Date:   Wed,  9 Oct 2019 22:59:40 +0200 (CEST)
From:   Michal Kubecek <mkubecek@...e.cz>
To:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jiri Pirko <jiri@...nulli.us>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        John Linville <linville@...driver.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Johannes Berg <johannes@...solutions.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next v7 13/17] ethtool: add standard notification handler

The ethtool netlink notifications have the same format as related GET
replies so that if generic GET handling framework is used to process GET
requests, its callbacks and instance of struct get_request_ops can be
also used to compose corresponding notification message.

Provide function ethnl_std_notify() to be used as notification handler in
ethnl_notify_handlers table.

Signed-off-by: Michal Kubecek <mkubecek@...e.cz>
---
 net/ethtool/netlink.c | 89 +++++++++++++++++++++++++++++++++++++++++++
 net/ethtool/netlink.h |  3 +-
 2 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 47b6aefa0bf9..dc52d912e0dd 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -7,6 +7,7 @@
 static struct genl_family ethtool_genl_family;
 
 static bool ethnl_ok __read_mostly;
+static u32 ethnl_bcast_seq;
 
 #define __LINK_MODE_NAME(speed, type, duplex) \
 	#speed "base" #type "/" #duplex
@@ -257,6 +258,18 @@ struct sk_buff *ethnl_reply_init(size_t payload, struct net_device *dev, u8 cmd,
 	return NULL;
 }
 
+static void *ethnl_bcastmsg_put(struct sk_buff *skb, u8 cmd)
+{
+	return genlmsg_put(skb, 0, ++ethnl_bcast_seq, &ethtool_genl_family, 0,
+			   cmd);
+}
+
+static int ethnl_multicast(struct sk_buff *skb, struct net_device *dev)
+{
+	return genlmsg_multicast_netns(&ethtool_genl_family, dev_net(dev), skb,
+				       0, ETHNL_MCGRP_MONITOR, GFP_KERNEL);
+}
+
 /* GET request helpers */
 
 /**
@@ -588,6 +601,82 @@ static int ethnl_get_done(struct netlink_callback *cb)
 	return 0;
 }
 
+static const struct get_request_ops *ethnl_std_notify_to_ops(unsigned int cmd)
+{
+	WARN_ONCE(1, "unexpected notification type %u\n", cmd);
+	return NULL;
+}
+
+/* generic notification handler */
+static void ethnl_std_notify(struct net_device *dev, unsigned int cmd,
+			     const void *data)
+{
+	struct ethnl_reply_data *reply_data;
+	const struct get_request_ops *ops;
+	struct ethnl_req_info *req_info;
+	struct sk_buff *skb;
+	void *reply_payload;
+	int reply_len;
+	int ret;
+
+	ops = ethnl_std_notify_to_ops(cmd);
+	if (!ops)
+		return;
+	req_info = kzalloc(ops->req_info_size, GFP_KERNEL);
+	if (!req_info)
+		return;
+	reply_data = kmalloc(ops->reply_data_size, GFP_KERNEL);
+	if (!reply_data) {
+		kfree(req_info);
+		return;
+	}
+
+	req_info->dev = dev;
+	req_info->global_flags |= ETHTOOL_GFLAG_COMPACT_BITSETS;
+
+	ethnl_init_reply_data(reply_data, ops, dev);
+	ret = ops->prepare_data(req_info, reply_data, NULL);
+	if (ret < 0)
+		goto err_cleanup;
+	reply_len = ops->reply_size(req_info, reply_data);
+	if (ret < 0)
+		goto err_cleanup;
+	ret = -ENOMEM;
+	skb = genlmsg_new(reply_len, GFP_KERNEL);
+	if (!skb)
+		goto err_cleanup;
+	reply_payload = ethnl_bcastmsg_put(skb, cmd);
+	if (!reply_payload)
+		goto err_skb;
+	ret = ethnl_fill_reply_header(skb, dev, ops->hdr_attr);
+	if (ret < 0)
+		goto err_msg;
+	ret = ops->fill_reply(skb, req_info, reply_data);
+	if (ret < 0)
+		goto err_msg;
+	if (ops->cleanup_data)
+		ops->cleanup_data(reply_data);
+
+	genlmsg_end(skb, reply_payload);
+	kfree(reply_data);
+	kfree(req_info);
+	ethnl_multicast(skb, dev);
+	return;
+
+err_msg:
+	WARN_ONCE(ret == -EMSGSIZE,
+		  "calculated message payload length (%d) not sufficient\n",
+		  reply_len);
+err_skb:
+	nlmsg_free(skb);
+err_cleanup:
+	if (ops->cleanup_data)
+		ops->cleanup_data(reply_data);
+	kfree(reply_data);
+	kfree(req_info);
+	return;
+}
+
 /* notifications */
 
 typedef void (*ethnl_notify_handler_t)(struct net_device *dev, unsigned int cmd,
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index a0ae47bebe51..23e82a4dd265 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -316,7 +316,8 @@ static inline void ethnl_after_ops(struct net_device *dev)
  * infrastructure. When used, a pointer to an instance of this structure is to
  * be added to &get_requests array and generic handlers ethnl_get_doit(),
  * ethnl_get_dumpit(), ethnl_get_start() and ethnl_get_done() used in
- * @ethnl_genl_ops
+ * @ethnl_genl_ops; ethnl_std_notify() can be used in @ethnl_notify_handlers
+ * to send notifications of the corresponding type.
  */
 struct get_request_ops {
 	u8			request_cmd;
-- 
2.23.0

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