Subject: Re: [PATCH net-next v7 14/17] ethtool: set link settings with LINKINFO_SET request

From: Jiri Pirko <[email-masked]>
Date: Thu, 10 Oct 2019 17:37:54 +0200

Wed, Oct 09, 2019 at 10:59:43PM CEST, [email-masked] wrote:
>Implement LINKINFO_SET netlink request to set link settings queried by
>LINKINFO_GET message.
>
>Only physical port, phy MDIO address and MDI(-X) control can be set,
>attempt to modify MDI(-X) status and transceiver is rejected.
>
>When any data is modified, ETHTOOL_MSG_LINKINFO_NTF message in the same
>format as reply to LINKINFO_GET request is sent to notify userspace about
>the changes. The same notification is also sent when these settings are
>modified using the ioctl interface.
>

It is a bit confusing and harder to follow when you have set and notify
code in the same patch. Could you please split?

[...]

>+/* LINKINFO_SET */
>+
>+static const struct nla_policy linkinfo_hdr_policy[ETHTOOL_A_HEADER_MAX + 1] = {
>+	[ETHTOOL_A_HEADER_UNSPEC]		= { .type = NLA_REJECT },
>+	[ETHTOOL_A_HEADER_DEV_INDEX]		= { .type = NLA_U32 },
>+	[ETHTOOL_A_HEADER_DEV_NAME]		= { .type = NLA_NUL_STRING,
>+						    .len = IFNAMSIZ - 1 },
>+	[ETHTOOL_A_HEADER_GFLAGS]		= { .type = NLA_U32 },
>+	[ETHTOOL_A_HEADER_RFLAGS]		= { .type = NLA_REJECT },
>+};

This is what I was talking about in the other email. These common attrs
should have common policy and should be parsed by generic netlink code
by default and be available for ethnl_set_linkinfo() in info->attrs.

>+
>+static const struct nla_policy
>+linkinfo_set_policy[ETHTOOL_A_LINKINFO_MAX + 1] = {
>+	[ETHTOOL_A_LINKINFO_UNSPEC]		= { .type = NLA_REJECT },
>+	[ETHTOOL_A_LINKINFO_HEADER]		= { .type = NLA_NESTED },
>+	[ETHTOOL_A_LINKINFO_PORT]		= { .type = NLA_U8 },
>+	[ETHTOOL_A_LINKINFO_PHYADDR]		= { .type = NLA_U8 },
>+	[ETHTOOL_A_LINKINFO_TP_MDIX]		= { .type = NLA_REJECT },
>+	[ETHTOOL_A_LINKINFO_TP_MDIX_CTRL]	= { .type = NLA_U8 },
>+	[ETHTOOL_A_LINKINFO_TRANSCEIVER]	= { .type = NLA_REJECT },
>+};
>+
>+int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info)
>+{
>+	struct nlattr *tb[ETHTOOL_A_LINKINFO_MAX + 1];
>+	struct ethtool_link_ksettings ksettings = {};
>+	struct ethtool_link_settings *lsettings;
>+	struct ethnl_req_info req_info = {};
>+	struct net_device *dev;
>+	bool mod = false;
>+	int ret;
>+
>+	ret = nlmsg_parse(info->nlhdr, GENL_HDRLEN, tb,
>+			  ETHTOOL_A_LINKINFO_MAX, linkinfo_set_policy,
>+			  info->extack);

Yeah, genl code should do this parse..

>+	if (ret < 0)
>+		return ret;
>+	ret = ethnl_parse_header(&req_info, tb[ETHTOOL_A_LINKINFO_HEADER],
>+				 genl_info_net(info), info->extack,
>+				 linkinfo_hdr_policy, true);

and pre_doit should do this one.

