css);
458 worker->blkcg_css = work->identity->blkcg_css;
463 static void io_wq_switch_creds(struct io_worker *worker,
464 struct io_wq_work *work)
466 const struct cred *old_creds = override_creds(work->identity->creds);
468 worker->cur_creds = work->identity->creds;
469 if (worker->saved_creds)
470 put_cred(old_creds); /* creds set by previous switch */
472 worker->saved_creds = old_creds;
475 static void io_impersonate_work(struct io_worker *worker,
476 struct io_wq_work *work)
478 if ((work->flags & IO_WQ_WORK_FILES) &&
479 current->files != work->identity->files) {
481 current->files = work->identity->files;
482 current->nsproxy = work->identity->nsproxy;
483 task_unlock(current);
484 if (!work->identity->files) {
485 /* failed grabbing files, ensure work gets cancelled */
486 work->flags |= IO_WQ_WORK_CANCEL;
489 if ((work->flags & IO_WQ_WORK_FS) && current->fs != work->identity->fs)
490 current->fs = work->identity->fs;
491 if ((work->flags & IO_WQ_WORK_MM) && work->identity->mm != worker->mm)
492 io_wq_switch_mm(worker, work);
493 if ((work->flags & IO_WQ_WORK_CREDS) &&
494 worker->cur_creds != work->identity->creds)
495 io_wq_switch_creds(worker, work);
496 if (work->flags & IO_WQ_WORK_FSIZE)
497 current->signal->rlim[RLIMIT_FSIZE].rlim_cur = work->identity->fsize;
498 else if (current->signal->rlim[RLIMIT_FSIZE].rlim_cur != RLIM_INFINITY)
499 current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
500 io_wq_switch_blkcg(worker, work);
502 current->loginuid = work->identity->loginuid;
503 current->sessionid = work->identity->sessionid;
507 static void io_assign_current_work(struct io_worker *worker,
508 struct io_wq_work *work)
511 /* flush pending signals before assigning new work */
512 if (signal_pending(current))
513 flush_signals(current);
518 current->loginuid = KUIDT_INIT(AUDIT_UID_UNSET);
519 current->sessionid = AUDIT_SID_UNSET;
522 spin_lock_irq(&worker->lock);
523 worker->cur_work = work;
524 spin_unlock_irq(&worker->lock);
527 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
529 static void io_worker_handle_work(struct io_worker *worker)
530 __releases(wqe->lock)
532 struct io_wqe *wqe = worker->wqe;
533 struct io_wq *wq = wqe->wq;
536 struct io_wq_work *work;
539 * If we got some work, mark us as busy. If we didn't, but
540 * the list isn't empty, it means we stalled on hashed work.
541 * Mark us stalled so we don't keep looking for work when we
542 * can't make progress, any work completion or insertion will
543 * clear the stalled flag.
545 work = io_get_next_work(wqe);
547 __io_worker_busy(wqe, worker, work);
548 else if (!wq_list_empty(&wqe->work_list))
549 wqe->flags |= IO_WQE_FLAG_STALLED;
551 raw_spin_unlock_irq(&wqe->lock);
554 io_assign_current_work(worker, work);
556 /* handle a whole dependent link */
558 struct io_wq_work *next_hashed, *linked;
559 unsigned int hash = io_get_work_hash(work);
561 next_hashed = wq_next_work(work);
562 io_impersonate_work(worker, work);
564 io_assign_current_work(worker, NULL);
566 linked = wq->free_work(work);
568 if (!work && linked && !io_wq_is_hashed(linked)) {
572 io_assign_current_work(worker, work);
574 io_wqe_enqueue(wqe, linked);
576 if (hash != -1U && !next_hashed) {
577 raw_spin_lock_irq(&wqe->lock);
578 wqe->hash_map &= ~BIT_ULL(hash);
579 wqe->flags &= ~IO_WQE_FLAG_STALLED;
580 /* skip unnecessary unlock-lock wqe->lock */
583 raw_spin_unlock_irq(&wqe->lock);
587 raw_spin_lock_irq(&wqe->lock);
591 static int io_wqe_worker(void *data)
593 struct io_worker *worker = data;
594 struct io_wqe *wqe = worker->wqe;
595 struct io_wq *wq = wqe->wq;
597 io_worker_start(wqe, worker);
599 while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
600 set_current_state(TASK_INTERRUPTIBLE);
602 raw_spin_lock_irq(&wqe->lock);
603 if (io_wqe_run_queue(wqe)) {
604 __set_current_state(TASK_RUNNING);
605 io_worker_handle_work(worker);
608 /* drops the lock on success, retry */
609 if (__io_worker_idle(wqe, worker)) {
610 __release(&wqe->lock);
613 raw_spin_unlock_irq(&wqe->lock);
614 if (signal_pending(current))
615 flush_signals(current);
616 if (schedule_timeout(WORKER_IDLE_TIMEOUT))
618 /* timed out, exit unless we're the fixed worker */
619 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
620 !(worker->flags & IO_WORKER_F_FIXED))
624 if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
625 raw_spin_lock_irq(&wqe->lock);
626 if (!wq_list_empty(&wqe->work_list))
627 io_worker_handle_work(worker);
629 raw_spin_unlock_irq(&wqe->lock);
632 io_worker_exit(worker);
637 * Called when a worker is scheduled in. Mark us as currently running.
