linux-kernel - Re: [PATCH liburing] Test wait after under-consuming

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Date:   Fri, 13 Dec 2019 11:41:35 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH liburing] Test wait after under-consuming

On 12/13/2019 11:06 AM, Pavel Begunkov wrote:
> In case of an error submission won't consume all sqes. This tests that
> it will get back to the userspace even if (to_submit == to_wait)
> 
> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
> ---
>  test/link.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 55 insertions(+), 1 deletion(-)
> 
> diff --git a/test/link.c b/test/link.c
> index 8ec1649..93653f3 100644
> --- a/test/link.c
> +++ b/test/link.c
> @@ -384,6 +384,55 @@ err:
>  	return 1;
>  }
>  
> +static int test_early_fail_and_wait(struct io_uring *ring)
> +{
> +	struct io_uring_cqe *cqe;
> +	struct io_uring_sqe *sqe;
> +	int ret, submitted, i;
> +	const int invalid_fd = 42;
> +	struct iovec iov = { .iov_base = NULL, .iov_len = 0 };
> +
> +	sqe = io_uring_get_sqe(ring);
> +	if (!sqe) {
> +		printf("get sqe failed\n");
> +		goto err;
> +	}
> +
> +	io_uring_prep_readv(sqe, invalid_fd, &iov, 1, 0);
> +	sqe->user_data = 1;
> +	sqe->flags |= IOSQE_IO_LINK;
> +
> +	sqe = io_uring_get_sqe(ring);
> +	if (!sqe) {
> +		printf("get sqe failed\n");
> +		goto err;
> +	}
> +
> +	io_uring_prep_nop(sqe);
> +	sqe->user_data = 2;
> +
> +	submitted = io_uring_submit_and_wait(ring, 2);
> +	if (submitted == -EAGAIN)
> +		return 0;

As io_uring isn't recreated for each test case, I need to complete all
cqes in any case. I'll resend

> +	if (submitted <= 0) {
> +		printf("sqe submit failed: %d\n", submitted);
> +		goto err;
> +	}
> +
> +	for (i = 0; i < 2; i++) {
> +		ret = io_uring_wait_cqe(ring, &cqe);
> +		if (ret < 0) {
> +			printf("wait completion %d\n", ret);
> +			goto err;
> +		}
> +		io_uring_cqe_seen(ring, cqe);
> +	}
> +
> +	return 0;
> +err:
> +	return 1;
> +}
> +
>  int main(int argc, char *argv[])
>  {
>  	struct io_uring ring, poll_ring;
> @@ -400,7 +449,6 @@ int main(int argc, char *argv[])
>  	if (ret) {
>  		printf("poll_ring setup failed\n");
>  		return 1;
> -
>  	}
>  
>  	ret = test_single_link(&ring);
> @@ -439,5 +487,11 @@ int main(int argc, char *argv[])
>  		return ret;
>  	}
>  
> +	ret = test_early_fail_and_wait(&ring);
> +	if (ret) {
> +		fprintf(stderr, "test_early_fail_and_wait\n");
> +		return ret;
> +	}
> +
>  	return 0;
>  }
> 

-- 
Pavel Begunkov