ethtool: add LINKINFO_NTF notification

Send ETHTOOL_MSG_LINKINFO_NTF notification message whenever device link
settings are modified using ETHTOOL_MSG_LINKINFO_SET netlink message or
ETHTOOL_SLINKSETTINGS or ETHTOOL_SSET ioctl commands.

The notification message has the same format as reply to LINKINFO_GET
request. ETHTOOL_MSG_LINKINFO_SET netlink request only triggers the
notification if there is a change but the ioctl command handlers do not
check if there is an actual change and trigger the notification whenever
the commands are executed.

As all work is done by ethnl_default_notify() handler and callback
functions introduced to handle LINKINFO_GET requests, all that remains is
adding entries for ETHTOOL_MSG_LINKINFO_NTF into ethnl_notify_handlers and
ethnl_default_notify_ops lookup tables and calls to ethtool_notify() where
needed.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ethtool-netlink.rst

@@ -189,6 +189,7 @@ Kernel to userspace:
   ===================================== ================================
   ``ETHTOOL_MSG_STRSET_GET_REPLY``      string set contents
   ``ETHTOOL_MSG_LINKINFO_GET_REPLY``    link settings
+  ``ETHTOOL_MSG_LINKINFO_NTF``          link settings notification
   ===================================== ================================
 
 ``GET`` requests are sent by userspace applications to retrieve device

include/uapi/linux/ethtool_netlink.h

@@ -28,6 +28,7 @@ enum {
 	ETHTOOL_MSG_KERNEL_NONE,
 	ETHTOOL_MSG_STRSET_GET_REPLY,
 	ETHTOOL_MSG_LINKINFO_GET_REPLY,
+	ETHTOOL_MSG_LINKINFO_NTF,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,

net/ethtool/ioctl.c

@@ -26,6 +26,7 @@
 #include <net/devlink.h>
 #include <net/xdp_sock.h>
 #include <net/flow_offload.h>
+#include <linux/ethtool_netlink.h>
 
 #include "common.h"
 
@@ -571,7 +572,10 @@ static int ethtool_set_link_ksettings(struct net_device *dev,
 	    != link_ksettings.base.link_mode_masks_nwords)
 		return -EINVAL;
 
-	return dev->ethtool_ops->set_link_ksettings(dev, &link_ksettings);
+	err = dev->ethtool_ops->set_link_ksettings(dev, &link_ksettings);
+	if (err >= 0)
+		ethtool_notify(dev, ETHTOOL_MSG_LINKINFO_NTF, NULL);
+	return err;
 }
 
 /* Query device for its ethtool_cmd settings.
@@ -620,6 +624,7 @@ static int ethtool_set_settings(struct net_device *dev, void __user *useraddr)
 {
 	struct ethtool_link_ksettings link_ksettings;
 	struct ethtool_cmd cmd;
+	int ret;
 
 	ASSERT_RTNL();
 
@@ -632,7 +637,10 @@ static int ethtool_set_settings(struct net_device *dev, void __user *useraddr)
 		return -EINVAL;
 	link_ksettings.base.link_mode_masks_nwords =
 		__ETHTOOL_LINK_MODE_MASK_NU32;
-	return dev->ethtool_ops->set_link_ksettings(dev, &link_ksettings);
+	ret = dev->ethtool_ops->set_link_ksettings(dev, &link_ksettings);
+	if (ret >= 0)
+		ethtool_notify(dev, ETHTOOL_MSG_LINKINFO_NTF, NULL);
+	return ret;
 }
 
 static noinline_for_stack int ethtool_get_drvinfo(struct net_device *dev,

net/ethtool/linkinfo.c

@@ -155,6 +155,8 @@ int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info)
 	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_ops_complete(dev);

net/ethtool/netlink.c

@@ -509,6 +509,7 @@ static int ethnl_default_done(struct netlink_callback *cb)
 
 static const struct ethnl_request_ops *
 ethnl_default_notify_ops[ETHTOOL_MSG_KERNEL_MAX + 1] = {
+	[ETHTOOL_MSG_LINKINFO_NTF]	= &ethnl_linkinfo_request_ops,
 };
 
 /* default notification handler */
@@ -589,6 +590,7 @@ 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_default_notify,
 };
 
 void ethtool_notify(struct net_device *dev, unsigned int cmd, const void *data)