639 void io_wq_worker_running(struct task_struct *tsk)
641 struct io_worker *worker = kthread_data(tsk);
642 struct io_wqe *wqe = worker->wqe;
644 if (!(worker->flags & IO_WORKER_F_UP))
646 if (worker->flags & IO_WORKER_F_RUNNING)
648 worker->flags |= IO_WORKER_F_RUNNING;
649 io_wqe_inc_running(wqe, worker);
653 * Called when worker is going to sleep. If there are no workers currently
654 * running and we have work pending, wake up a free one or have the manager
657 void io_wq_worker_sleeping(struct task_struct *tsk)
659 struct io_worker *worker = kthread_data(tsk);
660 struct io_wqe *wqe = worker->wqe;
662 if (!(worker->flags & IO_WORKER_F_UP))
664 if (!(worker->flags & IO_WORKER_F_RUNNING))
667 worker->flags &= ~IO_WORKER_F_RUNNING;
669 raw_spin_lock_irq(&wqe->lock);
670 io_wqe_dec_running(wqe, worker);
671 raw_spin_unlock_irq(&wqe->lock);
674 static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
676 struct io_wqe_acct *acct = &wqe->acct[index];
677 struct io_worker *worker;
679 worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
683 refcount_set(&worker->ref, 1);
684 worker->nulls_node.pprev = NULL;
686 spin_lock_init(&worker->lock);
688 worker->task = kthread_create_on_node(io_wqe_worker, worker, wqe->node,
689 "io_wqe_worker-%d/%d", index, wqe->node);
690 if (IS_ERR(worker->task)) {
694 kthread_bind_mask(worker->task, cpumask_of_node(wqe->node));
696 raw_spin_lock_irq(&wqe->lock);
697 hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
698 list_add_tail_rcu(&worker->all_list, &wqe->all_list);
699 worker->flags |= IO_WORKER_F_FREE;
700 if (index == IO_WQ_ACCT_BOUND)
701 worker->flags |= IO_WORKER_F_BOUND;
702 if (!acct->nr_workers && (worker->flags & IO_WORKER_F_BOUND))
703 worker->flags |= IO_WORKER_F_FIXED;
705 raw_spin_unlock_irq(&wqe->lock);
707 if (index == IO_WQ_ACCT_UNBOUND)
708 atomic_inc(&wq->user->processes);
710 refcount_inc(&wq->refs);
711 wake_up_process(worker->task);
715 static inline bool io_wqe_need_worker(struct io_wqe *wqe, int index)
716 __must_hold(wqe->lock)
718 struct io_wqe_acct *acct = &wqe->acct[index];
720 /* if we have available workers or no work, no need */
721 if (!hlist_nulls_empty(&wqe->free_list) || !io_wqe_run_queue(wqe))
723 return acct->nr_workers < acct->max_workers;
727 * Iterate the passed in list and call the specific function for each
728 * worker that isn't exiting
730 static bool io_wq_for_each_worker(struct io_wqe *wqe,
731 bool (*func)(struct io_worker *, void *),
734 struct io_worker *worker;
737 list_for_each_entry_rcu(worker, &wqe->all_list, all_list) {
738 if (io_worker_get(worker)) {
739 /* no task if node is/was offline */
741 ret = func(worker, data);
742 io_worker_release(worker);
751 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
753 wake_up_process(worker->task);
758 * Manager thread. Tasked with creating new workers, if we need them.
