| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Basic worker thread pool for io_uring |
| * |
| * Copyright (C) 2019 Jens Axboe |
| * |
| */ |
| #include <linux/kernel.h> |
| #include <linux/init.h> |
| #include <linux/errno.h> |
| #include <linux/sched/signal.h> |
| #include <linux/percpu.h> |
| #include <linux/slab.h> |
| #include <linux/rculist_nulls.h> |
| #include <linux/cpu.h> |
| #include <linux/task_work.h> |
| #include <linux/audit.h> |
| #include <uapi/linux/io_uring.h> |
| |
| #include "io-wq.h" |
| |
| #define WORKER_IDLE_TIMEOUT (5 * HZ) |
| |
| enum { |
| IO_WORKER_F_UP = 1, /* up and active */ |
| IO_WORKER_F_RUNNING = 2, /* account as running */ |
| IO_WORKER_F_FREE = 4, /* worker on free list */ |
| IO_WORKER_F_BOUND = 8, /* is doing bounded work */ |
| }; |
| |
| enum { |
| IO_WQ_BIT_EXIT = 0, /* wq exiting */ |
| }; |
| |
| enum { |
| IO_ACCT_STALLED_BIT = 0, /* stalled on hash */ |
| }; |
| |
| /* |
| * One for each thread in a wqe pool |
| */ |
| struct io_worker { |
| refcount_t ref; |
| unsigned flags; |
| struct hlist_nulls_node nulls_node; |
| struct list_head all_list; |
| struct task_struct *task; |
| struct io_wqe *wqe; |
| |
| struct io_wq_work *cur_work; |
| struct io_wq_work *next_work; |
| raw_spinlock_t lock; |
| |
| struct completion ref_done; |
| |
| unsigned long create_state; |
| struct callback_head create_work; |
| int create_index; |
| |
| union { |
| struct rcu_head rcu; |
| struct work_struct work; |
| }; |
| }; |
| |
| #if BITS_PER_LONG == 64 |
| #define IO_WQ_HASH_ORDER 6 |
| #else |
| #define IO_WQ_HASH_ORDER 5 |
| #endif |
| |
| #define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER) |
| |
| struct io_wqe_acct { |
| unsigned nr_workers; |
| unsigned max_workers; |
| int index; |
| atomic_t nr_running; |
| raw_spinlock_t lock; |
| struct io_wq_work_list work_list; |
| unsigned long flags; |
| }; |
| |
| enum { |
| IO_WQ_ACCT_BOUND, |
| IO_WQ_ACCT_UNBOUND, |
| IO_WQ_ACCT_NR, |
| }; |
| |
| /* |
| * Per-node worker thread pool |
| */ |
| struct io_wqe { |
| raw_spinlock_t lock; |
| struct io_wqe_acct acct[IO_WQ_ACCT_NR]; |
| |
| int node; |
| |
| struct hlist_nulls_head free_list; |
| struct list_head all_list; |
| |
| struct wait_queue_entry wait; |
| |
| struct io_wq *wq; |
| struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS]; |
| |
| cpumask_var_t cpu_mask; |
| }; |
| |
| /* |
| * Per io_wq state |
| */ |
| struct io_wq { |
| unsigned long state; |
| |
| free_work_fn *free_work; |
| io_wq_work_fn *do_work; |
| |
| struct io_wq_hash *hash; |
| |
| atomic_t worker_refs; |
| struct completion worker_done; |
| |
| struct hlist_node cpuhp_node; |
| |
| struct task_struct *task; |
| |
| struct io_wqe *wqes[]; |
| }; |
| |
| static enum cpuhp_state io_wq_online; |
| |
| struct io_cb_cancel_data { |
| work_cancel_fn *fn; |
| void *data; |
| int nr_running; |
| int nr_pending; |
| bool cancel_all; |
| }; |
| |
| static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index); |
| static void io_wqe_dec_running(struct io_worker *worker); |
| static bool io_acct_cancel_pending_work(struct io_wqe *wqe, |
| struct io_wqe_acct *acct, |
| struct io_cb_cancel_data *match); |
| static void create_worker_cb(struct callback_head *cb); |
| static void io_wq_cancel_tw_create(struct io_wq *wq); |
| |
| static bool io_worker_get(struct io_worker *worker) |
| { |
| return refcount_inc_not_zero(&worker->ref); |
| } |
| |
| static void io_worker_release(struct io_worker *worker) |
| { |
| if (refcount_dec_and_test(&worker->ref)) |
| complete(&worker->ref_done); |
| } |
| |
| static inline struct io_wqe_acct *io_get_acct(struct io_wqe *wqe, bool bound) |
| { |
| return &wqe->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND]; |
| } |
| |
| static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe, |
| struct io_wq_work *work) |
| { |
| return io_get_acct(wqe, !(work->flags & IO_WQ_WORK_UNBOUND)); |
| } |
| |
| static inline struct io_wqe_acct *io_wqe_get_acct(struct io_worker *worker) |
| { |
| return io_get_acct(worker->wqe, worker->flags & IO_WORKER_F_BOUND); |
| } |
| |
| static void io_worker_ref_put(struct io_wq *wq) |
| { |
| if (atomic_dec_and_test(&wq->worker_refs)) |
| complete(&wq->worker_done); |
| } |
| |
| static void io_worker_cancel_cb(struct io_worker *worker) |
| { |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| |
| atomic_dec(&acct->nr_running); |
| raw_spin_lock(&worker->wqe->lock); |
| acct->nr_workers--; |
| raw_spin_unlock(&worker->wqe->lock); |
| io_worker_ref_put(wq); |
| clear_bit_unlock(0, &worker->create_state); |
| io_worker_release(worker); |
| } |
| |
| static bool io_task_worker_match(struct callback_head *cb, void *data) |
| { |
| struct io_worker *worker; |
