linux/fs/io-wq.c
Colin Ian King b1b2fc3574 io-wq: remove redundant initialization of variable ret
The variable ret is being initialized with a value that is never read, the
assignment is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210615143424.60449-1-colin.king@canonical.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15 15:37:51 -06:00

1068 lines
25 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Basic worker thread pool for io_uring
*
* Copyright (C) 2019 Jens Axboe
*
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched/signal.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/rculist_nulls.h>
#include <linux/cpu.h>
#include <linux/tracehook.h>
#include "io-wq.h"
#define WORKER_IDLE_TIMEOUT (5 * HZ)
enum {
IO_WORKER_F_UP = 1, /* up and active */
IO_WORKER_F_RUNNING = 2, /* account as running */
IO_WORKER_F_FREE = 4, /* worker on free list */
IO_WORKER_F_FIXED = 8, /* static idle worker */
IO_WORKER_F_BOUND = 16, /* is doing bounded work */
};
enum {
IO_WQ_BIT_EXIT = 0, /* wq exiting */
};
enum {
IO_WQE_FLAG_STALLED = 1, /* stalled on hash */
};
/*
* One for each thread in a wqe pool
*/
struct io_worker {
refcount_t ref;
unsigned flags;
struct hlist_nulls_node nulls_node;
struct list_head all_list;
struct task_struct *task;
struct io_wqe *wqe;
struct io_wq_work *cur_work;
spinlock_t lock;
struct completion ref_done;
struct rcu_head rcu;
};
#if BITS_PER_LONG == 64
#define IO_WQ_HASH_ORDER 6
#else
#define IO_WQ_HASH_ORDER 5
#endif
#define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
struct io_wqe_acct {
unsigned nr_workers;
unsigned max_workers;
int index;
atomic_t nr_running;
};
enum {
IO_WQ_ACCT_BOUND,
IO_WQ_ACCT_UNBOUND,
};
/*
* Per-node worker thread pool
*/
struct io_wqe {
struct {
raw_spinlock_t lock;
struct io_wq_work_list work_list;
unsigned flags;
} ____cacheline_aligned_in_smp;
int node;
struct io_wqe_acct acct[2];
struct hlist_nulls_head free_list;
struct list_head all_list;
struct wait_queue_entry wait;
struct io_wq *wq;
struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
};
/*
* Per io_wq state
*/
struct io_wq {
unsigned long state;
free_work_fn *free_work;
io_wq_work_fn *do_work;
struct io_wq_hash *hash;
atomic_t worker_refs;
struct completion worker_done;
struct hlist_node cpuhp_node;
struct task_struct *task;
struct io_wqe *wqes[];
};
static enum cpuhp_state io_wq_online;
struct io_cb_cancel_data {
work_cancel_fn *fn;
void *data;
int nr_running;
int nr_pending;
bool cancel_all;
};
static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index);
static bool io_worker_get(struct io_worker *worker)
{
return refcount_inc_not_zero(&worker->ref);
}
static void io_worker_release(struct io_worker *worker)
{
if (refcount_dec_and_test(&worker->ref))
complete(&worker->ref_done);
}
static inline struct io_wqe_acct *io_get_acct(struct io_wqe *wqe, bool bound)
{
return &wqe->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
}
static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
struct io_wq_work *work)
{
return io_get_acct(wqe, !(work->flags & IO_WQ_WORK_UNBOUND));
}
static inline struct io_wqe_acct *io_wqe_get_acct(struct io_worker *worker)
{
return io_get_acct(worker->wqe, worker->flags & IO_WORKER_F_BOUND);
}
static void io_worker_ref_put(struct io_wq *wq)
{
if (atomic_dec_and_test(&wq->worker_refs))
complete(&wq->worker_done);
}
static void io_worker_exit(struct io_worker *worker)
{
struct io_wqe *wqe = worker->wqe;
struct io_wqe_acct *acct = io_wqe_get_acct(worker);
unsigned flags;
if (refcount_dec_and_test(&worker->ref))
complete(&worker->ref_done);
wait_for_completion(&worker->ref_done);
preempt_disable();
current->flags &= ~PF_IO_WORKER;
flags = worker->flags;
worker->flags = 0;
if (flags & IO_WORKER_F_RUNNING)
atomic_dec(&acct->nr_running);
worker->flags = 0;
preempt_enable();
raw_spin_lock_irq(&wqe->lock);
if (flags & IO_WORKER_F_FREE)
hlist_nulls_del_rcu(&worker->nulls_node);
list_del_rcu(&worker->all_list);
acct->nr_workers--;
raw_spin_unlock_irq(&wqe->lock);
kfree_rcu(worker, rcu);
io_worker_ref_put(wqe->wq);
do_exit(0);
}
static inline bool io_wqe_run_queue(struct io_wqe *wqe)
__must_hold(wqe->lock)
{
if (!wq_list_empty(&wqe->work_list) &&
!(wqe->flags & IO_WQE_FLAG_STALLED))
return true;
return false;
}
/*
* Check head of free list for an available worker. If one isn't available,
* caller must create one.
