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io-wq: provide an io_wq_put_and_exit() helper 

If we put the io-wq from io_uring, we really want it to exit. Provide
a helper that does that for us. Couple that with not having the manager
hold a reference to the 'wq' and the normal SQPOLL exit will tear down
the io-wq context appropriate.

On the io-wq side, our wq context is per task, so only the task itself
is manipulating ->manager and hence it's safe to check and clear without
any extra locking. We just need to ensure that the manager task stays
around, in case it exits.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-02-26 13:48:19 -07:00
parent 8629397e6e
commit afcc4015d1
3 changed files with 21 additions and 11 deletions
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29
fs/io-wq.c
View File

@ -749,7 +749,7 @@ static int io_wq_manager(void *data)
sprintf(buf, "iou-mgr-%d", wq->task_pid);
set_task_comm(current, buf);
current->flags |= PF_IO_WORKER;
wq->manager = current;
wq->manager = get_task_struct(current);
complete(&wq->started);
@ -771,9 +771,7 @@ static int io_wq_manager(void *data)
/* we might not ever have created any workers */
if (atomic_read(&wq->worker_refs))
wait_for_completion(&wq->worker_done);
wq->manager = NULL;
complete(&wq->exited);
io_wq_put(wq);
do_exit(0);
}
@ -816,8 +814,6 @@ static int io_wq_fork_manager(struct io_wq *wq)
return 0;
reinit_completion(&wq->worker_done);
clear_bit(IO_WQ_BIT_EXIT, &wq->state);
refcount_inc(&wq->refs);
current->flags |= PF_IO_WORKER;
ret = io_wq_fork_thread(io_wq_manager, wq);
current->flags &= ~PF_IO_WORKER;
@ -1089,6 +1085,16 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
return ERR_PTR(ret);
}
static void io_wq_destroy_manager(struct io_wq *wq)
{
if (wq->manager) {
wake_up_process(wq->manager);
wait_for_completion(&wq->exited);
put_task_struct(wq->manager);
wq->manager = NULL;
}
}
static void io_wq_destroy(struct io_wq *wq)
{
int node;
@ -1096,10 +1102,7 @@ static void io_wq_destroy(struct io_wq *wq)
cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
set_bit(IO_WQ_BIT_EXIT, &wq->state);
if (wq->manager) {
wake_up_process(wq->manager);
wait_for_completion(&wq->exited);
}
io_wq_destroy_manager(wq);
spin_lock_irq(&wq->hash->wait.lock);
for_each_node(node) {
@ -1112,7 +1115,6 @@ static void io_wq_destroy(struct io_wq *wq)
io_wq_put_hash(wq->hash);
kfree(wq->wqes);
kfree(wq);
}
void io_wq_put(struct io_wq *wq)
@ -1121,6 +1123,13 @@ void io_wq_put(struct io_wq *wq)
io_wq_destroy(wq);
}
void io_wq_put_and_exit(struct io_wq *wq)
{
set_bit(IO_WQ_BIT_EXIT, &wq->state);
io_wq_destroy_manager(wq);
io_wq_put(wq);
}
static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
{
struct task_struct *task = worker->task;

1
fs/io-wq.h
View File

@ -114,6 +114,7 @@ struct io_wq_data {
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data);
void io_wq_put(struct io_wq *wq);
void io_wq_put_and_exit(struct io_wq *wq);
void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work);
void io_wq_hash_work(struct io_wq_work *work, void *val);

2
fs/io_uring.c
View File

@ -8857,7 +8857,7 @@ void __io_uring_files_cancel(struct files_struct *files)
if (files) {
io_uring_remove_task_files(tctx);
if (tctx->io_wq) {
io_wq_put(tctx->io_wq);
io_wq_put_and_exit(tctx->io_wq);
tctx->io_wq = NULL;
}
}