| |
| if (cb->func != create_worker_cb) |
| return false; |
| worker = container_of(cb, struct io_worker, create_work); |
| return worker == data; |
| } |
| |
| static void io_worker_exit(struct io_worker *worker) |
| { |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| |
| while (1) { |
| struct callback_head *cb = task_work_cancel_match(wq->task, |
| io_task_worker_match, worker); |
| |
| if (!cb) |
| break; |
| io_worker_cancel_cb(worker); |
| } |
| |
| io_worker_release(worker); |
| wait_for_completion(&worker->ref_done); |
| |
| raw_spin_lock(&wqe->lock); |
| if (worker->flags & IO_WORKER_F_FREE) |
| hlist_nulls_del_rcu(&worker->nulls_node); |
| list_del_rcu(&worker->all_list); |
| raw_spin_unlock(&wqe->lock); |
| io_wqe_dec_running(worker); |
| worker->flags = 0; |
| preempt_disable(); |
| current->flags &= ~PF_IO_WORKER; |
| preempt_enable(); |
| |
| kfree_rcu(worker, rcu); |
| io_worker_ref_put(wqe->wq); |
| do_exit(0); |
| } |
| |
| static inline bool io_acct_run_queue(struct io_wqe_acct *acct) |
| { |
| bool ret = false; |
| |
| raw_spin_lock(&acct->lock); |
| if (!wq_list_empty(&acct->work_list) && |
| !test_bit(IO_ACCT_STALLED_BIT, &acct->flags)) |
| ret = true; |
| raw_spin_unlock(&acct->lock); |
| |
| return ret; |
| } |
| |
| /* |
| * Check head of free list for an available worker. If one isn't available, |
| * caller must create one. |
| */ |
| static bool io_wqe_activate_free_worker(struct io_wqe *wqe, |
| struct io_wqe_acct *acct) |
| __must_hold(RCU) |
| { |
| struct hlist_nulls_node *n; |
| struct io_worker *worker; |
| |
| /* |
| * Iterate free_list and see if we can find an idle worker to |
| * activate. If a given worker is on the free_list but in the process |
| * of exiting, keep trying. |
| */ |
| hlist_nulls_for_each_entry_rcu(worker, n, &wqe->free_list, nulls_node) { |
| if (!io_worker_get(worker)) |
| continue; |
| if (io_wqe_get_acct(worker) != acct) { |
| io_worker_release(worker); |
| continue; |
| } |
| if (wake_up_process(worker->task)) { |
| io_worker_release(worker); |
| return true; |
| } |
| io_worker_release(worker); |
| } |
| |
| return false; |
| } |
| |
| /* |
| * We need a worker. If we find a free one, we're good. If not, and we're |
| * below the max number of workers, create one. |
| */ |
| static bool io_wqe_create_worker(struct io_wqe *wqe, struct io_wqe_acct *acct) |
| { |
| /* |
| * Most likely an attempt to queue unbounded work on an io_wq that |
| * wasn't setup with any unbounded workers. |
| */ |
| if (unlikely(!acct->max_workers)) |
| pr_warn_once("io-wq is not configured for unbound workers"); |
| |
| raw_spin_lock(&wqe->lock); |
| if (acct->nr_workers >= acct->max_workers) { |
| raw_spin_unlock(&wqe->lock); |
| return true; |
| } |
| acct->nr_workers++; |
| raw_spin_unlock(&wqe->lock); |
| atomic_inc(&acct->nr_running); |
| atomic_inc(&wqe->wq->worker_refs); |
| return create_io_worker(wqe->wq, wqe, acct->index); |
| } |
| |
| static void io_wqe_inc_running(struct io_worker *worker) |
| { |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| |
| atomic_inc(&acct->nr_running); |
| } |
| |
| static void create_worker_cb(struct callback_head *cb) |
| { |
| struct io_worker *worker; |
| struct io_wq *wq; |
| struct io_wqe *wqe; |
| struct io_wqe_acct *acct; |
| bool do_create = false; |
| |
| worker = container_of(cb, struct io_worker, create_work); |
| wqe = worker->wqe; |
| wq = wqe->wq; |
| acct = &wqe->acct[worker->create_index]; |
| raw_spin_lock(&wqe->lock); |
| if (acct->nr_workers < acct->max_workers) { |
| acct->nr_workers++; |
| do_create = true; |
| } |
| raw_spin_unlock(&wqe->lock); |
| if (do_create) { |
| create_io_worker(wq, wqe, worker->create_index); |
| } else { |
| atomic_dec(&acct->nr_running); |
| io_worker_ref_put(wq); |
| } |
| clear_bit_unlock(0, &worker->create_state); |
| io_worker_release(worker); |
| } |
| |
| static bool io_queue_worker_create(struct io_worker *worker, |
| struct io_wqe_acct *acct, |
| task_work_func_t func) |
| { |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| |
| /* raced with exit, just ignore create call */ |
| if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) |
| goto fail; |
| if (!io_worker_get(worker)) |
| goto fail; |
| /* |
| * create_state manages ownership of create_work/index. We should |
| * only need one entry per worker, as the worker going to sleep |
| * will trigger the condition, and waking will clear it once it |
| * runs the task_work. |
| */ |
| if (test_bit(0, &worker->create_state) || |
| test_and_set_bit_lock(0, &worker->create_state)) |
| goto fail_release; |
| |
| atomic_inc(&wq->worker_refs); |
| init_task_work(&worker->create_work, func); |
| worker->create_index = acct->index; |
