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adeaa3f290
A recent fix stopped clearing PF_IO_WORKER from current->flags on exit,
which meant that we can now call inc/dec running on the worker after it
has been removed if it ends up scheduling in/out as part of exit.
If this happens after an RCU grace period has passed, then the struct
pointed to by current->worker_private may have been freed, and we can
now be accessing memory that is freed.
Ensure this doesn't happen by clearing the task worker_private field.
Both io_wq_worker_running() and io_wq_worker_sleeping() check this
field before going any further, and we don't need any accounting etc
done after this worker has exited.
Fixes: fd37b88400
("io_uring/io-wq: don't clear PF_IO_WORKER on exit")
Reported-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1352 lines
32 KiB
C
1352 lines
32 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Basic worker thread pool for io_uring
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*
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* Copyright (C) 2019 Jens Axboe
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*
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/sched/signal.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/rculist_nulls.h>
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#include <linux/cpu.h>
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#include <linux/task_work.h>
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#include <linux/audit.h>
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#include <linux/mmu_context.h>
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#include <uapi/linux/io_uring.h>
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#include "io-wq.h"
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#include "slist.h"
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#include "io_uring.h"
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#define WORKER_IDLE_TIMEOUT (5 * HZ)
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enum {
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IO_WORKER_F_UP = 1, /* up and active */
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IO_WORKER_F_RUNNING = 2, /* account as running */
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IO_WORKER_F_FREE = 4, /* worker on free list */
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IO_WORKER_F_BOUND = 8, /* is doing bounded work */
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};
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enum {
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IO_WQ_BIT_EXIT = 0, /* wq exiting */
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};
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enum {
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IO_ACCT_STALLED_BIT = 0, /* stalled on hash */
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};
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/*
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* One for each thread in a wq pool
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*/
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struct io_worker {
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refcount_t ref;
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unsigned flags;
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struct hlist_nulls_node nulls_node;
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struct list_head all_list;
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struct task_struct *task;
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struct io_wq *wq;
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struct io_wq_work *cur_work;
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struct io_wq_work *next_work;
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raw_spinlock_t lock;
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struct completion ref_done;
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unsigned long create_state;
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struct callback_head create_work;
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int create_index;
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union {
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struct rcu_head rcu;
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struct work_struct work;
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};
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};
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#if BITS_PER_LONG == 64
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#define IO_WQ_HASH_ORDER 6
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#else
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#define IO_WQ_HASH_ORDER 5
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#endif
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#define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
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struct io_wq_acct {
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unsigned nr_workers;
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unsigned max_workers;
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int index;
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atomic_t nr_running;
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raw_spinlock_t lock;
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struct io_wq_work_list work_list;
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unsigned long flags;
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};
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enum {
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IO_WQ_ACCT_BOUND,
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IO_WQ_ACCT_UNBOUND,
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IO_WQ_ACCT_NR,
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};
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/*
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* Per io_wq state
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*/
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struct io_wq {
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unsigned long state;
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free_work_fn *free_work;
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io_wq_work_fn *do_work;
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struct io_wq_hash *hash;
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atomic_t worker_refs;
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struct completion worker_done;
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struct hlist_node cpuhp_node;
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struct task_struct *task;
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struct io_wq_acct acct[IO_WQ_ACCT_NR];
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/* lock protects access to elements below */
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raw_spinlock_t lock;
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struct hlist_nulls_head free_list;
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struct list_head all_list;
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struct wait_queue_entry wait;
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struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
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cpumask_var_t cpu_mask;
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};
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static enum cpuhp_state io_wq_online;
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struct io_cb_cancel_data {
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work_cancel_fn *fn;
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void *data;
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int nr_running;
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int nr_pending;
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bool cancel_all;
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};
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static bool create_io_worker(struct io_wq *wq, int index);
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static void io_wq_dec_running(struct io_worker *worker);
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static bool io_acct_cancel_pending_work(struct io_wq *wq,
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struct io_wq_acct *acct,
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struct io_cb_cancel_data *match);
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static void create_worker_cb(struct callback_head *cb);
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static void io_wq_cancel_tw_create(struct io_wq *wq);
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static bool io_worker_get(struct io_worker *worker)
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{
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return refcount_inc_not_zero(&worker->ref);
