Re: [PATCH net-next 1/5] net/ethtool: add netlink interface for the PLCA RS

[Leon Romanovsky <leon@kernel.org>]

On Wed, Jan 04, 2023 at 03:05:44PM +0100, Piergiorgio Beruto wrote:
> Add support for configuring the PLCA Reconciliation Sublayer on
> multi-drop PHYs that support IEEE802.3cg-2019 Clause 148 (e.g.,
> 10BASE-T1S). This patch adds the appropriate netlink interface
> to ethtool.
> 
> Signed-off-by: Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
> ---
>  Documentation/networking/ethtool-netlink.rst | 138 ++++++++++
>  MAINTAINERS                                  |   6 +
>  include/linux/ethtool.h                      |  12 +
>  include/linux/phy.h                          |  57 ++++
>  include/uapi/linux/ethtool_netlink.h         |  25 ++
>  net/ethtool/Makefile                         |   2 +-
>  net/ethtool/netlink.c                        |  29 ++
>  net/ethtool/netlink.h                        |   6 +
>  net/ethtool/plca.c                           | 276 +++++++++++++++++++
>  9 files changed, 550 insertions(+), 1 deletion(-)
>  create mode 100644 net/ethtool/plca.c

<...>

> --- /dev/null
> +++ b/net/ethtool/plca.c
> @@ -0,0 +1,276 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/phy.h>
> +#include <linux/ethtool_netlink.h>
> +
> +#include "netlink.h"
> +#include "common.h"
> +
> +struct plca_req_info {
> +	struct ethnl_req_info		base;
> +};
> +
> +struct plca_reply_data {
> +	struct ethnl_reply_data		base;
> +	struct phy_plca_cfg		plca_cfg;
> +	struct phy_plca_status		plca_st;
> +};
> +
> +// Helpers ------------------------------------------------------------------ //
> +
> +#define PLCA_REPDATA(__reply_base) \
> +	container_of(__reply_base, struct plca_reply_data, base)
> +
> +static inline void plca_update_sint(int *dst, const struct nlattr *attr,
> +				    bool *mod)

No inline function in *.c files.

> +{
> +	if (attr) {
> +		*dst = nla_get_u32(attr);
> +		*mod = true;
> +	}

Success oriented approach, please
if (!attr)
  return;

> +}
> +
> +// PLCA get configuration message ------------------------------------------- //
> +
> +const struct nla_policy ethnl_plca_get_cfg_policy[] = {
> +	[ETHTOOL_A_PLCA_HEADER]		=
> +		NLA_POLICY_NESTED(ethnl_header_policy),
> +};
> +
> +static int plca_get_cfg_prepare_data(const struct ethnl_req_info *req_base,
> +				     struct ethnl_reply_data *reply_base,
> +				     struct genl_info *info)
> +{
> +	struct plca_reply_data *data = PLCA_REPDATA(reply_base);
> +	struct net_device *dev = reply_base->dev;
> +	const struct ethtool_phy_ops *ops;
> +	int ret;
> +
> +	// check that the PHY device is available and connected
> +	if (!dev->phydev) {
> +		ret = -EOPNOTSUPP;
> +		goto out;
> +	}
> +
> +	// note: rtnl_lock is held already by ethnl_default_doit
> +	ops = ethtool_phy_ops;
> +	if (!ops || !ops->get_plca_cfg) {
> +		ret = -EOPNOTSUPP;
> +		goto out;
> +	}
> +
> +	ret = ethnl_ops_begin(dev);
> +	if (ret < 0)
> +		goto out;

I see that many places in the code used this ret > 0 check, but it looks
like the right check is if (ret).

Thanks