| if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) { |
| /* |
| * EXIT may have been set after checking it above, check after |
| * adding the task_work and remove any creation item if it is |
| * now set. wq exit does that too, but we can have added this |
| * work item after we canceled in io_wq_exit_workers(). |
| */ |
| if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) |
| io_wq_cancel_tw_create(wq); |
| io_worker_ref_put(wq); |
| return true; |
| } |
| io_worker_ref_put(wq); |
| clear_bit_unlock(0, &worker->create_state); |
| fail_release: |
| io_worker_release(worker); |
| fail: |
| atomic_dec(&acct->nr_running); |
| io_worker_ref_put(wq); |
| return false; |
| } |
| |
| static void io_wqe_dec_running(struct io_worker *worker) |
| { |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| struct io_wqe *wqe = worker->wqe; |
| |
| if (!(worker->flags & IO_WORKER_F_UP)) |
| return; |
| |
| if (!atomic_dec_and_test(&acct->nr_running)) |
| return; |
| if (!io_acct_run_queue(acct)) |
| return; |
| |
| atomic_inc(&acct->nr_running); |
| atomic_inc(&wqe->wq->worker_refs); |
| io_queue_worker_create(worker, acct, create_worker_cb); |
| } |
| |
| /* |
| * Worker will start processing some work. Move it to the busy list, if |
| * it's currently on the freelist |
| */ |
| static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker) |
| { |
| if (worker->flags & IO_WORKER_F_FREE) { |
| worker->flags &= ~IO_WORKER_F_FREE; |
| raw_spin_lock(&wqe->lock); |
| hlist_nulls_del_init_rcu(&worker->nulls_node); |
| raw_spin_unlock(&wqe->lock); |
| } |
| } |
| |
| /* |
| * No work, worker going to sleep. Move to freelist, and unuse mm if we |
| * have one attached. Dropping the mm may potentially sleep, so we drop |
| * the lock in that case and return success. Since the caller has to |
| * retry the loop in that case (we changed task state), we don't regrab |
| * the lock if we return success. |
| */ |
| static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker) |
| __must_hold(wqe->lock) |
| { |
| if (!(worker->flags & IO_WORKER_F_FREE)) { |
| worker->flags |= IO_WORKER_F_FREE; |
| hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list); |
| } |
| } |
| |
| static inline unsigned int io_get_work_hash(struct io_wq_work *work) |
| { |
| return work->flags >> IO_WQ_HASH_SHIFT; |
| } |
| |
| static bool io_wait_on_hash(struct io_wqe *wqe, unsigned int hash) |
| { |
| struct io_wq *wq = wqe->wq; |
| bool ret = false; |
| |
| spin_lock_irq(&wq->hash->wait.lock); |
| if (list_empty(&wqe->wait.entry)) { |
| __add_wait_queue(&wq->hash->wait, &wqe->wait); |
| if (!test_bit(hash, &wq->hash->map)) { |
| __set_current_state(TASK_RUNNING); |
| list_del_init(&wqe->wait.entry); |
| ret = true; |
| } |
| } |
| spin_unlock_irq(&wq->hash->wait.lock); |
| return ret; |
| } |
| |
| static struct io_wq_work *io_get_next_work(struct io_wqe_acct *acct, |
| struct io_worker *worker) |
| __must_hold(acct->lock) |
| { |
| struct io_wq_work_node *node, *prev; |
| struct io_wq_work *work, *tail; |
| unsigned int stall_hash = -1U; |
| struct io_wqe *wqe = worker->wqe; |
| |
| wq_list_for_each(node, prev, &acct->work_list) { |
| unsigned int hash; |
| |
| work = container_of(node, struct io_wq_work, list); |
| |
| /* not hashed, can run anytime */ |
| if (!io_wq_is_hashed(work)) { |
| wq_list_del(&acct->work_list, node, prev); |
| return work; |
| } |
| |
| hash = io_get_work_hash(work); |
| /* all items with this hash lie in [work, tail] */ |
| tail = wqe->hash_tail[hash]; |
| |
| /* hashed, can run if not already running */ |
| if (!test_and_set_bit(hash, &wqe->wq->hash->map)) { |
| wqe->hash_tail[hash] = NULL; |
| wq_list_cut(&acct->work_list, &tail->list, prev); |
| return work; |
| } |
| if (stall_hash == -1U) |
| stall_hash = hash; |
| /* fast forward to a next hash, for-each will fix up @prev */ |
| node = &tail->list; |
| } |
| |
| if (stall_hash != -1U) { |
| bool unstalled; |
| |
| /* |
| * Set this before dropping the lock to avoid racing with new |
| * work being added and clearing the stalled bit. |
| */ |
| set_bit(IO_ACCT_STALLED_BIT, &acct->flags); |
| raw_spin_unlock(&acct->lock); |
| unstalled = io_wait_on_hash(wqe, stall_hash); |
| raw_spin_lock(&acct->lock); |
| if (unstalled) { |
| clear_bit(IO_ACCT_STALLED_BIT, &acct->flags); |
| if (wq_has_sleeper(&wqe->wq->hash->wait)) |
| wake_up(&wqe->wq->hash->wait); |
| } |
| } |
| |
| return NULL; |
| } |
| |
| static bool io_flush_signals(void) |
| { |
| if (unlikely(test_thread_flag(TIF_NOTIFY_SIGNAL))) { |
| __set_current_state(TASK_RUNNING); |
| clear_notify_signal(); |
| if (task_work_pending(current)) |
| task_work_run(); |
| return true; |
| } |
| return false; |
| } |
| |
| static void io_assign_current_work(struct io_worker *worker, |
