Re: [PATCH 5.13] io_uring: don't set IORING_SQ_NEED_WAKEUP when sqthread is dying

[Pavel Begunkov <asml.silence@gmail.com>]

On 4/27/21 1:45 PM, Hao Xu wrote:
> we don't need to re-fork the sqthread over exec, so no need to set
> IORING_SQ_NEED_WAKEUP when sqthread is dying.

It forces users to call io_uring_enter() for it to return
-EOWNERDEAD. Consider that scenario with the ring given
away to some other task not in current group, e.g. via socket.

if (ctx->flags & IORING_SETUP_SQPOLL) {
	io_cqring_overflow_flush(ctx, false);

	ret = -EOWNERDEAD;
	if (unlikely(ctx->sq_data->thread == NULL)) {
		goto out;
	}
	...
}

btw, can use a comment

> 
> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
> ---
>  fs/io_uring.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 6b578c380e73..92dcd1c21516 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -6897,8 +6897,6 @@ static int io_sq_thread(void *data)
>  
>  	io_uring_cancel_sqpoll(sqd);
>  	sqd->thread = NULL;
> -	list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
> -		io_ring_set_wakeup_flag(ctx);
>  	io_run_task_work();
>  	io_run_task_work_head(&sqd->park_task_work);
>  	mutex_unlock(&sqd->lock);
> 

-- 
Pavel Begunkov