[PATCH net-next v8 14/14] ethtool: provide link state with LINKSTATE_GET request

From: Michal Kubecek
Date: Sun Dec 22 2019 - 18:46:31 EST

Implement LINKSTATE_GET netlink request to get link state information.

At the moment, only link up flag as provided by ETHTOOL_GLINK ioctl command
is returned.

LINKSTATE_GET request can be used with NLM_F_DUMP (without device
identification) to request the information for all devices in current
network namespace providing the data.

Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>
---
Documentation/networking/ethtool-netlink.rst | 33 ++++++++-
include/uapi/linux/ethtool_netlink.h | 14 ++++
net/ethtool/Makefile | 3 +-
net/ethtool/common.c | 8 +++
net/ethtool/common.h | 3 +
net/ethtool/ioctl.c | 8 +--
net/ethtool/linkstate.c | 74 ++++++++++++++++++++
net/ethtool/netlink.c | 8 +++
net/ethtool/netlink.h | 1 +
9 files changed, 146 insertions(+), 6 deletions(-)
create mode 100644 net/ethtool/linkstate.c

diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index 03aee9f3c0c5..45ccee940306 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -174,6 +174,7 @@ Userspace to kernel:
``ETHTOOL_MSG_LINKINFO_SET`` set link settings
``ETHTOOL_MSG_LINKMODES_GET`` get link modes info
``ETHTOOL_MSG_LINKMODES_SET`` set link modes info
+ ``ETHTOOL_MSG_LINKSTATE_GET`` get link state
===================================== ================================

Kernel to userspace:
@@ -184,6 +185,7 @@ Kernel to userspace:
``ETHTOOL_MSG_LINKINFO_NTF`` link settings notification
``ETHTOOL_MSG_LINKMODES_GET_REPLY`` link modes info
``ETHTOOL_MSG_LINKMODES_NTF`` link modes notification
+ ``ETHTOOL_MSG_LINKSTATE_GET_REPLY`` link state info
===================================== ================================

``GET`` requests are sent by userspace applications to retrieve device
@@ -382,6 +384,35 @@ is supposed to allow requesting changes without knowing what exactly kernel
supports.


+LINKSTATE_GET
+=============
+
+Requests link state information. At the moment, only link up/down flag (as
+provided by ``ETHTOOL_GLINK`` ioctl command) is provided but some future
+extensions are planned (e.g. link down reason). This request does not have any
+attributes.
+
+Request contents:
+
+ ==================================== ====== ==========================
+ ``ETHTOOL_A_LINKSTATE_HEADER`` nested request header
+ ==================================== ====== ==========================
+
+Kernel response contents:
+
+ ==================================== ====== ==========================
+ ``ETHTOOL_A_LINKSTATE_HEADER`` nested reply header
+ ``ETHTOOL_A_LINKSTATE_LINK`` u8 autonegotiation status
+ ==================================== ====== ==========================
+
+For most NIC drivers, the value of ``ETHTOOL_A_LINKSTATE_LINK`` returns
+carrier flag provided by ``netif_carrier_ok()`` but there are drivers which
+define their own handler.
+
+``LINKSTATE_GET`` allows dump requests (kernel returns reply messages for all
+devices supporting the request).
+
+
Request translation
===================

@@ -403,7 +434,7 @@ have their netlink replacement yet.
``ETHTOOL_GMSGLVL`` n/a
``ETHTOOL_SMSGLVL`` n/a
``ETHTOOL_NWAY_RST`` n/a
- ``ETHTOOL_GLINK`` n/a
+ ``ETHTOOL_GLINK`` ``ETHTOOL_MSG_LINKSTATE_GET``
``ETHTOOL_GEEPROM`` n/a
``ETHTOOL_SEEPROM`` n/a
``ETHTOOL_GCOALESCE`` n/a
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 35948df6d6e3..02f82f42a889 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -19,6 +19,7 @@ enum {
ETHTOOL_MSG_LINKINFO_SET,
ETHTOOL_MSG_LINKMODES_GET,
ETHTOOL_MSG_LINKMODES_SET,
+ ETHTOOL_MSG_LINKSTATE_GET,