| struct io_wq_work *work) |
| { |
| if (work) { |
| io_flush_signals(); |
| cond_resched(); |
| } |
| |
| raw_spin_lock(&worker->lock); |
| worker->cur_work = work; |
| worker->next_work = NULL; |
| raw_spin_unlock(&worker->lock); |
| } |
| |
| static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work); |
| |
| static void io_worker_handle_work(struct io_worker *worker) |
| { |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state); |
| |
| do { |
| struct io_wq_work *work; |
| |
| /* |
| * If we got some work, mark us as busy. If we didn't, but |
| * the list isn't empty, it means we stalled on hashed work. |
| * Mark us stalled so we don't keep looking for work when we |
| * can't make progress, any work completion or insertion will |
| * clear the stalled flag. |
| */ |
| raw_spin_lock(&acct->lock); |
| work = io_get_next_work(acct, worker); |
| raw_spin_unlock(&acct->lock); |
| if (work) { |
| __io_worker_busy(wqe, worker); |
| |
| /* |
| * Make sure cancelation can find this, even before |
| * it becomes the active work. That avoids a window |
| * where the work has been removed from our general |
| * work list, but isn't yet discoverable as the |
| * current work item for this worker. |
| */ |
| raw_spin_lock(&worker->lock); |
| worker->next_work = work; |
| raw_spin_unlock(&worker->lock); |
| } else { |
| break; |
| } |
| io_assign_current_work(worker, work); |
| __set_current_state(TASK_RUNNING); |
| |
| /* handle a whole dependent link */ |
| do { |
| struct io_wq_work *next_hashed, *linked; |
| unsigned int hash = io_get_work_hash(work); |
| |
| next_hashed = wq_next_work(work); |
| |
| if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND)) |
| work->flags |= IO_WQ_WORK_CANCEL; |
| wq->do_work(work); |
| io_assign_current_work(worker, NULL); |
| |
| linked = wq->free_work(work); |
| work = next_hashed; |
| if (!work && linked && !io_wq_is_hashed(linked)) { |
| work = linked; |
| linked = NULL; |
| } |
| io_assign_current_work(worker, work); |
| if (linked) |
| io_wqe_enqueue(wqe, linked); |
| |
| if (hash != -1U && !next_hashed) { |
| /* serialize hash clear with wake_up() */ |
| spin_lock_irq(&wq->hash->wait.lock); |
| clear_bit(hash, &wq->hash->map); |
| clear_bit(IO_ACCT_STALLED_BIT, &acct->flags); |
| spin_unlock_irq(&wq->hash->wait.lock); |
| if (wq_has_sleeper(&wq->hash->wait)) |
| wake_up(&wq->hash->wait); |
| } |
| } while (work); |
| } while (1); |
| } |
| |
| static int io_wqe_worker(void *data) |
| { |
| struct io_worker *worker = data; |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| bool last_timeout = false; |
| char buf[TASK_COMM_LEN]; |
| |
| worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING); |
| |
| snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid); |
| set_task_comm(current, buf); |
| |
| audit_alloc_kernel(current); |
| |
| while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) { |
| long ret; |
| |
| set_current_state(TASK_INTERRUPTIBLE); |
| while (io_acct_run_queue(acct)) |
| io_worker_handle_work(worker); |
| |
| raw_spin_lock(&wqe->lock); |
| /* timed out, exit unless we're the last worker */ |
| if (last_timeout && acct->nr_workers > 1) { |
| acct->nr_workers--; |
| raw_spin_unlock(&wqe->lock); |
| __set_current_state(TASK_RUNNING); |
| break; |
| } |
| last_timeout = false; |
| __io_worker_idle(wqe, worker); |
| raw_spin_unlock(&wqe->lock); |
| if (io_flush_signals()) |
| continue; |
| ret = schedule_timeout(WORKER_IDLE_TIMEOUT); |
| if (signal_pending(current)) { |
| struct ksignal ksig; |
| |
| if (!get_signal(&ksig)) |
| continue; |
| break; |
| } |
| last_timeout = !ret; |
| } |
| |
| if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) |
| io_worker_handle_work(worker); |
| |
| audit_free(current); |
| io_worker_exit(worker); |
| return 0; |
| } |
| |
| /* |
| * Called when a worker is scheduled in. Mark us as currently running. |
| */ |
| void io_wq_worker_running(struct task_struct *tsk) |
| { |
| struct io_worker *worker = tsk->worker_private; |
| |
| if (!worker) |
| return; |
| if (!(worker->flags & IO_WORKER_F_UP)) |
| return; |
| if (worker->flags & IO_WORKER_F_RUNNING) |
| return; |
| worker->flags |= IO_WORKER_F_RUNNING; |
| io_wqe_inc_running(worker); |
| } |
| |
| /* |
| * Called when worker is going to sleep. If there are no workers currently |
| * running and we have work pending, wake up a free one or create a new one. |
| */ |
| void io_wq_worker_sleeping(struct task_struct *tsk) |
| { |
| struct io_worker *worker = tsk->worker_private; |
| |
| if (!worker) |
| return; |
| if (!(worker->flags & IO_WORKER_F_UP)) |
| return; |
| if (!(worker->flags & IO_WORKER_F_RUNNING)) |
| return; |
| |
| worker->flags &= ~IO_WORKER_F_RUNNING; |
