Re: [PATCH] io_uring/net: fix a multishot termination case for recv

[Jens Axboe <axboe@kernel.dk>]

On 9/28/24 6:18 AM, Jens Axboe wrote:
> diff --git a/io_uring/net.c b/io_uring/net.c
> index f10f5a22d66a..18507658a921 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -1133,6 +1133,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>  	int ret, min_ret = 0;
>  	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
>  	size_t len = sr->len;
> +	bool mshot_finished;
>  
>  	if (!(req->flags & REQ_F_POLLED) &&
>  	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
> @@ -1187,6 +1188,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>  		req_set_fail(req);
>  	}
>  
> +	mshot_finished = ret <= 0;
>  	if (ret > 0)
>  		ret += sr->done_io;
>  	else if (sr->done_io)
> @@ -1194,7 +1196,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>  	else
>  		io_kbuf_recycle(req, issue_flags);
>  
> -	if (!io_recv_finish(req, &ret, kmsg, ret <= 0, issue_flags))
> +	if (!io_recv_finish(req, &ret, kmsg, mshot_finished, issue_flags))
>  		goto retry_multishot;
>  
>  	return ret;

On second thought, I don't think we can get into this situation -
sr->done_io is only ever used for recv if we had to retry after getting
some data. And that only happens if MSG_WAITALL is set, which is not
legal for multishot and will result in -EINVAL. So don't quite see how
we can run into this issue. But I could be missing something...

Comments?

-- 
Jens Axboe