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}
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static void io_worker_release(struct io_worker *worker)
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{
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if (refcount_dec_and_test(&worker->ref))
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complete(&worker->ref_done);
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}
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static inline struct io_wq_acct *io_get_acct(struct io_wq *wq, bool bound)
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{
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return &wq->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
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}
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static inline struct io_wq_acct *io_work_get_acct(struct io_wq *wq,
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struct io_wq_work *work)
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{
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return io_get_acct(wq, !(work->flags & IO_WQ_WORK_UNBOUND));
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}
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static inline struct io_wq_acct *io_wq_get_acct(struct io_worker *worker)
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{
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return io_get_acct(worker->wq, worker->flags & IO_WORKER_F_BOUND);
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}
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static void io_worker_ref_put(struct io_wq *wq)
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{
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if (atomic_dec_and_test(&wq->worker_refs))
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complete(&wq->worker_done);
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}
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static void io_worker_cancel_cb(struct io_worker *worker)
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{
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struct io_wq_acct *acct = io_wq_get_acct(worker);
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struct io_wq *wq = worker->wq;
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atomic_dec(&acct->nr_running);
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raw_spin_lock(&wq->lock);
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acct->nr_workers--;
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raw_spin_unlock(&wq->lock);
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io_worker_ref_put(wq);
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clear_bit_unlock(0, &worker->create_state);
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io_worker_release(worker);
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}
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static bool io_task_worker_match(struct callback_head *cb, void *data)
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{
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struct io_worker *worker;
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if (cb->func != create_worker_cb)
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return false;
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worker = container_of(cb, struct io_worker, create_work);
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return worker == data;
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}
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static void io_worker_exit(struct io_worker *worker)
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{
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struct io_wq *wq = worker->wq;
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while (1) {
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struct callback_head *cb = task_work_cancel_match(wq->task,
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io_task_worker_match, worker);
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if (!cb)
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break;
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io_worker_cancel_cb(worker);
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}
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io_worker_release(worker);
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wait_for_completion(&worker->ref_done);
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raw_spin_lock(&wq->lock);
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if (worker->flags & IO_WORKER_F_FREE)
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hlist_nulls_del_rcu(&worker->nulls_node);
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list_del_rcu(&worker->all_list);
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raw_spin_unlock(&wq->lock);
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io_wq_dec_running(worker);
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/*
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* this worker is a goner, clear ->worker_private to avoid any
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* inc/dec running calls that could happen as part of exit from
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* touching 'worker'.
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*/
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current->worker_private = NULL;
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kfree_rcu(worker, rcu);
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io_worker_ref_put(wq);
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do_exit(0);
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}
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static inline bool io_acct_run_queue(struct io_wq_acct *acct)
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{
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bool ret = false;
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raw_spin_lock(&acct->lock);
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if (!wq_list_empty(&acct->work_list) &&
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!test_bit(IO_ACCT_STALLED_BIT, &acct->flags))
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ret = true;
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raw_spin_unlock(&acct->lock);
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return ret;
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}
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/*
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* Check head of free list for an available worker. If one isn't available,
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* caller must create one.
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*/
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static bool io_wq_activate_free_worker(struct io_wq *wq,
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struct io_wq_acct *acct)
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__must_hold(RCU)
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{
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struct hlist_nulls_node *n;
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struct io_worker *worker;
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/*
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* Iterate free_list and see if we can find an idle worker to
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* activate. If a given worker is on the free_list but in the process
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* of exiting, keep trying.
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*/
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hlist_nulls_for_each_entry_rcu(worker, n, &wq->free_list, nulls_node) {
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if (!io_worker_get(worker))
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continue;
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if (io_wq_get_acct(worker) != acct) {
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io_worker_release(worker);
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continue;
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}
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if (wake_up_process(worker->task)) {
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io_worker_release(worker);
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return true;
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}
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io_worker_release(worker);
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}
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return false;
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}
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/*
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* We need a worker. If we find a free one, we're good. If not, and we're
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* below the max number of workers, create one.