| io_wqe_dec_running(worker); |
| } |
| |
| static void io_init_new_worker(struct io_wqe *wqe, struct io_worker *worker, |
| struct task_struct *tsk) |
| { |
| tsk->worker_private = worker; |
| worker->task = tsk; |
| set_cpus_allowed_ptr(tsk, wqe->cpu_mask); |
| tsk->flags |= PF_NO_SETAFFINITY; |
| |
| raw_spin_lock(&wqe->lock); |
| hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list); |
| list_add_tail_rcu(&worker->all_list, &wqe->all_list); |
| worker->flags |= IO_WORKER_F_FREE; |
| raw_spin_unlock(&wqe->lock); |
| wake_up_new_task(tsk); |
| } |
| |
| static bool io_wq_work_match_all(struct io_wq_work *work, void *data) |
| { |
| return true; |
| } |
| |
| static inline bool io_should_retry_thread(long err) |
| { |
| /* |
| * Prevent perpetual task_work retry, if the task (or its group) is |
| * exiting. |
| */ |
| if (fatal_signal_pending(current)) |
| return false; |
| |
| switch (err) { |
| case -EAGAIN: |
| case -ERESTARTSYS: |
| case -ERESTARTNOINTR: |
| case -ERESTARTNOHAND: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| static void create_worker_cont(struct callback_head *cb) |
| { |
| struct io_worker *worker; |
| struct task_struct *tsk; |
| struct io_wqe *wqe; |
| |
| worker = container_of(cb, struct io_worker, create_work); |
| clear_bit_unlock(0, &worker->create_state); |
| wqe = worker->wqe; |
| tsk = create_io_thread(io_wqe_worker, worker, wqe->node); |
| if (!IS_ERR(tsk)) { |
| io_init_new_worker(wqe, worker, tsk); |
| io_worker_release(worker); |
| return; |
| } else if (!io_should_retry_thread(PTR_ERR(tsk))) { |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| |
| atomic_dec(&acct->nr_running); |
| raw_spin_lock(&wqe->lock); |
| acct->nr_workers--; |
| if (!acct->nr_workers) { |
| struct io_cb_cancel_data match = { |
| .fn = io_wq_work_match_all, |
| .cancel_all = true, |
| }; |
| |
| raw_spin_unlock(&wqe->lock); |
| while (io_acct_cancel_pending_work(wqe, acct, &match)) |
| ; |
| } else { |
| raw_spin_unlock(&wqe->lock); |
| } |
| io_worker_ref_put(wqe->wq); |
| kfree(worker); |
| return; |
| } |
| |
| /* re-create attempts grab a new worker ref, drop the existing one */ |
| io_worker_release(worker); |
| schedule_work(&worker->work); |
| } |
| |
| static void io_workqueue_create(struct work_struct *work) |
| { |
| struct io_worker *worker = container_of(work, struct io_worker, work); |
| struct io_wqe_acct *acct = io_wqe_get_acct(worker); |
| |
| if (!io_queue_worker_create(worker, acct, create_worker_cont)) |
| kfree(worker); |
| } |
| |
| static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index) |
| { |
| struct io_wqe_acct *acct = &wqe->acct[index]; |
| struct io_worker *worker; |
| struct task_struct *tsk; |
| |
| __set_current_state(TASK_RUNNING); |
| |
| worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node); |
| if (!worker) { |
| fail: |
| atomic_dec(&acct->nr_running); |
| raw_spin_lock(&wqe->lock); |
| acct->nr_workers--; |
| raw_spin_unlock(&wqe->lock); |
| io_worker_ref_put(wq); |
| return false; |
| } |
| |
| refcount_set(&worker->ref, 1); |
| worker->wqe = wqe; |
| raw_spin_lock_init(&worker->lock); |
| init_completion(&worker->ref_done); |
| |
| if (index == IO_WQ_ACCT_BOUND) |
| worker->flags |= IO_WORKER_F_BOUND; |
| |
| tsk = create_io_thread(io_wqe_worker, worker, wqe->node); |
| if (!IS_ERR(tsk)) { |
| io_init_new_worker(wqe, worker, tsk); |
| } else if (!io_should_retry_thread(PTR_ERR(tsk))) { |
| kfree(worker); |
| goto fail; |
| } else { |
| INIT_WORK(&worker->work, io_workqueue_create); |
| schedule_work(&worker->work); |
| } |
| |
| return true; |
| } |
| |
| /* |
| * Iterate the passed in list and call the specific function for each |
| * worker that isn't exiting |
| */ |
| static bool io_wq_for_each_worker(struct io_wqe *wqe, |
| bool (*func)(struct io_worker *, void *), |
| void *data) |
| { |
| struct io_worker *worker; |
| bool ret = false; |
| |
| list_for_each_entry_rcu(worker, &wqe->all_list, all_list) { |
| if (io_worker_get(worker)) { |
| /* no task if node is/was offline */ |
| if (worker->task) |
| ret = func(worker, data); |
| io_worker_release(worker); |
| if (ret) |
| break; |
| } |
| } |
| |
| return ret; |
| } |
| |
| static bool io_wq_worker_wake(struct io_worker *worker, void *data) |
| { |
| __set_notify_signal(worker->task); |
| wake_up_process(worker->task); |
| return false; |
| } |
| |
| static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe) |
| { |
| struct io_wq *wq = wqe->wq; |
| |
| do { |
| work->flags |= IO_WQ_WORK_CANCEL; |
| wq->do_work(work); |
| work = wq->free_work(work); |
| } while (work); |
| } |
| |
| static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work) |
| { |
| struct io_wqe_acct *acct = io_work_get_acct(wqe, work); |
