linux/fs/io-wq.c
Jens Axboe 991468dcf1 io_uring: explicitly catch any illegal async queue attempt
Catch an illegal case to queue async from an unrelated task that got
the ring fd passed to it. This should not be possible to hit, but
better be proactive and catch it explicitly. io-wq is extended to
check for early IO_WQ_WORK_CANCEL being set on a work item as well,
so it can run the request through the normal cancelation path.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-23 16:44:51 -06:00

1127 lines
26 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/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];
cpumask_var_t cpu_mask;
};
/*
* Per io_wq state
*/
struct io_wq {
unsigned long state;
free_work_fn *free_work;
io_wq_work_fn *do_work;
struct io_wq_hash *hash;
atomic_t worker_refs;
struct completion worker_done;
struct hlist_node cpuhp_node;
struct task_struct *task;
struct io_wqe *wqes[];
};
static enum cpuhp_state io_wq_online;
struct io_cb_cancel_data {
work_cancel_fn *fn;
void *data;
int nr_running;
int nr_pending;
bool cancel_all;
};
static 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.
*/
if (unlikely(!acct->max_workers))
pr_warn_once("io-wq is not configured for unbound 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, wqe->cpu_mask);
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 io-wq is exiting for this task, or if the request has explicitly
* been marked as one that should not get executed, cancel it here.
*/
if (test_bit(IO_WQ_BIT_EXIT, &wqe->wq->state) ||
(work->flags & IO_WQ_WORK_CANCEL)) {
io_run_cancel(work, wqe);
return;
}
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);
if (WARN_ON_ONCE(!bounded))
return ERR_PTR(-EINVAL);
wq = kzalloc(struct_size(wq, wqes, nr_node_ids), GFP_KERNEL);
if (!wq)
return ERR_PTR(-ENOMEM);
ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
if (ret)
goto err_wq;
refcount_inc(&data->hash->refs);
wq->hash = data->hash;
wq->free_work = data->free_work;
wq->do_work = data->do_work;
ret = -ENOMEM;
for_each_node(node) {
struct io_wqe *wqe;
int alloc_node = node;
if (!node_online(alloc_node))
alloc_node = NUMA_NO_NODE;
wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
if (!wqe)
goto err;
if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL))
goto err;
cpumask_copy(wqe->cpu_mask, cpumask_of_node(node));
wq->wqes[node] = wqe;
wqe->node = alloc_node;
wqe->acct[IO_WQ_ACCT_BOUND].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) {
if (!wq->wqes[node])
continue;
free_cpumask_var(wq->wqes[node]->cpu_mask);
kfree(wq->wqes[node]);
}
err_wq:
kfree(wq);
return ERR_PTR(ret);
}
static bool io_task_work_match(struct callback_head *cb, void *data)
{
struct 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);
free_cpumask_var(wqe->cpu_mask);
kfree(wqe);
}
io_wq_put_hash(wq->hash);
kfree(wq);
}
void io_wq_put_and_exit(struct io_wq *wq)
{
WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
io_wq_exit_workers(wq);
io_wq_destroy(wq);
}
struct online_data {
unsigned int cpu;
bool online;
};
static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
{
struct online_data *od = data;
if (od->online)
cpumask_set_cpu(od->cpu, worker->wqe->cpu_mask);
else
cpumask_clear_cpu(od->cpu, worker->wqe->cpu_mask);
return false;
}
static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online)
{
struct online_data od = {
.cpu = cpu,
.online = online
};
int i;
rcu_read_lock();
for_each_node(i)
io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, &od);
rcu_read_unlock();
return 0;
}
static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
{
struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
return __io_wq_cpu_online(wq, cpu, true);
}
static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
{
struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
return __io_wq_cpu_online(wq, cpu, false);
}
int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask)
{
int i;
rcu_read_lock();
for_each_node(i) {
struct io_wqe *wqe = wq->wqes[i];
if (mask)
cpumask_copy(wqe->cpu_mask, mask);
else
cpumask_copy(wqe->cpu_mask, cpumask_of_node(i));
}
rcu_read_unlock();
return 0;
}
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);