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![Jens Axboe](/assets/img/avatar_default.png)
If the original task is (or has) exited, then the task work will not get queued properly. Allow for using the io-wq manager task to queue this work for execution, and ensure that the io-wq manager notices and runs this work if woken up (or exiting). Reported-by: Dan Melnic <dmm@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
1138 lines
27 KiB
C
1138 lines
27 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/mm.h>
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#include <linux/mmu_context.h>
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#include <linux/sched/mm.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/kthread.h>
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#include <linux/rculist_nulls.h>
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#include <linux/fs_struct.h>
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#include <linux/task_work.h>
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#include "io-wq.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_EXITING = 8, /* worker exiting */
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IO_WORKER_F_FIXED = 16, /* static idle worker */
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IO_WORKER_F_BOUND = 32, /* 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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IO_WQ_BIT_CANCEL = 1, /* cancel work on list */
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IO_WQ_BIT_ERROR = 2, /* error on setup */
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};
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enum {
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IO_WQE_FLAG_STALLED = 1, /* stalled on hash */
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};
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/*
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* One for each thread in a wqe 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_wqe *wqe;
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struct io_wq_work *cur_work;
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spinlock_t lock;
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struct rcu_head rcu;
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struct mm_struct *mm;
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const struct cred *cur_creds;
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const struct cred *saved_creds;
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struct files_struct *restore_files;
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struct fs_struct *restore_fs;
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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_wqe_acct {
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unsigned nr_workers;
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unsigned max_workers;
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atomic_t nr_running;
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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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};
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/*
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* Per-node worker thread pool
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*/
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struct io_wqe {
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struct {
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spinlock_t lock;
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struct io_wq_work_list work_list;
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unsigned long hash_map;
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unsigned flags;
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} ____cacheline_aligned_in_smp;
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int node;
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struct io_wqe_acct acct[2];
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struct hlist_nulls_head free_list;
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struct list_head all_list;
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struct io_wq *wq;
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struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
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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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struct io_wqe **wqes;
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unsigned long state;
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free_work_fn *free_work;
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struct task_struct *manager;
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struct user_struct *user;
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refcount_t refs;
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struct completion done;
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refcount_t use_refs;
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};
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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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wake_up_process(worker->task);
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}
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/*
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* Note: drops the wqe->lock if returning true! The caller must re-acquire
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* the lock in that case. Some callers need to restart handling if this
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* happens, so we can't just re-acquire the lock on behalf of the caller.
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*/
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static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker)
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{
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bool dropped_lock = false;
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if (worker->saved_creds) {
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revert_creds(worker->saved_creds);
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worker->cur_creds = worker->saved_creds = NULL;
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}
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if (current->files != worker->restore_files) {
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__acquire(&wqe->lock);
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spin_unlock_irq(&wqe->lock);
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dropped_lock = true;
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task_lock(current);
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current->files = worker->restore_files;
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task_unlock(current);
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}
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if (current->fs != worker->restore_fs)
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current->fs = worker->restore_fs;
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/*
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* If we have an active mm, we need to drop the wq lock before unusing
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* it. If we do, return true and let the caller retry the idle loop.
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*/
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if (worker->mm) {
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if (!dropped_lock) {
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__acquire(&wqe->lock);
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spin_unlock_irq(&wqe->lock);
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dropped_lock = true;
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}
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__set_current_state(TASK_RUNNING);
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set_fs(KERNEL_DS);
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unuse_mm(worker->mm);
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mmput(worker->mm);
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worker->mm = NULL;
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}
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return dropped_lock;
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}
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static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
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struct io_wq_work *work)
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{
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if (work->flags & IO_WQ_WORK_UNBOUND)
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return &wqe->acct[IO_WQ_ACCT_UNBOUND];
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return &wqe->acct[IO_WQ_ACCT_BOUND];
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}
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static inline struct io_wqe_acct *io_wqe_get_acct(struct io_wqe *wqe,
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struct io_worker *worker)
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{
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if (worker->flags & IO_WORKER_F_BOUND)
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return &wqe->acct[IO_WQ_ACCT_BOUND];
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return &wqe->acct[IO_WQ_ACCT_UNBOUND];
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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_wqe *wqe = worker->wqe;
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struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
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unsigned nr_workers;
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/*
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* If we're not at zero, someone else is holding a brief reference
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* to the worker. Wait for that to go away.