*/
static bool io_wqe_activate_free_worker(struct io_wqe *wqe)
__must_hold(RCU)
{
struct hlist_nulls_node *n;
struct io_worker *worker;
n = rcu_dereference(hlist_nulls_first_rcu(&wqe->free_list));
if (is_a_nulls(n))
return false;
worker = hlist_nulls_entry(n, struct io_worker, nulls_node);
if (io_worker_get(worker)) {
wake_up_process(worker->task);
io_worker_release(worker);
return true;
}
return false;
}
/*
* We need a worker. If we find a free one, we're good. If not, and we're
* below the max number of workers, create one.
*/
static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
{
bool ret;
/*
* Most likely an attempt to queue unbounded work on an io_wq that
* wasn't setup with any unbounded workers.
*/
WARN_ON_ONCE(!acct->max_workers);
rcu_read_lock();
ret = io_wqe_activate_free_worker(wqe);
rcu_read_unlock();
if (!ret && acct->nr_workers < acct->max_workers) {
atomic_inc(&acct->nr_running);
atomic_inc(&wqe->wq->worker_refs);
create_io_worker(wqe->wq, wqe, acct->index);
}
}
static void io_wqe_inc_running(struct io_worker *worker)
{
struct io_wqe_acct *acct = io_wqe_get_acct(worker);
atomic_inc(&acct->nr_running);
}
struct create_worker_data {
struct callback_head work;
struct io_wqe *wqe;
int index;
};
static void create_worker_cb(struct callback_head *cb)
{
struct create_worker_data *cwd;
struct io_wq *wq;
cwd = container_of(cb, struct create_worker_data, work);
wq = cwd->wqe->wq;
create_io_worker(wq, cwd->wqe, cwd->index);
kfree(cwd);
}
static void io_queue_worker_create(struct io_wqe *wqe, struct io_wqe_acct *acct)
{
struct create_worker_data *cwd;
struct io_wq *wq = wqe->wq;
/* raced with exit, just ignore create call */
if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
goto fail;
cwd = kmalloc(sizeof(*cwd), GFP_ATOMIC);
if (cwd) {
init_task_work(&cwd->work, create_worker_cb);
cwd->wqe = wqe;
cwd->index = acct->index;
if (!task_work_add(wq->task, &cwd->work, TWA_SIGNAL))
return;
kfree(cwd);
}
fail:
atomic_dec(&acct->nr_running);
io_worker_ref_put(wq);
}
static void io_wqe_dec_running(struct io_worker *worker)
__must_hold(wqe->lock)
{
struct io_wqe_acct *acct = io_wqe_get_acct(worker);
struct io_wqe *wqe = worker->wqe;
if (!(worker->flags & IO_WORKER_F_UP))
return;
if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe)) {
atomic_inc(&acct->nr_running);
atomic_inc(&wqe->wq->worker_refs);
io_queue_worker_create(wqe, acct);
}
}
/*
* Worker will start processing some work. Move it to the busy list, if
* it's currently on the freelist
*/
static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
struct io_wq_work *work)
__must_hold(wqe->lock)
{
bool worker_bound, work_bound;
BUILD_BUG_ON((IO_WQ_ACCT_UNBOUND ^ IO_WQ_ACCT_BOUND) != 1);
if (worker->flags & IO_WORKER_F_FREE) {
worker->flags &= ~IO_WORKER_F_FREE;
hlist_nulls_del_init_rcu(&worker->nulls_node);
}
/*
* If worker is moving from bound to unbound (or vice versa), then
* ensure we update the running accounting.