| unsigned int hash; |
| struct io_wq_work *tail; |
| |
| if (!io_wq_is_hashed(work)) { |
| append: |
| wq_list_add_tail(&work->list, &acct->work_list); |
| return; |
| } |
| |
| hash = io_get_work_hash(work); |
| tail = wqe->hash_tail[hash]; |
| wqe->hash_tail[hash] = work; |
| if (!tail) |
| goto append; |
| |
| wq_list_add_after(&work->list, &tail->list, &acct->work_list); |
| } |
| |
| static bool io_wq_work_match_item(struct io_wq_work *work, void *data) |
| { |
| return work == data; |
| } |
| |
| static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work) |
| { |
| struct io_wqe_acct *acct = io_work_get_acct(wqe, work); |
| struct io_cb_cancel_data match; |
| unsigned work_flags = work->flags; |
| bool do_create; |
| |
| /* |
| * If io-wq is exiting for this task, or if the request has explicitly |
| * been marked as one that should not get executed, cancel it here. |
| */ |
| if (test_bit(IO_WQ_BIT_EXIT, &wqe->wq->state) || |
| (work->flags & IO_WQ_WORK_CANCEL)) { |
| io_run_cancel(work, wqe); |
| return; |
| } |
| |
| raw_spin_lock(&acct->lock); |
| io_wqe_insert_work(wqe, work); |
| clear_bit(IO_ACCT_STALLED_BIT, &acct->flags); |
| raw_spin_unlock(&acct->lock); |
| |
| raw_spin_lock(&wqe->lock); |
| rcu_read_lock(); |
| do_create = !io_wqe_activate_free_worker(wqe, acct); |
| rcu_read_unlock(); |
| |
| raw_spin_unlock(&wqe->lock); |
| |
| if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) || |
| !atomic_read(&acct->nr_running))) { |
| bool did_create; |
| |
| did_create = io_wqe_create_worker(wqe, acct); |
| if (likely(did_create)) |
| return; |
| |
| raw_spin_lock(&wqe->lock); |
| if (acct->nr_workers) { |
| raw_spin_unlock(&wqe->lock); |
| return; |
| } |
| raw_spin_unlock(&wqe->lock); |
| |
| /* fatal condition, failed to create the first worker */ |
| match.fn = io_wq_work_match_item, |
| match.data = work, |
| match.cancel_all = false, |
| |
| io_acct_cancel_pending_work(wqe, acct, &match); |
| } |
| } |
| |
| void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work) |
| { |
| struct io_wqe *wqe = wq->wqes[numa_node_id()]; |
| |
| io_wqe_enqueue(wqe, work); |
| } |
| |
| /* |
| * Work items that hash to the same value will not be done in parallel. |
| * Used to limit concurrent writes, generally hashed by inode. |
| */ |
| void io_wq_hash_work(struct io_wq_work *work, void *val) |
| { |
| unsigned int bit; |
| |
| bit = hash_ptr(val, IO_WQ_HASH_ORDER); |
| work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT)); |
| } |
| |
| static bool __io_wq_worker_cancel(struct io_worker *worker, |
| struct io_cb_cancel_data *match, |
| struct io_wq_work *work) |
| { |
| if (work && match->fn(work, match->data)) { |
| work->flags |= IO_WQ_WORK_CANCEL; |
| __set_notify_signal(worker->task); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| static bool io_wq_worker_cancel(struct io_worker *worker, void *data) |
| { |
| struct io_cb_cancel_data *match = data; |
| |
| /* |
| * Hold the lock to avoid ->cur_work going out of scope, caller |
| * may dereference the passed in work. |
| */ |
| raw_spin_lock(&worker->lock); |
| if (__io_wq_worker_cancel(worker, match, worker->cur_work) || |
| __io_wq_worker_cancel(worker, match, worker->next_work)) |
| match->nr_running++; |
| raw_spin_unlock(&worker->lock); |
| |
| return match->nr_running && !match->cancel_all; |
| } |
| |
| static inline void io_wqe_remove_pending(struct io_wqe *wqe, |
| struct io_wq_work *work, |
| struct io_wq_work_node *prev) |
| { |
| struct io_wqe_acct *acct = io_work_get_acct(wqe, work); |
| unsigned int hash = io_get_work_hash(work); |
| struct io_wq_work *prev_work = NULL; |
| |
| if (io_wq_is_hashed(work) && work == wqe->hash_tail[hash]) { |
| if (prev) |
| prev_work = container_of(prev, struct io_wq_work, list); |
| if (prev_work && io_get_work_hash(prev_work) == hash) |
| wqe->hash_tail[hash] = prev_work; |
| else |
| wqe->hash_tail[hash] = NULL; |
| } |
| wq_list_del(&acct->work_list, &work->list, prev); |
| } |
| |
| static bool io_acct_cancel_pending_work(struct io_wqe *wqe, |
| struct io_wqe_acct *acct, |
| struct io_cb_cancel_data *match) |
| { |
| struct io_wq_work_node *node, *prev; |
| struct io_wq_work *work; |
| |
| raw_spin_lock(&acct->lock); |
| wq_list_for_each(node, prev, &acct->work_list) { |
| work = container_of(node, struct io_wq_work, list); |
| if (!match->fn(work, match->data)) |
| continue; |
| io_wqe_remove_pending(wqe, work, prev); |
| raw_spin_unlock(&acct->lock); |
| io_run_cancel(work, wqe); |
| match->nr_pending++; |
| /* not safe to continue after unlock */ |
| return true; |
| } |
| raw_spin_unlock(&acct->lock); |
| |
| return false; |
| } |
| |
| static void io_wqe_cancel_pending_work(struct io_wqe *wqe, |