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*/
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set_current_state(TASK_INTERRUPTIBLE);
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if (!refcount_dec_and_test(&worker->ref))
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schedule();
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__set_current_state(TASK_RUNNING);
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preempt_disable();
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current->flags &= ~PF_IO_WORKER;
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if (worker->flags & IO_WORKER_F_RUNNING)
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atomic_dec(&acct->nr_running);
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if (!(worker->flags & IO_WORKER_F_BOUND))
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atomic_dec(&wqe->wq->user->processes);
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worker->flags = 0;
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preempt_enable();
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spin_lock_irq(&wqe->lock);
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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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if (__io_worker_unuse(wqe, worker)) {
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__release(&wqe->lock);
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spin_lock_irq(&wqe->lock);
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}
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acct->nr_workers--;
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nr_workers = wqe->acct[IO_WQ_ACCT_BOUND].nr_workers +
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wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers;
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spin_unlock_irq(&wqe->lock);
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/* all workers gone, wq exit can proceed */
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if (!nr_workers && refcount_dec_and_test(&wqe->wq->refs))
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complete(&wqe->wq->done);
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kfree_rcu(worker, rcu);
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}
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static inline bool io_wqe_run_queue(struct io_wqe *wqe)
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__must_hold(wqe->lock)
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{
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if (!wq_list_empty(&wqe->work_list) &&
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!(wqe->flags & IO_WQE_FLAG_STALLED))
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return true;
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return false;
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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 wake up the wq manager to create one.
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*/
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static bool io_wqe_activate_free_worker(struct io_wqe *wqe)
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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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n = rcu_dereference(hlist_nulls_first_rcu(&wqe->free_list));
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if (is_a_nulls(n))
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return false;
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worker = hlist_nulls_entry(n, struct io_worker, nulls_node);
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if (io_worker_get(worker)) {
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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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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, wake up the manager to create one.
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*/
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static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
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{
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bool ret;
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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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WARN_ON_ONCE(!acct->max_workers);
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rcu_read_lock();
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ret = io_wqe_activate_free_worker(wqe);
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rcu_read_unlock();
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if (!ret && acct->nr_workers < acct->max_workers)
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wake_up_process(wqe->wq->manager);
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}
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static void io_wqe_inc_running(struct io_wqe *wqe, struct io_worker *worker)
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{
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struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
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atomic_inc(&acct->nr_running);
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}
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static void io_wqe_dec_running(struct io_wqe *wqe, struct io_worker *worker)
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__must_hold(wqe->lock)
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{
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struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
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if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe))
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io_wqe_wake_worker(wqe, acct);
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}
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static void io_worker_start(struct io_wqe *wqe, struct io_worker *worker)
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{
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allow_kernel_signal(SIGINT);
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current->flags |= PF_IO_WORKER;
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worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
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worker->restore_files = current->files;
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worker->restore_fs = current->fs;
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io_wqe_inc_running(wqe, worker);
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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_wqe *wqe, struct io_worker *worker,
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struct io_wq_work *work)
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__must_hold(wqe->lock)
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{
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bool worker_bound, work_bound;
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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_del_init_rcu(&worker->nulls_node);
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}
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/*
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* If worker is moving from bound to unbound (or vice versa), then
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* ensure we update the running accounting.
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*/
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worker_bound = (worker->flags & IO_WORKER_F_BOUND) != 0;
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work_bound = (work->flags & IO_WQ_WORK_UNBOUND) == 0;
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if (worker_bound != work_bound) {
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io_wqe_dec_running(wqe, worker);
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if (work_bound) {
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worker->flags |= IO_WORKER_F_BOUND;
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wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers--;
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wqe->acct[IO_WQ_ACCT_BOUND].nr_workers++;
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atomic_dec(&wqe->wq->user->processes);
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} else {
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worker->flags &= ~IO_WORKER_F_BOUND;
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wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers++;
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wqe->acct[IO_WQ_ACCT_BOUND].nr_workers--;
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atomic_inc(&wqe->wq->user->processes);
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}
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io_wqe_inc_running(wqe, worker);
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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, and unuse mm if we
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* have one attached. Dropping the mm may potentially sleep, so we drop
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* the lock in that case and return success. Since the caller has to
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* retry the loop in that case (we changed task state), we don't regrab
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* the lock if we return success.
