| // 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/mm.h> |
| #include <linux/mmu_context.h> |
| #include <linux/sched/mm.h> |
| #include <linux/percpu.h> |
| #include <linux/slab.h> |
| #include <linux/kthread.h> |
| #include <linux/rculist_nulls.h> |
| #include <linux/fs_struct.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_EXITING = 8, /* worker exiting */ |
| IO_WORKER_F_FIXED = 16, /* static idle worker */ |
| IO_WORKER_F_BOUND = 32, /* is doing bounded work */ |
| }; |
| |
| enum { |
| IO_WQ_BIT_EXIT = 0, /* wq exiting */ |
| IO_WQ_BIT_CANCEL = 1, /* cancel work on list */ |
| IO_WQ_BIT_ERROR = 2, /* error on setup */ |
| }; |
| |
| enum { |
| IO_WQE_FLAG_STALLED = 1, /* 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; |
| spinlock_t lock; |
| |
| struct rcu_head rcu; |
| struct mm_struct *mm; |
| const struct cred *cur_creds; |
| const struct cred *saved_creds; |
| struct files_struct *restore_files; |
| struct fs_struct *restore_fs; |
| }; |
| |
| #if BITS_PER_LONG == 64 |
| #define IO_WQ_HASH_ORDER 6 |
| #else |
| #define IO_WQ_HASH_ORDER 5 |
| #endif |
| |
| struct io_wqe_acct { |
| unsigned nr_workers; |
| unsigned max_workers; |
| atomic_t nr_running; |
| }; |
| |
| enum { |
| IO_WQ_ACCT_BOUND, |
| IO_WQ_ACCT_UNBOUND, |
| }; |
| |
| /* |
| * Per-node worker thread pool |
| */ |
| struct io_wqe { |
| struct { |
| spinlock_t lock; |
| struct io_wq_work_list work_list; |
| unsigned long hash_map; |
| unsigned flags; |
| } ____cacheline_aligned_in_smp; |
| |
| int node; |
| struct io_wqe_acct acct[2]; |
| |
| struct hlist_nulls_head free_list; |
| struct list_head all_list; |
| |
| struct io_wq *wq; |
| }; |
| |
| /* |
| * Per io_wq state |
| */ |
| struct io_wq { |
| struct io_wqe **wqes; |
| unsigned long state; |
| |
| free_work_fn *free_work; |
| |
| struct task_struct *manager; |
| struct user_struct *user; |
| refcount_t refs; |
| struct completion done; |
| |
| refcount_t use_refs; |
| }; |
| |
| 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)) |
| wake_up_process(worker->task); |
| } |
| |
| /* |
| * Note: drops the wqe->lock if returning true! The caller must re-acquire |
| * the lock in that case. Some callers need to restart handling if this |
| * happens, so we can't just re-acquire the lock on behalf of the caller. |
| */ |
| static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker) |
| { |
| bool dropped_lock = false; |
| |
| if (worker->saved_creds) { |
| revert_creds(worker->saved_creds); |
| worker->cur_creds = worker->saved_creds = NULL; |
| } |
| |
| if (current->files != worker->restore_files) { |
| __acquire(&wqe->lock); |
| spin_unlock_irq(&wqe->lock); |
| dropped_lock = true; |
| |
| task_lock(current); |
| current->files = worker->restore_files; |
| task_unlock(current); |
| } |
| |
| if (current->fs != worker->restore_fs) |
| current->fs = worker->restore_fs; |
| |
| /* |
| * If we have an active mm, we need to drop the wq lock before unusing |
| * it. If we do, return true and let the caller retry the idle loop. |
| */ |
| if (worker->mm) { |
| if (!dropped_lock) { |
| __acquire(&wqe->lock); |
| spin_unlock_irq(&wqe->lock); |
| dropped_lock = true; |
| } |
| __set_current_state(TASK_RUNNING); |
| set_fs(KERNEL_DS); |
| unuse_mm(worker->mm); |
| mmput(worker->mm); |
| worker->mm = NULL; |
| } |
| |
| return dropped_lock; |
| } |
| |
| static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe, |
| struct io_wq_work *work) |
| { |
| if (work->flags & IO_WQ_WORK_UNBOUND) |
| return &wqe->acct[IO_WQ_ACCT_UNBOUND]; |
| |
| return &wqe->acct[IO_WQ_ACCT_BOUND]; |
| } |
| |
| static inline struct io_wqe_acct *io_wqe_get_acct(struct io_wqe *wqe, |
