Re: [PATCH V3 4/9] io_uring: move marking REQ_F_CQE_SKIP out of io_free_req()

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

On 5/11/24 01:12, Ming Lei wrote:
> Prepare for supporting sqe group, which requires to post group leader's
> CQE after all members' CQEs are posted. For group leader request, we can't
> do that in io_req_complete_post, and REQ_F_CQE_SKIP can't be set in
> io_free_req().

Can you elaborate what exactly we can't do and why?

> So move marking REQ_F_CQE_SKIP out of io_free_req().

That makes io_free_req() a very confusing function, it tells
that it just frees the request but in reality can post a
CQE. If you really need it, just add a new function.

  
> No functional change.
> 
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>   io_uring/io_uring.c | 5 +++--
>   io_uring/timeout.c  | 3 +++
>   2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index e4be930e0f1e..c184c9a312df 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -1027,8 +1027,6 @@ __cold void io_free_req(struct io_kiocb *req)
>   {
>   	/* refs were already put, restore them for io_req_task_complete() */
>   	req->flags &= ~REQ_F_REFCOUNT;
> -	/* we only want to free it, don't post CQEs */
> -	req->flags |= REQ_F_CQE_SKIP;
>   	req->io_task_work.func = io_req_task_complete;
>   	io_req_task_work_add(req);
>   }
> @@ -1797,6 +1795,9 @@ struct io_wq_work *io_wq_free_work(struct io_wq_work *work)
>   	if (req_ref_put_and_test(req)) {
>   		if (req->flags & IO_REQ_LINK_FLAGS)
>   			nxt = io_req_find_next(req);
> +
> +		/* we have posted CQEs in io_req_complete_post() */
> +		req->flags |= REQ_F_CQE_SKIP;
>   		io_free_req(req);
>   	}
>   	return nxt ? &nxt->work : NULL;
> diff --git a/io_uring/timeout.c b/io_uring/timeout.c
> index 1c9bf07499b1..202f540aa314 100644
> --- a/io_uring/timeout.c
> +++ b/io_uring/timeout.c
> @@ -47,6 +47,9 @@ static inline void io_put_req(struct io_kiocb *req)
>   {
>   	if (req_ref_put_and_test(req)) {
>   		io_queue_next(req);
> +
> +		/* we only want to free it, don't post CQEs */
> +		req->flags |= REQ_F_CQE_SKIP;
>   		io_free_req(req);
>   	}
>   }

-- 
Pavel Begunkov