Re: [PATCH -next] io-wq: Remove duplicate code in io_workqueue_create()

From: Hao Xu
Date: Sun Sep 12 2021 - 11:38:11 EST


在 2021/9/11 下午4:58, Bixuan Cui 写道:
While task_work_add() in io_workqueue_create() is true,
then duplicate code is executed:

-> clear_bit_unlock(0, &worker->create_state);
-> io_worker_release(worker);
-> atomic_dec(&acct->nr_running);
-> io_worker_ref_put(wq);
-> return false;

-> clear_bit_unlock(0, &worker->create_state); // back to io_workqueue_create()
-> io_worker_release(worker);
-> kfree(worker);

The io_worker_release() and clear_bit_unlock() are executed twice.

Fixes: 3146cba99aa2 ("io-wq: make worker creation resilient against signals")
Signed-off-by: Bixuan Cui <cuibixuan@xxxxxxxxxx>
---
fs/io-wq.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 6c55362c1f99..95d0eaed7c00 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -329,8 +329,10 @@ static bool io_queue_worker_create(struct io_worker *worker,
init_task_work(&worker->create_work, func);
worker->create_index = acct->index;
- if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL))
+ if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
+ clear_bit_unlock(0, &worker->create_state);
return true;
+ }
clear_bit_unlock(0, &worker->create_state);
fail_release:
io_worker_release(worker);
@@ -723,11 +725,8 @@ static void io_workqueue_create(struct work_struct *work)
struct io_worker *worker = container_of(work, struct io_worker, work);
struct io_wqe_acct *acct = io_wqe_get_acct(worker);
- if (!io_queue_worker_create(worker, acct, create_worker_cont)) {
- clear_bit_unlock(0, &worker->create_state);
- io_worker_release(worker);
+ if (!io_queue_worker_create(worker, acct, create_worker_cont))
kfree(worker);
- }
}
static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)

AFAIK, this looks reasonable for me.