| struct io_worker *worker) |
| { |
| if (worker->flags & IO_WORKER_F_BOUND) |
| return &wqe->acct[IO_WQ_ACCT_BOUND]; |
| |
| return &wqe->acct[IO_WQ_ACCT_UNBOUND]; |
| } |
| |
| static void io_worker_exit(struct io_worker *worker) |
| { |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker); |
| unsigned nr_workers; |
| |
| /* |
| * If we're not at zero, someone else is holding a brief reference |
| * to the worker. Wait for that to go away. |
| */ |
| set_current_state(TASK_INTERRUPTIBLE); |
| if (!refcount_dec_and_test(&worker->ref)) |
| schedule(); |
| __set_current_state(TASK_RUNNING); |
| |
| preempt_disable(); |
| current->flags &= ~PF_IO_WORKER; |
| if (worker->flags & IO_WORKER_F_RUNNING) |
| atomic_dec(&acct->nr_running); |
| if (!(worker->flags & IO_WORKER_F_BOUND)) |
| atomic_dec(&wqe->wq->user->processes); |
| worker->flags = 0; |
| preempt_enable(); |
| |
| spin_lock_irq(&wqe->lock); |
| hlist_nulls_del_rcu(&worker->nulls_node); |
| list_del_rcu(&worker->all_list); |
| if (__io_worker_unuse(wqe, worker)) { |
| __release(&wqe->lock); |
| spin_lock_irq(&wqe->lock); |
| } |
| acct->nr_workers--; |
| nr_workers = wqe->acct[IO_WQ_ACCT_BOUND].nr_workers + |
| wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers; |
| spin_unlock_irq(&wqe->lock); |
| |
| /* all workers gone, wq exit can proceed */ |
| if (!nr_workers && refcount_dec_and_test(&wqe->wq->refs)) |
| complete(&wqe->wq->done); |
| |
| kfree_rcu(worker, rcu); |
| } |
| |
| static inline bool io_wqe_run_queue(struct io_wqe *wqe) |
| __must_hold(wqe->lock) |
| { |
| if (!wq_list_empty(&wqe->work_list) && |
| !(wqe->flags & IO_WQE_FLAG_STALLED)) |
| return true; |
| return false; |
| } |
| |
| /* |
| * Check head of free list for an available worker. If one isn't available, |
| * caller must wake up the wq manager to create one. |
| */ |
| static bool io_wqe_activate_free_worker(struct io_wqe *wqe) |
| __must_hold(RCU) |
| { |
| struct hlist_nulls_node *n; |
| struct io_worker *worker; |
| |
| n = rcu_dereference(hlist_nulls_first_rcu(&wqe->free_list)); |
| if (is_a_nulls(n)) |
| return false; |
| |
| worker = hlist_nulls_entry(n, struct io_worker, nulls_node); |
| if (io_worker_get(worker)) { |
| wake_up_process(worker->task); |
| io_worker_release(worker); |
| return true; |
| } |
| |
| 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, wake up the manager to create one. |
| */ |
| static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct) |
| { |
| bool ret; |
| |
| /* |
| * Most likely an attempt to queue unbounded work on an io_wq that |
| * wasn't setup with any unbounded workers. |
| */ |
| WARN_ON_ONCE(!acct->max_workers); |
| |
| rcu_read_lock(); |
| ret = io_wqe_activate_free_worker(wqe); |
| rcu_read_unlock(); |
| |
| if (!ret && acct->nr_workers < acct->max_workers) |
| wake_up_process(wqe->wq->manager); |
| } |
| |
| static void io_wqe_inc_running(struct io_wqe *wqe, struct io_worker *worker) |
| { |
| struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker); |
| |
| atomic_inc(&acct->nr_running); |
| } |
| |
| static void io_wqe_dec_running(struct io_wqe *wqe, struct io_worker *worker) |
| __must_hold(wqe->lock) |
| { |
| struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker); |
| |
| if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe)) |
| io_wqe_wake_worker(wqe, acct); |
| } |
| |
| static void io_worker_start(struct io_wqe *wqe, struct io_worker *worker) |
| { |
| allow_kernel_signal(SIGINT); |
| |
| current->flags |= PF_IO_WORKER; |
| |
| worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING); |
| worker->restore_files = current->files; |