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*/
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static bool __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
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__must_hold(wqe->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, &wqe->free_list);
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}
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return __io_worker_unuse(wqe, worker);
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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 struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
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__must_hold(wqe->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 hash;
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wq_list_for_each(node, prev, &wqe->work_list) {
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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(&wqe->work_list, node, prev);
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return work;
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}
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/* hashed, can run if not already running */
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hash = io_get_work_hash(work);
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if (!(wqe->hash_map & BIT(hash))) {
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wqe->hash_map |= BIT(hash);
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/* all items with this hash lie in [work, tail] */
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tail = wqe->hash_tail[hash];
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wqe->hash_tail[hash] = NULL;
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wq_list_cut(&wqe->work_list, &tail->list, prev);
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return work;
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}
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}
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return NULL;
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}
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static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work)
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{
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if (worker->mm) {
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unuse_mm(worker->mm);
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mmput(worker->mm);
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worker->mm = NULL;
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}
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if (!work->mm) {
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set_fs(KERNEL_DS);
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return;
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}
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if (mmget_not_zero(work->mm)) {
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use_mm(work->mm);
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if (!worker->mm)
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set_fs(USER_DS);
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worker->mm = work->mm;
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/* hang on to this mm */
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work->mm = NULL;
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return;
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}
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/* failed grabbing mm, ensure work gets cancelled */
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work->flags |= IO_WQ_WORK_CANCEL;
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}
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static void io_wq_switch_creds(struct io_worker *worker,
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struct io_wq_work *work)
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{
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const struct cred *old_creds = override_creds(work->creds);
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worker->cur_creds = work->creds;
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if (worker->saved_creds)
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put_cred(old_creds); /* creds set by previous switch */
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else
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worker->saved_creds = old_creds;
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}
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static void io_impersonate_work(struct io_worker *worker,
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struct io_wq_work *work)
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{
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if (work->files && current->files != work->files) {
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task_lock(current);
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current->files = work->files;
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task_unlock(current);
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}
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if (work->fs && current->fs != work->fs)
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current->fs = work->fs;
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if (work->mm != worker->mm)
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io_wq_switch_mm(worker, work);
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if (worker->cur_creds != work->creds)
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io_wq_switch_creds(worker, work);
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}
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static void io_assign_current_work(struct io_worker *worker,
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struct io_wq_work *work)
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{
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if (work) {
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/* flush pending signals before assigning new work */
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if (signal_pending(current))
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flush_signals(current);
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cond_resched();
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}
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spin_lock_irq(&worker->lock);
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worker->cur_work = work;
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spin_unlock_irq(&worker->lock);
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}
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static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
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static void io_worker_handle_work(struct io_worker *worker)
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__releases(wqe->lock)
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{
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struct io_wqe *wqe = worker->wqe;
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struct io_wq *wq = wqe->wq;
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do {
|
|
struct io_wq_work *work;
|
|
unsigned int hash;
|
|
get_next:
|
|
/*
|
|
* If we got some work, mark us as busy. If we didn't, but
|
|
* the list isn't empty, it means we stalled on hashed work.
|
|
* Mark us stalled so we don't keep looking for work when we
|
|
* can't make progress, any work completion or insertion will
|
|
* clear the stalled flag.
|
|
*/
|
|
work = io_get_next_work(wqe);
|
|
if (work)
|
|
__io_worker_busy(wqe, worker, work);
|
|
else if (!wq_list_empty(&wqe->work_list))
|
|
wqe->flags |= IO_WQE_FLAG_STALLED;
|
|
|
|
spin_unlock_irq(&wqe->lock);
|
|
if (!work)
|
|
break;
|
|
io_assign_current_work(worker, work);
|
|
|
|
/* handle a whole dependent link */
|
|
do {
|
|
struct io_wq_work *old_work, *next_hashed, *linked;
|
|
|
|
next_hashed = wq_next_work(work);
|
|
io_impersonate_work(worker, work);
|
|
/*
|
|
* OK to set IO_WQ_WORK_CANCEL even for uncancellable
|
|
* work, the worker function will do the right thing.