*/
worker_bound = (worker->flags & IO_WORKER_F_BOUND) != 0;
work_bound = (work->flags & IO_WQ_WORK_UNBOUND) == 0;
if (worker_bound != work_bound) {
int index = work_bound ? IO_WQ_ACCT_UNBOUND : IO_WQ_ACCT_BOUND;
io_wqe_dec_running(worker);
worker->flags ^= IO_WORKER_F_BOUND;
wqe->acct[index].nr_workers--;
wqe->acct[index ^ 1].nr_workers++;
io_wqe_inc_running(worker);
}
}
/*
* No work, worker going to sleep. Move to freelist, and unuse mm if we
* have one attached. Dropping the mm may potentially sleep, so we drop
* the lock in that case and return success. Since the caller has to
* retry the loop in that case (we changed task state), we don't regrab
* the lock if we return success.
*/
static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
__must_hold(wqe->lock)
{
if (!(worker->flags & IO_WORKER_F_FREE)) {
worker->flags |= IO_WORKER_F_FREE;
hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
}
}
static inline unsigned int io_get_work_hash(struct io_wq_work *work)
{
return work->flags >> IO_WQ_HASH_SHIFT;
}
static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
{
struct io_wq *wq = wqe->wq;
spin_lock(&wq->hash->wait.lock);
if (list_empty(&wqe->wait.entry)) {
__add_wait_queue(&wq->hash->wait, &wqe->wait);
if (!test_bit(hash, &wq->hash->map)) {
__set_current_state(TASK_RUNNING);
list_del_init(&wqe->wait.entry);
}
}
spin_unlock(&wq->hash->wait.lock);
}
static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
__must_hold(wqe->lock)
{
struct io_wq_work_node *node, *prev;
struct io_wq_work *work, *tail;
unsigned int stall_hash = -1U;
wq_list_for_each(node, prev, &wqe->work_list) {
unsigned int hash;
work = container_of(node, struct io_wq_work, list);
/* not hashed, can run anytime */
if (!io_wq_is_hashed(work)) {
wq_list_del(&wqe->work_list, node, prev);
return work;
}
hash = io_get_work_hash(work);
/* all items with this hash lie in [work, tail] */
tail = wqe->hash_tail[hash];
/* hashed, can run if not already running */
if (!test_and_set_bit(hash, &wqe->wq->hash->map)) {
wqe->hash_tail[hash] = NULL;
wq_list_cut(&wqe->work_list, &tail->list, prev);
return work;
}
if (stall_hash == -1U)
stall_hash = hash;
/* fast forward to a next hash, for-each will fix up @prev */
node = &tail->list;
}
if (stall_hash != -1U) {
raw_spin_unlock(&wqe->lock);
io_wait_on_hash(wqe, stall_hash);
raw_spin_lock(&wqe->lock);
}
return NULL;
}
static bool io_flush_signals(void)
{
if (unlikely(test_thread_flag(TIF_NOTIFY_SIGNAL))) {
__set_current_state(TASK_RUNNING);
tracehook_notify_signal();
return true;
}
return false;
}
static void io_assign_current_work(struct io_worker *worker,
struct io_wq_work *work)
{
if (work) {
io_flush_signals();
cond_resched();
}
spin_lock_irq(&worker->lock);
worker->cur_work = work;
spin_unlock_irq(&worker->lock);
}
static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
static void io_worker_handle_work(struct io_worker *worker)
__releases(wqe->lock)
{
struct io_wqe *wqe = worker->wqe;
struct io_wq *wq = wqe->wq;
bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state);
do {
struct io_wq_work *work;
get_next:
/*
* If we got some work, mark us as busy. If we didn't, but
* the list isn't empty, it means we stalled on hashed work.
* Mark us stalled so we don't keep looking for work when we
* can't make progress, any work completion or insertion will
* clear the stalled flag.