| worker->restore_fs = current->fs; |
| io_wqe_inc_running(wqe, worker); |
| } |
| |
| /* |
| * 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, |
| struct io_wq_work *work) |
| __must_hold(wqe->lock) |
| { |
| bool worker_bound, work_bound; |
| |
| if (worker->flags & IO_WORKER_F_FREE) { |
| worker->flags &= ~IO_WORKER_F_FREE; |
| hlist_nulls_del_init_rcu(&worker->nulls_node); |
| } |
| |
| /* |
| * If worker is moving from bound to unbound (or vice versa), then |
| * ensure we update the running accounting. |
| */ |
| worker_bound = (worker->flags & IO_WORKER_F_BOUND) != 0; |
| work_bound = (work->flags & IO_WQ_WORK_UNBOUND) == 0; |
| if (worker_bound != work_bound) { |
| io_wqe_dec_running(wqe, worker); |
| if (work_bound) { |
| worker->flags |= IO_WORKER_F_BOUND; |
| wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers--; |
| wqe->acct[IO_WQ_ACCT_BOUND].nr_workers++; |
| atomic_dec(&wqe->wq->user->processes); |
| } else { |
| worker->flags &= ~IO_WORKER_F_BOUND; |
| wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers++; |
| wqe->acct[IO_WQ_ACCT_BOUND].nr_workers--; |
| atomic_inc(&wqe->wq->user->processes); |
| } |
| io_wqe_inc_running(wqe, worker); |
| } |
| } |
| |
| /* |
| * 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 bool __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); |
| } |
| |
| return __io_worker_unuse(wqe, worker); |
| } |
| |
| static struct io_wq_work *io_get_next_work(struct io_wqe *wqe, unsigned *hash) |
| __must_hold(wqe->lock) |
| { |
| struct io_wq_work_node *node, *prev; |
| struct io_wq_work *work; |
| |
| wq_list_for_each(node, prev, &wqe->work_list) { |
| work = container_of(node, struct io_wq_work, list); |
| |
| /* not hashed, can run anytime */ |
| if (!(work->flags & IO_WQ_WORK_HASHED)) { |
| wq_node_del(&wqe->work_list, node, prev); |
| return work; |
| } |
| |
| /* hashed, can run if not already running */ |
| *hash = work->flags >> IO_WQ_HASH_SHIFT; |
| if (!(wqe->hash_map & BIT(*hash))) { |
| wqe->hash_map |= BIT(*hash); |
| wq_node_del(&wqe->work_list, node, prev); |
| return work; |
| } |
| } |
| |
| return NULL; |
| } |
| |
| static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work) |
| { |
| if (worker->mm) { |
| unuse_mm(worker->mm); |
| mmput(worker->mm); |
| worker->mm = NULL; |
| } |
| if (!work->mm) { |
| set_fs(KERNEL_DS); |
| return; |
| } |
| if (mmget_not_zero(work->mm)) { |
| use_mm(work->mm); |
| if (!worker->mm) |
| set_fs(USER_DS); |
| worker->mm = work->mm; |
| /* hang on to this mm */ |
| work->mm = NULL; |
| return; |
| } |
| |
| /* failed grabbing mm, ensure work gets cancelled */ |
| work->flags |= IO_WQ_WORK_CANCEL; |
| } |
| |
| static void io_wq_switch_creds(struct io_worker *worker, |
| struct io_wq_work *work) |
| { |
| const struct cred *old_creds = override_creds(work->creds); |
| |
| worker->cur_creds = work->creds; |
| if (worker->saved_creds) |
| put_cred(old_creds); /* creds set by previous switch */ |
| else |
| worker->saved_creds = old_creds; |
| } |
| |
| static void io_impersonate_work(struct io_worker *worker, |
| struct io_wq_work *work) |
| { |
| if (work->files && current->files != work->files) { |
| task_lock(current); |
| current->files = work->files; |
| task_unlock(current); |
| } |
| if (work->fs && current->fs != work->fs) |
| current->fs = work->fs; |
| if (work->mm != worker->mm) |
| io_wq_switch_mm(worker, work); |
| if (worker->cur_creds != work->creds) |
| io_wq_switch_creds(worker, work); |
| } |
| |
| static void io_assign_current_work(struct io_worker *worker, |
| struct io_wq_work *work) |
| { |
| if (work) { |
| /* flush pending signals before assigning new work */ |