|
|
*/
|
|
if (test_bit(IO_WQ_BIT_CANCEL, &wq->state))
|
|
work->flags |= IO_WQ_WORK_CANCEL;
|
|
|
|
hash = io_get_work_hash(work);
|
|
linked = old_work = work;
|
|
linked->func(&linked);
|
|
linked = (old_work == linked) ? NULL : linked;
|
|
|
|
work = next_hashed;
|
|
if (!work && linked && !io_wq_is_hashed(linked)) {
|
|
work = linked;
|
|
linked = NULL;
|
|
}
|
|
io_assign_current_work(worker, work);
|
|
wq->free_work(old_work);
|
|
|
|
if (linked)
|
|
io_wqe_enqueue(wqe, linked);
|
|
|
|
if (hash != -1U && !next_hashed) {
|
|
spin_lock_irq(&wqe->lock);
|
|
wqe->hash_map &= ~BIT_ULL(hash);
|
|
wqe->flags &= ~IO_WQE_FLAG_STALLED;
|
|
/* dependent work is not hashed */
|
|
hash = -1U;
|
|
/* skip unnecessary unlock-lock wqe->lock */
|
|
if (!work)
|
|
goto get_next;
|
|
spin_unlock_irq(&wqe->lock);
|
|
}
|
|
} while (work);
|
|
|
|
spin_lock_irq(&wqe->lock);
|
|
} while (1);
|
|
}
|
|
|
|
static int io_wqe_worker(void *data)
|
|
{
|
|
struct io_worker *worker = data;
|
|
struct io_wqe *wqe = worker->wqe;
|
|
struct io_wq *wq = wqe->wq;
|
|
|
|
io_worker_start(wqe, worker);
|
|
|
|
while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
loop:
|
|
spin_lock_irq(&wqe->lock);
|
|
if (io_wqe_run_queue(wqe)) {
|
|
__set_current_state(TASK_RUNNING);
|
|
io_worker_handle_work(worker);
|
|
goto loop;
|
|
}
|
|
/* drops the lock on success, retry */
|
|
if (__io_worker_idle(wqe, worker)) {
|
|
__release(&wqe->lock);
|
|
goto loop;
|
|
}
|
|
spin_unlock_irq(&wqe->lock);
|
|
if (signal_pending(current))
|
|
flush_signals(current);
|
|
if (schedule_timeout(WORKER_IDLE_TIMEOUT))
|
|
continue;
|
|
/* timed out, exit unless we're the fixed worker */
|
|
if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
|
|
!(worker->flags & IO_WORKER_F_FIXED))
|
|
break;
|
|
}
|
|
|
|
if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
|
|
spin_lock_irq(&wqe->lock);
|
|
if (!wq_list_empty(&wqe->work_list))
|
|
io_worker_handle_work(worker);
|
|
else
|
|
spin_unlock_irq(&wqe->lock);
|
|
}
|
|
|
|
io_worker_exit(worker);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Called when a worker is scheduled in. Mark us as currently running.
|
|
*/
|
|
void io_wq_worker_running(struct task_struct *tsk)
|
|
{
|
|
struct io_worker *worker = kthread_data(tsk);
|
|
struct io_wqe *wqe = worker->wqe;
|
|
|
|
if (!(worker->flags & IO_WORKER_F_UP))
|
|
return;
|
|
if (worker->flags & IO_WORKER_F_RUNNING)
|
|
return;
|
|
worker->flags |= IO_WORKER_F_RUNNING;
|
|
io_wqe_inc_running(wqe, worker);
|
|
}
|
|
|
|
/*
|
|
* Called when worker is going to sleep. If there are no workers currently
|
|
* running and we have work pending, wake up a free one or have the manager
|
|
* set one up.