/* add new constants above here */
__ETHTOOL_MSG_USER_CNT,
@@ -33,6 +34,7 @@ enum {
ETHTOOL_MSG_LINKINFO_NTF,
ETHTOOL_MSG_LINKMODES_GET_REPLY,
ETHTOOL_MSG_LINKMODES_NTF,
+ ETHTOOL_MSG_LINKSTATE_GET_REPLY,

/* add new constants above here */
__ETHTOOL_MSG_KERNEL_CNT,
@@ -181,6 +183,18 @@ enum {
ETHTOOL_A_LINKMODES_MAX = __ETHTOOL_A_LINKMODES_CNT - 1
};

+/* LINKSTATE */
+
+enum {
+ ETHTOOL_A_LINKSTATE_UNSPEC,
+ ETHTOOL_A_LINKSTATE_HEADER, /* nest - _A_HEADER_* */
+ ETHTOOL_A_LINKSTATE_LINK, /* u8 */
+
+ /* add new constants above here */
+ __ETHTOOL_A_LINKSTATE_CNT,
+ ETHTOOL_A_LINKSTATE_MAX = __ETHTOOL_A_LINKSTATE_CNT - 1
+};
+
/* generic netlink info */
#define ETHTOOL_GENL_NAME "ethtool"
#define ETHTOOL_GENL_VERSION 1
diff --git a/net/ethtool/Makefile b/net/ethtool/Makefile
index 8023da6672ce..9a1332fb0cc6 100644
--- a/net/ethtool/Makefile
+++ b/net/ethtool/Makefile
@@ -4,4 +4,5 @@ obj-y += ioctl.o common.o

obj-$(CONFIG_ETHTOOL_NETLINK) += ethtool_nl.o

-ethtool_nl-y := netlink.o bitset.o strset.o linkinfo.o linkmodes.o
+ethtool_nl-y := netlink.o bitset.o strset.o linkinfo.o linkmodes.o \
+ linkstate.o
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 1d4a0aeff2cb..e621b1694d2f 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -217,3 +217,11 @@ convert_legacy_settings_to_link_ksettings(
= legacy_settings->eth_tp_mdix_ctrl;
return retval;
}
+
+int __ethtool_get_link(struct net_device *dev)
+{
+ if (!dev->ethtool_ops->get_link)
+ return -EOPNOTSUPP;
+
+ return netif_running(dev) && dev->ethtool_ops->get_link(dev);
+}
diff --git a/net/ethtool/common.h b/net/ethtool/common.h
index c8a237402729..5c5f7dc90cd4 100644
--- a/net/ethtool/common.h
+++ b/net/ethtool/common.h
@@ -3,6 +3,7 @@
#ifndef _ETHTOOL_COMMON_H
#define _ETHTOOL_COMMON_H

+#include <linux/netdevice.h>
#include <linux/ethtool.h>

/* compose link mode index from speed, type and duplex */
@@ -19,6 +20,8 @@ extern const char
phy_tunable_strings[__ETHTOOL_PHY_TUNABLE_COUNT][ETH_GSTRING_LEN];
extern const char link_mode_names[][ETH_GSTRING_LEN];

+int __ethtool_get_link(struct net_device *dev);
+
bool convert_legacy_settings_to_link_ksettings(
struct ethtool_link_ksettings *link_ksettings,
const struct ethtool_cmd *legacy_settings);
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 65aaa7db17d5..b11037bb245d 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1365,12 +1365,12 @@ static int ethtool_nway_reset(struct net_device *dev)
static int ethtool_get_link(struct net_device *dev, char __user *useraddr)
{
struct ethtool_value edata = { .cmd = ETHTOOL_GLINK };
+ int link = __ethtool_get_link(dev);

- if (!dev->ethtool_ops->get_link)
- return -EOPNOTSUPP;
-
- edata.data = netif_running(dev) && dev->ethtool_ops->get_link(dev);
+ if (link < 0)
+ return link;

