Re: [PATCH 2/3] io_uring/msg_ring: cleanup posting to IOPOLL vs !IOPOLL ring

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

On 3/28/24 18:52, Jens Axboe wrote:
> Move the posting outside the checking and locking, it's cleaner that
> way.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>   io_uring/msg_ring.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
> index cd6dcf634ba3..d1f66a40b4b4 100644
> --- a/io_uring/msg_ring.c
> +++ b/io_uring/msg_ring.c
> @@ -147,13 +147,11 @@ static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
>   	if (target_ctx->flags & IORING_SETUP_IOPOLL) {
>   		if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
>   			return -EAGAIN;
> -		if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
> -			ret = 0;
> -		io_double_unlock_ctx(target_ctx);
> -	} else {
> -		if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
> -			ret = 0;
>   	}

A side note, maybe we should just get rid of double locking, it's always
horrible, and always do the job via tw. With DEFER_TASKRUN it only benefits
when rings and bound to the same task => never for any sane use case, so it's
only about !DEFER_TASKRUN. Simpler but also more predictable for general
latency and so on since you need to wait/grab two locks.


> +	if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
> +		ret = 0;
> +	if (target_ctx->flags & IORING_SETUP_IOPOLL)
> +		io_double_unlock_ctx(target_ctx);
>   	return ret;
>   }
>   

-- 
Pavel Begunkov