| if (signal_pending(current)) |
| flush_signals(current); |
| cond_resched(); |
| } |
| |
| spin_lock_irq(&worker->lock); |
| worker->cur_work = work; |
| spin_unlock_irq(&worker->lock); |
| } |
| |
| static void io_worker_handle_work(struct io_worker *worker) |
| __releases(wqe->lock) |
| { |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| unsigned hash = -1U; |
| |
| do { |
| struct io_wq_work *work; |
| get_next: |
| /* |
| * 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. |
| */ |
| work = io_get_next_work(wqe, &hash); |
| if (work) |
| __io_worker_busy(wqe, worker, work); |
| else if (!wq_list_empty(&wqe->work_list)) |
| wqe->flags |= IO_WQE_FLAG_STALLED; |
| |
| spin_unlock_irq(&wqe->lock); |
| if (!work) |
| break; |
| io_assign_current_work(worker, work); |
| |
| /* handle a whole dependent link */ |
| do { |
| struct io_wq_work *old_work; |
| |
| io_impersonate_work(worker, work); |
| /* |
| * OK to set IO_WQ_WORK_CANCEL even for uncancellable |
| * work, the worker function will do the right thing. |
| */ |
| if (test_bit(IO_WQ_BIT_CANCEL, &wq->state)) |
| work->flags |= IO_WQ_WORK_CANCEL; |
| |
| old_work = work; |
| work->func(&work); |
| work = (old_work == work) ? NULL : work; |
| io_assign_current_work(worker, work); |
| wq->free_work(old_work); |
| |
| if (hash != -1U) { |
| spin_lock_irq(&wqe->lock); |
| wqe->hash_map &= ~BIT_ULL(hash); |
| wqe->flags &= ~IO_WQE_FLAG_STALLED; |
| /* dependent work is not hashed */ |
| hash = -1U; |
| /* skip unnecessary unlock-lock wqe->lock */ |
| if (!work) |
| goto get_next; |
| spin_unlock_irq(&wqe->lock); |
| } |
| } while (work); |
| |
| spin_lock_irq(&wqe->lock); |
| } while (1); |
| } |
| |
| static int io_wqe_worker(void *data) |
| { |
| struct io_worker *worker = data; |
| struct io_wqe *wqe = worker->wqe; |
| struct io_wq *wq = wqe->wq; |
| |
| io_worker_start(wqe, worker); |
| |
| while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) { |
| set_current_state(TASK_INTERRUPTIBLE); |
| loop: |
| spin_lock_irq(&wqe->lock); |
| if (io_wqe_run_queue(wqe)) { |
| __set_current_state(TASK_RUNNING); |
| io_worker_handle_work(worker); |
| goto loop; |
| } |
| /* drops the lock on success, retry */ |
| if (__io_worker_idle(wqe, worker)) { |
| __release(&wqe->lock); |
| goto loop; |
| } |
| spin_unlock_irq(&wqe->lock); |
| if (signal_pending(current)) |
| flush_signals(current); |
| if (schedule_timeout(WORKER_IDLE_TIMEOUT)) |
| continue; |
| /* timed out, exit unless we're the fixed worker */ |
| if (test_bit(IO_WQ_BIT_EXIT, &wq->state) || |
| !(worker->flags & IO_WORKER_F_FIXED)) |
| break; |
| } |
| |
| if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) { |
| spin_lock_irq(&wqe->lock); |
| if (!wq_list_empty(&wqe->work_list)) |
| io_worker_handle_work(worker); |
| else |
| spin_unlock_irq(&wqe->lock); |
| } |
| |
| 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 = kthread_data(tsk); |
| struct io_wqe *wqe = worker->wqe; |
| |
| 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(wqe, 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 have the manager |
| * set one up. |
| */ |
| void io_wq_worker_sleeping(struct task_struct *tsk) |
| { |
| struct io_worker *worker = kthread_data(tsk); |
| struct io_wqe *wqe = worker->wqe; |
| |
| if (!(worker->flags & IO_WORKER_F_UP)) |
| return; |
| if (!(worker->flags & IO_WORKER_F_RUNNING)) |
| return; |
| |
| worker->flags &= ~IO_WORKER_F_RUNNING; |
| |
| spin_lock_irq(&wqe->lock); |
| io_wqe_dec_running(wqe, worker); |
| spin_unlock_irq(&wqe->lock); |
| } |
| |
| 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; |
| |
| worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node); |