| struct io_cb_cancel_data *match) |
| { |
| int i; |
| retry: |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) { |
| struct io_wqe_acct *acct = io_get_acct(wqe, i == 0); |
| |
| if (io_acct_cancel_pending_work(wqe, acct, match)) { |
| if (match->cancel_all) |
| goto retry; |
| break; |
| } |
| } |
| } |
| |
| static void io_wqe_cancel_running_work(struct io_wqe *wqe, |
| struct io_cb_cancel_data *match) |
| { |
| rcu_read_lock(); |
| io_wq_for_each_worker(wqe, io_wq_worker_cancel, match); |
| rcu_read_unlock(); |
| } |
| |
| enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel, |
| void *data, bool cancel_all) |
| { |
| struct io_cb_cancel_data match = { |
| .fn = cancel, |
| .data = data, |
| .cancel_all = cancel_all, |
| }; |
| int node; |
| |
| /* |
| * First check pending list, if we're lucky we can just remove it |
| * from there. CANCEL_OK means that the work is returned as-new, |
| * no completion will be posted for it. |
| * |
| * Then check if a free (going busy) or busy worker has the work |
| * currently running. If we find it there, we'll return CANCEL_RUNNING |
| * as an indication that we attempt to signal cancellation. The |
| * completion will run normally in this case. |
| * |
| * Do both of these while holding the wqe->lock, to ensure that |
| * we'll find a work item regardless of state. |
| */ |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| |
| io_wqe_cancel_pending_work(wqe, &match); |
| if (match.nr_pending && !match.cancel_all) |
| return IO_WQ_CANCEL_OK; |
| |
| raw_spin_lock(&wqe->lock); |
| io_wqe_cancel_running_work(wqe, &match); |
| raw_spin_unlock(&wqe->lock); |
| if (match.nr_running && !match.cancel_all) |
| return IO_WQ_CANCEL_RUNNING; |
| } |
| |
| if (match.nr_running) |
| return IO_WQ_CANCEL_RUNNING; |
| if (match.nr_pending) |
| return IO_WQ_CANCEL_OK; |
| return IO_WQ_CANCEL_NOTFOUND; |
| } |
| |
| static int io_wqe_hash_wake(struct wait_queue_entry *wait, unsigned mode, |
| int sync, void *key) |
| { |
| struct io_wqe *wqe = container_of(wait, struct io_wqe, wait); |
| int i; |
| |
| list_del_init(&wait->entry); |
| |
| rcu_read_lock(); |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) { |
| struct io_wqe_acct *acct = &wqe->acct[i]; |
| |
| if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags)) |
| io_wqe_activate_free_worker(wqe, acct); |
| } |
| rcu_read_unlock(); |
| return 1; |
| } |
| |
| struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data) |
| { |
| int ret, node, i; |
| struct io_wq *wq; |
| |
| if (WARN_ON_ONCE(!data->free_work || !data->do_work)) |
| return ERR_PTR(-EINVAL); |
| if (WARN_ON_ONCE(!bounded)) |
| return ERR_PTR(-EINVAL); |
| |
| wq = kzalloc(struct_size(wq, wqes, nr_node_ids), GFP_KERNEL); |
| if (!wq) |
| return ERR_PTR(-ENOMEM); |
| ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node); |
| if (ret) |
| goto err_wq; |
| |
| refcount_inc(&data->hash->refs); |
| wq->hash = data->hash; |
| wq->free_work = data->free_work; |
| wq->do_work = data->do_work; |
| |
| ret = -ENOMEM; |
| for_each_node(node) { |
| struct io_wqe *wqe; |
| int alloc_node = node; |
| |
| if (!node_online(alloc_node)) |
| alloc_node = NUMA_NO_NODE; |
| wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node); |
| if (!wqe) |
| goto err; |
| if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL)) |
| goto err; |
| cpumask_copy(wqe->cpu_mask, cpumask_of_node(node)); |
| wq->wqes[node] = wqe; |
| wqe->node = alloc_node; |
| wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded; |
| wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers = |
| task_rlimit(current, RLIMIT_NPROC); |
| INIT_LIST_HEAD(&wqe->wait.entry); |
| wqe->wait.func = io_wqe_hash_wake; |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) { |
| struct io_wqe_acct *acct = &wqe->acct[i]; |
| |
| acct->index = i; |
| atomic_set(&acct->nr_running, 0); |
| INIT_WQ_LIST(&acct->work_list); |
| raw_spin_lock_init(&acct->lock); |
| } |
| wqe->wq = wq; |
| raw_spin_lock_init(&wqe->lock); |
| INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0); |
| INIT_LIST_HEAD(&wqe->all_list); |
| } |
| |
| wq->task = get_task_struct(data->task); |
| atomic_set(&wq->worker_refs, 1); |
| init_completion(&wq->worker_done); |
| return wq; |
| err: |
| io_wq_put_hash(data->hash); |
| cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node); |
| for_each_node(node) { |
| if (!wq->wqes[node]) |
| continue; |
| free_cpumask_var(wq->wqes[node]->cpu_mask); |
| kfree(wq->wqes[node]); |
| } |
| err_wq: |
| kfree(wq); |
| return ERR_PTR(ret); |
| } |
| |
| static bool io_task_work_match(struct callback_head *cb, void *data) |
| { |
| struct io_worker *worker; |
| |
| if (cb->func != create_worker_cb && cb->func != create_worker_cont) |
