ethtool: add CHANNELS_NTF notification

Send ETHTOOL_MSG_CHANNELS_NTF notification whenever channel counts of
a network device are modified using ETHTOOL_MSG_CHANNELS_SET netlink
message or ETHTOOL_SCHANNELS ioctl request.
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/ethtool-netlink.rst

@@ -220,6 +220,7 @@ Kernel to userspace:
   ``ETHTOOL_MSG_RINGS_GET_REPLY``       ring sizes
   ``ETHTOOL_MSG_RINGS_NTF``             ring sizes
   ``ETHTOOL_MSG_CHANNELS_GET_REPLY``    channel counts
+  ``ETHTOOL_MSG_CHANNELS_NTF``          channel counts
   ===================================== =================================
 
 ``GET`` requests are sent by userspace applications to retrieve device

include/uapi/linux/ethtool_netlink.h

@@ -59,6 +59,7 @@ enum {
 	ETHTOOL_MSG_RINGS_GET_REPLY,
 	ETHTOOL_MSG_RINGS_NTF,
 	ETHTOOL_MSG_CHANNELS_GET_REPLY,
+	ETHTOOL_MSG_CHANNELS_NTF,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,

net/ethtool/channels.c

@@ -213,6 +213,9 @@ int ethnl_set_channels(struct sk_buff *skb, struct genl_info *info)
 		}
 
 	ret = dev->ethtool_ops->set_channels(dev, &channels);
+	if (ret < 0)
+		goto out_ops;
+	ethtool_notify(dev, ETHTOOL_MSG_CHANNELS_NTF, NULL);
 
 out_ops:
 	ethnl_ops_complete(dev);

net/ethtool/ioctl.c

@@ -1649,6 +1649,7 @@ static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
 	u16 from_channel, to_channel;
 	u32 max_rx_in_use = 0;
 	unsigned int i;
+	int ret;
 
 	if (!dev->ethtool_ops->set_channels || !dev->ethtool_ops->get_channels)
 		return -EOPNOTSUPP;
@@ -1680,7 +1681,10 @@ static noinline_for_stack int ethtool_set_channels(struct net_device *dev,
 		if (xdp_get_umem_from_qid(dev, i))
 			return -EINVAL;
 
-	return dev->ethtool_ops->set_channels(dev, &channels);
+	ret = dev->ethtool_ops->set_channels(dev, &channels);
+	if (!ret)
+		ethtool_notify(dev, ETHTOOL_MSG_CHANNELS_NTF, NULL);
+	return ret;
 }
 
 static int ethtool_get_pauseparam(struct net_device *dev, void __user *useraddr)

net/ethtool/netlink.c

@@ -534,6 +534,7 @@ ethnl_default_notify_ops[ETHTOOL_MSG_KERNEL_MAX + 1] = {
 	[ETHTOOL_MSG_FEATURES_NTF]	= &ethnl_features_request_ops,
 	[ETHTOOL_MSG_PRIVFLAGS_NTF]	= &ethnl_privflags_request_ops,
 	[ETHTOOL_MSG_RINGS_NTF]		= &ethnl_rings_request_ops,
+	[ETHTOOL_MSG_CHANNELS_NTF]	= &ethnl_channels_request_ops,
 };
 
 /* default notification handler */
@@ -622,6 +623,7 @@ static const ethnl_notify_handler_t ethnl_notify_handlers[] = {
 	[ETHTOOL_MSG_FEATURES_NTF]	= ethnl_default_notify,
 	[ETHTOOL_MSG_PRIVFLAGS_NTF]	= ethnl_default_notify,
 	[ETHTOOL_MSG_RINGS_NTF]		= ethnl_default_notify,
+	[ETHTOOL_MSG_CHANNELS_NTF]	= ethnl_default_notify,
 };
 
 void ethtool_notify(struct net_device *dev, unsigned int cmd, const void *data)