| if (!worker) |
| return false; |
| |
| refcount_set(&worker->ref, 1); |
| worker->nulls_node.pprev = NULL; |
| worker->wqe = wqe; |
| spin_lock_init(&worker->lock); |
| |
| worker->task = kthread_create_on_node(io_wqe_worker, worker, wqe->node, |
| "io_wqe_worker-%d/%d", index, wqe->node); |
| if (IS_ERR(worker->task)) { |
| kfree(worker); |
| return false; |
| } |
| |
| spin_lock_irq(&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; |
| if (index == IO_WQ_ACCT_BOUND) |
| worker->flags |= IO_WORKER_F_BOUND; |
| if (!acct->nr_workers && (worker->flags & IO_WORKER_F_BOUND)) |
| worker->flags |= IO_WORKER_F_FIXED; |
| acct->nr_workers++; |
| spin_unlock_irq(&wqe->lock); |
| |
| if (index == IO_WQ_ACCT_UNBOUND) |
| atomic_inc(&wq->user->processes); |
| |
| wake_up_process(worker->task); |
| return true; |
| } |
| |
| static inline bool io_wqe_need_worker(struct io_wqe *wqe, int index) |
| __must_hold(wqe->lock) |
| { |
| struct io_wqe_acct *acct = &wqe->acct[index]; |
| |
| /* if we have available workers or no work, no need */ |
| if (!hlist_nulls_empty(&wqe->free_list) || !io_wqe_run_queue(wqe)) |
| return false; |
| return acct->nr_workers < acct->max_workers; |
| } |
| |
| /* |
| * Manager thread. Tasked with creating new workers, if we need them. |
| */ |
| static int io_wq_manager(void *data) |
| { |
| struct io_wq *wq = data; |
| int workers_to_create = num_possible_nodes(); |
| int node; |
| |
| /* create fixed workers */ |
| refcount_set(&wq->refs, workers_to_create); |
| for_each_node(node) { |
| if (!node_online(node)) |
| continue; |
| if (!create_io_worker(wq, wq->wqes[node], IO_WQ_ACCT_BOUND)) |
| goto err; |
| workers_to_create--; |
| } |
| |
| while (workers_to_create--) |
| refcount_dec(&wq->refs); |
| |
| complete(&wq->done); |
| |
| while (!kthread_should_stop()) { |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| bool fork_worker[2] = { false, false }; |
| |
| if (!node_online(node)) |
| continue; |
| |
| spin_lock_irq(&wqe->lock); |
| if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND)) |
| fork_worker[IO_WQ_ACCT_BOUND] = true; |
| if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND)) |
| fork_worker[IO_WQ_ACCT_UNBOUND] = true; |
| spin_unlock_irq(&wqe->lock); |
| if (fork_worker[IO_WQ_ACCT_BOUND]) |
| create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND); |
| if (fork_worker[IO_WQ_ACCT_UNBOUND]) |
| create_io_worker(wq, wqe, IO_WQ_ACCT_UNBOUND); |
| } |
| set_current_state(TASK_INTERRUPTIBLE); |
| schedule_timeout(HZ); |
| } |
| |
| return 0; |
| err: |
| set_bit(IO_WQ_BIT_ERROR, &wq->state); |
| set_bit(IO_WQ_BIT_EXIT, &wq->state); |
| if (refcount_sub_and_test(workers_to_create, &wq->refs)) |
| complete(&wq->done); |
| return 0; |
| } |
| |
| static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct, |
| struct io_wq_work *work) |
| { |
| bool free_worker; |
| |
| if (!(work->flags & IO_WQ_WORK_UNBOUND)) |
| return true; |
| if (atomic_read(&acct->nr_running)) |
| return true; |
| |
| rcu_read_lock(); |
| free_worker = !hlist_nulls_empty(&wqe->free_list); |
| rcu_read_unlock(); |
| if (free_worker) |
| return true; |
| |
| if (atomic_read(&wqe->wq->user->processes) >= acct->max_workers && |
| !(capable(CAP_SYS_RESOURCE) || capable(CAP_SYS_ADMIN))) |
| return false; |
| |
| return true; |
| } |
| |
| static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe) |
| { |
| struct io_wq *wq = wqe->wq; |
| |
| do { |
| struct io_wq_work *old_work = work; |
| |
| work->flags |= IO_WQ_WORK_CANCEL; |
| work->func(&work); |
| work = (work == old_work) ? NULL : work; |
| wq->free_work(old_work); |
| } while (work); |