| return false; |
| worker = container_of(cb, struct io_worker, create_work); |
| return worker->wqe->wq == data; |
| } |
| |
| void io_wq_exit_start(struct io_wq *wq) |
| { |
| set_bit(IO_WQ_BIT_EXIT, &wq->state); |
| } |
| |
| static void io_wq_cancel_tw_create(struct io_wq *wq) |
| { |
| struct callback_head *cb; |
| |
| while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) { |
| struct io_worker *worker; |
| |
| worker = container_of(cb, struct io_worker, create_work); |
| io_worker_cancel_cb(worker); |
| } |
| } |
| |
| static void io_wq_exit_workers(struct io_wq *wq) |
| { |
| int node; |
| |
| if (!wq->task) |
| return; |
| |
| io_wq_cancel_tw_create(wq); |
| |
| rcu_read_lock(); |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| |
| io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL); |
| } |
| rcu_read_unlock(); |
| io_worker_ref_put(wq); |
| wait_for_completion(&wq->worker_done); |
| |
| for_each_node(node) { |
| spin_lock_irq(&wq->hash->wait.lock); |
| list_del_init(&wq->wqes[node]->wait.entry); |
| spin_unlock_irq(&wq->hash->wait.lock); |
| } |
| put_task_struct(wq->task); |
| wq->task = NULL; |
| } |
| |
| static void io_wq_destroy(struct io_wq *wq) |
| { |
| int node; |
| |
| cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node); |
| |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| struct io_cb_cancel_data match = { |
| .fn = io_wq_work_match_all, |
| .cancel_all = true, |
| }; |
| io_wqe_cancel_pending_work(wqe, &match); |
| free_cpumask_var(wqe->cpu_mask); |
| kfree(wqe); |
| } |
| io_wq_put_hash(wq->hash); |
| kfree(wq); |
| } |
| |
| void io_wq_put_and_exit(struct io_wq *wq) |
| { |
| WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state)); |
| |
| io_wq_exit_workers(wq); |
| io_wq_destroy(wq); |
| } |
| |
| struct online_data { |
| unsigned int cpu; |
| bool online; |
| }; |
| |
| static bool io_wq_worker_affinity(struct io_worker *worker, void *data) |
| { |
| struct online_data *od = data; |
| |
| if (od->online) |
| cpumask_set_cpu(od->cpu, worker->wqe->cpu_mask); |
| else |
| cpumask_clear_cpu(od->cpu, worker->wqe->cpu_mask); |
| return false; |
| } |
| |
| static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online) |
| { |
| struct online_data od = { |
| .cpu = cpu, |
| .online = online |
| }; |
| int i; |
| |
| rcu_read_lock(); |
| for_each_node(i) |
| io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, &od); |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node) |
| { |
| struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node); |
| |
| return __io_wq_cpu_online(wq, cpu, true); |
| } |
| |
| static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node) |
| { |
| struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node); |
| |
| return __io_wq_cpu_online(wq, cpu, false); |
| } |
| |
| int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask) |
| { |
| int i; |
| |
| rcu_read_lock(); |
| for_each_node(i) { |
| struct io_wqe *wqe = wq->wqes[i]; |
| |
| if (mask) |
| cpumask_copy(wqe->cpu_mask, mask); |
| else |
| cpumask_copy(wqe->cpu_mask, cpumask_of_node(i)); |
| } |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| /* |
| * Set max number of unbounded workers, returns old value. If new_count is 0, |
| * then just return the old value. |
| */ |
| int io_wq_max_workers(struct io_wq *wq, int *new_count) |
| { |
| int prev[IO_WQ_ACCT_NR]; |
| bool first_node = true; |
| int i, node; |
| |
| BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND != (int) IO_WQ_BOUND); |
| BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND); |
| BUILD_BUG_ON((int) IO_WQ_ACCT_NR != 2); |
| |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) { |
| if (new_count[i] > task_rlimit(current, RLIMIT_NPROC)) |
| new_count[i] = task_rlimit(current, RLIMIT_NPROC); |
| } |
| |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) |
| prev[i] = 0; |
| |
| rcu_read_lock(); |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| struct io_wqe_acct *acct; |
| |
| raw_spin_lock(&wqe->lock); |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) { |
| acct = &wqe->acct[i]; |
| if (first_node) |
| prev[i] = max_t(int, acct->max_workers, prev[i]); |
| if (new_count[i]) |
| acct->max_workers = new_count[i]; |
| } |
| raw_spin_unlock(&wqe->lock); |
| first_node = false; |
| } |
| rcu_read_unlock(); |
| |
| for (i = 0; i < IO_WQ_ACCT_NR; i++) |
| new_count[i] = prev[i]; |
| |
| return 0; |
| } |
| |
| static __init int io_wq_init(void) |
| { |
| int ret; |
| |
| ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online", |
| io_wq_cpu_online, io_wq_cpu_offline); |
| if (ret < 0) |
| return ret; |
| io_wq_online = ret; |
| return 0; |
| } |
| subsys_initcall(io_wq_init); |