linux-kernel - Re: [PATCH -next] io-wq: Remove duplicate code in io_workqueue

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Message-ID: <49d9bb13-a7b3-48b5-20ef-d3b72052f92b@linux.alibaba.com>
Date:   Sun, 12 Sep 2021 23:36:01 +0800
From:   Hao Xu <haoxu@...ux.alibaba.com>
To:     Bixuan Cui <cuibixuan@...wei.com>, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org
Cc:     axboe@...nel.dk, asml.silence@...il.com,
        Joseph Qi <joseph.qi@...ux.alibaba.com>
Subject: Re: [PATCH -next] io-wq: Remove duplicate code in
 io_workqueue_create()

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@...wei.com>
> ---
>   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.