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*/
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static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct)
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{
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/*
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* Most likely an attempt to queue unbounded work on an io_wq that
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* wasn't setup with any unbounded workers.
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*/
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if (unlikely(!acct->max_workers))
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pr_warn_once("io-wq is not configured for unbound workers");
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raw_spin_lock(&wq->lock);
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if (acct->nr_workers >= acct->max_workers) {
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raw_spin_unlock(&wq->lock);
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return true;
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}
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acct->nr_workers++;
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raw_spin_unlock(&wq->lock);
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atomic_inc(&acct->nr_running);
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atomic_inc(&wq->worker_refs);
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return create_io_worker(wq, acct->index);
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}
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static void io_wq_inc_running(struct io_worker *worker)
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{
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struct io_wq_acct *acct = io_wq_get_acct(worker);
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atomic_inc(&acct->nr_running);
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}
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static void create_worker_cb(struct callback_head *cb)
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{
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struct io_worker *worker;
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struct io_wq *wq;
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struct io_wq_acct *acct;
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bool do_create = false;
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worker = container_of(cb, struct io_worker, create_work);
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wq = worker->wq;
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acct = &wq->acct[worker->create_index];
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raw_spin_lock(&wq->lock);
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if (acct->nr_workers < acct->max_workers) {
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acct->nr_workers++;
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do_create = true;
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}
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raw_spin_unlock(&wq->lock);
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if (do_create) {
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create_io_worker(wq, worker->create_index);
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} else {
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atomic_dec(&acct->nr_running);
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io_worker_ref_put(wq);
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}
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clear_bit_unlock(0, &worker->create_state);
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io_worker_release(worker);
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}
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static bool io_queue_worker_create(struct io_worker *worker,
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struct io_wq_acct *acct,
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task_work_func_t func)
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{
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struct io_wq *wq = worker->wq;
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/* raced with exit, just ignore create call */
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if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
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goto fail;
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if (!io_worker_get(worker))
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goto fail;
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/*
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* create_state manages ownership of create_work/index. We should
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* only need one entry per worker, as the worker going to sleep
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* will trigger the condition, and waking will clear it once it
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* runs the task_work.
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*/
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if (test_bit(0, &worker->create_state) ||
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test_and_set_bit_lock(0, &worker->create_state))
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goto fail_release;
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atomic_inc(&wq->worker_refs);
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init_task_work(&worker->create_work, func);
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worker->create_index = acct->index;
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if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
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/*
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* EXIT may have been set after checking it above, check after
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* adding the task_work and remove any creation item if it is
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* now set. wq exit does that too, but we can have added this
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* work item after we canceled in io_wq_exit_workers().
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*/
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if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
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io_wq_cancel_tw_create(wq);
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io_worker_ref_put(wq);
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return true;
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}
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io_worker_ref_put(wq);
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clear_bit_unlock(0, &worker->create_state);
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fail_release:
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io_worker_release(worker);
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fail:
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atomic_dec(&acct->nr_running);
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io_worker_ref_put(wq);
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return false;
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}
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static void io_wq_dec_running(struct io_worker *worker)
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{
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struct io_wq_acct *acct = io_wq_get_acct(worker);
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struct io_wq *wq = worker->wq;
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if (!(worker->flags & IO_WORKER_F_UP))
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return;
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if (!atomic_dec_and_test(&acct->nr_running))
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return;
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if (!io_acct_run_queue(acct))
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return;
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atomic_inc(&acct->nr_running);
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atomic_inc(&wq->worker_refs);
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io_queue_worker_create(worker, acct, create_worker_cb);
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}
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/*
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* Worker will start processing some work. Move it to the busy list, if
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* it's currently on the freelist
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*/
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static void __io_worker_busy(struct io_wq *wq, struct io_worker *worker)
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{
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if (worker->flags & IO_WORKER_F_FREE) {
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worker->flags &= ~IO_WORKER_F_FREE;
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raw_spin_lock(&wq->lock);
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hlist_nulls_del_init_rcu(&worker->nulls_node);
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raw_spin_unlock(&wq->lock);
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}
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}
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/*
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* No work, worker going to sleep. Move to freelist.