760 static int io_wq_manager(void *data)
762 struct io_wq *wq = data;
765 /* create fixed workers */
766 refcount_set(&wq->refs, 1);
767 for_each_node(node) {
768 if (!node_online(node))
770 if (create_io_worker(wq, wq->wqes[node], IO_WQ_ACCT_BOUND))
772 set_bit(IO_WQ_BIT_ERROR, &wq->state);
773 set_bit(IO_WQ_BIT_EXIT, &wq->state);
779 while (!kthread_should_stop()) {
780 if (current->task_works)
783 for_each_node(node) {
784 struct io_wqe *wqe = wq->wqes[node];
785 bool fork_worker[2] = { false, false };
787 if (!node_online(node))
790 raw_spin_lock_irq(&wqe->lock);
791 if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND))
792 fork_worker[IO_WQ_ACCT_BOUND] = true;
793 if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND))
794 fork_worker[IO_WQ_ACCT_UNBOUND] = true;
795 raw_spin_unlock_irq(&wqe->lock);
796 if (fork_worker[IO_WQ_ACCT_BOUND])
797 create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND);
798 if (fork_worker[IO_WQ_ACCT_UNBOUND])
799 create_io_worker(wq, wqe, IO_WQ_ACCT_UNBOUND);
801 set_current_state(TASK_INTERRUPTIBLE);
802 schedule_timeout(HZ);
805 if (current->task_works)
809 if (refcount_dec_and_test(&wq->refs)) {
813 /* if ERROR is set and we get here, we have workers to wake */
814 if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
817 io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
823 static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct,
824 struct io_wq_work *work)
828 if (!(work->flags & IO_WQ_WORK_UNBOUND))
830 if (atomic_read(&acct->nr_running))
834 free_worker = !hlist_nulls_empty(&wqe->free_list);
839 if (atomic_read(&wqe->wq->user->processes) >= acct->max_workers &&
840 !(capable(CAP_SYS_RESOURCE) || capable(CAP_SYS_ADMIN)))
846 static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
848 struct io_wq *wq = wqe->wq;
851 work->flags |= IO_WQ_WORK_CANCEL;
853 work = wq->free_work(work);
857 static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work)
860 struct io_wq_work *tail;
862 if (!io_wq_is_hashed(work)) {
864 wq_list_add_tail(&work->list, &wqe->work_list);
868 hash = io_get_work_hash(work);
869 tail = wqe->hash_tail[hash];
870 wqe->hash_tail[hash] = work;
874 wq_list_add_after(&work->list, &tail->list, &wqe->work_list);
877 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
879 struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
884 * Do early check to see if we need a new unbound worker, and if we do,
885 * if we're allowed to do so. This isn't 100% accurate as there's a
886 * gap between this check and incrementing the value, but that's OK.
887 * It's close enough to not be an issue, fork() has the same delay.
889 if (unlikely(!io_wq_can_queue(wqe, acct, work))) {
890 io_run_cancel(work, wqe);
894 work_flags = work->flags;
895 raw_spin_lock_irqsave(&wqe->lock, flags);
896 io_wqe_insert_work(wqe, work);
897 wqe->flags &= ~IO_WQE_FLAG_STALLED;
898 raw_spin_unlock_irqrestore(&wqe->lock, flags);
900 if ((work_flags & IO_WQ_WORK_CONCURRENT) ||
901 !atomic_read(&acct->nr_running))
902 io_wqe_wake_worker(wqe, acct);
905 void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
907 struct io_wqe *wqe = wq->wqes[numa_node_id()];
909 io_wqe_enqueue(wqe, work);
913 * Work items that hash to the same value will not be done in parallel.
914 * Used to limit concurrent writes, generally hashed by inode.
916 void io_wq_hash_work(struct io_wq_work *work, void *val)
920 bit = hash_ptr(val, IO_WQ_HASH_ORDER);
921 work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
924 struct io_cb_cancel_data {
932 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
934 struct io_cb_cancel_data *match = data;
938 * Hold the lock to avoid ->cur_work going out of scope, caller
939 * may dereference the passed in work.
941 spin_lock_irqsave(&worker->lock, flags);
942 if (worker->cur_work &&
943 match->fn(worker->cur_work, match->data)) {
944 send_sig(SIGINT, worker->task, 1);
947 spin_unlock_irqrestore(&worker->lock, flags);
949 return match->nr_running && !match->cancel_all;
952 static inline void io_wqe_remove_pending(struct io_wqe *wqe,
953 struct io_wq_work *work,
954 struct io_wq_work_node *prev)
956 unsigned int hash = io_get_work_hash(work);
957 struct io_wq_work *prev_work = NULL;
959 if (io_wq_is_hashed(work) && work == wqe->hash_tail[hash]) {
961 prev_work = container_of(prev, struct io_wq_work, list);
962 if (prev_work && io_get_work_hash(prev_work) == hash)
963 wqe->hash_tail[hash] = prev_work;
965 wqe->hash_tail[hash] = NULL;
967 wq_list_del(&wqe->work_list, &work->list, prev);
970 static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
971 struct io_cb_cancel_data *match)
973 struct io_wq_work_node *node, *prev;
974 struct io_wq_work *work;
978 raw_spin_lock_irqsave(&wqe->lock, flags);
979 wq_list_for_each(node, prev, &wqe->work_list) {
980 work = container_of(node, struct io_wq_work, list);
981 if (!match->fn(work, match->data))
983 io_wqe_remove_pending(wqe, work, prev);
984 raw_spin_unlock_irqrestore(&wqe->lock, flags);
985 io_run_cancel(work, wqe);
987 if (!match->cancel_all)
990 /* not safe to continue after unlock */
993 raw_spin_unlock_irqrestore(&wqe->lock, flags);
996 static void io_wqe_cancel_running_work(struct io_wqe *wqe,
997 struct io_cb_cancel_data *match)
1000 io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
1004 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
1005 void *data, bool cancel_all)
1007 struct io_cb_cancel_data match = {
1010 .cancel_all = cancel_all,
1015 * First check pending list, if we're lucky we can just remove it
1016 * from there. CANCEL_OK means that the work is returned as-new,
1017 * no completion will be posted for it.
