On 16/11/2019 04:53, Jens Axboe wrote:
> We have an issue with timeout links that are deeper in the submit chain,
> because we only handle it upfront, not from later submissions. Move the
> prep + issue of the timeout link to the async work prep handler, and do
> it normally for non-async queue. If we validate and prepare the timeout
> links upfront when we first see them, there's nothing stopping us from
> supporting any sort of nesting.
> 
> Fixes: 2665abfd757f ("io_uring: add support for linked SQE timeouts")
> Reported-by: Pavel Begunkov <asml.silence@gmail.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---

> @@ -923,6 +942,7 @@ static void io_fail_links(struct io_kiocb *req)
>  			io_cqring_fill_event(link, -ECANCELED);
>  			__io_double_put_req(link);
>  		}
> +		kfree(sqe_to_free);
>  	}
>  
>  	io_commit_cqring(ctx);
> @@ -2668,8 +2688,12 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
>  
>  	/* if a dependent link is ready, pass it back */
>  	if (!ret && nxt) {
> -		io_prep_async_work(nxt);
> +		struct io_kiocb *link;
> +
> +		io_prep_async_work(nxt, &link);
>  		*workptr = &nxt->work;
Are we safe here without synchronisation?
Probably io_link_timeout_fn() may miss the new value
(doing io-wq cancel).


> +		if (link)
> +			io_queue_linked_timeout(link);
>  	}
>  }
>  

-- 
Pavel Begunkov