|
|
*/
|
|
void io_wq_worker_sleeping(struct task_struct *tsk)
|
|
{
|
|
struct io_worker *worker = kthread_data(tsk);
|
|
struct io_wqe *wqe = worker->wqe;
|
|
|
|
if (!(worker->flags & IO_WORKER_F_UP))
|
|
return;
|
|
if (!(worker->flags & IO_WORKER_F_RUNNING))
|
|
return;
|
|
|
|
worker->flags &= ~IO_WORKER_F_RUNNING;
|
|
|
|
spin_lock_irq(&wqe->lock);
|
|
io_wqe_dec_running(wqe, worker);
|
|
spin_unlock_irq(&wqe->lock);
|
|
}
|
|
|
|
static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
|
|
{
|
|
struct io_wqe_acct *acct =&wqe->acct[index];
|
|
struct io_worker *worker;
|
|
|
|
worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
|
|
if (!worker)
|
|
return false;
|
|
|
|
refcount_set(&worker->ref, 1);
|
|
worker->nulls_node.pprev = NULL;
|
|
worker->wqe = wqe;
|
|
spin_lock_init(&worker->lock);
|
|
|
|
worker->task = kthread_create_on_node(io_wqe_worker, worker, wqe->node,
|
|
"io_wqe_worker-%d/%d", index, wqe->node);
|
|
if (IS_ERR(worker->task)) {
|
|
kfree(worker);
|
|
return false;
|
|
}
|
|
|
|
spin_lock_irq(&wqe->lock);
|
|
hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
|
|
list_add_tail_rcu(&worker->all_list, &wqe->all_list);
|
|
worker->flags |= IO_WORKER_F_FREE;
|
|
if (index == IO_WQ_ACCT_BOUND)
|
|
worker->flags |= IO_WORKER_F_BOUND;
|
|
if (!acct->nr_workers && (worker->flags & IO_WORKER_F_BOUND))
|
|
worker->flags |= IO_WORKER_F_FIXED;
|
|
acct->nr_workers++;
|
|
spin_unlock_irq(&wqe->lock);
|
|
|
|
if (index == IO_WQ_ACCT_UNBOUND)
|
|
atomic_inc(&wq->user->processes);
|
|
|
|
wake_up_process(worker->task);
|
|
return true;
|
|
}
|
|
|
|
static inline bool io_wqe_need_worker(struct io_wqe *wqe, int index)
|
|
__must_hold(wqe->lock)
|
|
{
|
|
struct io_wqe_acct *acct = &wqe->acct[index];
|
|
|
|
/* if we have available workers or no work, no need */
|
|
if (!hlist_nulls_empty(&wqe->free_list) || !io_wqe_run_queue(wqe))
|
|
return false;
|
|
return acct->nr_workers < acct->max_workers;
|
|
}
|
|
|
|
/*
|
|
* Manager thread. Tasked with creating new workers, if we need them.
|
|
*/
|
|
static int io_wq_manager(void *data)
|
|
{
|
|
struct io_wq *wq = data;
|
|
int workers_to_create = num_possible_nodes();
|
|
int node;
|
|
|
|
/* create fixed workers */
|
|
refcount_set(&wq->refs, workers_to_create);
|
|
for_each_node(node) {
|
|
if (!node_online(node))
|
|
continue;
|
|
if (!create_io_worker(wq, wq->wqes[node], IO_WQ_ACCT_BOUND))
|
|
goto err;
|
|
workers_to_create--;
|
|
}
|
|
|
|
while (workers_to_create--)
|
|
refcount_dec(&wq->refs);
|
|
|
|
complete(&wq->done);
|
|
|
|
while (!kthread_should_stop()) {
|
|
if (current->task_works)
|
|
task_work_run();
|
|
|
|
for_each_node(node) {
|
|
struct io_wqe *wqe = wq->wqes[node];
|
|
bool fork_worker[2] = { false, false };
|
|
|
|
if (!node_online(node))
|
|
continue;
|
|
|
|
spin_lock_irq(&wqe->lock);
|
|
if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND))
|
|
fork_worker[IO_WQ_ACCT_BOUND] = true;
|
|
if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND))
|
|
fork_worker[IO_WQ_ACCT_UNBOUND] = true;
|
|
spin_unlock_irq(&wqe->lock);
|
|
if (fork_worker[IO_WQ_ACCT_BOUND])
|
|
create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND);
|
|
if (fork_worker[IO_WQ_ACCT_UNBOUND])