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*/
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static void __io_worker_idle(struct io_wq *wq, struct io_worker *worker)
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__must_hold(wq->lock)
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{
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if (!(worker->flags & IO_WORKER_F_FREE)) {
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worker->flags |= IO_WORKER_F_FREE;
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hlist_nulls_add_head_rcu(&worker->nulls_node, &wq->free_list);
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}
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}
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static inline unsigned int io_get_work_hash(struct io_wq_work *work)
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{
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return work->flags >> IO_WQ_HASH_SHIFT;
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}
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static bool io_wait_on_hash(struct io_wq *wq, unsigned int hash)
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{
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bool ret = false;
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spin_lock_irq(&wq->hash->wait.lock);
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if (list_empty(&wq->wait.entry)) {
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__add_wait_queue(&wq->hash->wait, &wq->wait);
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if (!test_bit(hash, &wq->hash->map)) {
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__set_current_state(TASK_RUNNING);
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list_del_init(&wq->wait.entry);
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ret = true;
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}
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}
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spin_unlock_irq(&wq->hash->wait.lock);
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return ret;
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}
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static struct io_wq_work *io_get_next_work(struct io_wq_acct *acct,
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struct io_worker *worker)
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__must_hold(acct->lock)
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{
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struct io_wq_work_node *node, *prev;
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struct io_wq_work *work, *tail;
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unsigned int stall_hash = -1U;
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struct io_wq *wq = worker->wq;
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wq_list_for_each(node, prev, &acct->work_list) {
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unsigned int hash;
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work = container_of(node, struct io_wq_work, list);
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/* not hashed, can run anytime */
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if (!io_wq_is_hashed(work)) {
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wq_list_del(&acct->work_list, node, prev);
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return work;
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}
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hash = io_get_work_hash(work);
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/* all items with this hash lie in [work, tail] */
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tail = wq->hash_tail[hash];
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/* hashed, can run if not already running */
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if (!test_and_set_bit(hash, &wq->hash->map)) {
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wq->hash_tail[hash] = NULL;
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wq_list_cut(&acct->work_list, &tail->list, prev);
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return work;
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}
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if (stall_hash == -1U)
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stall_hash = hash;
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/* fast forward to a next hash, for-each will fix up @prev */
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node = &tail->list;
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}
|
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|
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if (stall_hash != -1U) {
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bool unstalled;
|
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|
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/*
|
|
* Set this before dropping the lock to avoid racing with new
|
|
* work being added and clearing the stalled bit.
|
|
*/
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set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
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|
raw_spin_unlock(&acct->lock);
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|
unstalled = io_wait_on_hash(wq, stall_hash);
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raw_spin_lock(&acct->lock);
|
|
if (unstalled) {
|
|
clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
|
|
if (wq_has_sleeper(&wq->hash->wait))
|
|
wake_up(&wq->hash->wait);
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void io_assign_current_work(struct io_worker *worker,
|
|
struct io_wq_work *work)
|
|
{
|
|
if (work) {
|
|
io_run_task_work();
|
|
cond_resched();
|
|
}
|
|
|
|
raw_spin_lock(&worker->lock);
|
|
worker->cur_work = work;
|
|
worker->next_work = NULL;
|
|
raw_spin_unlock(&worker->lock);
|
|
}
|
|
|
|
static void io_worker_handle_work(struct io_worker *worker)
|
|
{
|
|
struct io_wq_acct *acct = io_wq_get_acct(worker);
|
|
struct io_wq *wq = worker->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(wq, 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_wq_enqueue(wq, 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_wq_worker(void *data)
|
|
{
|
|
struct io_worker *worker = data;
|
|
struct io_wq_acct *acct = io_wq_get_acct(worker);
|
|
struct io_wq *wq = worker->wq;
|
|
bool exit_mask = false, 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);
|
|
while (io_acct_run_queue(acct))
|
|
io_worker_handle_work(worker);
|
|
|
|
raw_spin_lock(&wq->lock);
|
|
/*
|
|
* Last sleep timed out. Exit if we're not the last worker,
|
|
* or if someone modified our affinity.