*/
work = io_get_next_work(wqe);
if (work)
__io_worker_busy(wqe, worker, work);
else if (!wq_list_empty(&wqe->work_list))
wqe->flags |= IO_WQE_FLAG_STALLED;
raw_spin_unlock_irq(&wqe->lock);
if (!work)
break;
io_assign_current_work(worker, work);
__set_current_state(TASK_RUNNING);
/* handle a whole dependent link */
do {
struct io_wq_work *next_hashed, *linked;
unsigned int hash = io_get_work_hash(work);
next_hashed = wq_next_work(work);
if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND))
work->flags |= IO_WQ_WORK_CANCEL;
wq->do_work(work);
io_assign_current_work(worker, NULL);
linked = wq->free_work(work);
work = next_hashed;
if (!work && linked && !io_wq_is_hashed(linked)) {
work = linked;
linked = NULL;
}
io_assign_current_work(worker, work);
if (linked)
io_wqe_enqueue(wqe, linked);
if (hash != -1U && !next_hashed) {
clear_bit(hash, &wq->hash->map);
if (wq_has_sleeper(&wq->hash->wait))
wake_up(&wq->hash->wait);
raw_spin_lock_irq(&wqe->lock);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
/* skip unnecessary unlock-lock wqe->lock */
if (!work)
goto get_next;
raw_spin_unlock_irq(&wqe->lock);
}
} while (work);
raw_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;
char buf[TASK_COMM_LEN];
worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
set_task_comm(current, buf);
while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
long ret;
set_current_state(TASK_INTERRUPTIBLE);
loop:
raw_spin_lock_irq(&wqe->lock);
if (io_wqe_run_queue(wqe)) {
io_worker_handle_work(worker);
goto loop;
}
__io_worker_idle(wqe, worker);
raw_spin_unlock_irq(&wqe->lock);
if (io_flush_signals())
continue;
ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
if (signal_pending(current)) {
struct ksignal ksig;
if (!get_signal(&ksig))
continue;
break;
}
if (ret)
continue;
/* timed out, exit unless we're the fixed worker */
if (!(worker->flags & IO_WORKER_F_FIXED))
break;
}
if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
raw_spin_lock_irq(&wqe->lock);
io_worker_handle_work(worker);
}
io_worker_exit(worker);
return 0;
}
/*
* Called when a worker is scheduled in. Mark us as currently running.
*/
void io_wq_worker_running(struct task_struct *tsk)
{
struct io_worker *worker = tsk->pf_io_worker;
if (!worker)
return;
if (!(worker->flags & IO_WORKER_F_UP))
return;
if (worker->flags & IO_WORKER_F_RUNNING)
return;
worker->flags |= IO_WORKER_F_RUNNING;
io_wqe_inc_running(worker);
}
/*
* Called when worker is going to sleep. If there are no workers currently
* running and we have work pending, wake up a free one or create a new one.
