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-rw-r--r--io_uring/io-wq.c1414
1 files changed, 1414 insertions, 0 deletions
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
new file mode 100644
index 000000000..fe8594a03
--- /dev/null
+++ b/io_uring/io-wq.c
@@ -0,0 +1,1414 @@
+// 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/tracehook.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;
+ 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;
+ 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[2];
+
+ 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);
+}
+
+bool io_wq_worker_stopped(void)
+{
+ struct io_worker *worker = current->pf_io_worker;
+
+ if (WARN_ON_ONCE(!io_wq_current_is_worker()))
+ return true;
+
+ return test_bit(IO_WQ_BIT_EXIT, &worker->wqe->wq->state);
+}
+
+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);
+ }
+
+ if (refcount_dec_and_test(&worker->ref))
+ complete(&worker->ref_done);
+ 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);
+ preempt_disable();
+ io_wqe_dec_running(worker);
+ worker->flags = 0;
+ current->flags &= ~PF_IO_WORKER;
+ preempt_enable();
+ raw_spin_unlock(&wqe->lock);
+
+ 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)
+{
+ if (!wq_list_empty(&acct->work_list) &&
+ !test_bit(IO_ACCT_STALLED_BIT, &acct->flags))
+ return true;
+ return false;
+}
+
+/*
+ * 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)
+ __must_hold(wqe->lock)
+{
+ 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) && io_acct_run_queue(acct)) {
+ atomic_inc(&acct->nr_running);
+ atomic_inc(&wqe->wq->worker_refs);
+ raw_spin_unlock(&wqe->lock);
+ io_queue_worker_create(worker, acct, create_worker_cb);
+ raw_spin_lock(&wqe->lock);
+ }
+}
+
+/*
+ * 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)
+{
+ if (worker->flags & IO_WORKER_F_FREE) {
+ worker->flags &= ~IO_WORKER_F_FREE;
+ hlist_nulls_del_init_rcu(&worker->nulls_node);
+ }
+}
+
+/*
+ * 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(wqe->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(&wqe->lock);
+ unstalled = io_wait_on_hash(wqe, stall_hash);
+ raw_spin_lock(&wqe->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 (test_thread_flag(TIF_NOTIFY_SIGNAL) || current->task_works) {
+ __set_current_state(TASK_RUNNING);
+ tracehook_notify_signal();
+ 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();
+ }
+
+ spin_lock(&worker->lock);
+ worker->cur_work = work;
+ 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)
+ __releases(wqe->lock)
+{
+ 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;
+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(acct, worker);
+ if (work)
+ __io_worker_busy(wqe, worker, work);
+
+ raw_spin_unlock(&wqe->lock);
+ if (!work)
+ 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);
+ raw_spin_lock(&wqe->lock);
+ /* skip unnecessary unlock-lock wqe->lock */
+ if (!work)
+ goto get_next;
+ raw_spin_unlock(&wqe->lock);
+ }
+ } while (work);
+
+ raw_spin_lock(&wqe->lock);
+ } 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);
+
+ while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
+ long ret;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+loop:
+ raw_spin_lock(&wqe->lock);
+ if (io_acct_run_queue(acct)) {
+ io_worker_handle_work(worker);
+ goto loop;
+ }
+ /* 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)) {
+ raw_spin_lock(&wqe->lock);
+ io_worker_handle_work(worker);
+ }
+
+ 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->pf_io_worker;
+
+ 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->pf_io_worker;
+
+ 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;
+
+ raw_spin_lock(&worker->wqe->lock);
+ io_wqe_dec_running(worker);
+ raw_spin_unlock(&worker->wqe->lock);
+}
+
+static void io_init_new_worker(struct io_wqe *wqe, struct io_worker *worker,
+ struct task_struct *tsk)
+{
+ tsk->pf_io_worker = 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,
+ };
+
+ while (io_acct_cancel_pending_work(wqe, acct, &match))
+ raw_spin_lock(&wqe->lock);
+ }
+ 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;
+ 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);
+ 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(&wqe->lock);
+ io_wqe_insert_work(wqe, work);
+ clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+
+ 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);
+ /* fatal condition, failed to create the first worker */
+ if (!acct->nr_workers) {
+ struct io_cb_cancel_data match = {
+ .fn = io_wq_work_match_item,
+ .data = work,
+ .cancel_all = false,
+ };
+
+ if (io_acct_cancel_pending_work(wqe, acct, &match))
+ raw_spin_lock(&wqe->lock);
+ }
+ raw_spin_unlock(&wqe->lock);
+ }
+}
+
+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, 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.
+ */
+ spin_lock(&worker->lock);
+ if (worker->cur_work &&
+ match->fn(worker->cur_work, match->data)) {
+ set_notify_signal(worker->task);
+ match->nr_running++;
+ }
+ 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)
+ __releases(wqe->lock)
+{
+ struct io_wq_work_node *node, *prev;
+ struct io_wq_work *work;
+
+ 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(&wqe->lock);
+ io_run_cancel(work, wqe);
+ match->nr_pending++;
+ /* not safe to continue after unlock */
+ return true;
+ }
+
+ return false;
+}
+
+static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
+ struct io_cb_cancel_data *match)
+{
+ int i;
+retry:
+ raw_spin_lock(&wqe->lock);
+ 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;
+ return;
+ }
+ }
+ raw_spin_unlock(&wqe->lock);
+}
+
+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.
+ */
+ 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;
+ }
+
+ /*
+ * 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.
+ */
+ for_each_node(node) {
+ struct io_wqe *wqe = wq->wqes[node];
+
+ io_wqe_cancel_running_work(wqe, &match);
+ 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;
+ wq->wqes[node] = wqe;
+ if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL))
+ goto err;
+ cpumask_copy(wqe->cpu_mask, cpumask_of_node(node));
+ 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);
+ }
+ 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);
+ /*
+ * Only the worker continuation helper has worker allocated and
+ * hence needs freeing.
+ */
+ if (cb->func == create_worker_cont)
+ kfree(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 < 2; 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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-19 14:52:34 +0000