|
|
create_io_worker(wq, wqe, IO_WQ_ACCT_UNBOUND);
|
|
}
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
schedule_timeout(HZ);
|
|
}
|
|
|
|
if (current->task_works)
|
|
task_work_run();
|
|
|
|
return 0;
|
|
err:
|
|
set_bit(IO_WQ_BIT_ERROR, &wq->state);
|
|
set_bit(IO_WQ_BIT_EXIT, &wq->state);
|
|
if (refcount_sub_and_test(workers_to_create, &wq->refs))
|
|
complete(&wq->done);
|
|
return 0;
|
|
}
|
|
|
|
static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct,
|
|
struct io_wq_work *work)
|
|
{
|
|
bool free_worker;
|
|
|
|
if (!(work->flags & IO_WQ_WORK_UNBOUND))
|
|
return true;
|
|
if (atomic_read(&acct->nr_running))
|
|
return true;
|
|
|
|
rcu_read_lock();
|
|
free_worker = !hlist_nulls_empty(&wqe->free_list);
|
|
rcu_read_unlock();
|
|
if (free_worker)
|
|
return true;
|
|
|
|
if (atomic_read(&wqe->wq->user->processes) >= acct->max_workers &&
|
|
!(capable(CAP_SYS_RESOURCE) || capable(CAP_SYS_ADMIN)))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
|
|
{
|
|
struct io_wq *wq = wqe->wq;
|
|
|
|
do {
|
|
struct io_wq_work *old_work = work;
|
|
|
|
work->flags |= IO_WQ_WORK_CANCEL;
|
|
work->func(&work);
|
|
work = (work == old_work) ? NULL : work;
|
|
wq->free_work(old_work);
|
|
} while (work);
|
|
}
|
|
|
|
static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work)
|
|
{
|
|
unsigned int hash;
|
|
struct io_wq_work *tail;
|
|
|
|
if (!io_wq_is_hashed(work)) {
|
|
append:
|
|
wq_list_add_tail(&work->list, &wqe->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, &wqe->work_list);
|
|
}
|
|
|
|
static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
|
|
{
|
|
struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
|
|
int work_flags;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* Do early check to see if we need a new unbound worker, and if we do,
|
|
* if we're allowed to do so. This isn't 100% accurate as there's a
|
|
* gap between this check and incrementing the value, but that's OK.
|
|
* It's close enough to not be an issue, fork() has the same delay.
|
|
*/
|
|
if (unlikely(!io_wq_can_queue(wqe, acct, work))) {
|
|
io_run_cancel(work, wqe);
|
|
return;
|
|
}
|
|
|
|
work_flags = work->flags;
|
|
spin_lock_irqsave(&wqe->lock, flags);
|
|
io_wqe_insert_work(wqe, work);
|
|
wqe->flags &= ~IO_WQE_FLAG_STALLED;
|
|
spin_unlock_irqrestore(&wqe->lock, flags);
|
|
|
|
if ((work_flags & IO_WQ_WORK_CONCURRENT) ||
|
|
!atomic_read(&acct->nr_running))
|
|
io_wqe_wake_worker(wqe, acct);
|
|
}
|
|
|
|
void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
|
|
{
|
|
struct io_wqe *wqe = wq->wqes[numa_node_id()];
|
|
|
|
io_wqe_enqueue(wqe, work);
|
|
}
|
|
|
|
/*
|
|
* 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_wqe_worker_send_sig(struct io_worker *worker, void *data)
|
|
{
|
|
send_sig(SIGINT, worker->task, 1);
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Iterate the passed in list and call the specific function for each
|
|
* worker that isn't exiting
|
|
*/
|
|
static bool io_wq_for_each_worker(struct io_wqe *wqe,
|
|
bool (*func)(struct io_worker *, void *),
|
|
void *data)
|
|
{
|
|
struct io_worker *worker;
|
|
bool ret = false;
|
|
|
|
list_for_each_entry_rcu(worker, &wqe->all_list, all_list) {
|
|