|
|
*/
|
|
if (last_timeout && (exit_mask || acct->nr_workers > 1)) {
|
|
acct->nr_workers--;
|
|
raw_spin_unlock(&wq->lock);
|
|
__set_current_state(TASK_RUNNING);
|
|
break;
|
|
}
|
|
last_timeout = false;
|
|
__io_worker_idle(wq, worker);
|
|
raw_spin_unlock(&wq->lock);
|
|
if (io_run_task_work())
|
|
continue;
|
|
ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
|
|
if (signal_pending(current)) {
|
|
struct ksignal ksig;
|
|
|
|
if (!get_signal(&ksig))
|
|
continue;
|
|
break;
|
|
}
|
|
if (!ret) {
|
|
last_timeout = true;
|
|
exit_mask = !cpumask_test_cpu(raw_smp_processor_id(),
|
|
wq->cpu_mask);
|
|
}
|
|
}
|
|
|
|
if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
|
|
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->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_wq_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_wq_dec_running(worker);
|
|
}
|
|
|
|
static void io_init_new_worker(struct io_wq *wq, struct io_worker *worker,
|
|
struct task_struct *tsk)
|
|
{
|
|
tsk->worker_private = worker;
|
|
worker->task = tsk;
|
|
set_cpus_allowed_ptr(tsk, wq->cpu_mask);
|
|
|
|
raw_spin_lock(&wq->lock);
|
|
hlist_nulls_add_head_rcu(&worker->nulls_node, &wq->free_list);
|
|
list_add_tail_rcu(&worker->all_list, &wq->all_list);
|
|
worker->flags |= IO_WORKER_F_FREE;
|
|
raw_spin_unlock(&wq->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_wq *wq;
|
|
|
|
worker = container_of(cb, struct io_worker, create_work);
|
|
clear_bit_unlock(0, &worker->create_state);
|
|
wq = worker->wq;
|
|
tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
|
|
if (!IS_ERR(tsk)) {
|
|
io_init_new_worker(wq, worker, tsk);
|
|
io_worker_release(worker);
|
|
return;
|
|
} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
|
|
struct io_wq_acct *acct = io_wq_get_acct(worker);
|
|
|
|
atomic_dec(&acct->nr_running);
|
|
raw_spin_lock(&wq->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(&wq->lock);
|
|
while (io_acct_cancel_pending_work(wq, acct, &match))
|
|
;
|
|
} else {
|
|
raw_spin_unlock(&wq->lock);
|
|
}
|
|
io_worker_ref_put(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_wq_acct *acct = io_wq_get_acct(worker);
|
|
|
|
if (!io_queue_worker_create(worker, acct, create_worker_cont))
|
|
kfree(worker);
|
|
}
|
|
|
|
static bool create_io_worker(struct io_wq *wq, int index)
|
|
{
|
|
struct io_wq_acct *acct = &wq->acct[index];
|
|
struct io_worker *worker;
|
|
struct task_struct *tsk;
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
worker = kzalloc(sizeof(*worker), GFP_KERNEL);
|
|
if (!worker) {
|
|
fail:
|
|
atomic_dec(&acct->nr_running);
|
|
raw_spin_lock(&wq->lock);
|
|
acct->nr_workers--;
|
|
raw_spin_unlock(&wq->lock);
|
|
io_worker_ref_put(wq);
|
|
return false;
|
|
}
|
|
|
|
refcount_set(&worker->ref, 1);
|
|
worker->wq = wq;
|
|
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_wq_worker, worker, NUMA_NO_NODE);
|
|
if (!IS_ERR(tsk)) {
|
|
io_init_new_worker(wq, 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_wq *wq,
|
|
bool (*func)(struct io_worker *, void *),
|
|
void *data)
|
|
{
|
|
struct io_worker *worker;
|
|
bool ret = false;
|
|
|
|
list_for_each_entry_rcu(worker, &wq->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_wq *wq)
