+++ /dev/null
-// 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);
projects / people / ms / linux.git / blobdiff