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
);