Re: [PATCH 6/6] io_uring: enable multishot mode for accept

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

On 9/3/21 12:00 PM, Hao Xu wrote:
> Update io_accept_prep() to enable multishot mode for accept operation.
> 
> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
> ---
>  fs/io_uring.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index eb81d37dce78..34612646ae3c 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -4861,6 +4861,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>  static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  {
>  	struct io_accept *accept = &req->accept;
> +	bool is_multishot;
>  
>  	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
>  		return -EINVAL;
> @@ -4872,14 +4873,23 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	accept->flags = READ_ONCE(sqe->accept_flags);
>  	accept->nofile = rlimit(RLIMIT_NOFILE);
>  
> +	is_multishot = accept->flags & IORING_ACCEPT_MULTISHOT;
> +	if (is_multishot && (req->flags & REQ_F_FORCE_ASYNC))
> +		return -EINVAL;

Why REQ_F_FORCE_ASYNC is not allowed? It doesn't sound like there
should be any problem, would just eventually go looping
poll_wait + tw

> +
>  	accept->file_slot = READ_ONCE(sqe->file_index);
>  	if (accept->file_slot && ((req->open.how.flags & O_CLOEXEC) ||
> -				  (accept->flags & SOCK_CLOEXEC)))
> +				  (accept->flags & SOCK_CLOEXEC) || is_multishot))
>  		return -EINVAL;
> -	if (accept->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
> +	if (accept->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK | IORING_ACCEPT_MULTISHOT))
>  		return -EINVAL;
>  	if (SOCK_NONBLOCK != O_NONBLOCK && (accept->flags & SOCK_NONBLOCK))
>  		accept->flags = (accept->flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
> +	if (is_multishot) {
> +		req->flags |= REQ_F_APOLL_MULTISHOT;
> +		accept->flags &= ~IORING_ACCEPT_MULTISHOT;
> +	}
> +
>  	return 0;
>  }
>  
> 

-- 
Pavel Begunkov