1019 for_each_node(node) {
1020 struct io_wqe *wqe = wq->wqes[node];
1022 io_wqe_cancel_pending_work(wqe, &match);
1023 if (match.nr_pending && !match.cancel_all)
1024 return IO_WQ_CANCEL_OK;
1028 * Now check if a free (going busy) or busy worker has the work
1029 * currently running. If we find it there, we'll return CANCEL_RUNNING
1030 * as an indication that we attempt to signal cancellation. The
1031 * completion will run normally in this case.
1033 for_each_node(node) {
1034 struct io_wqe *wqe = wq->wqes[node];
1036 io_wqe_cancel_running_work(wqe, &match);
1037 if (match.nr_running && !match.cancel_all)
1038 return IO_WQ_CANCEL_RUNNING;
1041 if (match.nr_running)
1042 return IO_WQ_CANCEL_RUNNING;
1043 if (match.nr_pending)
1044 return IO_WQ_CANCEL_OK;
1045 return IO_WQ_CANCEL_NOTFOUND;
1048 struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
1050 int ret = -ENOMEM, node;
1053 if (WARN_ON_ONCE(!data->free_work || !data->do_work))
1054 return ERR_PTR(-EINVAL);
1056 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
1058 return ERR_PTR(-ENOMEM);
1060 wq->wqes = kcalloc(nr_node_ids, sizeof(struct io_wqe *), GFP_KERNEL);
1064 ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1068 wq->free_work = data->free_work;
1069 wq->do_work = data->do_work;
1071 /* caller must already hold a reference to this */
1072 wq->user = data->user;
1075 for_each_node(node) {
1077 int alloc_node = node;
1079 if (!node_online(alloc_node))
1080 alloc_node = NUMA_NO_NODE;
1081 wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
1084 wq->wqes[node] = wqe;
1085 wqe->node = alloc_node;
1086 wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
1087 atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
1089 wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
1090 task_rlimit(current, RLIMIT_NPROC);
1092 atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0);
1094 raw_spin_lock_init(&wqe->lock);
1095 INIT_WQ_LIST(&wqe->work_list);
1096 INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
1097 INIT_LIST_HEAD(&wqe->all_list);
1100 init_completion(&wq->done);
1102 wq->manager = kthread_create(io_wq_manager, wq, "io_wq_manager");
1103 if (!IS_ERR(wq->manager)) {
1104 wake_up_process(wq->manager);
1105 wait_for_completion(&wq->done);
1106 if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
1110 refcount_set(&wq->use_refs, 1);
1111 reinit_completion(&wq->done);
1115 ret = PTR_ERR(wq->manager);
1116 complete(&wq->done);
1118 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1120 kfree(wq->wqes[node]);
1125 return ERR_PTR(ret);
1128 bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
1130 if (data->free_work != wq->free_work || data->do_work != wq->do_work)
1133 return refcount_inc_not_zero(&wq->use_refs);
1136 static void __io_wq_destroy(struct io_wq *wq)
1140 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1142 set_bit(IO_WQ_BIT_EXIT, &wq->state);
1144 kthread_stop(wq->manager);
1148 io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
1151 wait_for_completion(&wq->done);
1154 kfree(wq->wqes[node]);
1159 void io_wq_destroy(struct io_wq *wq)
1161 if (refcount_dec_and_test(&wq->use_refs))
1162 __io_wq_destroy(wq);
1165 struct task_struct *io_wq_get_task(struct io_wq *wq)
1170 static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
1172 struct task_struct *task = worker->task;
1176 rq = task_rq_lock(task, &rf);
1177 do_set_cpus_allowed(task, cpumask_of_node(worker->wqe->node));
1178 task->flags |= PF_NO_SETAFFINITY;
1179 task_rq_unlock(rq, task, &rf);
1183 static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
1185 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1190 io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, NULL);
1195 static __init int io_wq_init(void)
1199 ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
1200 io_wq_cpu_online, NULL);
1206 subsys_initcall(io_wq_init);