if (io_worker_get(worker)) {
|
|
/* no task if node is/was offline */
|
|
if (worker->task)
|
|
ret = func(worker, data);
|
|
io_worker_release(worker);
|
|
if (ret)
|
|
break;
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
void io_wq_cancel_all(struct io_wq *wq)
|
|
{
|
|
int node;
|
|
|
|
set_bit(IO_WQ_BIT_CANCEL, &wq->state);
|
|
|
|
rcu_read_lock();
|
|
for_each_node(node) {
|
|
struct io_wqe *wqe = wq->wqes[node];
|
|
|
|
io_wq_for_each_worker(wqe, io_wqe_worker_send_sig, NULL);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
struct io_cb_cancel_data {
|
|
work_cancel_fn *fn;
|
|
void *data;
|
|
};
|
|
|
|
static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
|
|
{
|
|
struct io_cb_cancel_data *match = data;
|
|
unsigned long flags;
|
|
bool ret = false;
|
|
|
|
/*
|
|
* Hold the lock to avoid ->cur_work going out of scope, caller
|
|
* may dereference the passed in work.
|
|
*/
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
if (worker->cur_work &&
|
|
!(worker->cur_work->flags & IO_WQ_WORK_NO_CANCEL) &&
|
|
match->fn(worker->cur_work, match->data)) {
|
|
send_sig(SIGINT, worker->task, 1);
|
|
ret = true;
|
|
}
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
|
|
struct io_cb_cancel_data *match)
|
|
{
|
|
struct io_wq_work_node *node, *prev;
|
|
struct io_wq_work *work;
|
|
unsigned long flags;
|
|
bool found = false;
|
|
|
|
/*
|
|
* First check pending list, if we're lucky we can just remove it
|
|
* from there. CANCEL_OK means that the work is returned as-new,
|
|
* no completion will be posted for it.
|
|
*/
|
|
spin_lock_irqsave(&wqe->lock, flags);
|
|
wq_list_for_each(node, prev, &wqe->work_list) {
|
|
work = container_of(node, struct io_wq_work, list);
|
|
|
|
if (match->fn(work, match->data)) {
|
|
wq_list_del(&wqe->work_list, node, prev);
|
|
found = true;
|
|
break;
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&wqe->lock, flags);
|
|
|
|
if (found) {
|
|
io_run_cancel(work, wqe);
|
|
return IO_WQ_CANCEL_OK;
|
|
}
|
|
|
|
/*
|
|
* Now check if a free (going busy) or busy worker has the work
|
|
* currently running. If we find it there, we'll return CANCEL_RUNNING
|
|
* as an indication that we attempt to signal cancellation. The
|
|
* completion will run normally in this case.
|
|
*/
|
|
rcu_read_lock();
|
|
found = io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
|
|
rcu_read_unlock();
|
|
return found ? IO_WQ_CANCEL_RUNNING : IO_WQ_CANCEL_NOTFOUND;
|
|
}
|
|
|
|
enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
|
|
void *data)
|
|
{
|
|
struct io_cb_cancel_data match = {
|
|
.fn = cancel,
|
|
.data = data,
|
|
};
|
|
enum io_wq_cancel ret = IO_WQ_CANCEL_NOTFOUND;
|
|
int node;
|
|
|
|
for_each_node(node) {
|
|
struct io_wqe *wqe = wq->wqes[node];
|
|
|
|
ret = io_wqe_cancel_work(wqe, &match);
|
|
if (ret != IO_WQ_CANCEL_NOTFOUND)
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static bool io_wq_io_cb_cancel_data(struct io_wq_work *work, void *data)
|
|
{
|
|
return work == data;
|
|
}
|
|
|
|
enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork)
|
|
{
|
|
return io_wq_cancel_cb(wq, io_wq_io_cb_cancel_data, (void *)cwork);
|
|
}
|
|
|
|
static bool io_wq_pid_match(struct io_wq_work *work, void *data)