>+	if (ret < 0)
>+		return ret;
>+	dev = req_info.dev;
>+	if (!dev->ethtool_ops->get_link_ksettings ||
>+	    !dev->ethtool_ops->set_link_ksettings)
>+		return -EOPNOTSUPP;
>+
>+	rtnl_lock();
>+	ret = ethnl_before_ops(dev);
>+	if (ret < 0)
>+		goto out_rtnl;
>+
>+	ret = __ethtool_get_link_ksettings(dev, &ksettings);
>+	if (ret < 0) {
>+		if (info)
>+			GENL_SET_ERR_MSG(info, "failed to retrieve link settings");
>+		goto out_ops;
>+	}
>+	lsettings = &ksettings.base;
>+
>+	ethnl_update_u8(&lsettings->port, tb[ETHTOOL_A_LINKINFO_PORT], &mod);
>+	ethnl_update_u8(&lsettings->phy_address, tb[ETHTOOL_A_LINKINFO_PHYADDR],
>+			&mod);
>+	ethnl_update_u8(&lsettings->eth_tp_mdix_ctrl,
>+			tb[ETHTOOL_A_LINKINFO_TP_MDIX_CTRL], &mod);
>+
>+	ret = 0;
>+	if (mod) {

	if (!mod)
		goto out_ops;

?

>+		ret = dev->ethtool_ops->set_link_ksettings(dev, &ksettings);
>+		if (ret < 0)
>+			GENL_SET_ERR_MSG(info, "link settings update failed");
>+		else
>+			ethtool_notify(dev, ETHTOOL_MSG_LINKINFO_NTF, NULL);
>+	}
>+
>+out_ops:
>+	ethnl_after_ops(dev);
>+out_rtnl:
>+	rtnl_unlock();
>+	dev_put(dev);
>+	return ret;
>+}
>diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
>index dc52d912e0dd..5b9d12656e97 100644
>--- a/net/ethtool/netlink.c
>+++ b/net/ethtool/netlink.c
>@@ -603,6 +603,11 @@ static int ethnl_get_done(struct netlink_callback *cb)
> 
> static const struct get_request_ops *ethnl_std_notify_to_ops(unsigned int cmd)
> {
>+	switch (cmd) {
>+	case ETHTOOL_MSG_LINKINFO_NTF:
>+		return &linkinfo_request_ops;
>+	};
>+
> 	WARN_ONCE(1, "unexpected notification type %u\n", cmd);
> 	return NULL;
> }
>@@ -683,6 +688,7 @@ typedef void (*ethnl_notify_handler_t)(struct net_device *dev, unsigned int cmd,
> 				       const void *data);
> 
> static const ethnl_notify_handler_t ethnl_notify_handlers[] = {
>+	[ETHTOOL_MSG_LINKINFO_NTF]	= ethnl_std_notify,

Correct me if I'm wrong, but this is the only notification I found in
this patchset. Do you expect other then ethnl_std_notify() handler?
Bacause otherwise this can ba simplified down to just a single table
similar you have for GET.

> };
> 
> void ethtool_notify(struct net_device *dev, unsigned int cmd, const void *data)
>@@ -717,6 +723,11 @@ static const struct genl_ops ethtool_genl_ops[] = {
> 		.dumpit	= ethnl_get_dumpit,
> 		.done	= ethnl_get_done,
> 	},
>+	{
>+		.cmd	= ETHTOOL_MSG_LINKINFO_SET,
>+		.flags	= GENL_UNS_ADMIN_PERM,
>+		.doit	= ethnl_set_linkinfo,
>+	},
> };
> 
> static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
>diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
>index 23e82a4dd265..ca136dd7ea02 100644
>--- a/net/ethtool/netlink.h
>+++ b/net/ethtool/netlink.h
>@@ -350,4 +350,6 @@ struct get_request_ops {
> extern const struct get_request_ops strset_request_ops;
> extern const struct get_request_ops linkinfo_request_ops;
> 
>+int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);
>+
> #endif /* _NET_ETHTOOL_NETLINK_H */
>-- 
>2.23.0
>