Re: [PATCH 1/1] io_uring/rw: forbid multishot async reads

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

On 2/17/25 13:37, Pavel Begunkov wrote:
> At the moment we can't sanely handle queuing an async request from a
> multishot context, so disable them. It shouldn't matter as pollable
> files / socekts don't normally do async.

I forgot:

Reported-by: chase xd <sl1589472800@gmail.com>

> 
> Cc: stable@vger.kernel.org
> Fixes: fc68fcda04910 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>   io_uring/rw.c | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/io_uring/rw.c b/io_uring/rw.c
> index 96b42c331267..4bda46c5eb20 100644
> --- a/io_uring/rw.c
> +++ b/io_uring/rw.c
> @@ -878,7 +878,15 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
>   	if (unlikely(ret))
>   		return ret;
>   
> -	ret = io_iter_do_read(rw, &io->iter);
> +	if (unlikely(req->opcode == IORING_OP_READ_MULTISHOT)) {
> +		void *cb_copy = rw->kiocb.ki_complete;
> +
> +		rw->kiocb.ki_complete = NULL;
> +		ret = io_iter_do_read(rw, &io->iter);
> +		rw->kiocb.ki_complete = cb_copy;
> +	} else {
> +		ret = io_iter_do_read(rw, &io->iter);
> +	}
>   
>   	/*
>   	 * Some file systems like to return -EOPNOTSUPP for an IOCB_NOWAIT
> @@ -902,7 +910,8 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
>   	} else if (ret == -EIOCBQUEUED) {
>   		return IOU_ISSUE_SKIP_COMPLETE;
>   	} else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
> -		   (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
> +		   (req->flags & REQ_F_NOWAIT) || !need_complete_io(req) ||
> +		   (issue_flags & IO_URING_F_MULTISHOT)) {
>   		/* read all, failed, already did sync or don't want to retry */
>   		goto done;
>   	}

-- 
Pavel Begunkov