|
|
{
|
|
pid_t pid = (pid_t) (unsigned long) data;
|
|
|
|
return work->task_pid == pid;
|
|
}
|
|
|
|
enum io_wq_cancel io_wq_cancel_pid(struct io_wq *wq, pid_t pid)
|
|
{
|
|
void *data = (void *) (unsigned long) pid;
|
|
|
|
return io_wq_cancel_cb(wq, io_wq_pid_match, data);
|
|
}
|
|
|
|
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
|
|
{
|
|
int ret = -ENOMEM, node;
|
|
struct io_wq *wq;
|
|
|
|
if (WARN_ON_ONCE(!data->free_work))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
wq = kzalloc(sizeof(*wq), GFP_KERNEL);
|
|
if (!wq)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
wq->wqes = kcalloc(nr_node_ids, sizeof(struct io_wqe *), GFP_KERNEL);
|
|
if (!wq->wqes) {
|
|
kfree(wq);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
wq->free_work = data->free_work;
|
|
|
|
/* caller must already hold a reference to this */
|
|
wq->user = data->user;
|
|
|
|
for_each_node(node) {
|
|
struct io_wqe *wqe;
|
|
int alloc_node = node;
|
|
|
|
if (!node_online(alloc_node))
|
|
alloc_node = NUMA_NO_NODE;
|
|
wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
|
|
if (!wqe)
|
|
goto err;
|
|
wq->wqes[node] = wqe;
|
|
wqe->node = alloc_node;
|
|
wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
|
|
atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
|
|
if (wq->user) {
|
|
wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
|
|
task_rlimit(current, RLIMIT_NPROC);
|
|
}
|
|
atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0);
|
|
wqe->wq = wq;
|
|
spin_lock_init(&wqe->lock);
|
|
INIT_WQ_LIST(&wqe->work_list);
|
|
INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
|
|
INIT_LIST_HEAD(&wqe->all_list);
|
|
}
|
|
|
|
init_completion(&wq->done);
|
|
|
|
wq->manager = kthread_create(io_wq_manager, wq, "io_wq_manager");
|
|
if (!IS_ERR(wq->manager)) {
|
|
wake_up_process(wq->manager);
|
|
wait_for_completion(&wq->done);
|
|
if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
|
|
ret = -ENOMEM;
|
|
goto err;
|
|
}
|
|
refcount_set(&wq->use_refs, 1);
|
|
reinit_completion(&wq->done);
|
|
return wq;
|
|
}
|
|
|
|
ret = PTR_ERR(wq->manager);
|
|
complete(&wq->done);
|
|
err:
|
|
for_each_node(node)
|
|
kfree(wq->wqes[node]);
|
|
kfree(wq->wqes);
|
|
kfree(wq);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
|
|
{
|
|
if (data->free_work != wq->free_work)
|
|
return false;
|
|
|
|
return refcount_inc_not_zero(&wq->use_refs);
|
|
}
|
|
|
|
static bool io_wq_worker_wake(struct io_worker *worker, void *data)
|
|
{
|
|
wake_up_process(worker->task);
|
|
return false;
|
|
}
|
|
|
|
static void __io_wq_destroy(struct io_wq *wq)
|
|
{
|
|
int node;
|
|
|
|
set_bit(IO_WQ_BIT_EXIT, &wq->state);
|
|
if (wq->manager)
|
|
kthread_stop(wq->manager);
|
|
|
|
rcu_read_lock();
|
|
for_each_node(node)
|
|
io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
|
|
rcu_read_unlock();
|
|
|
|
wait_for_completion(&wq->done);
|
|
|
|
for_each_node(node)
|
|
kfree(wq->wqes[node]);
|
|
kfree(wq->wqes);
|
|
kfree(wq);
|
|
}
|
|
|
|
void io_wq_destroy(struct io_wq *wq)
|
|
{
|
|
if (refcount_dec_and_test(&wq->use_refs))
|
|
__io_wq_destroy(wq);
|
|
}
|
|
|
|
struct task_struct *io_wq_get_task(struct io_wq *wq)
|
|
{
|
|
return wq->manager;
|
|
}
|