|
|
{
|
|
do {
|
|
work->flags |= IO_WQ_WORK_CANCEL;
|
|
wq->do_work(work);
|
|
work = wq->free_work(work);
|
|
} while (work);
|
|
}
|
|
|
|
static void io_wq_insert_work(struct io_wq *wq, struct io_wq_work *work)
|
|
{
|
|
struct io_wq_acct *acct = io_work_get_acct(wq, 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 = wq->hash_tail[hash];
|
|
wq->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;
|
|
}
|
|
|
|
void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
|
|
{
|
|
struct io_wq_acct *acct = io_work_get_acct(wq, 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, &wq->state) ||
|
|
(work->flags & IO_WQ_WORK_CANCEL)) {
|
|
io_run_cancel(work, wq);
|
|
return;
|
|
}
|
|
|
|
raw_spin_lock(&acct->lock);
|
|
io_wq_insert_work(wq, work);
|
|
clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
|
|
raw_spin_unlock(&acct->lock);
|
|
|
|
raw_spin_lock(&wq->lock);
|
|
rcu_read_lock();
|
|
do_create = !io_wq_activate_free_worker(wq, acct);
|
|
rcu_read_unlock();
|
|
|
|
raw_spin_unlock(&wq->lock);
|
|
|
|
if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
|
|
!atomic_read(&acct->nr_running))) {
|
|
bool did_create;
|
|
|
|
did_create = io_wq_create_worker(wq, acct);
|
|
if (likely(did_create))
|
|
return;
|
|
|
|
raw_spin_lock(&wq->lock);
|
|
if (acct->nr_workers) {
|
|
raw_spin_unlock(&wq->lock);
|
|
return;
|
|
}
|
|
raw_spin_unlock(&wq->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(wq, acct, &match);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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_wq_remove_pending(struct io_wq *wq,
|
|
struct io_wq_work *work,
|
|
struct io_wq_work_node *prev)
|
|
{
|
|
struct io_wq_acct *acct = io_work_get_acct(wq, work);
|
|
unsigned int hash = io_get_work_hash(work);
|
|
struct io_wq_work *prev_work = NULL;
|
|
|
|
if (io_wq_is_hashed(work) && work == wq->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)
|
|
wq->hash_tail[hash] = prev_work;
|
|
else
|
|
wq->hash_tail[hash] = NULL;
|
|
}
|
|
wq_list_del(&acct->work_list, &work->list, prev);
|
|
}
|
|
|
|
static bool io_acct_cancel_pending_work(struct io_wq *wq,
|
|
struct io_wq_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_wq_remove_pending(wq, work, prev);
|
|
raw_spin_unlock(&acct->lock);
|
|
io_run_cancel(work, wq);
|
|
match->nr_pending++;
|
|
/* not safe to continue after unlock */
|
|
return true;
|
|
}
|
|
raw_spin_unlock(&acct->lock);
|
|
|
|
return false;
|
|
}
|
|
|
|
static void io_wq_cancel_pending_work(struct io_wq *wq,
|
|
struct io_cb_cancel_data *match)
|
|
{
|
|
int i;
|
|
retry:
|
|
for (i = 0; i < IO_WQ_ACCT_NR; i++) {
|
|
struct io_wq_acct *acct = io_get_acct(wq, i == 0);
|
|
|
|
if (io_acct_cancel_pending_work(wq, acct, match)) {
|
|
if (match->cancel_all)
|
|
goto retry;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void io_wq_cancel_running_work(struct io_wq *wq,
|
|
struct io_cb_cancel_data *match)
|
|
{
|
|
rcu_read_lock();
|
|
io_wq_for_each_worker(wq, 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,
|
|
};
|
|
|
|
/*
|
|
* 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 wq->lock, to ensure that
|
|
* we'll find a work item regardless of state.