+ edata.data = link;
if (copy_to_user(useraddr, &edata, sizeof(edata)))
return -EFAULT;
return 0;
diff --git a/net/ethtool/linkstate.c b/net/ethtool/linkstate.c
new file mode 100644
index 000000000000..2740cde0a182
--- /dev/null
+++ b/net/ethtool/linkstate.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "netlink.h"
+#include "common.h"
+
+struct linkstate_req_info {
+ struct ethnl_req_info base;
+};
+
+struct linkstate_reply_data {
+ struct ethnl_reply_data base;
+ int link;
+};
+
+#define LINKSTATE_REPDATA(__reply_base) \
+ container_of(__reply_base, struct linkstate_reply_data, base)
+
+static const struct nla_policy
+linkstate_get_policy[ETHTOOL_A_LINKSTATE_MAX + 1] = {
+ [ETHTOOL_A_LINKSTATE_UNSPEC] = { .type = NLA_REJECT },
+ [ETHTOOL_A_LINKSTATE_HEADER] = { .type = NLA_NESTED },
+ [ETHTOOL_A_LINKSTATE_LINK] = { .type = NLA_REJECT },
+};
+
+static int linkstate_prepare_data(const struct ethnl_req_info *req_base,
+ struct ethnl_reply_data *reply_base,
+ struct genl_info *info)
+{
+ struct linkstate_reply_data *data = LINKSTATE_REPDATA(reply_base);
+ struct net_device *dev = reply_base->dev;
+ int ret;
+
+ ret = ethnl_ops_begin(dev);
+ if (ret < 0)
+ return ret;
+ data->link = __ethtool_get_link(dev);
+ ethnl_ops_complete(dev);
+
+ return 0;
+}
+
+static int linkstate_reply_size(const struct ethnl_req_info *req_base,
+ const struct ethnl_reply_data *reply_base)
+{
+ return nla_total_size(sizeof(u8)) /* LINKSTATE_LINK */
+ + 0;
+}
+
+static int linkstate_fill_reply(struct sk_buff *skb,
+ const struct ethnl_req_info *req_base,
+ const struct ethnl_reply_data *reply_base)
+{
+ struct linkstate_reply_data *data = LINKSTATE_REPDATA(reply_base);
+
+ if (data->link >= 0 &&
+ nla_put_u8(skb, ETHTOOL_A_LINKSTATE_LINK, !!data->link))
+ return -EMSGSIZE;
+
+ return 0;
+}
+
+const struct ethnl_request_ops ethnl_linkstate_request_ops = {
+ .request_cmd = ETHTOOL_MSG_LINKSTATE_GET,
+ .reply_cmd = ETHTOOL_MSG_LINKSTATE_GET_REPLY,
+ .hdr_attr = ETHTOOL_A_LINKSTATE_HEADER,
+ .max_attr = ETHTOOL_A_LINKSTATE_MAX,
+ .req_info_size = sizeof(struct linkstate_req_info),
+ .reply_data_size = sizeof(struct linkstate_reply_data),
+ .request_policy = linkstate_get_policy,
+
+ .prepare_data = linkstate_prepare_data,
+ .reply_size = linkstate_reply_size,
+ .fill_reply = linkstate_fill_reply,
+};
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 1b5e1bd26504..4ca96c7b86b3 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -210,6 +210,7 @@ ethnl_default_requests[__ETHTOOL_MSG_USER_CNT] = {
[ETHTOOL_MSG_STRSET_GET] = &ethnl_strset_request_ops,
[ETHTOOL_MSG_LINKINFO_GET] = &ethnl_linkinfo_request_ops,
[ETHTOOL_MSG_LINKMODES_GET] = &ethnl_linkmodes_request_ops,
+ [ETHTOOL_MSG_LINKSTATE_GET] = &ethnl_linkstate_request_ops,
};

static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
@@ -645,6 +646,13 @@ static const struct genl_ops ethtool_genl_ops[] = {
.flags = GENL_UNS_ADMIN_PERM,
.doit = ethnl_set_linkmodes,
},
+ {
+ .cmd = ETHTOOL_MSG_LINKSTATE_GET,
+ .doit = ethnl_default_doit,
+ .start = ethnl_default_start,
+ .dumpit = ethnl_default_dumpit,
+ .done = ethnl_default_done,
+ },
};

static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index c9faf983b54d..6b9bed30ee47 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -333,6 +333,7 @@ struct ethnl_request_ops {
extern const struct ethnl_request_ops ethnl_strset_request_ops;
extern const struct ethnl_request_ops ethnl_linkinfo_request_ops;
extern const struct ethnl_request_ops ethnl_linkmodes_request_ops;
+extern const struct ethnl_request_ops ethnl_linkstate_request_ops;

int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);
int ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info);
--
2.24.1