| } |
| |
| 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); |
| int work_flags; |
| unsigned long flags; |
| |
| /* |
| * Do early check to see if we need a new unbound worker, and if we do, |
| * if we're allowed to do so. This isn't 100% accurate as there's a |
| * gap between this check and incrementing the value, but that's OK. |
| * It's close enough to not be an issue, fork() has the same delay. |
| */ |
| if (unlikely(!io_wq_can_queue(wqe, acct, work))) { |
| io_run_cancel(work, wqe); |
| return; |
| } |
| |
| work_flags = work->flags; |
| spin_lock_irqsave(&wqe->lock, flags); |
| wq_list_add_tail(&work->list, &wqe->work_list); |
| wqe->flags &= ~IO_WQE_FLAG_STALLED; |
| spin_unlock_irqrestore(&wqe->lock, flags); |
| |
| if ((work_flags & IO_WQ_WORK_CONCURRENT) || |
| !atomic_read(&acct->nr_running)) |
| io_wqe_wake_worker(wqe, acct); |
| } |
| |
| 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); |
| } |
| |
| /* |
| * Enqueue work, hashed by some key. 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_enqueue_hashed(struct io_wq *wq, struct io_wq_work *work, void *val) |
| { |
| struct io_wqe *wqe = wq->wqes[numa_node_id()]; |
| unsigned bit; |
| |
| |
| bit = hash_ptr(val, IO_WQ_HASH_ORDER); |
| work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT)); |
| io_wqe_enqueue(wqe, work); |
| } |
| |
| static bool io_wqe_worker_send_sig(struct io_worker *worker, void *data) |
| { |
| send_sig(SIGINT, worker->task, 1); |
| return false; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| void io_wq_cancel_all(struct io_wq *wq) |
| { |
| int node; |
| |
| set_bit(IO_WQ_BIT_CANCEL, &wq->state); |
| |
| rcu_read_lock(); |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| |
| io_wq_for_each_worker(wqe, io_wqe_worker_send_sig, NULL); |
| } |
| rcu_read_unlock(); |
| } |
| |
| struct io_cb_cancel_data { |
| work_cancel_fn *fn; |
| void *data; |
| }; |
| |
| static bool io_wq_worker_cancel(struct io_worker *worker, void *data) |
| { |
| struct io_cb_cancel_data *match = data; |
| unsigned long flags; |
| bool ret = false; |
| |
| /* |
| * Hold the lock to avoid ->cur_work going out of scope, caller |
| * may dereference the passed in work. |
| */ |
| spin_lock_irqsave(&worker->lock, flags); |
| if (worker->cur_work && |
| !(worker->cur_work->flags & IO_WQ_WORK_NO_CANCEL) && |
| match->fn(worker->cur_work, match->data)) { |
| send_sig(SIGINT, worker->task, 1); |
| ret = true; |
| } |
| spin_unlock_irqrestore(&worker->lock, flags); |
| |
| return ret; |
| } |
| |
| static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe, |
| struct io_cb_cancel_data *match) |
| { |
| struct io_wq_work_node *node, *prev; |
| struct io_wq_work *work; |
| unsigned long flags; |
| bool found = false; |
| |
| /* |
| * 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. |
| */ |
| spin_lock_irqsave(&wqe->lock, flags); |
| wq_list_for_each(node, prev, &wqe->work_list) { |
| work = container_of(node, struct io_wq_work, list); |
| |
| if (match->fn(work, match->data)) { |
| wq_node_del(&wqe->work_list, node, prev); |
| found = true; |
| break; |
| } |
| } |
| spin_unlock_irqrestore(&wqe->lock, flags); |
| |
| if (found) { |
| io_run_cancel(work, wqe); |
| return IO_WQ_CANCEL_OK; |
| } |
| |
| /* |
| * Now 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. |
| */ |
| rcu_read_lock(); |
| found = io_wq_for_each_worker(wqe, io_wq_worker_cancel, match); |
| rcu_read_unlock(); |
| return found ? IO_WQ_CANCEL_RUNNING : IO_WQ_CANCEL_NOTFOUND; |
| } |
| |
| enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel, |
| void *data) |
| { |
| struct io_cb_cancel_data match = { |