*/
void io_wq_worker_sleeping(struct task_struct *tsk)
{
struct io_worker *worker = tsk->pf_io_worker;
if (!worker)
return;
if (!(worker->flags & IO_WORKER_F_UP))
return;
if (!(worker->flags & IO_WORKER_F_RUNNING))
return;
worker->flags &= ~IO_WORKER_F_RUNNING;
raw_spin_lock_irq(&worker->wqe->lock);
io_wqe_dec_running(worker);
raw_spin_unlock_irq(&worker->wqe->lock);
}
static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
{
struct io_wqe_acct *acct = &wqe->acct[index];
struct io_worker *worker;
struct task_struct *tsk;
__set_current_state(TASK_RUNNING);
worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
if (!worker)
goto fail;
refcount_set(&worker->ref, 1);
worker->nulls_node.pprev = NULL;
worker->wqe = wqe;
spin_lock_init(&worker->lock);
init_completion(&worker->ref_done);
tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
if (IS_ERR(tsk)) {
kfree(worker);
fail:
atomic_dec(&acct->nr_running);
io_worker_ref_put(wq);
return;
}
tsk->pf_io_worker = worker;
worker->task = tsk;
set_cpus_allowed_ptr(tsk, cpumask_of_node(wqe->node));
tsk->flags |= PF_NO_SETAFFINITY;
raw_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++;
raw_spin_unlock_irq(&wqe->lock);
wake_up_new_task(tsk);
}
/*
* Iterate the passed in list and call the specific function for each
* worker that isn't exiting
*/
static bool io_wq_for_each_worker(struct io_wqe *wqe,
bool (*func)(struct io_worker *, void *),
void *data)
{
struct io_worker *worker;
bool ret = false;
list_for_each_entry_rcu(worker, &wqe->all_list, all_list) {
if (io_worker_get(worker)) {
/* no task if node is/was offline */
if (worker->task)
ret = func(worker, data);
io_worker_release(worker);
if (ret)
break;
}
}
return ret;
}
static bool io_wq_worker_wake(struct io_worker *worker, void *data)
{
set_notify_signal(worker->task);
wake_up_process(worker->task);
return false;
}
static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
{
return true;
}
static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
{
struct io_wq *wq = wqe->wq;
do {
work->flags |= IO_WQ_WORK_CANCEL;
wq->do_work(work);
work = wq->free_work(work);
} while (work);
}
static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work)
{
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;
if (test_bit(IO_WQ_BIT_EXIT, &wqe->wq->state)) {
io_run_cancel(work, wqe);
return;
}
work_flags = work->flags;
raw_spin_lock_irqsave(&wqe->lock, flags);
io_wqe_insert_work(wqe, work);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
raw_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_wq_worker_cancel(struct io_worker *worker, void *data)
{
struct io_cb_cancel_data *match = data;
unsigned long flags;
/*
* 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 &&
match->fn(worker->cur_work, match->data)) {
set_notify_signal(worker->task);
match->nr_running++;
}
spin_unlock_irqrestore(&worker->lock, flags);
return match->nr_running && !match->cancel_all;
}
static inline void io_wqe_remove_pending(struct io_wqe *wqe,
struct io_wq_work *work,
struct io_wq_work_node *prev)
{
unsigned int hash = io_get_work_hash(work);
struct io_wq_work *prev_work = NULL;
if (io_wq_is_hashed(work) && work == wqe->hash_tail[hash]) {
if (prev)
prev_work = container_of(prev, struct io_wq_work, list);
if (prev_work && io_get_work_hash(prev_work) == hash)
wqe->hash_tail[hash] = prev_work;
else
wqe->hash_tail[hash] = NULL;
}
wq_list_del(&wqe->work_list, &work->list, prev);
}
static void io_wqe_cancel_pending_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;
retry:
raw_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))
continue;
io_wqe_remove_pending(wqe, work, prev);
raw_spin_unlock_irqrestore(&wqe->lock, flags);
io_run_cancel(work, wqe);
match->nr_pending++;
if (!match->cancel_all)
return;
/* not safe to continue after unlock */
goto retry;
}
raw_spin_unlock_irqrestore(&wqe->lock, flags);
}
static void io_wqe_cancel_running_work(struct io_wqe *wqe,
struct io_cb_cancel_data *match)
{
rcu_read_lock();
io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
rcu_read_unlock();
}
enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
void *data, bool cancel_all)
{
struct io_cb_cancel_data match = {
.fn = cancel,
.data = data,
.cancel_all = cancel_all,
};
int node;
/*
* First check pending list, if we're lucky we can just remove it
* from there. CANCEL_OK means that the work is returned as-new,
* no completion will be posted for it.
*/
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wqe_cancel_pending_work(wqe, &match);
if (match.nr_pending && !match.cancel_all)
return IO_WQ_CANCEL_OK;
}
/*
* Now check if a free (going busy) or busy worker has the work
* currently running. If we find it there, we'll return CANCEL_RUNNING
* as an indication that we attempt to signal cancellation. The
* completion will run normally in this case.
