Re: [PATCH] io_uring: avoid iowq again trap

[Hao Xu <haoxu.linux@icloud.com>]

On 5/13/22 18:24, Pavel Begunkov wrote:
> If an opcode handler semi-reliably returns -EAGAIN, io_wq_submit_work()

Hi Pavel,
When would it return -EAGAIN in non-IOPOLL mode?

> might continue busily hammer the same handler over and over again, which
> is not ideal. The -EAGAIN handling in question was put there only for
> IOPOLL, so restrict it to IOPOLL mode only.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>   fs/io_uring.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index e01f595f5b7d..3af1905efc78 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -7319,6 +7319,8 @@ static void io_wq_submit_work(struct io_wq_work *work)
>   		 * wait for request slots on the block side.
>   		 */
>   		if (!needs_poll) {
> +			if (!(req->ctx->flags & IORING_SETUP_IOPOLL))
> +				break;
>   			cond_resched();
>   			continue;
>   		}