| .fn = cancel, |
| .data = data, |
| }; |
| enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND; |
| int node; |
| |
| for_each_node(node) { |
| struct io_wqe *wqe = wq->wqes[node]; |
| |
| ret = io_wqe_cancel_work(wqe, &match); |
| if (ret != IO_WQ_CANCEL_NOTFOUND) |
| break; |
| } |
| |
| return ret; |
| } |
| |
| static bool io_wq_io_cb_cancel_data(struct io_wq_work *work, void *data) |
| { |
| return work == data; |
| } |
| |
| enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork) |
| { |
| return io_wq_cancel_cb(wq, io_wq_io_cb_cancel_data, (void *)cwork); |
| } |
| |
| static bool io_wq_pid_match(struct io_wq_work *work, void *data) |
| { |
| pid_t pid = (pid_t) (unsigned long) data; |
| |
| return work->task_pid == pid; |
| } |
| |
| enum io_wq_cancel io_wq_cancel_pid(struct io_wq *wq, pid_t pid) |
| { |
| void *data = (void *) (unsigned long) pid; |
| |
| return io_wq_cancel_cb(wq, io_wq_pid_match, data); |
| } |
| |
| struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data) |
| { |
| int ret = -ENOMEM, node; |
| struct io_wq *wq; |
| |
| if (WARN_ON_ONCE(!data->free_work)) |
| return ERR_PTR(-EINVAL); |
| |
| wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
| if (!wq) |
| return ERR_PTR(-ENOMEM); |
| |
| wq->wqes = kcalloc(nr_node_ids, sizeof(struct io_wqe *), GFP_KERNEL); |
| if (!wq->wqes) { |
| kfree(wq); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| wq->free_work = data->free_work; |
| |
| /* caller must already hold a reference to this */ |
| wq->user = data->user; |
| |
| 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; |
| wq->wqes[node] = wqe; |
| wqe->node = alloc_node; |
| wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded; |
| atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0); |
| if (wq->user) { |
| wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers = |
| task_rlimit(current, RLIMIT_NPROC); |
| } |
| atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0); |
| wqe->wq = wq; |
| spin_lock_init(&wqe->lock); |
| INIT_WQ_LIST(&wqe->work_list); |
| INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0); |
| INIT_LIST_HEAD(&wqe->all_list); |
| } |
| |
| init_completion(&wq->done); |
| |
| wq->manager = kthread_create(io_wq_manager, wq, "io_wq_manager"); |
| if (!IS_ERR(wq->manager)) { |
| wake_up_process(wq->manager); |
| wait_for_completion(&wq->done); |
| if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) { |
| ret = -ENOMEM; |
| goto err; |
| } |
| refcount_set(&wq->use_refs, 1); |
| reinit_completion(&wq->done); |
| return wq; |
| } |
| |
| ret = PTR_ERR(wq->manager); |
| complete(&wq->done); |
| err: |
| for_each_node(node) |
| kfree(wq->wqes[node]); |
| kfree(wq->wqes); |
| kfree(wq); |
| return ERR_PTR(ret); |
| } |
| |
| bool io_wq_get(struct io_wq *wq, struct io_wq_data *data) |
| { |
| if (data->free_work != wq->free_work) |
| return false; |
| |
| return refcount_inc_not_zero(&wq->use_refs); |
| } |
| |
| static bool io_wq_worker_wake(struct io_worker *worker, void *data) |
| { |
| wake_up_process(worker->task); |
| return false; |
| } |
| |
| static void __io_wq_destroy(struct io_wq *wq) |
| { |
| int node; |
| |
| set_bit(IO_WQ_BIT_EXIT, &wq->state); |
| if (wq->manager) |
| kthread_stop(wq->manager); |
| |
| rcu_read_lock(); |
| for_each_node(node) |
| io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL); |
| rcu_read_unlock(); |
| |
| wait_for_completion(&wq->done); |
| |
| for_each_node(node) |
| kfree(wq->wqes[node]); |
| kfree(wq->wqes); |
| kfree(wq); |
| } |
| |
| void io_wq_destroy(struct io_wq *wq) |
| { |
| if (refcount_dec_and_test(&wq->use_refs)) |
| __io_wq_destroy(wq); |
| } |