netdev - Re: [PATCH net-next] selftests: devmem: configure HDS threshold

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Message-ID: <CAHS8izN9CWwwUk0tfDy1iGrfwYLTD9paiF622jP4z4mgD844uw@mail.gmail.com>
Date: Mon, 30 Jun 2025 09:11:53 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Taehee Yoo <ap420073@...il.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, 
	edumazet@...gle.com, andrew+netdev@...n.ch, shuah@...nel.org, sdf@...ichev.me, 
	jdamato@...tly.com, netdev@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next] selftests: devmem: configure HDS threshold

On Mon, Jun 30, 2025 at 2:28 AM Taehee Yoo <ap420073@...il.com> wrote:
>
> The devmem TCP requires the hds-thresh value to be 0, but it doesn't
> change it automatically.
> Therefore, configure_hds_thresh() is added to handle this.
>
> The run_devmem_tests() now tests hds_thresh, but it skips test if the
> hds_thresh_max value is 0.
>
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
>  .../selftests/drivers/net/hw/ncdevmem.c       | 86 +++++++++++++++++++
>  1 file changed, 86 insertions(+)
>
> diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> index cc9b40d9c5d5..d78b5e5697d7 100644
> --- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> +++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> @@ -349,6 +349,72 @@ static int configure_headersplit(bool on)
>         return ret;
>  }
>
> +static int configure_hds_thresh(int len)
> +{
> +       struct ethtool_rings_get_req *get_req;
> +       struct ethtool_rings_get_rsp *get_rsp;
> +       struct ethtool_rings_set_req *req;
> +       struct ynl_error yerr;
> +       struct ynl_sock *ys;
> +       int ret;
> +
> +       ys = ynl_sock_create(&ynl_ethtool_family, &yerr);
> +       if (!ys) {
> +               fprintf(stderr, "YNL: %s\n", yerr.msg);
> +               return -1;
> +       }
> +
> +       req = ethtool_rings_set_req_alloc();
> +       ethtool_rings_set_req_set_header_dev_index(req, ifindex);
> +       ethtool_rings_set_req_set_hds_thresh(req, len);
> +       ret = ethtool_rings_set(ys, req);
> +       if (ret < 0)
> +               fprintf(stderr, "YNL failed: %s\n", ys->err.msg);
> +       ethtool_rings_set_req_free(req);
> +
> +       if (ret == 0) {
> +               get_req = ethtool_rings_get_req_alloc();
> +               ethtool_rings_get_req_set_header_dev_index(get_req, ifindex);
> +               get_rsp = ethtool_rings_get(ys, get_req);
> +               ethtool_rings_get_req_free(get_req);
> +               if (get_rsp)
> +                       fprintf(stderr, "HDS threshold: %d\n",
> +                               get_rsp->hds_thresh);
> +               ethtool_rings_get_rsp_free(get_rsp);
> +       }
> +
> +       ynl_sock_destroy(ys);
> +
> +       return ret;
> +}
> +
> +static int get_hds_thresh_max(void)
> +{
> +       struct ethtool_rings_get_req *get_req;
> +       struct ethtool_rings_get_rsp *get_rsp;
> +       struct ynl_error yerr;
> +       unsigned int ret = 0;
> +       struct ynl_sock *ys;
> +
> +       ys = ynl_sock_create(&ynl_ethtool_family, &yerr);
> +       if (!ys) {
> +               fprintf(stderr, "YNL: %s\n", yerr.msg);
> +               return -1;
> +       }
> +
> +       get_req = ethtool_rings_get_req_alloc();
> +       ethtool_rings_get_req_set_header_dev_index(get_req, ifindex);
> +       get_rsp = ethtool_rings_get(ys, get_req);
> +       ethtool_rings_get_req_free(get_req);
> +       if (get_rsp)
> +               ret = get_rsp->hds_thresh_max;
> +       ethtool_rings_get_rsp_free(get_rsp);
> +
> +       ynl_sock_destroy(ys);
> +
> +       return ret;
> +}
> +
>  static int configure_rss(void)
>  {
>         return run_command("sudo ethtool -X %s equal %d >&2", ifname, start_queue);
> @@ -565,6 +631,9 @@ static int do_server(struct memory_buffer *mem)
>         if (configure_headersplit(1))
>                 error(1, 0, "Failed to enable TCP header split\n");
>
> +       if (configure_hds_thresh(0))
> +               error(1, 0, "Failed to set HDS threshold\n");
> +

hds_thresh should probably be part of configuring headersplit.

But also, failing to set hds_thresh should not fail the test, to
maintain compatibility with drivers that don't support configuring
hds_thresh.