*/
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wqe_cancel_running_work(wqe, &match);
if (match.nr_running && !match.cancel_all)
return IO_WQ_CANCEL_RUNNING;
}
if (match.nr_running)
return IO_WQ_CANCEL_RUNNING;
if (match.nr_pending)
return IO_WQ_CANCEL_OK;
return IO_WQ_CANCEL_NOTFOUND;
}
static int io_wqe_hash_wake(struct wait_queue_entry *wait, unsigned mode,
int sync, void *key)
{
struct io_wqe *wqe = container_of(wait, struct io_wqe, wait);
list_del_init(&wait->entry);
rcu_read_lock();
io_wqe_activate_free_worker(wqe);
rcu_read_unlock();
return 1;
}
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
{
int ret, node;
struct io_wq *wq;
if (WARN_ON_ONCE(!data->free_work || !data->do_work))
return ERR_PTR(-EINVAL);
wq = kzalloc(struct_size(wq, wqes, nr_node_ids), GFP_KERNEL);
if (!wq)
return ERR_PTR(-ENOMEM);
ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
if (ret)
goto err_wq;
refcount_inc(&data->hash->refs);
wq->hash = data->hash;
wq->free_work = data->free_work;
wq->do_work = data->do_work;
ret = -ENOMEM;
for_each_node(node) {
struct io_wqe *wqe;
int alloc_node = node;
if (!node_online(alloc_node))
alloc_node = NUMA_NO_NODE;
wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
if (!wqe)
goto err;
wq->wqes[node] = wqe;
wqe->node = alloc_node;
wqe->acct[IO_WQ_ACCT_BOUND].index = IO_WQ_ACCT_BOUND;
wqe->acct[IO_WQ_ACCT_UNBOUND].index = IO_WQ_ACCT_UNBOUND;
wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
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->wait.func = io_wqe_hash_wake;
INIT_LIST_HEAD(&wqe->wait.entry);
wqe->wq = wq;
raw_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);
}
wq->task = get_task_struct(data->task);
atomic_set(&wq->worker_refs, 1);
init_completion(&wq->worker_done);
return wq;
err:
io_wq_put_hash(data->hash);
cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
for_each_node(node)
kfree(wq->wqes[node]);
err_wq:
kfree(wq);
return ERR_PTR(ret);
}
static bool io_task_work_match(struct callback_head *cb, void *data)
{
struct create_worker_data *cwd;
if (cb->func != create_worker_cb)
return false;
cwd = container_of(cb, struct create_worker_data, work);
return cwd->wqe->wq == data;
}
void io_wq_exit_start(struct io_wq *wq)
{
set_bit(IO_WQ_BIT_EXIT, &wq->state);
}
static void io_wq_exit_workers(struct io_wq *wq)
{
struct callback_head *cb;
int node;
if (!wq->task)
return;
while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
struct create_worker_data *cwd;
cwd = container_of(cb, struct create_worker_data, work);
atomic_dec(&cwd->wqe->acct[cwd->index].nr_running);
io_worker_ref_put(wq);
kfree(cwd);
}
rcu_read_lock();
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL);
}
rcu_read_unlock();
io_worker_ref_put(wq);
wait_for_completion(&wq->worker_done);
for_each_node(node) {
spin_lock_irq(&wq->hash->wait.lock);
list_del_init(&wq->wqes[node]->wait.entry);
spin_unlock_irq(&wq->hash->wait.lock);
}
put_task_struct(wq->task);
wq->task = NULL;
}
static void io_wq_destroy(struct io_wq *wq)
{
int node;
cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
for_each_node(node) {
struct io_wqe *wqe = wq->wqes[node];
struct io_cb_cancel_data match = {
.fn = io_wq_work_match_all,
.cancel_all = true,
};
io_wqe_cancel_pending_work(wqe, &match);
kfree(wqe);
}
io_wq_put_hash(wq->hash);
kfree(wq);
}
void io_wq_put_and_exit(struct io_wq *wq)
{
WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
io_wq_exit_workers(wq);
io_wq_destroy(wq);
}
static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
{
set_cpus_allowed_ptr(worker->task, cpumask_of_node(worker->wqe->node));
return false;
}
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);
int i;
rcu_read_lock();
for_each_node(i)
io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, NULL);
rcu_read_unlock();
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, NULL);
if (ret < 0)
return ret;
io_wq_online = ret;
return 0;
}
subsys_initcall(io_wq_init);