|
|
*/
|
|
io_wq_cancel_pending_work(wq, &match);
|
|
if (match.nr_pending && !match.cancel_all)
|
|
return IO_WQ_CANCEL_OK;
|
|
|
|
raw_spin_lock(&wq->lock);
|
|
io_wq_cancel_running_work(wq, &match);
|
|
raw_spin_unlock(&wq->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_wq_hash_wake(struct wait_queue_entry *wait, unsigned mode,
|
|
int sync, void *key)
|
|
{
|
|
struct io_wq *wq = container_of(wait, struct io_wq, wait);
|
|
int i;
|
|
|
|
list_del_init(&wait->entry);
|
|
|
|
rcu_read_lock();
|
|
for (i = 0; i < IO_WQ_ACCT_NR; i++) {
|
|
struct io_wq_acct *acct = &wq->acct[i];
|
|
|
|
if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags))
|
|
io_wq_activate_free_worker(wq, acct);
|
|
}
|
|
rcu_read_unlock();
|
|
return 1;
|
|
}
|
|
|
|
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
|
|
{
|
|
int ret, 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(sizeof(struct io_wq), 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;
|
|
|
|
if (!alloc_cpumask_var(&wq->cpu_mask, GFP_KERNEL))
|
|
goto err;
|
|
cpumask_copy(wq->cpu_mask, cpu_possible_mask);
|
|
wq->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
|
|
wq->acct[IO_WQ_ACCT_UNBOUND].max_workers =
|
|
task_rlimit(current, RLIMIT_NPROC);
|
|
INIT_LIST_HEAD(&wq->wait.entry);
|
|
wq->wait.func = io_wq_hash_wake;
|
|
for (i = 0; i < IO_WQ_ACCT_NR; i++) {
|
|
struct io_wq_acct *acct = &wq->acct[i];
|
|
|
|
acct->index = i;
|
|
atomic_set(&acct->nr_running, 0);
|
|
INIT_WQ_LIST(&acct->work_list);
|
|
raw_spin_lock_init(&acct->lock);
|
|
}
|
|
|
|
raw_spin_lock_init(&wq->lock);
|
|
INIT_HLIST_NULLS_HEAD(&wq->free_list, 0);
|
|
INIT_LIST_HEAD(&wq->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);
|
|
|
|
free_cpumask_var(wq->cpu_mask);
|
|
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->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)
|
|
{
|
|
if (!wq->task)
|
|
return;
|
|
|
|
io_wq_cancel_tw_create(wq);
|
|
|
|
rcu_read_lock();
|
|
io_wq_for_each_worker(wq, io_wq_worker_wake, NULL);
|
|
rcu_read_unlock();
|
|
io_worker_ref_put(wq);
|
|
wait_for_completion(&wq->worker_done);
|
|
|
|
spin_lock_irq(&wq->hash->wait.lock);
|
|
list_del_init(&wq->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)
|
|
{
|
|
struct io_cb_cancel_data match = {
|
|
.fn = io_wq_work_match_all,
|
|
.cancel_all = true,
|
|
};
|
|
|
|
cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
|
|
io_wq_cancel_pending_work(wq, &match);
|
|
free_cpumask_var(wq->cpu_mask);
|
|
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->wq->cpu_mask);
|
|
else
|
|
cpumask_clear_cpu(od->cpu, worker->wq->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
|
|
};
|
|
|
|
rcu_read_lock();
|
|
io_wq_for_each_worker(wq, 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)
|
|
{
|
|
rcu_read_lock();
|
|
if (mask)
|
|
cpumask_copy(wq->cpu_mask, mask);
|
|
else
|
|
cpumask_copy(wq->cpu_mask, cpu_possible_mask);
|
|
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)
|
|
{
|
|
struct io_wq_acct *acct;
|
|
int prev[IO_WQ_ACCT_NR];
|
|
int i;
|
|
|
|
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();
|
|
|
|
raw_spin_lock(&wq->lock);
|
|
for (i = 0; i < IO_WQ_ACCT_NR; i++) {
|
|
acct = &wq->acct[i];
|
|
prev[i] = max_t(int, acct->max_workers, prev[i]);
|
|
if (new_count[i])
|
|
acct->max_workers = new_count[i];
|
|
}
|
|
raw_spin_unlock(&wq->lock);
|
|
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);
|